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Sample records for breakers resolve trip

  1. IE Information No. 86-62: Potential problems in Westinghouse molded case circuit breakers equipped with a shunt trip

    International Nuclear Information System (INIS)

    On February 6, 1986, an open occurred or was discovered in the shunt trip coil (STC) circuitry which could have resulted in the failure of the associated breaker to trip open on an abnormal voltage condition at the Peach Bottom Reactor. The breaker is identified as an LBB 22250 MW type molded case circuit breaker manufactured by Westinghouse. The breaker is installed in a transfer panel to protect the 120-V 60 Hertz power supply to the reactor protection system (RPS) from undervoltage, overvoltage and under frequency conditions. The STC in series with a contact is activated through a toggle linkage by the breaker's moving main contact arms. The failure of the STC occurred when the contact did not open when the breaker tripped resulting in the overheating of the STC and ultimately in an open circuit in the shunt trip circuit. If the breaker had been subjected to an abnormal voltage condition after reset the open shunt trip circuit would have prevented breaker trip. On January 16 and 24, 1986 the same types of problems were identified in similar breakers at the Peach Bottom Unit 3 plant. On November 9, 1984, Limerick 1 reported an identical failure. It is essential that the STC remain operable to assure the circuit breaker trips in the event of an abnormal voltage condition. Administrative measures have been established to periodically test and verify the operability of the STC at the Peach Bottom and Limerick nuclear power plants

  2. Closeout of IE Bulletin 79-11: faulty overcurrent trip device in circuit breakers for engineered safety systems

    International Nuclear Information System (INIS)

    IE Bulletin 79-11 was issued May 22, 1979 as a result of information received in April 1979 from Westinghouse and an NRC licensee relating to the potential failure of a circuit breaker in an engineered safety system of a nuclear power plant. The defect of concern was a small hairline crack in the dashpot end cap of one of the three overcurrent trip devices of a Type DB-75 breaker. The Bulletin was also applicable to Type DB-50 breakers, because they use the same type of dashpot end cap. The defective end cap had been installed in 1973 as a replacement, in compliance with IE Bulletin 73-1. Westinghouse Technical Bulletin NSD-TB-79-02 was issued April 17, 1979 to alert utilities to the potential problem, to provide background information, to recommend review of calibration test data and retesting of erratic breakers, to advise visual examination of end caps for cracks and to call for replacement of cracked end caps. Evaluation of utility responses and NRC/IE inspection reports shows that 114 of the 129 current facilities do not use the affected breakers in safety-related systems. Followup items for the five facilities with open status are proposed. The Bulletin has been closed out for the remaining ten facilities with safety-related Westinghouse DB-50 and DB-75 breakers having dashpots, on the basis of acceptable utility responses and NRC/IE regional inspection reports

  3. IE Information Notice No. 85-16: Time/current trip curve discrepancy of ITE/Siemens-Allis molded case circuit breaker

    International Nuclear Information System (INIS)

    The staff recently received information from the Seabrook Nuclear Station describing a deficiency of the magnetic instantaneous trip element in the ITE-Siemens-Allis HE-3-M040 molded-case circuit breaker. These circuit breakers were housed in electrical panels supplied by Gould, Inc., Westminister, Maryland. The deficiency was discovered during the testing of an incoming shipment of these breakers. Specifically, the licensee reported that testing of an incoming shipment of 15 of these ITE/Siemens-Allis circuit breakers revealed that 10 of the 15 failed to pass the instantaneous magnetic overcurrent trip test. The pickup current values for the failed trip elements were higher than the published ITE time-current curve for this type of circuit breaker. However, the licensee also reports that approximately 75 of the same model of ITE/Siemens-Allis circuit breakers supplied in previous shipments have rested satisfactorily. Further investigation into the problem by the manufacturer led to the conclusion that the time-current trip range should be 600 to 1,000 amperes and not 400 to 700 amperes as previously published by the manufacturer. The manufacturer is now reissuing a new set of correct time-current curves that reflect the trip range of 600 to 1,000 amperes

  4. IE Information Notice No. 85-64: BBC Brown Boveri low-voltage K-line circuit breakers, with deficient overcurrent trip devices models OD-4 and 5

    International Nuclear Information System (INIS)

    On May 13, 1985, BBC Brown Boveri Inc. (BBC) made a 10 CFR Part 21 report to the NRC concerning a deficiency in the Models OD-4 and OD-5 overcurrent trip devices installed on K-line circuit breakers. The affected breakers were manufactured by BBC from October 1983 to March 1985 and may have incorrect short time delay band levers (links) installed in electromechanical overcurrent trip device models OD-4 and OD-5. The incorrect link could limit the travel of the short time armature and cause the short time element to be inoperative in the maximum (MAX) band. The May 13, 1985, report recommended that all K-line circuit breakers with the OD-4 and OD-5 overcurrent trip devices and any spare OD-4 and OD-5 overcurrent trip devices that were manufactured between October 1983 and March 1985, be inspected for an incorrect short time delay band link. Licensees known by BBC to have purchased K-line breakers or spare OD-4 or OD-5 overcurrent trip devices were notified of the possible defect and instructions provided for their inspection. Enclosed is a list of utilities and related facilities that were notified by BBC. However, BBC advised the NRC that there is a possibility that other utilities could be using K-line circuit breakers with the suspect OD-4 and OD-5 overcurrent trip devices. Therefore, all licensees are being notified of this possible defect

  5. NRC Information Notice No. 93-22: Tripping of Klockner-Moeller molded-case circuit breakers due to support lever failure

    International Nuclear Information System (INIS)

    On July 1, 1992, Virginia Electric and Power Company (VEPCO), licensee for North Anna Power Station (North Anna), Units 1 and 2, reported to the NRC that over a three-month period in 1992, three K-M model NZM6-63, 480-Vac MCCBs had tripped without appreciable load or fault condition or other electrical or mechanical transient. The three failed MCCBs were located in the cable vault and tunnel area of North Anna-2 and supplied power to motor operated valves in the charging and safety injection systems. The switch handles were found in the trip-free position and the breakers could not be relatched and reclosed. Examination of the internals of one of the three failed breakers revealed that its support lever (also described by VEPCO as a ''spring arm''), located in the rear compartment of the case, had fractured. This caused the breaker to trip and to become incapable of being reclosed. The NRC has determined that the support levers only in K-M model NZM6, NZM6b, and NZMH6 MCCBs, rated for 100 amperes and below and manufactured from 1972 on, have been made of the same type of plastic used in the support levers of the MCCBs that failed at North Anna-2

  6. Solid-State dc Circuit Breaker

    Science.gov (United States)

    Harvey, P.

    1983-01-01

    Circuit breaker with no moving parts protects direct-current (dc) loads. Current which circuit breaker opens (trip current) is adjustable and so is time delay before breaker trips. Forward voltage drop rises from 0.6 to 1.2 V as current rises to trip point. Breaker has two terminals, like fuse, therefore replaces fuse in dc circuit. Powered by circuit it protects and reset by either turning off power source or disconnecting load.

  7. Circuit breaker operation and potential failure modes during an earthquake

    International Nuclear Information System (INIS)

    This study addresses the effect of a strong-motion earthquake on circuit breaker operation. It focuses on the loss of offsite power (LOSP) transient caused by a strong-motion earthquake at the Zion Nuclear Power Plant. This paper also describes the operator action necessary to prevent core melt if the above circuit breaker failure modes occur simultaneously on three 4.16 KV buses. Numerous circuit breakers important to plant safety, such as circuit breakers to diesel generators and engineered safety systems (ESS), must open and/or close during this transient while strong motion is occurring. Potential seismically-induced circuit-breaker failures modes were uncovered while the study was conducted. These failure modes include: circuit breaker fails to close; circuit breaker trips inadvertently; circuit breaker fails to reclose after trip. The causes of these failure modes include: Relay chatter causes the circuit breaker to trip; Relay chatter causes anti-pumping relays to seal-in which prevents automatic closure of circuit breakers; Load sequencer failures. The incorporation of these failure modes as well as other instrumentation and control failures into a limited scope seismic probabilistic risk assessment is also discussed in this paper

  8. Age-related degradation of Westinghouse 480-volt circuit breakers

    International Nuclear Information System (INIS)

    An aging assessment of Westinghouse DS-series low-voltage air circuit breakers was performed as part of the Nuclear Plant Aging Research (NPAR) program. The objectives of this study are to characterize age-related degradation within the breaker assembly and to identify maintenance practices to mitigate their effect. Since this study has been promulgated by the failures of the reactor trip breakers at the McGuire Nuclear Station in July 1987, results relating to the welds in the breaker pole lever welds are also discussed. The design and operation of DS-206 and DS-416 breakers were reviewed. Failure data from various national data bases were analyzed to identify the predominant failure modes, causes, and mechanisms. Additional operating experiences from one nuclear station and two industrial breaker-service companies were obtained to develop aging trends of various subcomponents. The responses of the utilities to the NRC Bulletin 88-01, which discusses the center pole lever welds, were analyzed to assess the final resolution of failures of welds in the reactor trips. Maintenance recommendations, made by the manufacturer to mitigate age-related degradation were reviewed, and recommendations for improving the monitoring of age-related degradation are discussed. As described in Volume 2 of this NUREG, the results from a test program to assess degradation in breaker parts through mechanical cycling are also included. The testing has characterized the cracking of center-pole lever welds, identified monitoring techniques to determine aging in breakers, and provided information to augment existing maintenance programs. Recommendations to improve breaker reliability using effective maintenance, testing, and inspection programs are suggested. 13 refs., 21 figs., 8 tabs

  9. Overriding Faulty Circuit Breakers

    Science.gov (United States)

    Robbins, Richard L.; Pierson, Thomas E.

    1987-01-01

    Retainer keeps power on in emergency. Simple mechanical device attaches to failed aircraft-type push/pull circuit breaker to restore electrical power temporarily until breaker replaced. Device holds push/pull button in closed position; unnecessary for crewmember to hold button in position by continual finger pressure. Sleeve and plug hold button in, overriding mechanical failure in circuit breaker. Windows in sleeve show button position.

  10. Automatic recloser circuit breaker integrated with GSM technology for power system notification

    Science.gov (United States)

    Lada, M. Y.; Khiar, M. S. A.; Ghani, S. A.; Nawawi, M. R. M.; Rahim, N. H.; Sinar, L. O. M.

    2015-05-01

    Lightning is one type of transient faults that usually cause the circuit breaker in the distribution board trip due to overload current detection. The instant tripping condition in the circuit breakers clears the fault in the system. Unfortunately most circuit breakers system is manually operated. The power line will be effectively re-energized after the clearing fault process is finished. Auto-reclose circuit is used on the transmission line to carry out the duty of supplying quality electrical power to customers. In this project, an automatic reclose circuit breaker for low voltage usage is designed. The product description is the Auto Reclose Circuit Breaker (ARCB) will trip if the current sensor detects high current which exceeds the rated current for the miniature circuit breaker (MCB) used. Then the fault condition will be cleared automatically and return the power line to normal condition. The Global System for Mobile Communication (GSM) system will send SMS to the person in charge if the tripping occurs. If the over current occurs in three times, the system will fully trip (open circuit) and at the same time will send an SMS to the person in charge. In this project a 1 A is set as the rated current and any current exceeding a 1 A will cause the system to trip or interrupted. This system also provides an additional notification for user such as the emergency light and warning system.

  11. Development of a HVDC prototype breaker. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Damsky, B L; Barkan, P; Imam, I; Permerlani, W; Anderson, J M; Carroll, J J; Hudson, J E; Pohl, R V; Solberg, W D; Sharbaugh, A H

    1980-06-01

    The significant design features of a high-voltage dc (HVDC) circuit breaker based on the commutation concept were developed. Tests of components indicate the breaker is capable of interrupting a fault current of 10 kA on a 400 kV system and absorbing up to 10 MJ of system energy without generating more than 1.6 per unit (P.U.) voltage of the system. Interactions of the breaker with a three-terminal network were studied, using a system simulator. An ultrafast hydraulic actuator system was developed for this program which enables the breaker to initiate the current limiting process within 5 ms after receipt of a trip signal. A new hydraulic valve, operated by a repulsion coil, minimizes the delay before motion begins. Interruption will occur in series-connected vacuum interrupters. A 400 kV circuit breaker is estimated to require eight breaks in series. Only a single break was tested as part of this program because of the scale and cost required for multibreak tests. System energy will be absorbed by zinc-oxide-based surge suppressors included as an integral part of the breaker. The overall design is envisioned as a dead tank type using pressurized SF/sub 6/ gas as a dielectric medium. The actuator and all control functions are located at ground potential, with easy access for inspection or adjustment. Operational specifications have been carried over from NEMA standards for ac power circuit breakers where applicable. The cost of one pole of this circuit breaker, when in regular production, has been estimated as two times the cost of a three-phase 500 kV ac circuit breaker.

  12. High temperature circuit breaker

    Science.gov (United States)

    Edwards, R. N.; Travis, E. F.

    1970-01-01

    Alternating current circuit breaker is suitable for reliable long-term service at 1000 deg F in the vacuum conditions of outer space. Construction materials are resistant to nuclear radiation and vacuum welding. Service test conditions and results are given.

  13. Latching overcurrent circuit breaker

    Science.gov (United States)

    Moore, M. L.

    1970-01-01

    Circuit breaker consists of a preset current amplitude sensor, and a lamp-photo-resistor combination in a feedback arrangement which energizes a power switching relay. The ac input power is removed from the load at predetermined current amplitudes.

  14. AUTOMATED ANALYSIS OF BREAKERS

    Directory of Open Access Journals (Sweden)

    E. M. Farhadzade

    2014-01-01

    Full Text Available Breakers relate to Electric Power Systems’ equipment, the reliability of which influence, to a great extend, on reliability of Power Plants. In particular, the breakers determine structural reliability of switchgear circuit of Power Stations and network substations. Failure in short-circuit switching off by breaker with further failure of reservation unit or system of long-distance protection lead quite often to system emergency.The problem of breakers’ reliability improvement and the reduction of maintenance expenses is becoming ever more urgent in conditions of systematic increasing of maintenance cost and repair expenses of oil circuit and air-break circuit breakers. The main direction of this problem solution is the improvement of diagnostic control methods and organization of on-condition maintenance. But this demands to use a great amount of statistic information about nameplate data of breakers and their operating conditions, about their failures, testing and repairing, advanced developments (software of computer technologies and specific automated information system (AIS.The new AIS with AISV logo was developed at the department: “Reliability of power equipment” of AzRDSI of Energy. The main features of AISV are:· to provide the security and data base accuracy;· to carry out systematic control of breakers conformity with operating conditions;· to make the estimation of individual  reliability’s value and characteristics of its changing for given combination of characteristics variety;· to provide personnel, who is responsible for technical maintenance of breakers, not only with information but also with methodological support, including recommendations for the given problem solving  and advanced methods for its realization.

  15. Circuit breaker and bus

    International Nuclear Information System (INIS)

    Two close-open operations are required each pulse cycle at approximately 3 MA with the breaker in series with the burn supply, both forming a leg in parallel with the E-coil and the homopolar. To conduct the 3-MA current, approximately 30 breaker units are connected in parallel. Each unit is equipped with a counterpulse capacitor bank, and the bus for the 30 units is provided with a common saturable reactor core made of strip steel wound around the bus. Oil breakers of a special design are chosen because of their high arc resistance facilitating the current transfer to the homopolar machine and for obtaining precision timing in opening and closing of the contacts. The precision timing is achieved by a shock wave method with the oil serving as hydraulic medium. Each of the parallel breaker units possesses two sets of contacts, a stationary and a transient one. A 1-mΩ resistor in series with the transient contacts of each breaker unit is to improve the current sharing. The bus consists of room temperature copper, stranded and transposed to help provide current equalization under transient conditions

  16. Design optimization and modification of reactor trip protection system of nuclear power unit of WWER

    International Nuclear Information System (INIS)

    When carrying out periodic test of nuclear power unit reactor trip protection system, it is necessary to disconnect trip breakers in turn. There are big risks in such kind of periodic tests and many unplanned trip events happened because of malfunction of equipment in reactor trip protection system periodic tests of foreign and domestic nuclear power units under operation, which caused great economic loss. The paper introduces the practical results of design optimization and modification of reactor trip protection system of a nuclear power unit of WWER. (authors)

  17. Plug Detector Bypass Breaker Guard

    Energy Technology Data Exchange (ETDEWEB)

    Horton, Joel Richard (Maryville, TN); Dearstone, Robert Link (Powell, TN)

    2000-01-01

    A method and apparatus wherein the apparatus is a container having an inner chamber, an inlet, an outlet, a breaker assembly having at least one blade within the inner chamber of the container and a motor for driving the blade. Material is supplied to the inner chamber of the container through the inlet of the container and the breaker assembly is operated to reduce any clumped material into unclumped material which is then dispensed from the container through the outlet of the container.

  18. Mass spectrometry of arcs in SF6 circuit breakers

    Science.gov (United States)

    Rüegsegger, W.; Meier, R.; Kneubühl, F. K.; Schötzau, H. J.

    1985-07-01

    Today, SF6 is used to a great extent as insulating and arc-quenching medium in high-voltage gas-blast circuit breakers. The arcing in SF6 during current interruption forms decomposition products. These can influence the arc-quenching properties of the circuit breaker. Furthermore, they can cause corrosion of the circuit breaker housing. In this comprehensive study we present results obtained for the first time from a direct mass spectrometric investigation of the exhaust gases of a high pressure SF6 arc in a model circuit breaker. Our mass spectrometric system consists of a time-of-flight mass spectrometer (TOFMS) equipped with a molecular beam sampling systems. This device allows us to measure mass spectra of high pressure sources with a time resolution of up to 10,000 spectra per second. We have determined the formation rate of the most abundant decomposition products in a SF6 arc at 1 bar. These products are SF4, CF4, WF6, SOF2, SO2, CS2 S2F2 and HF. The fast detection time inherent to our system permits also the determination of the formation of SF4, which is 0.45 0.50 Vol. %/(kJ/1SF6). In addition, we have studied the influence of water and oxygen impurities which are responsible for the production of highly corrosive HF. Finally, we have considered the influence of the thermal degradation of teflon (P.T.F.E.), which is used as nozzle and insulating material in circuit breakers. On this occasion we have demonstrated that CF4, which exhibits dielectric properties similar to SF6, is the main decomposition product formed from teflon. However, we have found that besides CF4 also excess carbon is formed, which is deposited on insulators of the model circuit breaker. Our time-resolved mass spectra reveal that the CF4 production from teflon is delayed by a few milliseconds with respect to the SF6 dissociation in the arc. This delay can influence the interrupting process of the circuit breaker by changing the plasma composition during the arcing period. Although our

  19. Reliability centered maintenance of power transformers and circuit breakers

    Energy Technology Data Exchange (ETDEWEB)

    Purucker, S.L.; Goeltz, R.T. [Oak Ridge National Lab., TN (United States); Hemmelman, K.; Price, R. [Bonneville Power Administration, Van Couver, WA (United States)

    1992-08-01

    At the Bonneville Power Administration (BPA), we have historically maintained high voltage equipment. Including transformers and power circuit breakers, on a time driven basis. While this has served our needs in the past, newer methods are needed to effectively maintain the power system in future years. Today aging equipment, maintenance backlogs, and budget constraints are a reality. BPA has initiated a research and development project to examine reliability centered maintenance (RCM) as an alternative to time based maintenance on high voltage equipment. Under RCM, the performance of each place of equipment is to be monitored by observing many operating parameters. For example, with circuit breakers we will observe (measure) the trip time, accumulated contact wear using I{sup 2}T, timing of the mechanism, plus several other parameters. Equipment performing below a predetermined level, or equipment having accumulated a large amount of ``usage`` will receive maintenance. The maintenance will restore full performance and preserve an acceptable service life for that piece of equipment. To develop and evaluate RCM concepts, BPA is installing a prototype system at our Alvey Substation on 4 transformers and 25 breakers.

  20. 46 CFR 169.670 - Circuit breakers.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Circuit breakers. 169.670 Section 169.670 Shipping COAST... Gross Tons § 169.670 Circuit breakers. Each circuit breaker must be of the manually reset type designed for— (a) Inverse time delay; (b) Instantaneous short circuit protection; and (c) Repeated opening...

  1. Plug Detector Bypass Breaker Guard

    Energy Technology Data Exchange (ETDEWEB)

    Horton, J.R.; Dearstone, R.L.

    2000-05-23

    A method and apparatus are disclosed wherein the apparatus is a container having an inner chamber, an inlet, an outlet, a breaker assembly having at least one blade within the inner chamber of the container and a motor for driving the blade. Material is supplied to the inner chamber of the container through the inlet of the container and the breaker assembly is operated to reduce any clumped material into unclumped material which is then dispensed from the container through the outlet of the container.

  2. Age-related degradation of Westinghouse 480-volt circuit breakers

    International Nuclear Information System (INIS)

    After the McGuire event in 1987 relating to failure of the center pole weld in one of its reactor trip breakers, activities were initiated by the NRC to investigate the probable causes. A review of operating experience suggested that the burning of coils, jamming of the operating mechanism, and deterioration of the contacts dominated the breakers failures. Although failures of the pole shaft weld were not included as one of the generic problems, the NRC augmented inspection team had suspected that these welds were substandard which led them to crack prematurely. A DS-416 low voltage air circuit breaker manufactured by Westinghouse was mechanically cycled to identify age-related degradations. This accelerated aging test was conducted for over 36,000 cycles during nine months. Three separate pole shafts, one with a 60 degree weld, one with a 120 degree and one with a 180 degree were used to characterize the cracking in the pole level welds. In addition, three different operating mechanisms and several other parts were replaced as they became inoperable. The testing yielded many useful results. The burning of the closing coils was found to be the effect of binding in the linkages that are connected to this device. Among the seven welds on the pole shaft, number-sign 1 and number-sign 3 were the critical ones which cracked first to cause misalignment of the pole levers, which, in turn, had led to many problems with the operating mechanism including the burning of coils, excessive wear in certain parts, and overstressed linkages. Based on these findings, a maintenance program is suggested to alleviate the age-related degradations that occur due to mechanical cycling of this type of breaker. 3 refs., 39 figs., 7 tabs

  3. Circuit breaker maintenance, sentinels on guard

    Energy Technology Data Exchange (ETDEWEB)

    Tanguay, F.

    2003-07-01

    Circuit breakers are essential components of every type and size of power system, and their maintenance is a matter of prime importance. This article provides a list of typical circuit breaker maintenance routines for each type of insulating medium and each type of breaker mechanism, and offers a number of useful tips to ensure the success of a circuit breaker maintenance program. It also suggests sources of information about maintenance programs for circuit breakers such as the National Electrical Testing Association's Maintenance Specifications, and companies that specialize in this type of service. 3 tabs.

  4. Present Status of Power Circuit Breaker and its Future

    Science.gov (United States)

    Yoshioka, Yoshio

    Gas circuit breaker and vacuum circuit breaker are the 2 main types of circuit breaker used in extra high voltage and medium voltage networks. After reviewing the history of these circuit breakers, their present status and technologies are described. As for future technology, computation of interrupting phenomena, SF6 gas less apparatus and expectation of the high voltage vacuum circuit breaker are discussed.

  5. What's new about generator circuit breakers

    International Nuclear Information System (INIS)

    The need for updating ANSI C37 Standards for AC high-voltage circuit breakers has become necessary because of the increased interest in power circuit breakers for generator application. These circuit breakers, which have continuous current ratings and rated short-circuit currents that are much higher than those presently covered by existing C37 Standards, take on added importance because they are being installed in critical AC power supplies at nuclear power stations

  6. High Speed Solid State Circuit Breaker

    Science.gov (United States)

    Podlesak, Thomas F.

    1993-01-01

    The U.S. Army Research Laboratory, Fort Monmouth, NJ, has developed and is installing two 3.3 MW high speed solid state circuit breakers at the Army's Pulse Power Center. These circuit breakers will interrupt 4160V three phase power mains in no more than 300 microseconds, two orders of magnitude faster than conventional mechanical contact type circuit breakers. These circuit breakers utilize Gate Turnoff Thyristors (GTO's) and are currently utility type devices using air cooling in an air conditioned enclosure. Future refinements include liquid cooling, either water or two phase organic coolant, and more advanced semiconductors. Each of these refinements promises a more compact, more reliable unit.

  7. Power two-step dc circuit breaker

    International Nuclear Information System (INIS)

    A two-step circuit breaker with replaceable current-conducting elements is described. It is designed for a breakjng capacity of 6x109 W (the maximum current is 150 kA) with the 80-100 μs time of current transfer from inductive storage to the load and thermal stability of 1011 A2xs. A pneumatic circuit breaker with replaceable elements is used as the first step, and exploding-wire circuit breaker as the second one. The circuit breaker measures 1650x1360x1495 mm and weighs 1 t

  8. HOW TO MAINTAIN SF6 CIRCUIT BREAKER

    OpenAIRE

    Snigdha Sharma, Hemant bharadwaj,

    2012-01-01

    India’s growing economy needs an efficient powertransmission system to meet the increasing demand forreliable and affordable power. Circuit breakers play animportant role in protection system of electrical powertransmission networks. A circuit breaker is anautomatically operated electrical switch which detects afault condition and interrupt immediately todiscontinue electrical flow. So its maintenance deservesspecial considerations in order to prevent theequipments an...

  9. Apollo 14 mission circuit breaker anomaly

    Science.gov (United States)

    1971-01-01

    Continuity through the circuit breaker in the mechanically closed condition was prevented by a foreign substance on the contact surface onboard Apollo 14. It was concluded that this was the only failure of this type in over 3400 units that were flown, and since no circuit breaker is a single-point failure for crew safety or mission success, no corrective action was taken.

  10. IE Information Notice No. 85-93: Westinghouse Type DS circuit breakers, potential failure of electric closing feature because of broken spring release latch lever

    International Nuclear Information System (INIS)

    On April 14, 1985, the Westinghouse Nuclear Services Integration Division (NSID) issued Technical Bulletin No. NSID-TB-85-17 advising their customers of a potential malfunction in Westinghouse Type DS Class 1E circuit breakers because of broken spring release latch levers. These electrically operated type DS breakers will not close electrically when the spring release latch lever has been broken off. Twenty-five broken levers have been reported and evaluated. This evaluation shows concentrations of incidents traceable to manufacturing in the following periods of time: early 1975, April 1976, and early 1978. This circuit breaker failure, as discussed, adversely affects the safety function (closing on demand) when the circuit breaker is used in the Engineered Safety Features Systems. However, this failure mode will not affect the safety trip function when it is used in the reactor protection system

  11. HARDWARE IMPLEMENTATION OF SOLID STATE CIRCUIT BREAKER IN MULTI BUS SYSTEM USING MOSFET

    Directory of Open Access Journals (Sweden)

    A.KALAI MURUGAN

    2013-03-01

    Full Text Available This paper describes about the implementation of Solid State Circuit Breaker in power system using MOSFET. The high power semiconductor switches can be used to separate the faulty portions from the rest of the power system in case of abnormal conditions. The Solid State Circuit Breaker is a topology made in the form of module, can protect power system and its components from faults. Existing mechanical circuit breakers are based on the principle of magnetically latching a pair of mechanical contacts shrouded by an arc chute for arc extinction. Very often unnecessary tripping results from a phenomenon known as, “rapid rise” which subsequently results in the demand for frequent maintenance. Due to the long turn-off delay of the present mechanical circuit breaker, significant voltage sag is experienced in the grid which affects the sensible loads. The distortions caused by the three phase short circuit can be reduced to 100 µs in the system with SSCB, in contrast to 100 ms achieved by the present technology and hence it improves the power quality. The SSCB uses high power anti parallel switches to carry bidirectional current. The load voltage is sensed and it is used to turn on and turn off the SSCB. The Eight bus system with SSCB is modeled and simulated using Matlab/Simulink. The hardware model is developed for implementation of SSCB using MOSFETand it is tested in the laboratory.

  12. Comprehensive aging assessment of circuit breakers and relays for nuclear plant aging research (NPAR) program Phase 2

    International Nuclear Information System (INIS)

    This paper discusses the research being sponsored by the Office of Regulatory Research, Nuclear Regulatory Commission as part of the Nuclear Plant Aging Research (NPAR) Program. It reports on the Phase 2 tasks which are to resolve technical safety issues related to the aging degradation of circuit breakers and relays. The objectives of Phase 2 are to: (1) identify and characterize aging and service wear effects of circuit breakers and relays which, if unchecked, could impair plant safety; (2) identify and develop methods of inspection, surveillance, and condition monitoring, and of evaluating residual life of circuit breakers and relays, which will assure timely detection of significant aging effects prior to loss of safety function; (3) evaluate the effectiveness of storage, maintenance, repair and replacement practices in mitigating the rate and extent of degradation in circuit breakers and relays caused by aging and service wear

  13. Physics of arcs in circuit breakers

    International Nuclear Information System (INIS)

    Some typical examples of circuit breakers are shown. Common to all these devices is that an electric arc is formed when the breaker operates which is responsible for the current interruption. The physics of those arcs can be described by the simplest single-fluid model of plasma physics which differs from the set of gas dynamic equations only by the following three terms: radiative energy transfer magnetic force and Joulean heating. These terms describe typical circuit breaker arc phenomena. This is discussed by means of three examples. The first example treats the influence of the radiative energy transfer on the temperature distribution of high-voltage circuit-breaker arcs. The second example is a discussion of the magnetic stability of circuit breaker arcs and the third example is concerned with the problem of flow turbulence produced at the arc boundary. The last effect is closely related to the current interruption process in high-voltage circuit breakers. A semi-empirical description of the turbulent heat exchange leads to a prediction of the breaking capacity for this type of circuit breaker. (author)

  14. Analytical Analysis and Case Study of Transient Behavior of Inrush Current in Power Transformer for Designing of Efficient Circuit Breakers

    Science.gov (United States)

    Harmanpreet, Singh, Sukhwinder; Kumar, Ashok; Kaur, Parneet

    2010-11-01

    Stability & security are main aspects in electrical power systems. Transformer protection is major issue of concern to system operation. There are many mall-trip cases of transformer protection are caused by inrush current problems. The phenomenon of transformer inrush current has been discussed in many papers since 1958. In this paper analytical analysis of inrush current in a transformer switched on dc and ac supply has been done. This analysis will help in design aspects of circuit breakers for better performance.

  15. hvdc circuit breakers using oscillating current techniques

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, N.; Chin, T.H.

    1966-08-01

    Little has been heard of high voltage direct current circuit breakers in recent years, since there has been a trend of opinion which argues that any desired network confirmation can be achieved by multiterminal operation without the necessity for employing circuit breakers. Yet this opinion is not entirely unanimous. A technique for breaking high voltage dc current was developed and experimental circuit breakers operating on these principles have sufficiently good performance characteristics to be used in practice. This technique makes use of oscillations created across the arc discharging electrodes. These techniques are here called oscillating current circuit breaking, to distinguish them clearly from the arc stretching techniques used heretofore in ordinary dc circuit breakers.

  16. Arc modelling in SF6 circuit breakers

    International Nuclear Information System (INIS)

    The paper presents the work done by an operator, EDF and two manufacturers to improve the physical models and numerical methods used to simulate the behavior of the plasma and cold gas around it in a breaking chamber of the HV SF6 circuit breaker, during the high-current phase. This work concerns flow phenomena, in particular incorporating compressibility and the study of turbulence, the coupling between these flow phenomena and electromagnetic phenomena, and finally, radiation - which plays an essential role in energy transfer during the high-current phase. For this latter aspect, emission but also absorption were proven to play a major role, and the two were introduced into the models. The paper presents the models developed and the results obtained with them for simulation of two circuit breaker mock-ups (a double-pressure circuit breaker mock-up and a self-expanding and rotating arc circuit breaker mock-up). (author)

  17. Experience with the Alpine Breaker Line Support

    Energy Technology Data Exchange (ETDEWEB)

    Habnicht, H.; Halbmayer, C.

    1989-01-01

    The Alpine Breaker Line Support is new, mechanised support equipment for stabilising the caving edge during depillaring operations. A short discussion is presented of some panel geometry variations used, and of performance data achieved. 5 figs.

  18. Circuit breaker for OHMIC-heating systems

    International Nuclear Information System (INIS)

    A circuit breaker for power amplification in inductive energy storage systems is described using commercially ac breakers in connection with a ''High-Pressure-Breaking-Element'' (HPBE). Dimensioning values for the HPBE are given. Currents up to 30 kA have been interrupted by paralleling 3 HPBEs. With one HPBE a current of 10 kA was switched off producing a voltage of 30 kV

  19. Trade, TRIPS, and pharmaceuticals.

    Science.gov (United States)

    Smith, Richard D; Correa, Carlos; Oh, Cecilia

    2009-02-21

    The World Trade Organization's Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPS) set global minimum standards for the protection of intellectual property, substantially increasing and expanding intellectual-property rights, and generated clear gains for the pharmaceutical industry and the developed world. The question of whether TRIPS generates gains for developing countries, in the form of increased exports, is addressed in this paper through consideration of the importance of pharmaceuticals in health-care trade, outlining the essential requirements, implications, and issues related to TRIPS, and TRIPS-plus, in which increased restrictions are imposed as part of bilateral free-trade agreements. TRIPS has not generated substantial gains for developing countries, but has further increased pharmaceutical trade in developed countries. The unequal trade between developed and developing countries (ie, exporting and importing high-value patented drugs, respectively) raises the issue of access to medicines, which is exacerbated by TRIPS-plus provisions, although many countries have not even enacted provision for TRIPS flexibilities. Therefore this paper focuses on options that are available to the health community for negotiation to their advantage under TRIPS, and within the presence of TRIPS-plus. PMID:19167054

  20. Cotton Trip in China

    Institute of Scientific and Technical Information of China (English)

    Wang Ting

    2010-01-01

    @@ During their trip in Beijing,the leadership delegation members,Charles Parker,Harrison Ashley(Vice President of NCC Ginner Services),along with Karin Malmstrom(China Director of CCI)shared a time to accept the interview,giving a general introduction about their China trip and the cotton industry in USA.

  1. Breaker Maintenance: Volume 3, Molded-Case circuit breakers

    International Nuclear Information System (INIS)

    Modeled-case circuit breakers (MCCBs) provide power and circuit protection in nuclear plant electrical distribution systems. Thus, their proper operation is essential to the safe and reliable operation of plant electrical distribution systems. This guide for both nuclear and non-nuclear power generating facilities will help improve the maintenance and reliability of MCCBs. The authors developed this guide to establish a working-level understanding of hardware performance trends, reliability, and failure modes from which maintenance practices could be specified. The first step in preparing this guide was an in-depth review of available operating experience and failure data, which was obtained from nuclear information sources such as EPRI's Nuclear Maintenance Applications Center. In addition, they evaluated some nonnuclear reliability data. Next, they investigated current industry practices, including a review of manufacturer's recommendations and numerous industry standards. Finally, they used the collective information to develop programmatic recommendations and, where appropriate, detailed inspection and test guidance. This guide offers many recommendations applicable to MCCB maintenance, such as an engineering description of MCCBs and their operation; an overview of reliability and failure data; programmatic recommendations, including inspection and test periodicity; detailed inspection and test guidance; and corrective maintenance recommendations. Supplementary information includes an overview of industry standards, a discussion of regulatory issues, and sample data sheets. An evaluation of operating experience indicates that a maintenance program need not be overly complicated to detect the predominant failure modes associated with MCCBs. Those implementating an MCCB maintenance and testing program, however, must recognize the inherent limitations associated with field-testing of these devices. 42 refs., 17 figs., 7 tabs

  2. Aging assessment of circuit breakers and relays

    International Nuclear Information System (INIS)

    The aging of circuit breakers and relays is important since these devices provide critical services for safety related systems in nuclear plants. Failures of these devices can cause loss of vital functions as well as creating fire hazards. The aging assessments discussed in this paper were sponsored by the U.S. Nuclear Regulatory Commission's Nuclear Plant Aging Research (NPAR) Program. This research is the Phase II effort in which a test program was initiated to investigate and categorize the aging of circuit breakers and relays. The significant elements of the research consisted of the following: determination of current and advanced Inspection, Surveillance and Condition Monitoring (ISCM) Techniques for circuit breakers and relays; laboratory tests, in which new and aged samples of common circuit breakers and relays were tested using these ISCM techniques; in-situ efforts, in which ISCM techniques were performed on equipment in two nuclear plants, and degradation tests, in which ISCM techniques were performed on purposely degraded samples of circuit breakers and relays

  3. 30 CFR 75.904 - Identification of circuit breakers.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Identification of circuit breakers. 75.904 Section 75.904 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE... Alternating Current Circuits § 75.904 Identification of circuit breakers. Circuit breakers shall be marked...

  4. 30 CFR 77.904 - Identification of circuit breakers.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Identification of circuit breakers. 77.904... COAL MINES Low- and Medium-Voltage Alternating Current Circuits § 77.904 Identification of circuit breakers. Circuit breakers shall be labeled to show which circuits they control unless identification...

  5. 30 CFR 75.900-1 - Circuit breakers; location.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Circuit breakers; location. 75.900-1 Section 75.900-1 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY... Alternating Current Circuits § 75.900-1 Circuit breakers; location. Circuit breakers used to protect...

  6. Switching phenomena in high-voltage circuit breakers

    International Nuclear Information System (INIS)

    The topics covered in this book include: general problems concerning current interruption, the physical arc model, and miscellaneous types of modern switching apparatus, such as gas circuit breakers, gas-insulated switch-gear, vacuum circuit breakers and high-voltage direct-current circuit breakers

  7. 30 CFR 75.800-1 - Circuit breakers; location.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Circuit breakers; location. 75.800-1 Section 75.800-1 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY... § 75.800-1 Circuit breakers; location. Circuit breakers protecting high-voltage circuits entering...

  8. A threshold for the Maker-Breaker clique game

    NARCIS (Netherlands)

    Muller, Tobias; Stojakovic, Milos

    2014-01-01

    We study the Maker-Breaker k-clique game played on the edge set of the random graph G(n, p). In this game, two players, Maker and Breaker, alternately claim unclaimed edges of G(n, p), until all the edges are claimed. Maker wins if he claims all the edges of a k-clique; Breaker wins otherwise. We de

  9. Lake Mason trip report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This document is a summary of the August 31, 1998 trip to Lake Mason to review the hydrology, current conditions, habitat and wildlife. This site visit occurred due...

  10. WIPP site and vicinity geological field trip

    International Nuclear Information System (INIS)

    The Environmental Evaluation Group (EEG) is conducting an assessment of the radiological health risks to people from the Waste Isolation Pilot Plant (WIPP). As a part of this work, EEG is making an effort to improve the understanding of those geological issues concerning the WIPP site which may affect the radiological consequences of the proposed repository. One of the important geological issues to be resolved is the timing and the nature of the dissolution processes which may have affected the WIPP site. EEG organized a two-day conference of geological scientists, titled Geotechnical Considerations for Radiological Hazard Assessment of WIPP on January 17-18, 1980. During this conference, it was realized that a field trip to the site would further clarify the different views on the geological processes active at the site. The field trip of June 16-18, 1980 was organized for this purpose. This report provides a summary of the field trip activities along with the participants post field trip comments. Important field stops are briefly described, followed by a more detailed discussion of critical geological issues. The report concludes with EEG's summary and recommendations to the US Department of Energy for further information needed to more adequately resolve concerns for the geologic and hydrologic integrity of the site

  11. Feasibility analysis of a novel hybrid-type superconducting circuit breaker in multi-terminal HVDC networks

    Science.gov (United States)

    Khan, Umer Amir; Lee, Jong-Geon; Seo, In-Jin; Amir, Faisal; Lee, Bang-Wook

    2015-11-01

    Voltage source converter-based HVDC systems (VSC-HVDC) are a better alternative than conventional thyristor-based HVDC systems, especially for developing multi-terminal HVDC systems (MTDC). However, one of the key obstacles in developing MTDC is the absence of an adequate protection system that can quickly detect faults, locate the faulty line and trip the HVDC circuit breakers (DCCBs) to interrupt the DC fault current. In this paper, a novel hybrid-type superconducting circuit breaker (SDCCB) is proposed and feasibility analyses of its application in MTDC are presented. The SDCCB has a superconducting fault current limiter (SFCL) located in the main current path to limit fault currents until the final trip signal is received. After the trip signal the IGBT located in the main line commutates the current into a parallel line where DC current is forced to zero by the combination of IGBTs and surge arresters. Fault simulations for three-, four- and five-terminal MTDC were performed and SDCCB performance was evaluated in these MTDC. Passive current limitation by SFCL caused a significant reduction of fault current interruption stress in the SDCCB. It was observed that the DC current could change direction in MTDC after a fault and the SDCCB was modified to break the DC current in both the forward and reverse directions. The simulation results suggest that the proposed SDCCB could successfully suppress the DC fault current, cause a timely interruption, and isolate the faulty HVDC line in MTDC.

  12. Circuit breaker timing tests : Part 1 : Timing tests are a powerful tool for troubleshooting faulty breakers

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    The circuits configuration of a power network must change constantly, with various parts of the installation in or out of service at different times. The major circuit interrupters are the disconnect-switch, the interrupter, and the circuit-breaker, which all enable the utility to take sections of the system in or out of service as required. Routine testing (test performed before delivery) of the circuit breaker, commissioning testing (test performed after installation), and periodic testing performed throughout the life of the circuit breaker are necessary to monitor the evolution. The timing test is one of the most important of these tests, and is used to measure the exact instant that the contact changes states, to verify the contacts' discrepancy, and to verify the contacts' travel and speed. The measurements are then compared with the established tolerance limits, and the right course of action can be determined with proper analysis of the results obtained. The most complicated of all power circuit interruption equipment remains the circuit breaker. The main components include the arcing chamber, the insertion resistor, the operating mechanism, and control. The correct closing action and breaking at the required moment is controlled by the circuit breaker, and it is required to execute various operation cycles and achieve fast breaking of short circuit currents. The different interrupting medium are mineral oil, compressed air, and sulfur hexafluoride. The advantages of each medium were briefly discussed. In the case of the oil circuit breaker, the oil is decomposed into gases (70 per cent hydrogen and 20 percent acetylene, and some carbon particles) by the arc, and were the first high voltage breakers. They are designed for fast reclose. The high and very high voltage applications was dominated by the air blast circuit until recently. The two major disadvantages of the air blast circuit breaker are the installation of expensive compression stations

  13. Large Eddy Simulation for Plunge Breaker and Sediment Suspension

    Institute of Scientific and Technical Information of China (English)

    BAI Yuchuan(白玉川); C.O.NG

    2002-01-01

    Breaking waves are a powerful agent for generating turbulence that plays an important role in many fluid dynamicalprocesses, particularly in the mixing of materials. Breaking waves can dislodge sediment and throw it into suspension,which will then be carried by wave-induced steady current and tidal flow. In order to investigate sediment suspension bybreaking waves, a numerical model based on large-eddy-simulation (LES) is developed. This numerical model can beused to simulate wave breaking and sediment suspension. The model consists of a free-surface model using the surfacemarker method combined with a two-dimensional model that solves the flow equations. The turbulence and the turbulentdiffusion are described by a large-eddy-simulation (LES) method where the large turbulence features are simulated bysolving the flow equations, and a subgrid model represents the small-scale turbulence that is not resolved by the flowmodel. A dynamic eddy viscosity subgrid scale stress model has been used for the present simulation. By applying thismodel to Stokes' wave breaking problem in the surf zone, we find that the model results agree very well with experimentaldata. By use of this model to simulation of the breaking process of a periodic wave, it can be found that the model canreproduce the complicated flow phenomena, especially the plunging breaker. It reflects the dynamic structures of roller orvortex in the plunging breaker, and when the wave breaks, many strong vortex structures will be produced in the innersurf zone where the concentration of suspended sediment can thereby become relatively high.

  14. Recent Trend of Vacuum Circuit Breakers

    Science.gov (United States)

    Saito, Hitoshi

    The recent trend in the development and the application of Vacuum Circuit Breakers (VCBs) as an environmental friendly equipment for electric power transmission and distribution is described. Using VCB's for circuit breakers and switchgear and extending the range of application of VCB's lead to reduce the usage of SF6 gas, whose global warming potential is approximately 23900 times that of CO2. The rated voltages and interruption currents of VCB's have increased up to 145 kV/40 kA for single break due to the improvement of the electrode materials and structures. Also, SF6 gas free switchgear up to 84 kV using compressed dry air insulation systems have been developed.

  15. Megavolt nanosecond generator with semiconductor current breaker

    CERN Document Server

    Bushlyakov, A I; Rukin, S N; Slovikovskij, B G; Timoshenkov, S P

    2002-01-01

    The heavy-current nanosecond generator with the pulse capacity up to 1.6 GW and output voltage of 0.5-1 MW is described. The generator contains four capacity storages, one induction storage and six solid body commutators: one thyristor, four magnetic commutators and a semiconductor current breaker on the SOS-diodes. The results of studies on the energy change-over efficiency through a semiconductor breaker by various external resistance loads as well as the results of the thermal and frequency tests are presented. It is established that selection of the optimal cooling system provides for the generator continuous mode of operation with the pulse sequence frequency from 300 Hz up to 850 Hz

  16. Science Activities for School Trips.

    Science.gov (United States)

    Quint, Walter C.

    1980-01-01

    Describes ways in which physics-learning activity packets can be used by high school students participating in trips organized by other departments. Provides an example of physics activities incorporated into an airplane trip to Disney World. (CS)

  17. Guam Commercial Purchases (Trip Ticket)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — DAWR collects Trip Ticket or purchase invoice data from vendors that buy fish directly from the fishermen. Similar to the trip ticket system in Saipan, this is a...

  18. Development of large-scale thyristor dc circuit breaker

    International Nuclear Information System (INIS)

    A study for developing a thyristor dc circuit breaker that is applicable to the Tokamak device for engineering feasibility is presented. The design and test of a unit circuit breaker consisting of 4kV-3kA thyristors connected 2 in series and 12 in parallel are described. And based on the results a 50kV-24kA thyristor dc circuit breaker is conceptually designed

  19. Video auditing techniques for breaker reject

    Energy Technology Data Exchange (ETDEWEB)

    Jenkins, B.M.; Corke, P.I.; O`Brien, G.D.; Waugh, J.M. [CSIRO (Australia). Division of Minerals

    1998-12-31

    Rotary breakers are used by many Australian coal mines to reduce the topsize of run of mine (ROM) coal to a size that can be handled by the processing plant. Coal that does not break to the designated topsize therefore passes out with the rock as breaker rejects. The degree of coal loss can be assessed manually by stop belt auditing of the reject belt, but this method is impractical for long-term monitoring of breaker rejects and breaker performance. Case studies of several open cut coal mines in the Bowen Basin of Central Queensland were made to determine the extent of the problem. The results indicated instances where significant losses did occur, but it was not possible to make an accurate estimate of the total value of the losses. This paper covers work undertaken to develop new auditing techniques for qualitative, quantitative and continuous monitoring of reject belt material which uses relatively low-cost equipment and mature technology. Initial work has concentrated on developing video surveillance techniques suitable for the range of environmental conditions typically encountered in the field. Multi-media methods are being developed for qualitative data presentation, and image analysis techniques are being investigated to extract basic quantitative information from video sequences, such as particle size and shape. Future work includes development of automatic methods using machine vision for 100% on-line inspection. The main attraction of the methodology being adopted is the potential to easily adapt the techniques to diagnostic and control functions. In situations where significant losses occur, this approach could open up many possibilities for reducing coal rejection or allowing its recovery from the rejects stream to improve productivity. 12 refs., 4 figs., 1 tab.

  20. Short- circuit tests of circuit breakers

    OpenAIRE

    Chorovský, P.

    2015-01-01

    This paper deals with short-circuit tests of low voltage electrical devices. In the first part of this paper, there are described basic types of short- circuit tests and their principles. Direct and indirect (synthetic) tests with more details are described in the second part. Each test and principles are explained separately. Oscilogram is obtained from short-circuit tests of circuit breakers at laboratory. The aim of this research work is to propose a test circuit for performing indirect test.

  1. Preliminary assessment of superconductor circuit breaker for space applications

    International Nuclear Information System (INIS)

    Circuit breakers utilizing high transition temperature superconductors (HTTSC) offer improved electrical power system control, protection, and reliability for use in space applications. The HTTSC circuit breaker presented here offers all the benefits of a fuse (small size, low weight, and high reliability) as well as the ability of circuit breakers to reapply power. In conjunction with automated system control the HTTSC circuit breaker will allow time delay following opening to permit computer controlled load reduction prior to remake. Deep space facing radiator technology can produce the necessary cooling. Performance parameters, including response times, are modeled using the SPICE computer package

  2. Gas breakers for tokamak OHMIC-heating duty

    International Nuclear Information System (INIS)

    The current interrupting capacity of air blast and SF6 breakers is reviewed for application in tokamak ohmic-heating circuits. Particular attention is paid to generator breakers for their large current interrupting capacity and suitability for ohmic-heating circuits

  3. A Full Hydro- and Morphodynamic Description of Breaker Bar Development

    DEFF Research Database (Denmark)

    Jacobsen, Niels Gjøl

    net cross shore suspended sediment transport flux as a function of either of the variables $\\zeta_0$, $\\Omega$, or $\\Omega_{HK}$. Secondly, the bed is allowed to evolve under the influence of the sediment transport processes. The development of breaker bars in both laboratory scale settings and...... prototype scale settings is considered. The temporal development of the cross shore profile is simulated for several combinations of wave forcing and sediment grain diameters. The variation is described with emphasis on the development of the crest level of the breaker bar, the variation in the bed shear...... stress on the crest of the breaker bar, and its migration speed. Additionally, a net onshore current over a breaker bar is considered, where this current mimics the presence of a horizontal circulation cell. The development of the breaker bar is described for different values of the net onshore current...

  4. Power multiple-action circuit breaker for an inductive storage

    International Nuclear Information System (INIS)

    Description and results of testing a circuit breaker for breaking capacity of approximately 2X109 W with the minimum time of current trasfer from inductive storage to the load of 3.6x10-4 at the voltage of 10 to 20 kV are presented. The circuit breaker employs the principle of arcless commutation when the circuit breaks during an artificial interruption of the current. A high power pneumatically driven commutator is used as the circuit breaker. The circuit breaker contact system contains two groups of basic and auxiliary immobile contacts which form a coaxial system. The circuit breaker has withstood 104 cycles, its thermal stability is 2x1010 A2s

  5. Peculiarities of the relays intended for operating trip coils of the high-voltage circuit breakers

    Directory of Open Access Journals (Sweden)

    Gurevich Vladimir

    2007-01-01

    Full Text Available Parameters of the subminiature electromagnetic relays used as output elements in microprocessor relay protection, do not correspond to technical specifications on these relay protection. The reasons of this discrepancy are analyzed. Contradictions and discrepancies of the international standards in this area are considered. It is shown, that absence of clearness in standards and mistakes in technical specifications of manufacturers of microprocessor protection do not allow estimating correctly technical parameters and lead to decrease in reliability of relay protection.

  6. Nanocrystallized cores for ground fault circuit breakers

    International Nuclear Information System (INIS)

    Nanocrystallized cores for ground fault circuit breaker (GFCB) can be manufactured for low exciting fields such as 2 A/m, with a low sensitivity to varied pulsed waveform currents (ΔBdyn/ΔBsin≥0.85) and ΔB>0.1 T. On the basis of an experimental and statistical study, it is shown that these GFCB working features are mainly correlated to the remanent induction Br. The results allow a well-controlled design of compact and reliable GFCB transformers

  7. Nanocrystallized cores for ground fault circuit breakers

    Science.gov (United States)

    Waeckerlé, T.; Fraisse, H.; Gautard, D.

    2003-01-01

    Nanocrystallized cores for ground fault circuit breaker (GFCB) can be manufactured for low exciting fields such as 2 A/m, with a low sensitivity to varied pulsed waveform currents (Δ Bdyn/Δ Bsin⩾0.85) and Δ B>0.1 T. On the basis of an experimental and statistical study, it is shown that these GFCB working features are mainly correlated to the remanent induction Br. The results allow a well-controlled design of compact and reliable GFCB transformers.

  8. NRC Information No. 90-41: Potential failure of General Electric Magne-Blast circuit breakers and AK circuit breakers

    International Nuclear Information System (INIS)

    This information notice is intended to alert addressees to potential safety concerns that may result from failures of GE vertical lift (AM) and horizontal draw-out (AMH) Magne-Blast circuit breakers utilizing ML-13 operating mechanisms to open or close them and AK circuit breakers. The particular breaker failures reported herein were caused by operating problems with prop springs, snap rings and lubricating grease. GE Nuclear Energy has informed the NRC that it is aware of these problems and that GE routinely checks and corrects them if the circuit breakers are serviced at one of the four GE nuclear service centers in the US. However, the NRC is aware that some utilities may have their circuit breakers repaired or serviced at facilities other than the four GE nuclear service centers

  9. 30 CFR 77.900-1 - Testing, examination, and maintenance of circuit breakers; procedures.

    Science.gov (United States)

    2010-07-01

    ... circuit breakers; procedures. 77.900-1 Section 77.900-1 Mineral Resources MINE SAFETY AND HEALTH... § 77.900-1 Testing, examination, and maintenance of circuit breakers; procedures. Circuit breakers... qualified as provided in § 77.103. In performing such tests, the circuit breaker auxiliaries or...

  10. 30 CFR 77.800-1 - Testing, examination, and maintenance of circuit breakers; procedures.

    Science.gov (United States)

    2010-07-01

    ... circuit breakers; procedures. 77.800-1 Section 77.800-1 Mineral Resources MINE SAFETY AND HEALTH..., examination, and maintenance of circuit breakers; procedures. (a) Circuit breakers and their auxiliary devices... circuit breaker and its auxiliary devices, and such repairs or adjustments as are indicated by such...

  11. 30 CFR 75.900-3 - Testing, examination, and maintenance of circuit breakers; procedures.

    Science.gov (United States)

    2010-07-01

    ... circuit breakers; procedures. 75.900-3 Section 75.900-3 Mineral Resources MINE SAFETY AND HEALTH... maintenance of circuit breakers; procedures. Circuit breakers protecting low- and medium-voltage alternating... such tests, actuating any of the circuit breaker auxiliaries or control circuits in any manner...

  12. Aging assessment of circuit breakers and relays

    International Nuclear Information System (INIS)

    The aging of circuit breakers and relays is important since these devices provide critical services for safety related systems in nuclear plants. Failures of these devices can cause loss of vital functions as well as creating fire hazards. The aging assessments discussed in this paper were sponsored by the U.S. Nuclear Regulatory Commission's Nuclear Plant Aging Research (NPAR) Program. The research has concentrated on identifying inspection, surveillance and condition monitoring (ISCM) techniques which are useful for detecting age degradation in these devices. Significant elements of the research consisted of the following, laboratory tests, in-situ efforts and degraded parts in a laboratory environment. This includes five types of relays and three types of circuit breakers. Nineteen different ISCM techniques were evaluated. New and aged devices were used to determine the effectiveness of each technique to detect the effects of aging. Aging effects were noted to be significant if they caused failure of the equipment or resulted in some other significant event, such as a fire hazard. The following techniques detected significant aging: visual inspection, infrared thermal measurements, vibration monitoring, pick up voltage, drop out voltage, pole and contact resistance and smoke detection. After the laboratory tests, the techniques which were effective, as well as some which still showed promise, were further evaluated in Duke Power Company's Catawba Nuclear Plant

  13. Calculation and comparison of circuit breaker parameters in Power World Simulator

    OpenAIRE

    Kuljinder Kaur,; Er. Simerpreet Singh

    2016-01-01

    A circuit breaker has ratings that an engineer uses for their application. These ratings define circuit breaker performance characteristics. A good understanding of Ratings allow the electrical engineer to make a proper comparison of various circuit breaker designs. In this research work, the different ratings of circuit breaker were calculated. The other objective of this work was comparison between ratings of existing circuit breaker and calculated ratings in POWER WORLD SIMU...

  14. Transient Ablation Regime in Circuit Breakers

    Science.gov (United States)

    Alexandre, Martin; Jean-Yves, Trepanier; Marcelo, Reggio; Guo, Xueyan

    2007-12-01

    Nozzle wall ablation caused by high temperature electric arcs is studied in the context of high voltage SF6 circuit breakers. The simplified ablation model used in litterature has been updated to take into account the unsteady state of ablation. Ablation rate and velocity are now calculated by a kinetic model using two layers of transition, between the bulk plasma and the ablating wall. The first layer (Knudsen layer), right by the wall, is a kinetic layer of a few mean-free path of thickness. The second layer is collision dominated and makes the transition between the kinetic layer and the plasma bulk. With this new coupled algorithm, it is now possible to calculate the temperature distribution inside the wall, as well as more accurate ablation rates.

  15. Arc modelling in SF{sub 6} circuit breakers

    Energy Technology Data Exchange (ETDEWEB)

    Verite, J.C. [Electricite de France, Clamart (France). Derection des Etudes et Recherches; Boucher, T.; Comte, A. [Electricite de France, Moret sur Loing (France). Direction des Etudes et Recherches; Delalondre, C. [Electricite de France, Chatou (France). Direction des Etudes et Recherches; Robin-Jouan, P.; Serres, E.; Texier, V. [GEC Alsthom, Villeurbanne (France). Direction Technique Haute et Moyenne Tension; Barrault, M.; Chevrier, P.; Fievet, C. [CEA Centre d`Etudes Nucleaires de Grenoble, 38 (France). Merlin Gerin

    1995-06-01

    The paper presents the work done by an operator, EDF and two manufacturers to improve the physical models and numerical methods used to simulate the behavior of the plasma and cold gas around it in a breaking chamber of the HV SF6 circuit breaker, during the high-current phase. This work concerns flow phenomena, in particular incorporating compressibility and the study of turbulence, the coupling between these flow phenomena and electromagnetic phenomena, and finally, radiation - which plays an essential role in energy transfer during the high-current phase. For this latter aspect, emission but also absorption were proven to play a major role, and the two were introduced into the models. The paper presents the models developed and the results obtained with them for simulation of two circuit breaker mock-ups (a double-pressure circuit breaker mock-up and a self-expanding and rotating arc circuit breaker mock-up). (author) 10 refs.

  16. The wave vane - A device to measure the breaker angle

    Digital Repository Service at National Institute of Oceanography (India)

    Chandramohan, P.; Nayak, B.U.; Anand, N.M.

    , ,~ ~ O BEACH c /~ ' ! , THEODOLITE Fig. 4. Definition sketch. 178 P. CHANDRAMOHAN ET AL. angle AOC can be calculated, which would be the wave breaker angle with respect to the coastline. It is assumed that the angle made by the crestline...

  17. Comprehensive aging assessment of circuit breakers and relays

    International Nuclear Information System (INIS)

    As part of the NRC Nuclear Plant Aging Research (NPAR) Program a comprehensive aging assessment was made of relays and circuit breakers. Relays and circuit breakers are important nuclear power plant equipment which are susceptible to degradation with time. This is a Phase II NPAR report which follows the NPAR strategy. Tests on naturally aged and degraded relays and circuit breakers were performed, in-situ measurements made and current, and improved methods for inspection, surveillance and monitoring (ISM) evaluated. Significant results described in this report were the identification of inspection, surveillance and monitoring methods which provide a higher level of assurance that aging will be detected and mitigated. The potential exists that implementation of the improved methods in nuclear plants would minimize and impact of aging and result in more cost effective maintenance on relays and circuit breakers

  18. Evaluation of generator circuit breaker applications / J.F. Fourie.

    OpenAIRE

    Fourie, Johannes Frederick

    2010-01-01

    The use of generator circuit breakers in power stations was investigated and evaluated. A feasibility study to determine if the additional capital cost required, when using a generator circuit breaker in a power station could be justified by the advantages it provides. The background to the study is provided through a technology and literature survey. Included in the technology review and the literature study is information on interruption mediums, the historic developments ...

  19. Hybrid HVDC circuit breaker with self-powered gate drives

    OpenAIRE

    Effah, Francis Boafo; Watson, Alan James; Ji, Chao; Amankwah, Emmanuel K.; Johnson, Christopher Mark; Davidson, Colin; Clare, Jon C.

    2016-01-01

    The ever increasing electric power demand and the advent of renewable energy sources have revived the interest in high-voltage direct current (HVDC) multi-terminal networks. However, the absence of a suitable circuit breaker or fault tolerant VSC station topologies with the required characteristics (such as operating speed) have, until recently, been an obstacle in the development of large scale multi-terminal networks for HVDC. This paper presents a hybrid HVDC circuit breaker concept which...

  20. The return trip effect: Why the return trip often seems to take less time

    OpenAIRE

    van de Ven, N.; van Rijswijk, L.; Roy, M.M.

    2011-01-01

    Three studies confirm the existence of the return trip effect: The return trip often seems shorter than the initial trip, even though the distance traveled and the actual time spent traveling are identical. A pretest shows that people indeed experience a return trip effect regularly, and the effect was found on a bus trip (Study 1), a bicycle trip (Study 2), and when participants watched a video of someone else traveling (Study 3). The return trip effect also existed when another, equidistant...

  1. Trip report Rainwater Basin Nebraska

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report is a summary a trip to Rainwater Basin Wetland Management District in 1991, and focuses on the hydrology and soil habitat types. It is part of the...

  2. CNMI Commercial Purchases (Trip Ticket)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Commonwealth of Northern Mariana Islands (CNMI), Division of Fish and Wildlife (DFW) collects 'Trip Ticket' or purchase invoice data from vendors that buy fish...

  3. Appraisal of boundary layer trips for landing gear testing

    Science.gov (United States)

    McCarthy, Philip; Feltham, Graham; Ekmekci, Alis

    2013-11-01

    Dynamic similarity during scaled model testing is difficult to maintain. Forced boundary layer transition via a surface protuberance is a common method used to address this issue, however few guidelines exist for the effective tripping of complex geometries, such as aircraft landing gears. To address this shortcoming, preliminary wind tunnel tests were performed at Re = 500,000. Surface transition visualisation and pressure measurements show that zigzag type trips of a given size and location are effective at promoting transition, thus preventing the formation of laminar separation bubbles and increasing the effective Reynolds number from the critical regime to the supercritical regime. Extension of these experiments to include three additional tripping methods (wires, roughness strips, CADCUT dots) in a range of sizes, at Reynolds number of 200,000 and below, have been performed in a recirculating water channel. Analysis of surface pressure measurements and time resolved PIV for each trip device, size and location has established a set of recommendations for successful use of tripping for future, low Reynolds number landing gear testing.

  4. LARGE EDDY SIMULATION FOR PLUNGING BREAKER WAVE

    Institute of Scientific and Technical Information of China (English)

    Bai Yu-chuan; Wang Zhao-yin

    2003-01-01

    As wave propagates into shallow water, the shoaling effect leads to increase of wave height, and at a certain position, the wave will be breaking. The breaking wave is powerful agents for generating turbulence, which plays an important role in most of the fluid dynamical processes in the surf zone, so a proper numerical model for describing the turbulent effect is needed urgently. A numerical model is set up to simulate the wave breaking process, which consists of a free surface model using the surface marker method and the vertical two-dimensional model that solves the flow equations. The turbulence is described by Large Eddy Simulation (LES) method where the larger turbulent features are simulated by solving the flow equations, and the small-scale turbulence that is represented by a sub-grid model. A dynamic eddy viscosity sub-grid scale stress model has been used for the present simulation. The large eddy simulation model, which we presented in this paper, can be used to study the propagation of a solitary wave in constant water depth and the shoaling of a non-breaking solitary wave on a beach. To track free-surface movements, The TUMMAC method is employed. By applying the model to wave breaking problem in the surf zone, we found that these model results compared very well with experimental data. In addition, this model is able to reproduce the complicated flow phenomena, especially the plunging breaker.

  5. Fast multiple-action circuit breaker with an electrodynamic drive

    International Nuclear Information System (INIS)

    Description and test results of a fast-response circuit breaker of multiplex action with an electrodynamic drive are presented. The circuit breaker contact system consists of a set of membrane-type hollow disk contacts alternating with all-metal disk contacts. The contact system is housed in a pressure-tight casing filled with transformer oil. The tests have shown the total resistance of the contact system to be equal to 6x10-6 Ohm at a compressed gas pressure in the contact system 6x105 Pa. Model tests of the circuit breaker, in the regime close to the nominal one, for the current commutation from inductive storage to the active load have shown the circuit breaker to be steadily commutating the current of 45 kA at the commutation voltage of 20 to 25 kV and current interruption time of 50 to 100 μs. The circuit breaker withstood some 103 cycles of response without replacement of the construction elements

  6. Life testing of a low voltage air circuit breaker

    International Nuclear Information System (INIS)

    A DS-416 low voltage air circuit breaker manufactured by Westinghouse was mechanically cycled to identify age-related degradation in the various breaker subcomponents, specifically the power-operated mechanism. This accelerated aging test was performed on one breaker unit for over 36,000 cycles. Three separate pole shafts, one with a 60-degree weld, one with a 120-degree weld, and one with a 180-degree weld in the third pole lever were used to characterize cracking in the welds. In addition, during the testing three different operating mechanisms and several other parts were replaced as they became inoperable. Among the seven welds on the pole shaft, No. 1 and No. 3 were found to be critical ones whose fracture can result in misalignment of the pole levers. This can lead to problems with the operating mechanism, including the burning of coils, excessive wear in certain parts, and overstressed linkages, Furthermore, the limiting service life of a number of subcomponents of the power-operated mechanism, including the operating mechanism itself, were assessed. Based on these findings, suggestions are provided to alleviate the age-related degradation that could occur as a result of normal closing and opening of the breaker contacts during its service life. Also, cause and effect analyses of various age-related degradation in various breaker parts are discussed

  7. 30 CFR 75.800 - High-voltage circuits; circuit breakers.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false High-voltage circuits; circuit breakers. 75.800... § 75.800 High-voltage circuits; circuit breakers. High-voltage circuits entering the underground area of any coal mine shall be protected by suitable circuit breakers of adequate interrupting...

  8. 30 CFR 75.800-4 - Testing, examination, and maintenance of circuit breakers; record.

    Science.gov (United States)

    2010-07-01

    ... circuit breakers; record. 75.800-4 Section 75.800-4 Mineral Resources MINE SAFETY AND HEALTH... Underground High-Voltage Distribution § 75.800-4 Testing, examination, and maintenance of circuit breakers... adjustment of all circuit breakers protecting high-voltage circuits which enter any underground area of...

  9. 30 CFR 77.809 - Identification of circuit breakers and disconnecting switches.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Identification of circuit breakers and disconnecting switches. 77.809 Section 77.809 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION... circuit breakers and disconnecting switches. Circuit breakers and disconnecting switches shall be...

  10. 30 CFR 75.800-3 - Testing, examination and maintenance of circuit breakers; procedures.

    Science.gov (United States)

    2010-07-01

    ... High-Voltage Distribution § 75.800-3 Testing, examination and maintenance of circuit breakers; procedures. (a) Circuit breakers and their auxiliary devices protecting underground high-voltage circuits... breakers; procedures. 75.800-3 Section 75.800-3 Mineral Resources MINE SAFETY AND HEALTH...

  11. 48 CFR 252.225-7038 - Restriction on Acquisition of Air Circuit Breakers.

    Science.gov (United States)

    2010-10-01

    ... of Air Circuit Breakers. 252.225-7038 Section 252.225-7038 Federal Acquisition Regulations System... Circuit Breakers. As prescribed in 225.7006-4(b), use the following clause: Restriction on Acquisition of Air Circuit Breakers (JUN 2005) Unless otherwise specified in its offer, the Contractor shall...

  12. 46 CFR 111.30-4 - Circuit breakers removable from the front.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Circuit breakers removable from the front. 111.30-4... ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Switchboards § 111.30-4 Circuit breakers removable from the front. Circuit breakers, when installed on generator or distribution switchboards, must be mounted or arranged...

  13. 30 CFR 75.900-4 - Testing, examination, and maintenance of circuit breakers; record.

    Science.gov (United States)

    2010-07-01

    ... circuit breakers; record. 75.900-4 Section 75.900-4 Mineral Resources MINE SAFETY AND HEALTH... maintenance of circuit breakers; record. The operator of any coal mine shall maintain a written record of each test, examination, repair, or adjustment of all circuit breakers protecting low- and...

  14. 30 CFR 75.809 - Identification of circuit breakers and disconnecting switches.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Identification of circuit breakers and... High-Voltage Distribution § 75.809 Identification of circuit breakers and disconnecting switches. Circuit breakers and disconnecting switches underground shall be marked for identification....

  15. 30 CFR 77.800-2 - Testing, examination, and maintenance of circuit breakers; record.

    Science.gov (United States)

    2010-07-01

    ... circuit breakers; record. 77.800-2 Section 77.800-2 Mineral Resources MINE SAFETY AND HEALTH..., examination, and maintenance of circuit breakers; record. The operator shall maintain a written record of each test, examination, repair, or adjustment of all circuit breakers protecting high-voltage circuits....

  16. 48 CFR 252.225-7037 - Evaluation of Offers for Air Circuit Breakers.

    Science.gov (United States)

    2010-10-01

    ... Air Circuit Breakers. 252.225-7037 Section 252.225-7037 Federal Acquisition Regulations System DEFENSE... CLAUSES Text of Provisions And Clauses 252.225-7037 Evaluation of Offers for Air Circuit Breakers. As prescribed in 225.7006-4(a), use the following provision: Evaluation of Offers for Air Circuit Breakers...

  17. Trip Generation Model Based on Destination Attractiveness

    Institute of Scientific and Technical Information of China (English)

    YAO Liya; GUAN Hongzhi; YAN Hai

    2008-01-01

    Traditional trip generation forecasting methods use unified average trip generation rates to determine trip generation volumes in various traffic zones without considering the individual characteristics of each traffic zone.Therefore,the results can have significant errors.To reduce the forecasting error produced by uniform trip generation rates for different traffic zones,the behavior of each traveler was studied instead of the characteristics of the traffic zone.This paper gives a method for calculating the trip efficiency and the effect of traffic zones combined with a destination selection model based on disaggregate theory for trip generation.Beijing data is used with the trip generation method to predict trip volumes.The results show that the disaggregate model in this paper is more accurate than the traditional method.An analysis of the factors influencing traveler behavior and destination selection shows that the attractiveness of the traffic zone strongly affects the trip generation volume.

  18. Extending temporary storage capacity with emulsion breakers

    International Nuclear Information System (INIS)

    The use of emulsion breakers injected into an oil spill recovery system was examined in both laboratory testing and at the OHMSETT test facility. The tests were designed to assess the injection/mixing/settling regimes needed for optimum water-removal performance from a meso-stable water-in-oil emulsion with an oil spill demulsifier. Different types of injection locations and mixing technologies were examined, including skimmer heads, cargo lines, tank inlets, as well as static in-line and mechanical technologies. During laboratory testing, water-in-oil emulsions and free water was pumped through various lengths of piping loops, an in-line mixer and 8 settling tanks. Following the injection of a demulsifier, the fluid was decanted to observe the emulsion breaking. At the OHMSETT test facility, a Desmi Terminator skimmer recovered the same emulsion from a polluted water surface. Different slick thicknesses, wave heights and recovery rates were used. A demulsifier was also injected into the recovered fluid which was allowed to separate in recovery tanks. The demulsifier efficiency was then measured. It was determined that the demulsifier significantly reduced the volume of water in the recovery tanks and the water content of the remaining emulsion. If free water content was greater than 60 per cent, then the effect of the surfactant was greatly reduced. If no free water was present, the level of turbulence was insufficient to promote emulsion breaking. More than 33 per cent free water content is needed to reduce the bulk viscosity of the fluid and to promote emulsion breaking. The degree of emulsion breaking also increased with increasing mixing energy. 10 refs., 5 tabs., 8 figs

  19. Inductive energy storage using high voltage vacuum circuit breakers

    International Nuclear Information System (INIS)

    Controlled thermonuclear fusion experiments currently being planned require large amounts of pulsed energy. Inductive energy storage systems (IES) appear to be attractive for at least two applications in the fusion research program: high beta devices and those employing turbulent heating. The well-known roadblock to successful implementation of IES is the development of a reliable and cost-effective off-switch capable of handling high currents and withstanding high recovery voltages. The University of Texas at Austin has a program to explore the application of conventional vacuum circuit breakers designed for use in AC systems, in conjunction with appropriate counter pulse circuits, as off-switches in inductive energy storage systems. The present paper describes the IES employing vacuum circuit breakers as off-switches. Since the deionization property of these circuit breakers is of great importance to the design and the cost of the counter-pulse circuit, a synthetic test installation to test these breakers has been conceived, designed and is being installed in the Fusion Research Center, University of Texas at Austin. Some design aspects of the facility will be discussed here. Finally, the results of the study on a mathematical model developed and optimized to determine the least cost system which meets both the requirements of an off-switch for IES Systems and the ratings of circuit breakers used in power systems has been discussed. This analysis indicates that the most important factor with respect to the system cost is the derating of the circuit breakers to obtain satisfactory lifetimes

  20. Moisture Sensor for Sulfur Hexafluoride (SF6)-filled Circuit Breakers

    Energy Technology Data Exchange (ETDEWEB)

    Sauers, I.

    2001-04-27

    Measurements at ORNL were made on the Kahn moisture sensor which Doble Engineering wants to evaluate for use in SF{sub 6} circuit breakers. Test conducted at ORNL indicate that vacuum conditions, as might be found in SF{sub 6} circuit breakers prior to filling with SF{sub 6}, could lead to significant changes in calibration, resulting in erroneous readings of moisture content. Similar effects might also be observed in cases where SF{sub 6} byproducts are present, due the reactivity of some of these byproducts with water.

  1. Thyristor circuit breaker for superconducting magnet protection system

    International Nuclear Information System (INIS)

    A thyristor circuit breaker for switching of power supply of a superconducting magnet at the moment of arising a normal zone is described. The breaker is developed on the basis of a static T1250 thyristor switcher of direct current. The switcher is assembled in the form of movable rack having 500x500x900 mm and 60 kg weight, which permits to easily connect it to any magnetic system. Working current is 1250A, working voltage is up to 1200 V, operation time is 210 μs

  2. Numaerical simulation of a SF6 circuit-breaker arc

    International Nuclear Information System (INIS)

    The design and the validation of high-voltage circuit breaker require more and more physical models which take into account complex phenomenae. We present here a numerical simulation of an SF6 arc established in a simplified geometry of a circuit breaker prototype. Our study deals specially with the turbulent flow, the boundary conditions of the arc roots on the electrodes, the influence of the electromagnetic strengths and the radiative transfer. The results concern a stationary state with fixed geometry and current intensity (I=2000 A)

  3. Programmable Low-Voltage Circuit Breaker and Tester

    Science.gov (United States)

    Greenfield, Terry

    2008-01-01

    An instrumentation system that would comprise a remotely controllable and programmable low-voltage circuit breaker plus several electric-circuit-testing subsystems has been conceived, originally for use aboard a spacecraft during all phases of operation from pre-launch testing through launch, ascent, orbit, descent, and landing. The system could also be adapted to similar use aboard aircraft. In comparison with remotely controllable circuit breakers heretofore commercially available, this system would be smaller, less massive, and capable of performing more functions, as needed for aerospace applications.

  4. Fracturing Fluid (Guar Polymer Gel Degradation Study by using Oxidative and Enzyme Breaker

    Directory of Open Access Journals (Sweden)

    Aung Kyaw

    2012-06-01

    Full Text Available Oxidative and enzyme breakers are used in this research project with the main objective to study on the degradation pattern of fracturing fluid (i.e., guar polymer gel as a function of time, temperature and breaker concentration itself. The fracturing fluid used in hydraulic fracturing or frac pack contain a chemical breakers to reduce the viscosity of the fluid intermingled with the proppant. Chemical breakers reduce viscosity of the guar polymer by cleaving the polymer into small-molecular-weight fragments. The reduction of viscosity will facilitate the flow-back of residual polymer providing rapid recovery of polymer from proppant pack. Ineffective breakers or misapplication of breakers can result in screen-outs or flow-back of viscous fluids both of which can significantly decrease the well productivity. Breaker activity of low to medium temperature range oxidative and enzyme breaker systems was evaluated. ViCon NF an oxidative breaker (Halliburton product and GBW 12- CD an enzyme breaker (BJ Services product were used in this research project with the main objective to study on the degradation pattern of fracturing fluid (guar polymer gel as a function of (time, temperature and breaker concentration itself. This study provides focuses on the way to mix the fracturing fluid, compositions of the fracturing fluid and how to conduct the crosslink and break test. Crosslink test indicate the optimum cross-linker concentration to produce good crosslink gel and the break test gave the characteristic of the gel during degradation process and also the break time. Besides relying on the laboratory experiment, information obtained from research on SPE and US Pattern papers were used to make a comparison study on oxidative and enzyme breakers properties. Degradation pattern observed from the break test showed that reduction in gel viscosity depends on time, temperature and breaker concentration. Observations from experiment also revealed that small

  5. Some experience with a gas flow model of circuit breaker

    Czech Academy of Sciences Publication Activity Database

    Čáp, D.; Pelikán, Vladimír; Sedláček, J.

    Plzeň : Západočeská univerzita, 2000, s. 21-26. ISBN 80-7082-718-1 R&D Projects: GA ČR GA102/00/P083 Keywords : gas flow * self-blast circuit breaker * CFD Subject RIV: JB - Sensors, Measurment, Regulation

  6. Remote control circuit breaker evaluation testing. [for space shuttles

    Science.gov (United States)

    Bemko, L. M.

    1974-01-01

    Engineering evaluation tests were performed on several models/types of remote control circuit breakers marketed in an attempt to gain some insight into their potential suitability for use on the space shuttle vehicle. Tests included the measurement of several electrical and operational performance parameters under laboratory ambient, space simulation, acceleration and vibration environmental conditions.

  7. IE Information No. 87-12: Potential problems with metal clad circuit breakers, General Electric type AKF-2-25

    International Nuclear Information System (INIS)

    This notice is to alert recipients of potential problems with the General Electric Company (GE) AKF-2-25 type circuit breakers failing to fully open on demand. The GE AKF type circuit breakers have been shown to be susceptible to failure as a result of binding within the breaker cam mechanism, unless proper maintenance procedures are developed and followed by individuals trained specifically to service the AKF breaker. Maintenance information is given that should be incorporated into programs for these circuit breakers

  8. One-trip drum operating instruction

    Energy Technology Data Exchange (ETDEWEB)

    Ruff, D.T.

    1994-10-01

    The one trip system is a bagless transfer system for egress of waste from gloveboxes into 55 gallon one-trip drums. The contents of this document give an overview of the assembly, loading, and handling of the one-trip drum for use in the WRAP-1 plant.

  9. Tourism, Field Trips and Geographic Education.

    Science.gov (United States)

    Dilsaver, Lary M.

    In university level geography education, both a market and a need exist for "learning trips" combining the elements of a field trip with those of a commercial tour. Planning such trips involves four steps. The first of these is to establish the conditions of the tour, including identification of the topical focus, specific destinations and sites…

  10. One-trip drum operating instruction

    International Nuclear Information System (INIS)

    The one trip system is a bagless transfer system for egress of waste from gloveboxes into 55 gallon one-trip drums. The contents of this document give an overview of the assembly, loading, and handling of the one-trip drum for use in the WRAP-1 plant

  11. Primary heat transport pump trip by ground fault (deterioration of insulation in the cable quick disconnect)

    International Nuclear Information System (INIS)

    At 08:29 Sept. 1, 1988, Wolsong unit 1 was operating at 100% full power when a primary heat transport pump was suddenly tripped by breaker trip due to ground fault in the power distribution connector assembly. Soon after the pump trip, the reactor was shut down automatically on low heat transport flow. Operators tried to restart the pump twice but failed. A field operator reported to the shift supervisor that he found an electrical spark and smoke at the vicinity of the pump when the pump started to run. Inspection showed that a power distribution connector assembly for making fast and easy power connections to the PHT pump motor, 3312-PM2, was damaged severely by thermal shock. Particularly, broken parts of the insulating plug flew away across the boiler room and dropped to the floor. Direct causes of the failure were bad contact and deterioration of integrity along the creep paths between the insulating plug and the connector housing. The failed connector assembly had been used for more than 7 years. Its status had been checked infrequently during the in-service period. The standard torque value was not applied to the installation of connectors. Therefore, we concluded that long term inservice in combinations of application of improper torque value induced failure of insulation. This paper describes the scenarios, causes of the event and corrective actions to prevent recurrence of this event. (author)

  12. Virtual Field Geologic Trip System

    Institute of Scientific and Technical Information of China (English)

    Jian Wang; Linfu Xue; Xiaojun Zhou

    2003-01-01

    Virtual Field Geologic Trip System (VFGTS) constructed by the technique of visualization can efficiently present geologic field information and widely used in the field of geologic education. This paper introduces the developing thinking of VFGTS and discusses the main implement processes. Building VFGTS mainly includes systemically gathering of field geological data, the building of virtual geological world, and displaying of virtual geologic world and human-computer interaction.

  13. Calculation and comparison of circuit breaker parameters in Power World Simulator

    Directory of Open Access Journals (Sweden)

    Kuljinder Kaur,

    2016-01-01

    Full Text Available A circuit breaker has ratings that an engineer uses for their application. These ratings define circuit breaker performance characteristics. A good understanding of Ratings allow the electrical engineer to make a proper comparison of various circuit breaker designs. In this research work, the different ratings of circuit breaker were calculated. The other objective of this work was comparison between ratings of existing circuit breaker and calculated ratings in POWER WORLD SIMULATOR. Further, the impact of time delay in circuit breaker was studied. These calculations were performed for rated current of 400 & 630 Amps. The results performed in POWER WORLD SIMULATOR were shown better and information gained from the analysis can be used for proper relay selection, settings, performances and coordination.

  14. An Overview of Dynamic Contact Resistance Measurement of HV Circuit Breakers

    Science.gov (United States)

    Bhole, A. A.; Gandhare, W. Z.

    2016-06-01

    With the deregulation of the electrical power industry, utilities and service companies are operating in a changing business environment. High voltage circuit breakers are extremely important for the function of modern electric power supply systems. The need to predict the proper function of circuit breaker grew over the years as the transmission networks expanded. The maintenance of circuit breakers deserves special consideration because of their importance for routine switching and for protection of other equipments. Electric transmission system breakups and equipment destruction can occur if a circuit breaker fails to operate because of a lack of preventive maintenance. Dynamic Contact Resistance Measurement (DCRM) is known as an effective technique for assessing the condition of power circuit breakers contacts and operating mechanism. This paper gives a general review about DCRM. It discusses the practical case studies on use of DCRM for condition assessment of high voltage circuit breakers.

  15. Recent development of puffer-type gas circuit breakers

    International Nuclear Information System (INIS)

    The development work and fundamental research achieved 360 kV/420 kV, 40 kA/50 kA circuit breakers. This paper reports that improved understanding of arc interruption and thermodynamic characteristics stimulated efforts to reduce the mechanical energy required in interruption by using the thermal energy of the arc itself. The technique that realized the energy saving materialized in the design to build up the pressure necessary for blasting the arc with the help of the arc itself. This concept is quite similar to that of self extinction in oil circuit breakers. The thermal energy is somehow fed back to the pressure buildup space to help the pressure buildup by mechanical drive

  16. High-voltage direct-current circuit breakers

    International Nuclear Information System (INIS)

    This paper reports that in 1954 the first high-voltage direct-current (HVDC) transmission system was put into operation between Gotland and the mainland of Sweden. Its system voltage and capacity were 100 kV and 20 MW, respectively. Since then many HVDC transmission systems have been planned, constructed, or commissioned in more than 30 places worldwide, and their total capacity is close to 40 GW. Most systems commissioned to date are two-terminal schemes, and HVDC breakers are not yet used in the high-potential main circuit of those systems, because the system is expected to perform well using only converter/inverter control even at a fault stage of the transmission line. However, even in a two-terminal scheme there are not a few merits in using an HVDC breaker when the system has two parallel transmission lines, that is, when it is a double-circuit system

  17. Investigation of a circuit breaker for the ASDEX fusion experiment at Garching

    International Nuclear Information System (INIS)

    In fusion experiments electric discharges are produced in the plasma by interrupting high currents in the ohmic heating coils using fast and powerful circuit breakers. Thereby high plasma currents are induced which heat the plasma. Results obtained with a standard circuit breaker capable of interrupting 30 kA at 20 kV are reported here. The lifetime of the breaker contacts is investigated. (orig.)

  18. The Solenarc circuit-breaker of high performance level

    International Nuclear Information System (INIS)

    After recalling the breaking principle involved in MV circuit-breakers manufactured by Merlin Gerin, it is showed how Solenarc technique enables specific problems to be solved that are set by the equipment of Eurodif plant at Tricastin and that represent constraints similar to those encountered with protective equipment for power station auxiliaries (high rated currents, long duration overloads, very high short-circuit currents, current breaks without natural passage through zero, etc.)

  19. Dynamic Skyline Computation with the Skyline Breaker Algorithm

    OpenAIRE

    Köppl, Dominik

    2014-01-01

    Given a sequential data input, we tackle parallel dynamic skyline computation of the read data by means of a spatial tree structure for indexing fine-grained feature vectors. For this purpose, we modified the Skyline Breaker algorithm that solves skyline computation with multiple local split decision trees concurrently. With this approach, we propose an algorithm for dynamic skyline computation that inherits the robustness against the dimension curse and different data distributions.

  20. Low-voltage circuit breaker arcs—simulation and measurements

    International Nuclear Information System (INIS)

    As one of the most important electrical components, the low-voltage circuit breaker (LVCB) has been widely used for protection in all types of low-voltage distribution systems. In particular, the low-voltage dc circuit breaker has been arousing great research interest in recent years. In this type of circuit breaker, an air arc is formed in the interrupting process which is a 3D transient arc in a complex chamber geometry with splitter plates. Controlling the arc evolution and the extinction are the most significant problems. This paper reviews published research works referring to LVCB arcs. Based on the working principle, the arcing process is divided into arc commutation, arc motion and arc splitting; we focus our attention on the modelling and measurement of these phases. In addition, previous approaches in papers of the critical physical phenomenon treatment are discussed, such as radiation, metal erosion, wall ablation and turbulence in the air arc. Recommendations for air arc modelling and measurement are presented for further investigation. (topical review)

  1. The plasma circuit breaker in its conducting phase

    International Nuclear Information System (INIS)

    Plasma circuit breakers are being actively studied at the present time as current interrupters and power peaking devices. These devices hold out the promise of creating effective, compact, and cheap sources of pulsed voltage (with pulse leading edges from tens of μsec down to 10 nsec). Such sources would solve problems in several areas of technology, notably pulsed controlled thermonuclear fusion. Here, the authors investigate the problem of penetration of a magnetic field into a plasma connector, which is equivalent to modeling the conducting phase of a plasma circuit breaker in its electron-magnetohydrodynamic (EMHD) stage. They show that the most universal mechanism for field penetration is associated with density gradients; in contrast to a number of previous papers, they find that our qualitative results depend very weakly on the mutual orientation of N and ∇n. They use the real parameters of a plasma in such a circuit breaker to construct a solution that describes a field penetration wave, taking into account anomalous resistance and electron heating

  2. Estimation of Siphon Breakers for Jordan Research and Training Reactor

    International Nuclear Information System (INIS)

    The pool water itself is the ultimate heat sink of the residual heat. Thus, it is very important to guarantee that the pool water level be higher than the minimum level from a safety point of view. The JRTR is an open pool-type research reactor and has a downward core flow. To meet the required net positive suction head (NPSHr) of the PCPs, some components of the Primary Cooling System (PCS) are installed below the core level. When a postulated pipe break occurs at below the reactor core position, the pool water can be drained below the core by siphon phenomena, and the core cannot be cooled by natural circulation. Therefore, siphon breakers are installed in the PCS to limit the pool water drain during and after all postulated initiating events. Because the open-type reactor is operating at low pressure and low temperature conditions, guillotine break LOCA (Loss of Coolant Accident) is almost impossible. However, for a design purpose, a pump casing rupture by a failure of moving part has been considered in this study. An estimation of the siphon breakers was performed with the analytical undershooting prediction model. 2.5-inch siphon break lines with siphon break valves were selected as siphon breakers for the JRTR

  3. Estimation of Siphon Breakers for Jordan Research and Training Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kwon-Yeong; Seo, Kyoungwoo; Chi, Dae Young [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-10-15

    The pool water itself is the ultimate heat sink of the residual heat. Thus, it is very important to guarantee that the pool water level be higher than the minimum level from a safety point of view. The JRTR is an open pool-type research reactor and has a downward core flow. To meet the required net positive suction head (NPSHr) of the PCPs, some components of the Primary Cooling System (PCS) are installed below the core level. When a postulated pipe break occurs at below the reactor core position, the pool water can be drained below the core by siphon phenomena, and the core cannot be cooled by natural circulation. Therefore, siphon breakers are installed in the PCS to limit the pool water drain during and after all postulated initiating events. Because the open-type reactor is operating at low pressure and low temperature conditions, guillotine break LOCA (Loss of Coolant Accident) is almost impossible. However, for a design purpose, a pump casing rupture by a failure of moving part has been considered in this study. An estimation of the siphon breakers was performed with the analytical undershooting prediction model. 2.5-inch siphon break lines with siphon break valves were selected as siphon breakers for the JRTR.

  4. Final report of experimental studies on siphon breaker

    International Nuclear Information System (INIS)

    Experimental studies on siphon breaker are a research reactor. Most research reactors are required to be contained in the enormous pool for a safety aspect. Because it is necessary to keep the reactor pool water level during normal operation, a pool water service system is designed to supply demineralized water. The water supply is automatically controlled by opening or closing a valve installed on the system with a signal. If the pool water loss is greater than the pool water make-up capacity and the pool level continues to drop, other system pumps or heaters should be stopped. For preventing to drop the pool water level above the reactor core, all system should be located above the core. However, a component of a system can be installed below the core level due to the component purpose. Then, the system should install a siphon breaker to cover the reactor core with pool water and to protect from a siphon leak of the reactor pool water during and after all postulated initiating events. The purpose of this research is to determine the siphon break type according to the research reactor types for designing the siphon breaker

  5. A mechanical arcless dc circuit breaker for a superconducting magnet system

    International Nuclear Information System (INIS)

    Next fusion research experiments plan to use many superconducting magnets. When a quench phenomenon is observed, the current should be interrupted to protect the magnet. Therefore, a dc circuit breaker is necessary. There are four technical situations to be considered for the dc circuit breaker system; (1) high rated current, (2) smaller size breaker, (3) high reliability and (4) no surge voltage during the interruption. The sizer of the breaker is limited by the arc current density of the contacts, and the low current density is better in the circuit breakers. A high rated current also needs the large contacts of the breaker. Here, we introduce a new type of dc circuit breaker system which does not generate an arc plasma between the contacts, equip the high rated current disconnecting switch and a fuse for the failure of the interruption, and use the conventional ac breaker. The switch size of the breaker is almost one hundred times smaller than that of the previous switch. (orig.)

  6. NRC Information No. 87-41: Failures of certain Brown Boveri Electric circuit breakers

    International Nuclear Information System (INIS)

    On April 20, 1987, Duquesne Light Company, the Beaver Valley Unit 2 licensee, notified the NRC of the failure of a BBE Type 5HK Class IE 4-KV circuit breaker. When the circuit breaker was racked onto the bus and 125-V DC control power was applied to the breaker's control circuit, the closing spring charged and the circuit breaker immediately closed and opened several times before the control power could be turned off. The licensee determined by field testing that the closing coil was not being energized. Another problem with BBE circuit breakers occurred at River Bend and was reported March 6, 1987. On February 6, 1987, with the unit at full power, the Division I diesel generator 4.16-KV output circuit breaker (Gould-Brown Boveri Type 5HK) failed to close during a weekly surveillance test. The licensee's inspection of the output circuit breaker revealed that a mounting bolt had fallen out of the closing spring charging motor, rendering the motor inoperable. Further investigation revealed several other circuit breakers that contained loose or missing charging motor mounting bolts. The licensee also stated that the River Bend circuit breaker preventive maintenance program, which the licensee believes to be in accordance with the vendor's recommendations, did not detect this problem. The licensee believes the root cause of the problem to be insufficient torquing of the charging motor mounting bolts by the vendor

  7. Assessment and modelling of switching technologies for application in HVDC-circuit breakers

    OpenAIRE

    Lund, Johan

    2011-01-01

    A key element for future DC-grids is a DC circuit breaker that in case of a short circuit fault reliably can turn off a short circuit current. AC circuit breakers are well known components that has been in use for a long time in AC-grids. The AC circuit breaker is designed to interrupt the current at its natural current zero crossings. In DC grids such does not exists, therefore AC breakers can not be directly applied in DC grids. Different concepts and technologies to solve this problem is a...

  8. Organizing small-scale scout trip abroad

    OpenAIRE

    Rautala, Camilla

    2016-01-01

    This thesis was commissioned by the Guides and Scouts of Finland (Suomen Partiolaiset – Finlands Scouter ry.) The thesis describes the organising process of a small-scale scout trip to the members of commissioning company. The Guides and Scouts of Finland directs the scout movement in Finland. The small-scale trips to national camps support the organisation’s objectives of educating world citizens. The objective of this thesis project was to plan and implemented well-organised trip to Bal...

  9. WIPP site and vicinity geological field trip

    International Nuclear Information System (INIS)

    The Environmental Evaluation Group is conducting an assessment of the radiological health risks to people from the Waste Isolation Pilot Plant. As a part of this work, EEG is making an effort to improve the understanding of those geological issues concerning the WIPP site which may affect the radiological consequences of the proposed repository. One of the important geological issues to be resolved is the timing and the nature of the dissolution processes which may have affected the WIPP site. EEG organized a two-day conference of geological scientists, on January 17-18, 1980. On the basis of the January conference and the June field trip, EEG has formed the following conclusions: (1) it has not been clearly established that the site or the surrounding area has been attacked by deep dissolution to render it unsuitable for the nuclear waste pilot repository; (2) the existence of an isolated breccia pipe at the site unaccompanied by a deep dissolution wedge, is a very remote possibility; (3) more specific information about the origin and the nature of the brine reservoirs is needed. An important question that should be resolved is whether each encounter with artesian brine represents a separate pocket or whether these occurrences are interconnected; (4) Anderson has postulated a major tectonic fault or a fracture system at the Basin margin along the San Simon Swale; (5) the area in the northern part of the WIPP site, identified from geophysical and bore hole data as the disturbed zone, should be further investigated to cleary understand the nature and significance of this structural anomaly; and (6) a major drawback encountered during the discussions of geological issues related to the WIPP site is the absence of published material that brings together all the known information related to a particular issue

  10. Risk analysis and control measures after turbine trip but reactor not trip

    International Nuclear Information System (INIS)

    Based on the work experience, this paper presents the phenomenon and risks that may occur after turbine trip but reactor not trip while full power operation of PWR nuclear power plant, and put forward control measures to discuss. (authors)

  11. Does a satisfying trip result in more future trips with that mode?

    OpenAIRE

    De Vos, Jonas; Schwanen, Tim; Van Acker, Veronique; Witlox, Frank

    2016-01-01

    Previous studies have indicated that travel satisfaction – the experienced emotions during, and cognitive evaluation of, a trip – can be affected by travel mode choice and other trip characteristics. However, as satisfactory trips might improve a person’s attitudes toward the used mode, persons may be more likely to use that same mode for future trips of the same kind. Hence, a cyclical process between travel mode choice and travel satisfaction might occur. In this paper we analyse this proce...

  12. Structure design of and experimental research on a two-stage laval foam breaker for foam fluid recycling.

    Science.gov (United States)

    Wang, Jin-song; Cao, Pin-lu; Yin, Kun

    2015-07-01

    Environmental, economical and efficient antifoaming technology is the basis for achievement of foam drilling fluid recycling. The present study designed a novel two-stage laval mechanical foam breaker that primarily uses vacuum generated by Coanda effect and Laval principle to break foam. Numerical simulation results showed that the value and distribution of negative pressure of two-stage laval foam breaker were larger than that of the normal foam breaker. Experimental results showed that foam-breaking efficiency of two-stage laval foam breaker was higher than that of normal foam breaker, when gas-to-liquid ratio and liquid flow rate changed. The foam-breaking efficiency of normal foam breaker decreased rapidly with increasing foam stability, whereas the two-stage laval foam breaker remained unchanged. Foam base fluid would be recycled using two-stage laval foam breaker, which would reduce the foam drilling cost sharply and waste disposals that adverse by affect the environment. PMID:26387358

  13. Status of the reactor trip in HANARO

    International Nuclear Information System (INIS)

    Unexpected reactor trip in HANARO since the first criticality in February, 1995 was investigated. The total numbers of the reactor trip events were 136 and it was 10.4 cases on average each year. During the early stage of the HANARO operation from 1995 to 1997, unexpected reactor trips were occurred frequently. 67% of the total unexpected reactor trips were occurred in that period, which were 91 cases. That duration was for a power ascension test as one of the reactor performance tests. The unexpected reactor trips were mainly caused by system problems and operators' error. Some cases were caused by electric power failure. The most frequent system problem was originated from fluctuation of the signal of the neutron power measuring system. To prevent the reactor trips by this phenomenon, the circuit of the neutron and thermal power, which was caused when the deviation of the neutron and thermal power is larger than 3MW while the reactor power increases. To reduce reactor the revised one. That has on effect on reducing unexpected reactor trips dramatically. Reactor trips have been occurred by the class-IV power failure or a few problems of system error but never by operators' error since 2000

  14. Status of the reactor TRIP in HANARO

    International Nuclear Information System (INIS)

    Unexpected reactor trip in HANARO since the first criticality in February, 1995 was investigated. The total numbers of the reactor trip events were 136 and it was 10.4 cases on average each year. During the early stage of the HANARO operation from 1995 to 1997, unexpected reactor trips were occurred frequently. 67% of the total unexpected reactor trips were occurred in that period, which were 91 cases. That duration was for a power ascension test as one of the reactor performance tests. The unexpected reactor trips were mainly caused by system problems and operators' error. Some cases were caused by electric power failure. The most frequent system problem was originated from fluctuation of the signal of the neutron power measuring system. To prevent the reactor trips by this phenomenon, the circuit of the reactor protection system was changed. Operators' error were occurred by mismatching of the neutron and thermal power, which was caused when the deviation of the neutron and thermal power is larger than 3 MW while the reactor power increases. To reduce reactor operators' error, operational procedure was revised and the operators have been trained with the revised one. That has on effect on reducing unexpected reactor trips dramatically. Reactor trips have been occurred by the class-IV power failure or a few problems of system error but never by operators' error since 2000. (author)

  15. 30 CFR 77.800 - High-voltage circuits; circuit breakers.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false High-voltage circuits; circuit breakers. 77.800... COAL MINES Surface High-Voltage Distribution § 77.800 High-voltage circuits; circuit breakers. High-voltage circuits supplying power to portable or mobile equipment shall be protected by suitable...

  16. 30 CFR 75.601-1 - Short circuit protection; ratings and settings of circuit breakers.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Short circuit protection; ratings and settings of circuit breakers. 75.601-1 Section 75.601-1 Mineral Resources MINE SAFETY AND HEALTH... Trailing Cables § 75.601-1 Short circuit protection; ratings and settings of circuit breakers....

  17. 30 CFR 77.900-2 - Testing, examination, and maintenance of circuit breakers; record.

    Science.gov (United States)

    2010-07-01

    ... circuit breakers; record. 77.900-2 Section 77.900-2 Mineral Resources MINE SAFETY AND HEALTH... § 77.900-2 Testing, examination, and maintenance of circuit breakers; record. The operator shall maintain a written record of each test, examination, repair or adjustment of all circuit...

  18. 48 CFR 225.7006 - Restriction on air circuit breakers for naval vessels.

    Science.gov (United States)

    2010-10-01

    ... on air circuit breakers for naval vessels. ... 48 Federal Acquisition Regulations System 3 2010-10-01 2010-10-01 false Restriction on air circuit breakers for naval vessels. 225.7006 Section 225.7006 Federal Acquisition Regulations System...

  19. Development, integration and testing of automated triggering circuit for hybrid DC circuit breaker

    International Nuclear Information System (INIS)

    A novel concept of Hybrid DC circuit breaker having combination of mechanical switch and static switch provides arc-less current commutation into the dump resistor during quench in superconducting magnet operation. The triggering of mechanical and static switches in Hybrid DC breaker can be automatized which can effectively reduce the overall current commutation time of hybrid DC circuit breaker and make the operation independent of opening time of mechanical switch. With this view, a dedicated control circuit (auto-triggering circuit) has been developed which can decide the timing and pulse duration for mechanical switch as well as static switch from the operating parameters. This circuit has been tested with dummy parameters and thereafter integrated with the actual test set up of hybrid DC circuit breaker. This paper deals with the conceptual design of the auto-triggering circuit, its control logic and operation. The test results of Hybrid DC circuit breaker using this circuit have also been discussed. (author)

  20. Current sharing between two vacuum circuit breaker units in parallel operation for large direct current interruption

    International Nuclear Information System (INIS)

    The inductive energy storage system (IES system) has been developed for the energy source of a fusion reactor. This paper presents the characteristics of circuit breaker units which will be used for the IES system. A small scale parallel breaking test circuit, in which two vacuum circuit breaker units are used, was constructed. The power source for the circuit was a condenser bank of 730 microfarad. The relation between arc voltage and arc current, and current wave forms in both vacuum valves operated in parallel were observed. Simulation calculation for the small scale circuit was performed. The obtained wave forms were similar to the measured forms. It was found that the current through both breakers was nearly balanced when the difference of breaking time of both breakers was small. Simulation calculation method for large scale parallel breakers was developed. Use of a series inductance of 100 microhenry will save the difference of breaking time. (Kato, T.)

  1. Extinction properties of electric arcs in high voltage circuit breakers

    Science.gov (United States)

    Ziani, A.; Moulai, H.

    2009-05-01

    This paper is devoted to the development of a 0D model of the electric arc extinction in SF6 high voltage circuit breakers taking into account the thermal radiation of the plasma, in addition to the conduction and convection phenomena. The Stefan-Boltzmann equation is coupled with the heat equation, and both equations are solved simultaneously in order to follow the evolution of the arc voltage and the conductance of the thermal plasma as functions of time. The obtained results are found to be in good agreement with experimental recordings.

  2. Study of a fast circuit breaker for high currents

    International Nuclear Information System (INIS)

    The circuit breaker presented here is capable of interrupting a 10kA current within 1μs and then sustain an over voltage of the order of 20kV for a 3mm insulation width. The construction is of the mechanical rupture type in which the replacement of a piece of conductor by an insulator is ensured by means of the explosion of a stoichiometric mixture of hydrogen and oxygen. The current is then transfered into a fuse which finally transfers the energy to the load or opens the circuit

  3. Implementasi Konsep Kecerdasan Buatan Dalam Rancang Bangun Game Brick Breaker

    OpenAIRE

    Ayuni, Wulan

    2011-01-01

    Games as a medium of entertainment has grown rapidly along with the development of technology as well. One of the elements that play an important role in a games is artificial intelligence. With artificial intelligence, expected elements in the games can act as natural as possible like human being. In this Brick Breaker games, the author apply the concept of fuzzy logic in determining the strength and agility of reflector board of the ball against the arrival of the ball. In designing of this...

  4. Superpower frequency generators with a plasma current breaker

    International Nuclear Information System (INIS)

    This review is dedicated to a new trend in the accelerator technique which are the generators of electron and roentgen radiation on the basis of a plasma current breaker (PCB) able of operation in the recurrent pulse mode. The basic results of studies on the PCB, schemes and design peculiarities of the frequency generators of the megavolt range developed on the basis thereof are presented. The prospects for developing frequency accelerators on the PCB basis, their maximum achievable parameters, resource of life and possible applications are considered. It is shown that the record-breaking high peak power of such accelerators may essentially increase the efficiency of radiation-biological technologies

  5. Increasing of Switching Abilities of High Voltage Circuit Breakers

    OpenAIRE

    RUSTEMLI, Sabir

    2015-01-01

    The most effective way of increasing switching abilities of high voltage circuit breakers in energy transmission systems is to influence around zero degree to short circuit currents (Maljkovic Z et al 2000; Gashimov, A.M et al. 2001;Antipov, K.M et al. 1985; Gashimov A.M 1991). For this reason, transformers neutral points should be grounded variously for limitation of asymmetric short circuit currents. But another way for this limitation is grounded of transformers neutral points over non-lin...

  6. Fellows in the Middle: Fabulous Field Trips

    Science.gov (United States)

    West, Mary Lou

    2008-05-01

    Montclair State University's NSF GK-12 Program focuses on grades 7 and 8 in five urban public school districts in northern New Jersey. Each year four fieldtrips are taken by the students, middle school teachers, and graduate student Fellows. Many interdisciplinary hands-on lessons are written for use before, during and after each trip with this year's theme of Earth history. The Sterling Hill Mine trip evoked lessons on geology, economics, crystal structure, density, and pH. A virtual trip (webcam link) to scientists in the rainforest of Panama prompted critical thinking, categorizing layers and animals, and construction of model food webs. In the field trip to the NJ School of Conservation the students will build model aquifers, measure tree heights, and measure stream flow to compare to their Hackensack River. Finally the students will travel to MSU for a Math/Science Day with research talks, lab tours, hands-on activities, and a poster session. In January 2008 seventeen teachers, Fellows, and grant personnel took a field trip to China to set up collaborations with researchers and schools in Beijing and Xi'an, including the Beijing Ancient Observatory. All field trips are fabulous! Next year (IYA) our theme will be planetary science and will feature field trips to the Newark Museum's Dreyfuss Planetarium, BCC Buehler Challenger & Science Center, and star parties. We look forward to invigorating middle school science and mathematics with exciting astronomy. Funded by NSF #0638708

  7. Thyristor DC circuit breakers for alcator C-MOD

    International Nuclear Information System (INIS)

    This paper reports on the Alcator C-MOD PF system which requires DC circuit breakers in 5 poloidal field magnets for plasma initiation. Vacuum circuit breakers developed for the Alcator A and Alcator C experiments offered a proven technology but marginal reliability and relatively high maintenance costs. The thick vacuum chamber walls and heavy steel superstructure of Alcator C-MOD make relatively low start-up voltages attractive to limit eddy currents during plasma initiation. Design values and simulations for 3 switches are presented. Switch sections are rated 2 kV maximum interrupting voltage with bipolar current ratings of 50, 25, and 15 kA. A pulse-forming network provides the required 400 μsec turn-off pulse to the SCRs. The design is strongly influenced by the parasitic inductance in bus and circuit components. Time and cost limits precluded the construction of prototypes, so extensive simulation of the circuit was required. Two separate simulation approaches were cross-checked for accuracy and consistency

  8. Analysis and full scale test of DC circuit breaker for tokamak device JT-60

    International Nuclear Information System (INIS)

    In recent large Tokamak nuclear fusion devices, the energy stored in inductance has become to be employed in order to ignite and heat plasma. The device for this purpose is operated very frequently for the sake of improving service efficiency. This has led to the necessity to obtain heavy duty, longer life DC circuit breakers. For example, in the critical plasma testing device JT-60, direct current of 92 kA must be broken at about 10 min intervals. The authors succeeded to stabilize vacuum arcs through the investigations on the method to apply a magnetic field in parallel with the arcs. This allowed to drastically increase the life and the breakable current of breakers. Thus they have developed the DC circuit breaker for JT-60 by connecting the breakers of this type in parallel, and have succeeded to break 44 kV-130 kA duty. In this paper, first the power supply circuit for a commutation coil and the DC circuit breaker, and next, the problems and experiments on parallel current sharing are described, and the DC circuit breaker made for trial and its full scale test are reported. The vacuum circuit breaker applying axial magnetic field is ideal. The key to success lies in parallel current sharing, and the unequal opening time for each parallel circuit must be minimized. Further, the balancing action to correct the unbalance in current sharing by employing a saturable reactor can also be expected. (Wakatsuki, Y.)

  9. Interactive effects of relay and circuit breaker aging in a safety-related system

    International Nuclear Information System (INIS)

    This paper provides an overview of the results of a program to evaluate the aging of circuit breakers and relays and the effects of that aging on the function of a safety system used in nuclear power plants. The program was performed under the Nuclear Plant Aging Research (NPAR) Program of the US Nuclear Regulatory Commission under subcontract to Brookhaven National Laboratory. There were two primary aspects to the program. In the first, the aging and failure modes of relays and circuit breakers were determined by evaluating the construction, design, and materials and the failure data related to nuclear power plant service. In the second, the interactions between a safety system and its relays and circuit breakers were evaluated to determine the effects of relay and circuit breaker aging on the function of the safety system. The aging of relays and circuit breakers was assessed through evaluation of failure data bases, discussions with utility personnel, and evaluation of equipment operating and maintenance manuals. The interaction study was based on an analysis of the safety injection system of a pressurized water reactor. The effects of stresses from the system were analyzed for the tendency to cause deterioration of the relays and circuit breakers in the system. Then the effect of the deterioration of relays and circuit breakers on the functional capability of the safety system was evaluated

  10. Large Pelagic Logbook Trip Survey (Vessels)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains catch and effort for fishing trips that are taken by vessels with a Federal permit issued for the swordfish and sharks under the Highly...

  11. Abnormal Events for Emergency Trip in HANARO

    International Nuclear Information System (INIS)

    This report gathers abnormal events related to emergency trip of HANARO that happened during its operation over 10 years since the first criticality on February 1995. The collected examples will be utilized to the HANARO's operators as a useful guide

  12. Pre-Trip Notification Database (PTNS)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The PTNS contains pre-trip notification data from vessels participating in the Northeast Multispecies groundfish fishery from 2010 to present and the Longfin squid...

  13. Trip report : Crescent Lake National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This trip report is on a visit to Crescent Lake National Wildlife Refuge on September 20 and 21 2001. Wetlands inspected on the Moore Drainage included Martin,...

  14. Lobster Processing and Sales Trip Report Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This is a federally mandated log which is required to be mailed in to NMFS after a fishing trip. This data set includes lobster processing and sales information...

  15. TRIPS and Pharmaceuticals: Implications for India

    OpenAIRE

    S. Mehta, Pradeep

    2012-01-01

    On the post-Uruguay Round world trade scenario, after the accords in agriculture and textiles and clothing, the Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPs) is the issue affecting developing countries like India. One of the seven intellectual properties covered under TRIPs is that of patents. It has been the contentious issue for several reasons. India is committed to amend its patent laws by the year 2005 (for technologies previously unprotected in its market). ...

  16. Trip electrical circuit of the gyrotion

    International Nuclear Information System (INIS)

    The electron cyclotron resonance heating system of INPE/LAP is shown and the trip electrical circuit of the gyrotron is described, together with its fundamental aspects. The trip electrical circuit consists basically of a series regulator circuit which regulates the output voltage level and controls the pulse width time. Besides that, a protection circuit for both tubes, regulator and gyrotron, against faults in the system. (author)

  17. Scrutinized: The TRIPS Agreement and Public Health

    OpenAIRE

    Subhan, Junaid

    2006-01-01

    SUMMARY The World Trade Organization’s (WTO’s) Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPS) of 1994 seeks to implement a uniform set of intellectual property protection across member nations to provide greater stability in international economic relations. Critics argue that the TRIPS agreement provides unnecessarily strong protection of intellectual property rights which serves to prevent the ill in developing nations from having access to affordable essential m...

  18. Improving power quality with reliable synchronized switching with spring operated high-voltage circuit-breakers

    Energy Technology Data Exchange (ETDEWEB)

    Solver, Carl E. [ABB, SP (Brazil). E-mail: antonio.baltasar.silva@br.abb.com

    1999-07-01

    This paper describes the design work aiming the achievement of a well defined and stable operating times of the HPL-B circuit-breaker. In the work , computer simulations of the motion of the complete mechanical system were conducted, a basis for optimisation of the opening and closing latches were established, and an overall robust design of the complete circuit-breaker performed as well. The HPL-B type SF6 puffer breakers, available for rated 245 to 800 kV voltages were considered in the work.

  19. Experiment of explosively actuated DC circuit breaker to protect superconducting magnet on quench

    International Nuclear Information System (INIS)

    The DC circuit breaker to protect superconducting magnet on quench must be reliable to limit the risk of their damage to an acceptable level. The scheme envisioned for TPX tokamak consisted of a traditional breaker connected in series with an explosively actuated breaker (EAB). EAB is partially sacrificed each time its operates but, due to its inherent simplicity, can be shown extremely reliable. Two prototypes of EAB have been tested under conditions which simulate the TPX application on a scale, in order to demonstrate feasibility and to develop a better understanding. (author)

  20. Field Trips as Valuable Learning Experiences in Geography Courses

    Science.gov (United States)

    Krakowka, Amy Richmond

    2012-01-01

    Field trips have been acknowledged as valuable learning experiences in geography. This article uses Kolb's (1984) experiential learning model to discuss how students learn and how field trips can help enhance learning. Using Kolb's experiential learning theory as a guide in the design of field trips helps ensure that field trips contribute to…

  1. The Effect of Current-Limiting Reactors on the Tripping of Short Circuits in High-Voltage Electrical Equipment

    Energy Technology Data Exchange (ETDEWEB)

    Volkov, M. S.; Gusev, Yu. P., E-mail: GusevYP@mpei.ru; Monakov, Yu. V.; Cho, Gvan Chun [National Research University “Moscow Power Engineering Institute,” (Russian Federation)

    2016-01-15

    The insertion of current-limiting reactors into electrical equipment operating at a voltage of 110 and 220 kV produces a change in the parameters of the transient recovery voltages at the contacts of the circuit breakers for disconnecting short circuits, which could be the reason for the increase in the duration of the short circuit, damage to the electrical equipment and losses in the power system. The results of mathematical modeling of the transients, caused by tripping of the short circuit in a reactive electric power transmission line are presented, and data are given on the negative effect of a current-limiting resistor on the rate of increase and peak value of the transient recovery voltages. Methods of ensuring the standard requirements imposed on the parameters of the transient recovery voltages when using current-limiting reactors in the high-voltage electrical equipment of power plants and substations are proposed and analyzed.

  2. The Effect of Current-Limiting Reactors on the Tripping of Short Circuits in High-Voltage Electrical Equipment

    International Nuclear Information System (INIS)

    The insertion of current-limiting reactors into electrical equipment operating at a voltage of 110 and 220 kV produces a change in the parameters of the transient recovery voltages at the contacts of the circuit breakers for disconnecting short circuits, which could be the reason for the increase in the duration of the short circuit, damage to the electrical equipment and losses in the power system. The results of mathematical modeling of the transients, caused by tripping of the short circuit in a reactive electric power transmission line are presented, and data are given on the negative effect of a current-limiting resistor on the rate of increase and peak value of the transient recovery voltages. Methods of ensuring the standard requirements imposed on the parameters of the transient recovery voltages when using current-limiting reactors in the high-voltage electrical equipment of power plants and substations are proposed and analyzed

  3. Every Speed Breaker Is A Source Of Power

    Directory of Open Access Journals (Sweden)

    N. N. Ghuge,

    2014-03-01

    Full Text Available Electricity in India, is a big problem which is faced by people who reside in the country. Electricity is the form of energy, Electricity is a basic part of nature and it is one of our most widely used forms of energy. We get electricity, which is a secondary energy source, from the conversion of other sources of energy, like coal, natural gas, oil, nuclear power and other natural sources, which are called primary sources. Before electricity generation began slightly over 100 years ago, we use kerosene lamps, and rooms were warmed by wood-burning or coal burning stoves. Direct current (DC electricity had been used in arc lights for outdoor lighting. In the late-1800s, Nikola Tesla pioneered the generation, transmission, and use of alternating current (AC electricity, which can be transmitted over much greater distances than direct current. Generating electricity by speed breakers is innovative and useful concept. R

  4. Modeling DC-circuit-breakers for long distance electricity transmission

    Science.gov (United States)

    Agnihotri, Ashutosh; Ebert, Ute; Hundsdorfer, Willem

    2014-10-01

    Modeling a circuit-breaker is a multiple timescale problem which involves a cascade of physical processes from avalanche phase to streamer, spark and post discharge phase, with a transition phase between each pair of processes. In particular, Jin Zhang and Bert van Heesch at Eindhoven University of Technology investigate now whether the conventional SF6 can be replaced by supercritical nitrogen. We focus on modeling space charge effects, gas heating and secondary electron emission from cathode. We develop a two-dimensional drift-diffusion model for streamers coupled to the Euler equations for the gas to study the related phenomena. We perform simulations to capture thermal shocks and induced pressure waves caused by the electrical breakdown of the surrounding gas. We include heat exchange mechanisms between the electrons/ions and the surrounding gas.

  5. Advances in low-voltage circuit breaker modelling

    International Nuclear Information System (INIS)

    This paper is devoted to the study of electric arc behaviour under the influence of an external magnetic field. This situation is close to that occurring in a low-voltage circuit breaker where an arc, after ignition, is submitted to the magnetic field of the circuit. After a discussion of the literature, we present our contribution. Two different methods are compared to take the magnetic effects into account. Arc displacement in the geometry studied is dealt within a specific development presented in this paper. We show the influence of the nature of the gas on the arc velocity and on possible re-strike using air and an air-PA6 mixture as the plasma gas

  6. A fast circuit breaker for 105A current

    International Nuclear Information System (INIS)

    A fast circuit breaker operated by an electromagnetic command has been realized. It can open very high currents in times in order of a few microseconds. By means of electromagnetic forces, a conductor is sent against rods and thus cut. The current is then transferred onto a fuse placed in parallel. The explosion of the fuse opens the circuit. A simplified set up has permitted to test some performances of the switch. A 240kA current has been opened in 6μs and a 5kV peak voltage simultaneously generated (half-width : 3μs). The transfer of a 130kA current has been realized in a time as small as 2μs

  7. OH breaker of ASDEX upgrade: closing switch without ignitrons

    International Nuclear Information System (INIS)

    The OH breaker serves for plasma breakdown. It switches a resistor in a current-carrying inductive circuit. It comprises an opening switch (Q1) and a closing switch (Q3). Both are assessed in detail by measuring the transient currents and voltages of the switching circuit. The closing switch is treated in more detail. It has to carry a dc current of up to 45 kA for several seconds. In this case the switching arc is normally taken by ignitrons and the dc current by vacuum tubes. This paper shows that closing vacuum tubes are capable of working without ignitrons. More than 1,350 Q3 switching actions have confirmed this and support the experimental and theoretical investigations. (orig.)

  8. Numerical Simulation of Gas Flow During Arcing Process for 252 kV Puffer Circuit Breakers

    Science.gov (United States)

    Wu, Junhui; Wang, Xiaohua; Ma, Zhiying; Rong, Mingzhe; Yan, Jing

    2011-12-01

    A numerical simulation model for 252 kV puffer circuit breaker is constructed, by using a proven commercial computational fluid dynamics (CFD) package, PHOENICS. The model takes into account the moving parts in the circuit breaker, turbulence enhanced momentum and energy transport, radiation transport. The arcing process in a SF6 puffer circuit breaker with two hollow contacts is simulated under different conditions, and the simulation results are verified with experimental results. Through simulation, the pressure, temperature and velocity in the arc quenching chamber can be obtained. The simulation model is also capable of predicting the influence of design parameters variations on breaker performance, and can thus help to reduce the number of short-circuit tests during the design stage.

  9. Modeling of Thermal Arcs in Molded Case Circuit Breakers in Air

    Science.gov (United States)

    Breden, Doug; Mahadevan, Shankar; Raja, Laxminarayan

    2015-09-01

    A general-purpose thermal plasma simulation tool (VizArc) was utilized to model a circuit breaker in atmospheric pressure air. The molded case circuit breaker (MCCB) circuit breaker works by separating two metal contacts when the breaking current is exceeded generating an arc. The self-consistent Lorentz force generated by the current pushes the arc into an array of splitter plates which quench the arc and break the circuit. The arc channel is modeled by coupling the electromagnetic equations with flow governing equations to model a multi-species, single-temperature quasi neutral arc plasma. Conjugate heat transfer to the metal splitter plates and vapor ablation into the gas are included in the model. The opening action of the moving contact armature is simulated dynamically in the simulation. The set of all governing equations and their implementation in the model will be discussed, and then the simulations of the MCCB circuit breaker using the model will be presented.

  10. Numerical Simulation of Gas Flow During Arcing Process for 252 kV Puffer Circuit Breakers

    International Nuclear Information System (INIS)

    A numerical simulation model for 252 kV puffer circuit breaker is constructed, by using a proven commercial computational fluid dynamics (CFD) package, PHOENICS. The model takes into account the moving parts in the circuit breaker, turbulence enhanced momentum and energy transport, radiation transport. The arcing process in a SF6 puffer circuit breaker with two hollow contacts is simulated under different conditions, and the simulation results are verified with experimental results. Through simulation, the pressure, temperature and velocity in the arc quenching chamber can be obtained. The simulation model is also capable of predicting the influence of design parameters variations on breaker performance, and can thus help to reduce the number of short-circuit tests during the design stage. (15th asian conference on electrical discharge)

  11. An aging assessment of relays and circuit breakers and system interactions

    International Nuclear Information System (INIS)

    This report provides an assessment of the aging of circuit breakers and relays which are vital components of the nuclear power plant electrical safety system, and was conducted under the auspices of the NRC Nuclear Aging Research (NPAR) Program. The study included protective, control, and logic relays, and molded-case and metal-clad switchgear circuit breakers. The relay failures were attributable to coil deterioration, changes in dimensions of critical organic components, and changes in characteristics of timing diaphragms from thermal deterioriation. Some of the failure modes will prevent fail-safe operation. The electrical control and mechanical portions of metal-clad switchgear were found to be more failure prone than the main contacts and arc extinguishing systems. Circuit breakers and relays in a PWR safety injection system were evaluated with respect to the aging induced by system operation. The effect of circuit breaker and relay deterioration on the ability of the system to perform its safety functions was also evaluated

  12. Modeling and Verification of Ultra-Fast Electro-Mechanical Actuators for HVDC Breakers

    OpenAIRE

    Bissal, Ara

    2015-01-01

    The continuously increasing demand for clean renewable energy has rekindled interest in multi-terminal high voltage direct current (HVDC) grids. Although such grids have several advantages and a great potential, their materialization has been thwarted due to the absence of HVDC breakers. In comparison with traditional alternating current (AC) breakers, they should operate and interrupt fault currents in a time frame of a few milliseconds. The aim of this thesis is focused on the design of ult...

  13. Approaching the Processes in the Generator Circuit Breaker at Disconnection through Sustainability Concepts

    OpenAIRE

    Carmen A. Bulucea; Nikos E. Mastorakis; Doru A. Nicola; Marc A. Rosen; Cornelia A. Bulucea

    2013-01-01

    Nowadays, the electric connection circuits of power plants (based on fossil fuels as well as renewable sources) entail generator circuit-breakers (GCBs) at the generator terminals, since the presence of that electric equipment offers many advantages related to the sustainability of a power plant. In an alternating current (a.c.) circuit the interruption of a short circuit is performed by the circuit-breaker at the natural passing through zero of the short-circuit current. During the current i...

  14. Application of thyristor circuit breaker to ohmic heating coil power supply systems

    International Nuclear Information System (INIS)

    New ohmic heating coil power supply systems which can generate high voltage are studied to insure their effective and economical use in nuclear fusion devices. Several systems are conceived by using normal, module, and multi-stage repetition types of thyristor circuit breakers. The operation of these systems are analyzed by digital simulation. It is seen that these thyristor circuit breakers are practical and applicable in ohmic heating coil power supply systems. (author)

  15. CFD Simulation of Transonic Flow in High-Voltage Circuit Breaker

    OpenAIRE

    Xiangyang Ye; Mahesh Dhotre

    2012-01-01

    A high-voltage circuit breaker is an indispensable piece of equipment in the electric transmission and distribution systems. Transonic flow typically occurs inside breaking chamber during the current interruption, which determines the insulating characteristics of gas. Therefore, accurate compressible flow simulations are required to improve the prediction of the breakdown voltages in various test duties of high-voltage circuit breakers. In this work, investigation of the impact of the solver...

  16. Experimental and theoretical analysis of vacuum circuit breaker prestrike effect on a transformer

    OpenAIRE

    Popov, M.; Smeets, RPP René; Sluis, van der, B.J.; Herdt, de, H; Declercq, J.

    2009-01-01

    The work presented in this paper deals with the investigation of circuit breaker prestrike effect that occurs during energizing a distribution transformer. An experimental test setup that consists of a supply transformer, a vacuum circuit breaker (VCB), a cable and a test transformer is built, and the prestrikes in the VCB are recorded. The test transformer is a prototype distribution transformer, with installed measuring points along transformer windings in each phase. Voltage oscillations a...

  17. On-line Monitoring System based on Vibration Signal of High Voltage Circuit Breaker

    OpenAIRE

    Chao Fu; Jing Hao

    2014-01-01

    High voltage circuit breaker is one of the most important switch apparatus in electrical power system. It play a role in the switch control, which can be used to switch the operating mode during normal operation (the equipment run or quit). In order to ensure the normal operation of the grid, it can be removed quickly when a malfunction on the device or circuit. Real-time online monitoring of high voltage circuit breaker can understand the running status, master the operation characteristics ...

  18. Dedicating Finite Volume Method to Electromagnetic Plasma Modeling: Circuit Breaker Application

    OpenAIRE

    Rondot, Loïc; Mazauric, Vincent; Delannoy, Yves; Meunier, Gérard

    2009-01-01

    For several applications including strong hydrodynamics constraints (like in a circuit breaker), Finite Element solvers are not suitable for fluid dynamical modeling. For these applications, the coupling between the Computational Fluid Dynamics and the electromagnetism modeling is not easy. In this context, a magnetodynamic formulation is developed using the Finite Volume Method to address specific issues in multiphysics involved in circuit breaker modeling. The principles of Finite Volume Me...

  19. Second trip system for NRU research reactor

    International Nuclear Information System (INIS)

    For the past four decades, the NRU research reactor has played an important role at the Chalk River Laboratories, Atomic Energy of Canada Limited, serving as one of its major research and isotope production facilities. To ensure that it continues as an effective facility, compliant with the current safety standards, a comprehensive upgrade program is underway. Adding a second trip system (STS) is part of this upgrade program, aiming at improving the effectiveness and reliability of the overall shutdown function. This document describes the main features and basic principles of the STS.The STS is an independent, seismically qualified trip system, that guarantees reactor shutdown even if the existing trip system fails. It is designed based on 2 out of 3 general coincidence logic, with minimal interferences and changes to the existing system. In addition to the manual trip in the main control room, a remote manual trip is provided in the new Qualified Emergency Response Centre, which is also seismically qualified and always accessible. Thus, for any reason, if the main control room becomes uninhabitable, the reactor still can be manually shut down from this centre. ((orig.))

  20. Replacement circuit breakers by retrofitting of 7.2 kV 63 kA TCB to VCB development

    International Nuclear Information System (INIS)

    Fuji Electric has maintained the facility of 6.9 kV metal-clad switchgear at Tokai-II Power Station, through periodic inspections since the first operation. Responding to the fact that the maintenance parts of the circuit breaker are becoming exhaustive, we developed two types of vacuum circuit breakers in order to promote the replace for minimal oil circuit breakers (TCB). This paper presents the development process and outline of the retrofitting VCB. (author)

  1. Study of the cost reduction possibilities on the secondary equipment of SION Vacuum Circuit Breaker from Siemens AG

    OpenAIRE

    Gil González, Alba

    2011-01-01

    The aim of this Master Thesis is to make a study of the cost reduction possibilities of the secondary equipment of SION Vacuum Circuit Breaker from Siemens AG. The secondary equipment of a circuit breaker consists of several auxiliary devices –usually electronic- which are necessary for operating and controlling the breaker. Regarding the most important requirements for the new M3 price driven market which are Price reduction and Standard technology, a study on the current situation and...

  2. Real Time Monitoring of SF6 Gas Pressure for Optimization Point on Wave Switching of SF6 Circuit Breaker

    OpenAIRE

    Ashish Maheshwari1 , Sunil Kumar Singla

    2013-01-01

    This paper introduce the real time analysis of sf6 gas pressure for optimizing point on wave switching of sf6 circuit breaker. Circuit Breaker plays an important role in today’s growing Indian economy in power systems. It provides protection to transmission equipment incorporated in transmission networks. SF6 Circuit Breaker is very important equipment in Power Systems which is used for up to 1200 kVbecause of its excellent performance. SF6 Gas plays a vital role to operate the Breaker. Also ...

  3. A 7.2kV, 63kA large-capacity, SF6-gas circuit breaker

    International Nuclear Information System (INIS)

    Mitsubishi Electric has developed an SF6-gas circuit breaker with a rated voltage of 7.2 kV and a rated interrupting current of 63 kA that offers the maximum capacity of circuit breakers for station service use in auxiliary equipment for nuclear- and thermal-power plants. The article reports on the construction features and performance achieved with this breaker. Housed in a metal-clad cubicle, this breaker displays many excellent features, including size reduction, higher reliability, and greater safety by employing a puffer-type, arc-extinguishing chamber, a column-enclosed grounded metallic tank, and a spring-operated mechanism. (author)

  4. Development of DC solenoid operation type 7.2 kV 63 kA vacuum circuit breaker

    International Nuclear Information System (INIS)

    Fuji Electric has maintained the facility of 6.9 kV metal-clad switchgear at Tokai-II Power Station, through periodic inspections since the first operation. Responding to the fact that the maintenance parts of the circuit breaker are becoming exhaustive, we developed two types of vacuum circuit breakers in order to promote the replace for minimal oil circuit breakers (TCB). This paper presents an overview of the development for DC solenoid operating type VCB, which is adopted for emergency circuit breaker. (author)

  5. NEWS: A trip to CERN

    Science.gov (United States)

    Ellison, A. D.

    2000-07-01

    the canteen. Over lunch we mixed with physicists of many different nationalities and backgrounds. Figure 1 Figure 1. In the afternoon we visited Microcosm, the CERN visitors centre, and the LEP control room and also the SPS. Here the students learned new applications for much of the physics of standing waves and resonance that they had been taught in the classroom. Later that night, we visited a bowling alley where momentum and collision theory were put into practice. The following morning we returned to CERN and visited the large magnet testing facility. Here again physics was brought to life. We saw superconducting magnets being assembled and tested and the students gained a real appreciation of the problems and principles involved. The afternoon was rounded off by a visit to a science museum in Geneva - well worth a visit, as some of us still use some of the apparatus on display. Friday was our last full day so we visited Chamonix in the northern Alps. In the morning, we ascended the Aiguille de Midi - by cable car. Twenty minutes and 3842 m later we emerged into 50 km h-1 winds and -10 °C temperature, not counting the -10 °C wind chill factor. A crisp packet provided an unusual demonstration of the effects of air pressure (figure 2). Figure 2 Figure 2. The views from the summit were very spectacular though a few people experienced mild altitude sickness. That afternoon the party went to the Mer de Glace. Being inside a 3 million year-old structure moving down a mountain at 3 cm per day was an interesting experience, as was a tot of whisky with 3 million year-old water. Once again the local scenery was very photogenic and the click and whirr of cameras was a constant background noise. Saturday morning saw an early start for the long drive home. Most students - and some staff - took the opportunity to catch up on their sleep. Thanks are due to many people without whom the trip would never have taken place. Anne Craige, Stuart Williams

  6. Round-trip boat on hydrogen

    International Nuclear Information System (INIS)

    The results of a feasibility study on a PEM (polymer-electrolyte membrane) fuel cell (FC) driven electric round-trip boat are presented and discussed. The study concerns the specification of a PEMFC system design, including a list of components. Also technical and environmental aspects are dealt with and compared with traditional battery-driven electric boats and diesel-driven boats

  7. The Educational Value of Field Trips

    Science.gov (United States)

    Greene, Jay P.; Kisida, Brian; Bowen, Daniel H.

    2014-01-01

    The school field trip has a long history in American public education. For decades, students have piled into yellow buses to visit a variety of cultural institutions, including art, natural history, and science museums, as well as theaters, zoos, and historical sites. Schools gladly endured the expense and disruption of providing field trips…

  8. Memorable Experiences of a Science Field Trip.

    Science.gov (United States)

    Knapp, Doug

    2000-01-01

    Attempts to learn more about memorable experiences associated with science field trips by conducting a 1-month and an 18-month evaluation of elementary school students who had participated in an environmental science program at a community park in a Midwestern city. Concludes that students' memories were nonspecific and disassociated from…

  9. No "big trips" for the universe

    CERN Document Server

    Faraoni, V

    2007-01-01

    It has been claimed in several papers that a phantom energy-dominated universe can undergo a ``big trip'', i.e., tunneling through a wormhole that grows faster than the cosmic substratum due to the accretion of phantom energy, and will reappear on the other mouth of the wormhole. We show that such claims are unfounded and contradict the Einstein equations.

  10. Southeast Region Headboat Survey-Trip Estimates by Type

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This is a summary of the number of trips by vessel/area/month/trip type through time and is a means of gauging headboat fishery effort and compliance through time.

  11. Automobile trip to Fish Springs, March 16, 1959

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — These memoranda describe trips to Fish Springs National Wildlife Refuge. The purpose of these trips was to access the condition of the land in the Fish Springs area.

  12. Laboratory effectiveness testing of water-in-oil emulsion breakers

    International Nuclear Information System (INIS)

    The physics and chemistry of water-in-oil emulsions dominate the development of effectiveness tests. Emulsions are variable in stability--this variability is largely dependent on oil type and degree of weathering. These factors complicate the development of a test. Emulsions which have low stability will apparently break easily with chemical emulsion breakers. Broken emulsions will form a foam-like material, called rag, which retains water which is not part of the stable emulsions. Analytical methods used to determine the final stability of the broken or unbroken emulsion were evaluated. Measurements of water content and viscosity measurements show correlation to emulsion stability. Viscosity provides a more reliable measure of emulsion stability but water content measurements are more convenient and are largely used in this study. Twelve tests were developed in the past. Two testing methods have been developed to a usable stage. These tests are described and data using them provided. The effects of mixing time, agent amount, settling time and mixing energy on effectiveness results are presented

  13. The ice-breaker effect: singing mediates fast social bonding.

    Science.gov (United States)

    Pearce, Eiluned; Launay, Jacques; Dunbar, Robin I M

    2015-10-01

    It has been proposed that singing evolved to facilitate social cohesion. However, it remains unclear whether bonding arises out of properties intrinsic to singing or whether any social engagement can have a similar effect. Furthermore, previous research has used one-off singing sessions without exploring the emergence of social bonding over time. In this semi-naturalistic study, we followed newly formed singing and non-singing (crafts or creative writing) adult education classes over seven months. Participants rated their closeness to their group and their affect, and were given a proxy measure of endorphin release, before and after their class, at three timepoints (months 1, 3 and 7). We show that although singers and non-singers felt equally connected by timepoint 3, singers experienced much faster bonding: singers demonstrated a significantly greater increase in closeness at timepoint 1, but the more gradual increase shown by non-singers caught up over time. This represents the first evidence for an 'ice-breaker effect' of singing in promoting fast cohesion between unfamiliar individuals, which bypasses the need for personal knowledge of group members gained through prolonged interaction. We argue that singing may have evolved to quickly bond large human groups of relative strangers, potentially through encouraging willingness to coordinate by enhancing positive affect. PMID:26587241

  14. Fast circuit breakers for 200 kA currents

    International Nuclear Information System (INIS)

    A circuit breaker operated by mechanical rupture, capable of opening very high currents in times of the order of ten microseconds has been realized. A copper conductor in the form of a T, fragilized at the joint of the arms and the leg, is ruptured by oil under a pressure of 3 kbars. This pressure is obtained by the magnetic forces of a 600 kA current pulse flowing in a coaxial conductor system. Current flowing in an inductive storage coil is transferred onto a fuse in 9 microseconds. The subsequent explosion of the fuse can either open the circuit and absorb all the stored energy or transfer it to any desired load. The switch is sufficiently reisolated to withstand the voltage peak thus created. A 200 kA current has thus been opened in 20 microseconds and a 9 kV overvoltage sustained. The system, because of its inherent symmetry, can be lengthened to obtain any desired current carrying capacity and requires a relatively small command energy

  15. Austenite stability in TRIP steels studied by synchrotron radiation

    NARCIS (Netherlands)

    Blondé, R.

    2014-01-01

    TRIP steel is a material providing great mechanical properties. Such steels show a good balance between high-strength and ductility, not only as a result of the fine microstructure, but also because of the well-known TRIP effect. The Transformation Induced-Plasticity (TRIP) phenomenon is the transfo

  16. Ohmic heating coil power supply using thyristor circuit breaker in a thermonuclear fusion device

    International Nuclear Information System (INIS)

    In a large scale Tokamak thermonuclear fusion device such as the critical plasma testing facility (JT60) presently under construction, mechanical breakers such as vacuum and air breakers are mostly used for interrupting DC heavy current which is supplied to the ohmic heating coils of inductive energy accumulation method. The practical use of the DC breakers employing thyristors has just been started because the history of thyristor development is short and thristors are still expensive, in spite of the advantages. In this paper, the circuit is investigated in which the excellent high speed controllability of thyristors is fully utilized, while the economy is taken into accout, and the experiment carried out with a unit model is described. It was found that a thyristor switch, which was constructed by connecting the high speed thyristors of peak off-state voltage rating 2,000 V and mean current rating 500 A in direct parallel, was able to interrupt 12.7 kA current in the power supply circuit of ohmic heating coils developed this time. In addition, the switch configuration was able to be greatly simplified. When the multistage raising of plasma current is required, the raise can be performed with a single thyristor breaker because it can make high speed control. Therefore, the capacity of the breaker can be doubly and drastically reduced. Also, if current unbalance might occur between thyristor switch units, it gives no problem since the time of reverse voltage after current interruption dispersed smaller as current increased. (Wakatsuki, Y.)

  17. Numerical Simulation of the Laval Annular Mechanical Foam Breaker for Foam Drilling

    Directory of Open Access Journals (Sweden)

    Pin Lu Cao

    2013-12-01

    Full Text Available The Computational Fluid Dynamics (CFD code, Fluent, is employed to simulate the flow phenomena inside the annular foam breaker in order to improve its performance. The numerical simulation results show that the value and the distribution of the negative pressure are very important for the annular foam breaker. The design of the Laval nozzle not only can increase the fluid velocity, but also can reduce the pressure value from -30.2 to -50.3 kPa compared with the common annular nozzle foam breaker. In order to improve the range of the internal negative pressure, the two-stage Laval annular foam breaker is designed in this study. The analysis results show the distance between the two annular slit have greatly influence on its performance. There is a small overlap area between the two negative pressure zones generated by the two annular slits. The smaller the value distance is, the larger the overlap zone is. When the value of the distance decreases to 50 mm, the minimum negative pressure can be reduced to approximately -65.5 kPa. Meanwhile, the range of the internal negative pressure is larger than the single Laval annular foam breaker, which is benefit to break foam.

  18. Biocompatible circuit-breaker chip for thermal management of biomedical microsystems

    International Nuclear Information System (INIS)

    This paper presents a thermoresponsive micro circuit breaker for biomedical applications specifically targeted at electronic intelligent implants. The circuit breaker is micromachined to have a shape-memory-alloy cantilever actuator as a normally closed temperature-sensitive switch to protect the device of interest from overheating, a critical safety feature for smart implants including those that are electrothermally driven with wireless micro heaters. The device is fabricated in a size of 1.5  ×  2.0  ×  0.46 mm3 using biocompatible materials and a chip-based titanium package, exhibiting a nominal cold-state resistance of 14 Ω. The breaker rapidly enters the full open condition when the chip temperature exceeds 63 °C, temporarily breaking the circuit of interest to lower its temperature until chip temperature drops to 51 °C, at which the breaker closes the circuit to allow current to flow through it again, physically limiting the maximum temperature of the circuit. This functionality is tested in combination with a wireless resonant heater powered by radio-frequency electromagnetic radiation, demonstrating self-regulation of heater temperature. The developed circuit-breaker chip operates in a fully passive manner that removes the need for active sensor and circuitry to achieve temperature regulation in a target device, contributing to the miniaturization of biomedical microsystems including electronic smart implants where thermal management is essential. (paper)

  19. Simulation of SLF Interrupting Performance for CO2 Gas Circuit Breaker based on Serially Connected 3 Arc Models

    Science.gov (United States)

    Koshizuka, Tadashi; Udagawa, Keisuke; Shinkai, Takeshi; Uchii, Toshiyuki; Kawano, Hiromichi

    This paper shows the simulation of SLF interrupting performances for CO2 gas circuit breakers. In the SLF interruption tests using 72kV-CO2 gas model circuit breakers, very large post arc currents were measured. This point is obviously difference between CO2 circuit breaker and SF6 one. To simulate the SLF interrupting performances for the SF6 gas circuit breakers, serially connected 3 arc models were developed. In the arc model, Cassie arc model and two Mayr arc models were serially connected. It was tried to use the arc model to simulate the SLF interrupting performances for CO2 circuit breaker. As a result, it was good agreement with the measurements and simulations. The large post arc currents could be simulated by the arc model. It was shown that the SLF interrupting performance of the CO2 circuit breaker was dependent on the Mayr model simulated around voltage extinction peak. On the other hand, the performance of the SF6 gas circuit breaker was dependent on the Mayr model simulated around current zero. From the result, it proved that most severe SLF condition for the CO2 gas circuit breaker was L75 or L80.

  20. Thermal and Electrodynamic Risk of Residual Current Devices in the Case of Back-Up Protection by Overcurrent Circuit Breakers

    Directory of Open Access Journals (Sweden)

    Stanisław Czapp

    2014-12-01

    Full Text Available Residual current operated circuit breakers without integral overcurrent protection should be back-up protected. As back-up protection devices, overcurrent circuit breakers are used. The maximum let-through energy and let-through current of the overcurrent devices were evaluated under laboratory conditions. The thermal and electrodynamic risk of residual current devices was analyzed.

  1. Using Virtual Field Trips to Connect Students with University Scientists: Core Elements and Evaluation of zipTrips[TM

    Science.gov (United States)

    Adedokun, Omolola A.; Hetzel, Kristin; Parker, Loran Carleton; Loizzo, Jamie; Burgess, Wilella D.; Robinson, J. Paul

    2012-01-01

    Physical field trips to scientists' work places have been shown to enhance student perceptions of science, scientists and science careers. Although virtual field trips (VFTs) have emerged as viable alternatives (or supplements) to traditional physical fieldtrips, little is known about the potential of virtual field trips to provide the same or…

  2. Propagation of the trip behavior in the VENUS vertex chamber

    International Nuclear Information System (INIS)

    The high voltage system of the VENUS vertex chamber occasionally trips by a discharge somewhere among cathode electrodes during data taking. This trip behavior induces often additional trips at other electrodes such as the skin and the grid electrodes in the vertex chamber. This propagation mechanism of trips is so complicated in this system related with multi-electrodes. Although the vertex chamber is already installed inside the VENUS detector and consequently the discharge is not able to observe directly, a trial to estimate the propagation has been done using only the information which appears around the trip circuits and the power supply of the vertex chamber. (author)

  3. Study of SLF Interruption that led the Development of SF6 Circuit Breaker

    Science.gov (United States)

    Ushio, Tsunero; Ito, Toshio; Mori, Fusao

    In 1953, the study committee on restriking voltage was organized by Electric Technology Research Association of Japan. The result of researches made by the committee was reported in 1956 CIGRE. The report pointed out the case of severe restriking voltage which is realized at some occasion of transmission line fault. That phenomenon was not so seriously noticed by the contemporary engineering circle, but a few years later, it was keenly discussed and recognized as “kilometric fault" or “short line fault" (SLF). Authors carried out intensive studies on the arc dynamics around current zero and had realized demerit of air blast circuit breakers and excellence of SF6 gas circuit breakers in case of SLF. This conclusion led to the development of original gas circuit breakers, and finally to the best and most reliable puffer type GCB, at that time. That was a big step to the age of SF6.

  4. Analysis of cold flow reestablishment time in a circuit breaker nozzle

    Science.gov (United States)

    Leone, S. A.; Nagamatsu, H. T.

    1983-01-01

    The deblocking process in a circuit breaker nozzle is similar to the flow starting process in a shock tunnel, and the computer uses this analogy to solve for the deblocking process by utilizing a diaphragm at the throat of a nozzle. At time equal to zero the diaphragm is broken and the throat area increases with time. It is a rarity to have the area as a function of both time and distance. Experimental data obtained from the RPI calibration shock tunnel are utilized to verify some of the calculated results with the area being a function of distance and the agreement is found to be good. The circuit breaker designer can utilize the computer simulation to estimate the deblocking time, an important parameter in the design of circuit breakers.

  5. CFD Simulation of Transonic Flow in High-Voltage Circuit Breaker

    Directory of Open Access Journals (Sweden)

    Xiangyang Ye

    2012-01-01

    Full Text Available A high-voltage circuit breaker is an indispensable piece of equipment in the electric transmission and distribution systems. Transonic flow typically occurs inside breaking chamber during the current interruption, which determines the insulating characteristics of gas. Therefore, accurate compressible flow simulations are required to improve the prediction of the breakdown voltages in various test duties of high-voltage circuit breakers. In this work, investigation of the impact of the solvers on the prediction capability of the breakdown voltages in capacitive switching is presented. For this purpose, a number of compressible nozzle flow validation cases have been presented. The investigation is then further extended for a real high-voltage circuit breaker geometry. The correlation between the flow prediction accuracy and the breakdown voltage prediction capability is identified.

  6. Design of a New Type of Distribution Valve for Hydraulic Breaker and Analysis of Energy Consumption

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Energy consumed by distribution valves causes an energy loss for the output energy of hydraulic breakers, which has a significant influence on its efficiency. A new type of distribution valve used for hydraulic breakers, designed to reduce energy consumption, is analyzed on the basis of the operating principle and energy loss of the current distribution valve. The new distribution valve adopts a cone valve and the optimization technique of unequal open degree for the valve port. Theoretical calculations and analyses have proven that the new distribution valve can reduce energy loss by 9.0127J, or energy consumption by 31%, during an impact cycle and the efficiency of the hydraulic breaker can be raised by 4.5%. It has the following characteristics: little leakage, little pressure loss and low energy consumption.

  7. Research on The Mechanical State Parameter Extraction Method of High Voltage Circuit Breakers

    Directory of Open Access Journals (Sweden)

    Yang Tianxu

    2013-05-01

    Full Text Available High voltage circuit breakers play an important role in the power system. So it is necessary to implement the state detection of breakers in order to ensure stable and reliable running of the grid. The purpose of state detection is to provide reliable basis of maintenance by extracting mechanical state parameters accurately. This paper mainly focuses on the coil current signal feature extraction algorithm. To settle the problem of too much noise mixed with the current signal and signal distortion, the discrete wavelet transform algorithm is used to extract the coil current signal parameters. This paper also designs the FIR filter to extract stroke and speed parameters from travel-time waveform. The experiments show that the difference between the theoretical results and test results processed by the method in this paper is very small and the test results are able to accurately reflect operation states and mechanical features of high voltage circuit breakers.

  8. Research on current sharing of paralleled IGBTs in different DC breaker circuit topologies

    Directory of Open Access Journals (Sweden)

    Chen Ying

    2016-01-01

    Full Text Available IGBT modules used in series and parallel to satisfy the requirement in high-power DC circuit breakers are often prone to large-current destruction due to current unbalance between paralleled IGBTs. It is of great importance to identify the current unbalance causes and to find a method optimizing the current sharing of paralleled IGBTs. In this paper the current-sharing influencing factors are discussed and verified by simulation. Two possible circuit topologies used in DC circuit breakers are proposed and simulated to see their performance in current sharing. The results show that one of them can provide us with a simple and effective method to achieve good current balancing in the DC circuit breaker application.

  9. Training department's role in human factor analysis during post-trip reviews

    International Nuclear Information System (INIS)

    Provide training is a frequent corrective action specified in a post-trip review report. This corrective action is most often decided upon by technical and operational staff, not training staff, without a detailed analysis of whether training can resolve the immediate problem or enhance employees' future performance. A more specific human factor or performance problem analysis would often reveal that training cannot impact or resolve the concern to avoid future occurrences. This human factor analysis is similar to Thomas Gilbert's Behavior Engineering Model (Human Competence, McGraw-Hill, 1978) or Robert Mager's/Peter Pipe's Performance Analysis (Analyzing Performance Problems, Pitman Learning, 1984). At Palo Verde Nuclear Generating Station, training analysts participate in post-trip reviews in order to conduct or provide input to this type of human factor and performance problem analysis. Their goal is to keep provide training out of corrective action statements unless training can in fact impact or resolve the problem. The analysts follow a plant specific logic diagram to identify human factors and to identify whether changes to the environment or to the person would best resolve the concern

  10. Westinghouse inadvertent plant trip reduction program

    International Nuclear Information System (INIS)

    During recent years, the nuclear power industry has become increasingly aware of the high average number of inadvertent plant trips experienced by commercial units in the United States versus similar experience in other countries, most strikingly, Japan. The need to address this problem stems from the potential consequences which include lost generating capacity (and lost revenue) for the utility, the cost of replacement power, reductions in component and plant life expectancies (due to cycling), and customer dissatisfaction. Perhaps another, more subtle, concern is the impact these trips have on the general public and the confidence that it has in the maturity of the commercial nuclear power program in the United States. This paper serves two purposes: first, it summarizes the program Westinghouse has established to reduce the frequency of unplanned automatic scrams, and second, it discusses several observations, made during the implementation of this program at different utilities

  11. Field trips along the Geological Transpyrenean Road

    Science.gov (United States)

    Burgio, Marion; Dekeyser, Dominique; Richert, Jean Paul; Gruneisen, Pierre; Vazquez-Prada, Diego; Lacazedieu, Annie

    2015-04-01

    GeolVal association, www.geolval.fr , in collaboration with Geoambiente association, created a serie of pedagogical explanations about Pyrenees landscapes along the road from France to Spain, linking the towns of Pau, Oloron,Jaca and Mallos de Riglos. It was a ten years work that lasted in 2008. http://www.routetranspyreneenne.com/home_f.php We can now use this "treasure" with tourists, students and mix some landscapes explanations from a road site with a little field trip along mountain in order to "touch" the rocks. We are working about the importance of field in the way the students understand geosciences and try to organize field trips that aim to simplify and make concrete some key concepts. We also began an interactive software version of this work, presented through a pilot application, made in collaboration with Total petroleum firm.

  12. The SMS-GPS-Trip-Method

    DEFF Research Database (Denmark)

    Reinau, Kristian Hegner; Harder, Henrik; Weber, Michael

    2015-01-01

    data, an approach which is not well suited for capturing data on experiences surrounding trips. Currently increasing research is being done on how to incorporate such data in traffic models, and there is therefore a need for a method, which is suited to collect such data. The new method presented in......This article presents a new method for collecting travel behavior data, based on a combination of GPS tracking and SMS technology, coined the SMS–GPS-Trip method. The state-of-the-art method for collecting data for activity based traffic models is a combination of travel diaries and GPS tracking...... this article builds on ideas from experience sampling methods (ESM) and it is well suited specifically for collecting such experience data. Given the use of SMS technology, this method makes it possible to reach a wide range of respondents. The usefulness of the new method is proven on a theoretical...

  13. Microstructural Development during Welding of TRIP steels

    OpenAIRE

    Amirthalingam, M.

    2010-01-01

    The Advanced High Strength Steels (AHSS) are promising solutions for the production of lighter automobiles which reduce fuel consumption and increase passenger safety by improving crash-worthiness. Transformation Induced Plasticity Steel (TRIP) are part of the advanced high strength steels which offers a high strength and toughness combination with excellent uniform elongation. However, the higher alloying content of these steel limits their weldability and the thermal cycle of a welding proc...

  14. Advanced Tourist Trip Planning Using Hybrid Recommender

    OpenAIRE

    Saso KOCESKI; Petrevska, Biljana

    2013-01-01

    The paper intends to underline that tourists’ and travelers’ behaviour and preferences have changed dramatically specifically in the way how they search for information. In order to create a tailor-made itinerary and enhance the way of planning a tourist trip, the paper suggests introduction of tourism recommendation systems. For this purpose, a methodology is proposed that assists all interested parties in planning their vacation in more intelligent and sophisticated way by generating a pers...

  15. Trip by Colonel and Mrs Hebbert. 1943

    OpenAIRE

    Hebbert, Henry Eric, 1893-1980, Colonel

    2004-01-01

    229 x 186 mm. A hand-drawn map showing the route of the Hebberts' trip through Eritrea to Ethiopia from Khartoum in 1943. In addition to the map, drawn in blue ink, there are annotations in black ink which read: 'Car Mileage Kh-Kh [presumably Khartoum-Khartoum] 3900 miles' and 'Chain dotted generally by car 3900 mile + By Mule (a) Semiam Mts [presumably Simen Mountains] (b) Lalibela'.

  16. Analysis of reactor coolant pump trip

    International Nuclear Information System (INIS)

    The trip of one reactor coolant pump accident is simulated with using the IAEA-developed WWER-1000 simulation computer software (IAEA-Code) in this article. The results are compared with the information presented for Bushehr Nuclear Power Plant for the same scenario (analyzed by the code Dynamika-97). The obtained results are compatible with the Bushehr Nuclear Power Plant's given data and show a good overall agreement between them

  17. TRIPs Agreement, Important Multilateral WTO Treaty

    Directory of Open Access Journals (Sweden)

    Oana-Maria Florescu

    2006-08-01

    Full Text Available This article aims at presenting the content and the frame of the TRIPs. Agreement. It starts by introducing the reader to the terms that defined the world economical climate by the time of the Agreement negociation. Also, it explains the need of having an Agreement on intellectual property rights with impact on the business world. Moreover, the article reviews the main provisions of the Agreement and the most important intellectual property rights.

  18. Your private trips with Carlson Wagonlit Travel

    CERN Multimedia

    Carlson Wagonlit Travel

    2015-01-01

    Your Carlson Wagonlit Travel agency at CERN (building 62) also organizes private trips!     Do not hesitate to contact the “Tourism” team, at your disposal from Monday to Friday from 8:30 a.m. to 4:30 p.m. Phone: 72763. E-mail: cern@carlsonwagonlit.ch. Since 1 January 2015, everyone working at CERN benefits from lower booking fees.

  19. Moisture Sensor for Sulfur Hexafluoride (SF6)-filled Circuit Breakers; FINAL

    International Nuclear Information System (INIS)

    Measurements at ORNL were made on the Kahn moisture sensor which Doble Engineering wants to evaluate for use in SF(sub 6) circuit breakers. Test conducted at ORNL indicate that vacuum conditions, as might be found in SF(sub 6) circuit breakers prior to filling with SF(sub 6), could lead to significant changes in calibration, resulting in erroneous readings of moisture content. Similar effects might also be observed in cases where SF(sub 6) byproducts are present, due the reactivity of some of these byproducts with water

  20. Pressure and Arc Voltage Measurement in a 252 kV SF6 Puffer Circuit Breaker

    Science.gov (United States)

    Zhong, Jianying; Guo, Yujing; Zhang, Hao

    2016-05-01

    The pressure distribution in an arcing chamber is critically important for the SF6 puffer circuit breaker design. In this paper, the pressure variation of four locations in the nozzle was measured by piezoresistive and fiber optical pressure sensors at two current levels of 10 kA and 50 kA. An arc voltage measurement was also taken. The results demonstrate that using either type of sensor with a connecting tube is able to detect the fast pressure variation in circuit breakers, however the possible distortion and delay to the pressure transient caused by the tube need further study.

  1. Scrutinized: the TRIPS agreement and public health.

    Science.gov (United States)

    Subhan, Junaid

    2006-07-01

    The World Trade Organization's (WTO's) Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPS) of 1994 seeks to implement a uniform set of intellectual property protection across member nations to provide greater stability in international economic relations. Critics argue that the TRIPS agreement provides unnecessarily strong protection of intellectual property rights which serves to prevent the ill in developing nations from having access to affordable essential medications. The first recommendation that this paper makes is to provide two sets of intellectual property protection, one that applies to essential medications such as AIDS drugs and certain antibiotics and another that applies to drugs that treat non-life threatening conditions. The second recommendation builds upon the first recommendation: if two sets of intellectual property protection legislation are enacted, patents on essential medications should be restricted to patents on processes rather than the product itself. The third recommendation seeks to amend the language of the TRIPS agreement to make it obligatory for member nations to implement provisions on compulsory licensing within their domestic legislation. PMID:18523624

  2. Stainless steels with trip/twip/sbip effect; Nichtrostende Staehle mit TRIP/TWIP/SBIP-Effekt

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, A.; Gutte, H.; Jahn, A.; Scheller, P.R. [Institut fuer Eisen- und Stahltechnologie, TU Bergakademie Freiberg (Germany)

    2009-08-15

    Economic austenitic steels with high energy absorption capability are in the focus of worldwide research activities, whereby the steels which show TRIP, TWIP and/or SBIP effects play a crucial role. New austenitic or austenitic-martensitic stainless steels with a high cold workability and energy absorption capability are currently developed and tested in laboratory scale at the Institute of Iron and Steel Technology at the Technical University Bergakademie Freiberg. The mechanical properties of these steels are essentially influenced by the TRIP, TWIP and SBIP effect, becoming evident in hot formed and solution annealed steels as well as in as-cast steels. The TRIP/TWIP/SBIP effects have a significant impact on the toughness and the strength of stainless steels consisting of metastable austenite. The TRIP effect owns a paramount position since it serves for a simultaneous increase of toughness and strength. The influences of alloying elements like manganese or nickel on the TRIP effect are in the centre of the investigations at the Institute of Iron and Steel Technology. These austenitic or austenitc-martensitic stainless steels provide the ability for new applications fields due to their excellent mechanical properties. Exemplary, in the Collaborative Research Centre SFB 799 ''TRIP-Matrix-Composites'', financed through the Deutsche Forschungsgemeinschaft DFG, the suitability of this new class of steels for cast components in ductile and transformation strengthened high performance (metal) ceramic composite materials will be investigated. (Abstract Copyright [2009], Wiley Periodicals, Inc.) [German] Weltweit verstaerken sich die Bemuehungen bei der Suche nach kostenguenstigen austenitischen Stahlgueten mit hohem Energieabsorptionsvermoegen. Dabei zeichnen sich verschiedene Forschungsrichtungen ab, die sich auf Staehle mit TRIP-, TWIP- und SBIP-Effekt{sup 1} oder entsprechenden Kombinationen konzentrieren. Am Institut fuer Eisen- und

  3. NRC Information Notice No. 93-26: Grease solidification causes molded case circuit breaker failure to close

    International Nuclear Information System (INIS)

    On March 26, 1992, an engineered safety feature actuated at the Nine Mile Point Nuclear Station Unit 2 because of the loss of output power from an uninterruptible power supply (UPS) while the loads were being transferred from UPS power to the maintenance supply power. During the transfer, the maintenance supply output circuit breaker (CB-4) failed to close causing a loss of power to the standby gas treatment system radiation monitoring cabinet, a false-high radiation signal, a group 9 primary containment isolation, the loss of a control room fire panel annunciator, and a loss of communication between the radiation monitoring system computer and non-Class 1E radiation monitors. The operator immediately took corrective action to manually close circuit breaker CB-4 and restore the UPS loads. The UPS loads lost power for approximately 12 minutes during the event. The cause of the failure of circuit breaker CB-4 to close was that the grease used at the pivot points inside the breaker had dried out and solidified. When the grease dried out, it caused increasing friction and gouging at the metal-to-metal contact areas. This friction caused the breaker to become increasingly more difficult to close, until, finally, the breaker would not close at all. The licensee located all breakers of the same make, model, and year as the one that failed and scheduled their replacement

  4. Comprehensive aging assessment of circuit breakers and relays for Nuclear Plant Aging Research (NPAR) Program Phase II

    International Nuclear Information System (INIS)

    The Phase I study - NUREG/CR-4715, BNL-NUREG-52017 AN,RV, An Aging Assessment Of Relays And Circuit Breakers And System Interactions, identified relays and circuit breakers used in nuclear plants, failure mechanisms of these relays and circuit breakers, that some failure mechanisms are age related, and that failure of safety systems is possible from relays and circuit breaker failures if adequate maintenance and testing are not performed. It also proposed some potential inspection, surveillance and condition monitoring methods to detect significant aging methods prior to loss of safety function. The objectives of Phase II are to: (1) identify and characterize aging and service wear effects of circuit breakers and relays which, if unchecked, could impair plant safety; (2) identify and develop methods of inspection, surveillance, and condition monitoring, and of evaluating residual life of circuit breakers and relays, which will assure timely detection of significant aging effects prior to loss of safety function; (3) evaluate the effectiveness of storage, maintenance, repair and replacement practices in mitigating the rate and extent of degradation in circuit breakers and relays caused by aging and service wear. The research results will be utilized to identify inspection, surveillance and condition monitoring needs, define inspection intervals, provide service life parameter limits and service life prediction methodology

  5. Metal-clad switchgear with large capacity vacuum circuit breaker in two-tier arrangement for nuclear power plants

    International Nuclear Information System (INIS)

    Accompanying the increase of main machinery capacity in nuclear power stations, the short-circuit capacity for 6.9 kV in-house auxiliary machinery circuit has increased, and a 63 kA circuit breaker has become necessary. Although magnetic breakers have been used as large capacity breakers so far, vacuum breakers which are more suitable for the recent environmental conditions of power stations have become employed. Hitachi Ltd. has developed the metal-clad switchboard with vacuum breakers of 7.2 kV, 1,200 to 3,000 A, and breaking current of 63 kA in two-tier arrangement. The main features of this breaker are small size, light weight, long life, labour-saving in maintenance and inspection, simple construction, easy handling, high reliability and safety. In addition, in this paper, the construction of the breaker and switchboard, aseismic property, and test results are described. The tests include the withstand voltage test, elevated temperature test, short period current test, short-circuit test, low current breaking test, continuous on-off test, on-off surge combination test and short-circuit breaking test under the condition of vacuum failure in one phase. The aseismic property is guaranteed by analyzing the vibration characteristics and the strength using computer-aided finite element method so that the performance required is satisfied. (Wakatsuki, Y.)

  6. Numerical simulation for arc-plasma dynamics during contact opening process in electrical circuit-breakers

    Science.gov (United States)

    Gupta, D. N.; Patil, G. N.; Srinivas, D.; Kale, S. S.; Potnis, S. B.

    2010-02-01

    The high-energy, high-current thermal plasma that develops between electric contacts in a gas circuit-breaker during circuit interruption is an important phenomenon in the power transmission industry. The high temperature and pressure arc dissipates the tremendous amount of energy generated by the fault current. Simultaneously, this energy has to be transferred away from the contacts to build the dielectric strength level of the circuit-breaker. In order to interrupt the current, the arc must be weakened and finally extinguished. We model these phenomena by using a computer software code based on the solution of the unsteady Euler equations of gas dynamics. We consider the equations of fluid flows. These equations are solved numerically in complex circuit breaker geometries using a finite-volume method. The domain is initially filled with SF6 gas. We begin our simulations from cold mode, where the fault current is not present (hence no arc). An axis-symmetric geometry of a 145 kV gas circuit-breaker is considered to study the pressure, density, and temperature profile during contact opening process.

  7. A study of plunging breaker mechanics by PIV measurements and a Navier-Stokes solver

    DEFF Research Database (Denmark)

    Emarat, Narumon; Forehand, David I. M.; Christensen, Erik Damgaard;

    2000-01-01

    The mechanics of a surf-zone plunging breaker are studied from Particle Image Velocimetry (PIV) measurements and a numerical model based on the Navier-Stokes equations, using a Volume of Fluid (VOF) method. An additional numerical model using a Boundary-Integral Method (BIM) is also used in order...

  8. On-line Monitoring System based on Vibration Signal of High Voltage Circuit Breaker

    Directory of Open Access Journals (Sweden)

    Chao Fu

    2014-04-01

    Full Text Available High voltage circuit breaker is one of the most important switch apparatus in electrical power system. It play a role in the switch control, which can be used to switch the operating mode during normal operation (the equipment run or quit. In order to ensure the normal operation of the grid, it can be removed quickly when a malfunction on the device or circuit. Real-time online monitoring of high voltage circuit breaker can understand the running status, master the operation characteristics and its tend of development. As early as possible find the potential faults then take preventive measures timely, so as to ensure the reliable operation of power system. Online monitoring of high voltage circuit breakers can reduce the premature or unnecessary maintenance and maintenance cost, improve pertinence of the maintenance firstly. Secondly, it can improve the life of the switching device and improve the reliability of electric power system significantly. In this paper, on-line monitoring system based on vibration signal of high voltage circuit breaker is presented

  9. Numerical simulation for arc-plasma dynamics during contact opening process in electrical circuit-breakers

    International Nuclear Information System (INIS)

    The high-energy, high-current thermal plasma that develops between electric contacts in a gas circuit-breaker during circuit interruption is an important phenomenon in the power transmission industry. The high temperature and pressure arc dissipates the tremendous amount of energy generated by the fault current. Simultaneously, this energy has to be transferred away from the contacts to build the dielectric strength level of the circuit-breaker. In order to interrupt the current, the arc must be weakened and finally extinguished. We model these phenomena by using a computer software code based on the solution of the unsteady Euler equations of gas dynamics. We consider the equations of fluid flows. These equations are solved numerically in complex circuit breaker geometries using a finite-volume method. The domain is initially filled with SF6 gas. We begin our simulations from cold mode, where the fault current is not present (hence no arc). An axis-symmetric geometry of a 145 kV gas circuit-breaker is considered to study the pressure, density, and temperature profile during contact opening process.

  10. Circuit-Breakers: Technical Terminology Bulletin. Terminotech, Vol. 1, No. 3.

    Science.gov (United States)

    General Electric Co. of Canada, Ltd., Montreal, Quebec.

    This issue of a bulletin of technological terminology is devoted to circuit breakers. A brief narrative on the subject is presented in both French and English. An English-French dictionary of terms comprises the bulk of the document. Explanatory illustrations are appended. (JB)

  11. Self-similar solutions of electron MHD equations and the theory of plasma current breaker

    International Nuclear Information System (INIS)

    Primary erosion conception of a plasma current breaker suggested an appearance of an vacuum gap near cathode, through which electromagnetic energy may reach the load. The theory of two-dimensional flows of electrons and ions of a quasineutral plasma near electrodes is given

  12. The Implications of the Use of Parental Choice as a Legal "Circuit Breaker"

    Science.gov (United States)

    Mead, Julie F.; Lewis, Maria M.

    2016-01-01

    This study explores four instances where parental choice has been employed as a legal "circuit breaker": (a) First Amendment Establishment Clause cases related to public funding, (b) Fourteenth Amendment Equal Protection cases regarding race-conscious student assignment, (c) Title IX regulations concerning single-sex education, and (d) a…

  13. Predictors of trips to food destinations

    Directory of Open Access Journals (Sweden)

    Kerr Jacqueline

    2012-05-01

    Full Text Available Abstract Background Food environment studies have focused on ethnic and income disparities in food access. Few studies have investigated distance travelled for food and did not aim to inform the geographic scales at which to study the relationship between food environments and obesity. Further, studies have not considered neighborhood design as a predictor of food purchasing behavior. Methods Atlanta residents (N = 4800 who completed a travel diary and reported purchasing or consuming food at one of five food locations were included in the analyses. A total of 11,995 food-related trips were reported. Using mixed modeling to adjust for clustering of trips by participants and households, person-level variables (e.g. demographics, neighborhood-level urban form measures, created in GIS, and trip characteristics (e.g. time of day, origin and destination were investigated as correlates of distance travelled for food and frequency of grocery store and fast food outlet trips. Results Mean travel distance for food ranged from 4.5 miles for coffee shops to 6.3 miles for superstores. Type of store, urban form, type of tour, day of the week and ethnicity were all significantly related to distance travelled for food. Origin and destination environment, type of tour, day of week, age, gender, income, ethnicity, vehicle access and obesity status were all significantly related to visiting a grocery store. Home neighborhood environment, day of week, type of tour, gender, income, education level, age, and obesity status were all significantly related to likelihood of visiting a fastfood outlet. Conclusions The present study demonstrated that people travel sizeable distances for food and this distance is related to urban. Results suggest that researchers need to employ different methods to characterize food environments than have been used to assess urban form in studies of physical activity. Food is most often purchased while traveling from locations other

  14. Hunton Group core workshop and field trip

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, K.S. [ed.

    1993-12-31

    The Late Ordovician-Silurian-Devonian Hunton Group is a moderately thick sequence of shallow-marine carbonates deposited on the south edge of the North American craton. This rock unit is a major target for petroleum exploration and reservoir development in the southern Midcontinent. The workshop described here was held to display cores, outcrop samples, and other reservoir-characterization studies of the Hunton Group and equivalent strata throughout the region. A field trip was organized to complement the workshop by allowing examination of excellent outcrops of the Hunton Group of the Arbuckle Mountains.

  15. 6.9-kV, 63-KA metal-clad switchgear with vacuum circuit breakers for nuclear power plants

    International Nuclear Information System (INIS)

    The technological advancement for larger capacities of vacuum circuit breakers in recent years has truly been prominent. Based on data of a series of in-house tests made so far and on performance in the field, Toshiba Corporation has developed a metal-clad switchgear with vacuum circuit breakers for nuclear power plants. Metal-clad switchgears for nuclear power plants are strongly required to have high reliability and large capacities. This paper describes results of a series of reliability tests made on the vacuum circuit breaker and resistance to earthquakes of the metal-clad switchgear required for use in a nuclear power plant

  16. Microstructure Evolution during Friction Stir Spot Welding of TRIP steel

    OpenAIRE

    Lomholt, Trine Colding; Somers, Marcel A. J.; da Silva Fanta, Alice Bastos; Pantleon, Karen

    2013-01-01

    TRansformation Induced Plasticity (TRIP) stål er udviklet til anvendelse i bilindustrien på grund af den fremragende kombination af høj styrke og formbarhed. Mikrostrukturen af TRIP stål er en kompleks blanding af mange mikrostruktur-dele: ferrit, bainit, martensit og austenit. TRIP effekten er aktiveret under indflydelse af ekstern mekanisk belastning, der fører til en martensitisk transformation af austenit. Martensit-dannelsen under deformation bidrager til de fremragende mekaniske egenska...

  17. A Label Correcting Algorithm for Dynamic Tourist Trip Planning

    OpenAIRE

    Jin Li; Peihua Fu

    2012-01-01

    One of the most important considerations for tourist in tourism is how to design an optimal trip planning. Selecting the most interesting points of interest and designing a personalized tourist trip is called a tourist trip design problem (TTDP) and, it can be modeled as a orienteering problem. However, most previous researches solve this problem in static network, which leads to unreasonable results. In this paper, to formulate this orienteering problem in a time-dependent network, a mathema...

  18. Trip Oriented Search on Activity Tra jectory

    Institute of Scientific and Technical Information of China (English)

    陈伟; 赵雷; 许佳捷; 刘冠锋; 郑凯; 周晓方

    2015-01-01

    Driven by the flourish of location-based services, trajectory search has received significant attentions in recent years. Different from existing studies that focus on searching trajectories with spatio-temporal information and text de-scriptions, we study a novel problem of searching trajectories with spatial distance, activities, and rating scores. Given a query q with a threshold of distance, a set of activities, a start point S and a destination E, trip oriented search on activity trajectory (TOSAT) returns k trajectories that can cover the activities with the highest rating scores within the threshold of distance. In addition, we extend the query with an order, i.e., order-sensitive trip oriented search on activity trajectory (OTOSAT), which takes both the order of activities in a query q and the order of trajectories into consideration. It is very challenging to answer TOSAT and OTOSAT efficiently due to the structural complexity of trajectory data with rating infor-mation. In order to tackle the problem efficiently, we develop a hybrid index AC-tree to organize trajectories. Moreover, the optimized variant RAC+-tree and novel algorithms are introduced with the goal of achieving higher performance. Extensive experiments based on real trajectory datasets demonstrate that the proposed index structures and algorithms are capable of achieving high efficiency and scalability.

  19. Mediating cultural borders during science field trips

    Science.gov (United States)

    Lebak, Kimberly

    2007-10-01

    In this paper, I analyze teacher and student roles in the teaching and learning of science at an informal learning center, The Outdoor Classroom. As a white middle class informal learning science teacher, I examine my struggles to teach science to students across boundaries of race, class, gender, and experience with the outdoors during field trips. Through the field trip I did not have the time or face-to-face experience to make sense of the students' culture, see their culture in terms of capital, and align my enactment to benefit their learning. Likewise, the students did not have the time or face-to-face experience with me in order to adapt their cultural capital and build the essential stocks of symbolic and social capital. This research demonstrates how the classroom teacher draws upon previous transactions and emotions to successfully engage her students in practices that promote the participation and learning of science. Through creating culturally adaptive ways of transacting, teachers can provide opportunities for their students to generate positive emotional energy and group solidarity in the learning of science at an informal science center.

  20. Ring aggregation pattern of Human Travel Trips

    CERN Document Server

    Wang, Zi-Yang; Zhu, Peng; Qin, Yong; Jia, Li-Min

    2015-01-01

    Although a lot of attentions have been paid to human mobility, the relationship between travel pattern with city structure is still unclear. Here we probe into this relationship by analyzing the metro passenger trip data.There are two unprecedented findings. One, from the average view a linear law exists between the individual's travel distance with his original distance to city center. The mechanism underlying is a travel pattern we called "ring aggregation", i.e., the daily movement of city passengers is just aggregating to a ring with roughly equal distance to city center.Interestingly, for the round trips the daily travel pattern can be regarded as a switching between the home ring at outer area with the office ring at the inner area. Second, this linear law and ring aggregation pattern seems to be an exclusive characteristic of the metro system. It can not be found in short distance transportation modes, such as bicycle and taxi, neither as multiple transportation modes. This means the ring aggregation p...

  1. RESOLVE Project

    Science.gov (United States)

    Parker, Ray; Coan, Mary; Cryderman, Kate; Captain, Janine

    2013-01-01

    The RESOLVE project is a lunar prospecting mission whose primary goal is to characterize water and other volatiles in lunar regolith. The Lunar Advanced Volatiles Analysis (LAVA) subsystem is comprised of a fluid subsystem that transports flow to the gas chromatograph - mass spectrometer (GC-MS) instruments that characterize volatiles and the Water Droplet Demonstration (WDD) that will capture and display water condensation in the gas stream. The LAVA Engineering Test Unit (ETU) is undergoing risk reduction testing this summer and fall within a vacuum chamber to understand and characterize component and integrated system performance. Testing of line heaters, printed circuit heaters, pressure transducers, temperature sensors, regulators, and valves in atmospheric and vacuum environments was done. Test procedures were developed to guide experimental tests and test reports to analyze and draw conclusions from the data. In addition, knowledge and experience was gained with preparing a vacuum chamber with fluid and electrical connections. Further testing will include integrated testing of the fluid subsystem with the gas supply system, near-infrared spectrometer, WDD, Sample Delivery System, and GC-MS in the vacuum chamber. This testing will provide hands-on exposure to a flight forward spaceflight subsystem, the processes associated with testing equipment in a vacuum chamber, and experience working in a laboratory setting. Examples of specific analysis conducted include: pneumatic analysis to calculate the WDD's efficiency at extracting water vapor from the gas stream to form condensation; thermal analysis of the conduction and radiation along a line connecting two thermal masses; and proportional-integral-derivative (PID) heater control analysis. Since LAVA is a scientific subsystem, the near-infrared spectrometer and GC-MS instruments will be tested during the ETU testing phase.

  2. Approaching the Processes in the Generator Circuit Breaker at Disconnection through Sustainability Concepts

    Directory of Open Access Journals (Sweden)

    Carmen A. Bulucea

    2013-03-01

    Full Text Available Nowadays, the electric connection circuits of power plants (based on fossil fuels as well as renewable sources entail generator circuit-breakers (GCBs at the generator terminals, since the presence of that electric equipment offers many advantages related to the sustainability of a power plant. In an alternating current (a.c. circuit the interruption of a short circuit is performed by the circuit-breaker at the natural passing through zero of the short-circuit current. During the current interruption, an electric arc is generated between the opened contacts of the circuit-breaker. This arc must be cooled and extinguished in a controlled way. Since the synchronous generator stator can flow via highly asymmetrical short-circuit currents, the phenomena which occur in the case of short-circuit currents interruption determine the main stresses of the generator circuit-breaker; the current interruption requirements of a GCB are significantly higher than for the distribution network circuit breakers. For shedding light on the proper moment when the generator circuit-breaker must operate, using the space phasor of the short-circuit currents, the time expression to the first zero passing of the short-circuit current is determined. Here, the manner is investigated in which various factors influence the delay of the zero passing of the short-circuit current. It is shown that the delay time is influenced by the synchronous machine parameters and by the load conditions which precede the short-circuit. Numerical simulations were conducted of the asymmetrical currents in the case of the sudden three-phase short circuit at the terminals of synchronous generators. Further in this study it is emphasized that although the phenomena produced in the electric arc at the terminals of the circuit-breaker are complicated and not completely explained, the concept of exergy is useful in understanding the physical phenomena. The article points out that just after the short

  3. NRC Information No. 89-86: Type HK circuit breakers missing close latch anti-shock springs

    International Nuclear Information System (INIS)

    During the recent refueling outage at Fermi Unit 2, the licensee inspected both safety-related and non-safety-related Type HK circuit breakers. The close latch anti-shock springs were observed to be missing in approximately 40 safety-related Type HK circuit breakers that had been manufactured outside of the previously identified timeframes. (The identified circuit breakers were manufactured in 1974.) Thus, the timeframes previously identified by the manufacturer (prior to 1973 and from June 1975 to June 1977) may not be totally inclusive. In addition, because of changes in corporate name, mergers, etc., Type HK circuit breakers may indicate manufacture by ITE, ITE Imperial, Gould, Brown Boveri, or a combination thereof. The current name of the manufacturer is ASEA Brown Boveri. Recipients may need to be cognizant of this when determining whether they utilize potentially affected equipment

  4. Mechanical Fault Diagnosis for HV Circuit Breakers Based on Ensemble Empirical Mode Decomposition Energy Entropy and Support Vector Machine

    Directory of Open Access Journals (Sweden)

    Jianfeng Zhang

    2015-01-01

    Full Text Available During the operation process of the high voltage circuit breaker, the changes of vibration signals can reflect the machinery states of the circuit breaker. The extraction of the vibration signal feature will directly influence the accuracy and practicability of fault diagnosis. This paper presents an extraction method based on ensemble empirical mode decomposition (EEMD. Firstly, the original vibration signals are decomposed into a finite number of stationary intrinsic mode functions (IMFs. Secondly, calculating the envelope of each IMF and separating the envelope by equal-time segment and then forming equal-time segment energy entropy to reflect the change of vibration signal are performed. At last, the energy entropies could serve as input vectors of support vector machine (SVM to identify the working state and fault pattern of the circuit breaker. Practical examples show that this diagnosis approach can identify effectively fault patterns of HV circuit breaker.

  5. RESOLVE Project

    Science.gov (United States)

    Parker, Ray O.

    2012-01-01

    The RESOLVE project is a lunar prospecting mission whose primary goal is to characterize water and other volatiles in lunar regolith. The Lunar Advanced Volatiles Analysis (LAVA) subsystem is comprised of a fluid subsystem that transports flow to the gas chromatograph- mass spectrometer (GC-MS) instruments that characterize volatiles and the Water Droplet Demonstration (WDD) that will capture and display water condensation in the gas stream. The LAVA Engineering Test Unit (ETU) is undergoing risk reduction testing this summer and fall within a vacuum chamber to understand and characterize C!Jmponent and integrated system performance. Ray will be assisting with component testing of line heaters, printed circuit heaters, pressure transducers, temperature sensors, regulators, and valves in atmospheric and vacuum environments. He will be developing procedures to guide these tests and test reports to analyze and draw conclusions from the data. In addition, he will gain experience with preparing a vacuum chamber with fluid and electrical connections. Further testing will include integrated testing of the fluid subsystem with the gas supply system, near-infrared spectrometer, WDD, Sample Delivery System, and GC-MS in the vacuum chamber. This testing will provide hands-on exposure to a flight forward spaceflight subsystem, the processes associated with testing equipment in a vacuum chamber, and experience working in a laboratory setting. Examples of specific analysis Ray will conduct include: pneumatic analysis to calculate the WOO's efficiency at extracting water vapor from the gas stream to form condensation; thermal analysis of the conduction and radiation along a line connecting two thermal masses; and proportional-integral-derivative (PID) heater control analysis. In this Research and Technology environment, Ray will be asked to problem solve real-time as issues arise. Since LAVA is a scientific subsystem, Ray will be utilizing his chemical engineering background to

  6. Mechanical Fault Diagnosis for HV Circuit Breakers Based on Ensemble Empirical Mode Decomposition Energy Entropy and Support Vector Machine

    OpenAIRE

    Jianfeng Zhang; Mingliang Liu; Keqi Wang; Laijun Sun

    2015-01-01

    During the operation process of the high voltage circuit breaker, the changes of vibration signals can reflect the machinery states of the circuit breaker. The extraction of the vibration signal feature will directly influence the accuracy and practicability of fault diagnosis. This paper presents an extraction method based on ensemble empirical mode decomposition (EEMD). Firstly, the original vibration signals are decomposed into a finite number of stationary intrinsic mode functions (IMFs)....

  7. Creating Local Field Trips: Seeing Geographical Principles through Empirical Eyes.

    Science.gov (United States)

    Wheeler, James O.

    1985-01-01

    Discusses how instructors can design a local field trip for undergraduate students enrolled in an economic geography class. The purpose of the field trip is to help students observe and interpret familiar scenes in terms of geographical concepts such as central place theory, changing land use, and spatial competition. (RM)

  8. Psychological Sense of Community and Group Cohesion on Wilderness Trips

    Science.gov (United States)

    Breunig, Mary; O'Connell, Tim; Todd, Sharon; Young, Anderson; Anderson, Lynn; Anderson, Dale

    2008-01-01

    A primary purpose of many wilderness trip programs is the development of positive interpersonal relationships and group experiences that lead to enhanced sense of community among group members. Although there is anecdotal evidence to support the development of sense of community on wilderness trips, there is little empirical evidence to support…

  9. Development of Teacher Attitude Scale towards the Field Trip

    Science.gov (United States)

    Tortop, Hasan Said

    2012-01-01

    A field trip is an excursion by group of students with teachers to a place away from classroom such as natural field, science center, and zoo. So, it is an important tool for renewable energy education. This study was carried out to develop a new scale for measuring teacher attitudes towards the field trip. Teacher attitude scale towards the field…

  10. The "Science" Behind a Successful Field Trip to the Zoo

    Science.gov (United States)

    Scott, Catherine Marie; Matthews, Catherine E.

    2011-01-01

    A field trip to the local zoo is often a staple in many elementary school curricula. Many zoos offer free entry to local teachers and their students. Teachers take students on field trips to enrich the curriculum, make connections to what students are learning in school, and provide students with meaningful learning experiences (Kisiel 2007).…

  11. Elementary school children's science learning from school field trips

    Science.gov (United States)

    Glick, Marilyn Petty

    This research examines the impact of classroom anchoring activities on elementary school students' science learning from a school field trip. Although there is prior research demonstrating that students can learn science from school field trips, most of this research is descriptive in nature and does not examine the conditions that enhance or facilitate such learning. The current study draws upon research in psychology and education to create an intervention that is designed to enhance what students learn from school science field trips. The intervention comprises of a set of "anchoring" activities that include: (1) Orientation to context, (2) Discussion to activate prior knowledge and generate questions, (3) Use of field notebooks during the field trip to record observations and answer questions generated prior to field trip, (4) Post-visit discussion of what was learned. The effects of the intervention are examined by comparing two groups of students: an intervention group which receives anchoring classroom activities related to their field trip and an equivalent control group which visits the same field trip site for the same duration but does not receive any anchoring classroom activities. Learning of target concepts in both groups was compared using objective pre and posttests. Additionally, a subset of students in each group were interviewed to obtain more detailed descriptive data on what children learned through their field trip.

  12. The Beginner's Guide to Interactive Virtual Field Trips

    Science.gov (United States)

    Zanetis, Jan

    2010-01-01

    For students, field trips can be the best of both worlds: a welcome and exciting break from day-to-day classroom activities and a memorable, real-world experience that will solidify the curriculum in their minds. Unfortunately, the most desirable trips--those to far-away, enticing destinations--have long been inaccessible to all but a select few,…

  13. Extended Aging of Ag/W Circuit Breaker Contacts: Influence on Surface Structure, Electrical Properties, and UL Testing Performance

    Science.gov (United States)

    Yu, Haibo; Kesim, M. Tumerkan; Sun, Yu; Harmon, Jason; Potter, Jonathan; Alpay, S. Pamir; Aindow, Mark

    2016-01-01

    Samples of 120 V, 30 A commercial circuit breakers were subjected to various aging treatments and the resulting microstructures at the surfaces of the Ag/W contacts were studied using a combination of x-ray diffraction, scanning electron microscopy, and energy-dispersive x-ray spectroscopy techniques. Breakers aged naturally in a hot, humid climate were compared to those subjected to accelerated aging in dry and humid environments. The most extensive oxidation was observed for contacts from breakers subjected to accelerated humid aging; these contacts exhibited thick surface layers consisting of Ag2O, Ag2WO4, Cu(OH)2•H2O, and WO3 phases. Far less surface degradation was observed for dry-aged contacts. Naturally aged contacts showed variations in degradation with more oxidation at the surface regions outside the physical contact area on the contact face. A correlation was found between the contact resistances measured from these samples following ASTM standard B 667-97 and the observed surface microstructures. To evaluate the effects of the surface oxides on breaker performance, humid-aged breakers were subjected to standardized UL overload/temperature-rise, endurance, and short-circuit testing following UL489. The contacts in these breakers exhibit similar microstructural and property changes to those observed previously for as-manufactured contacts after UL testing. These data illustrate the robust performance of this contact technology even after being subjected to aggressive artificial aging.

  14. LMPV circuit breakers: operation of a 15-kA unit with Wendelstein VII A, and laboratory tests of the next breaker generation

    International Nuclear Information System (INIS)

    The heart of the breaker, the liquid-metal plasma valve (LMPV), is a vacuum arc device which combines the most desirable properties of classical liquid-metal arc devices (such as ignitrons and multi-gap, multi-anode mercury valves) with those of classical (solid-cathode) vacuum arc devices (such as triggered vacuum gaps and vacuum interrupters). In this application, current interruption is achieved by forced commutation of the LMPV. Discharge voltage losses are eliminated during most of the current rev-up period by conducting the current, until shortly before interruption, in a relatively simple mechanical bypass switch (MBS) in parallel with the LMPV

  15. Development and formability analysis of TRIP seamless steel tube

    Institute of Scientific and Technical Information of China (English)

    Zhang Zicheng; Zhu Fuxian

    2014-01-01

    In this paper, the production technology of transformation induced plasticity (TRIP) steel was first introduced into the steel tube manufacture field to produce the steel tubes with high strength and plasticity. The TRIP seamless steel tubes with the microstructure of ferrite, bainite, retained austenite and a little martensite were successfully fabricated using a cold-drawn steel tube with two-stage heat treatment technique and continu- ous heat treatment process, respectively. The ring tensile test and cold bend test were carried out to study the formability of the newly developed TRIP seamless steel tube. The results showed that the TRIP seamless steel tubes have a good cold formability, and they are available to be used in the tube hydroforming process. In ad- dition, the equipment of continuous heat treatment developed in the current study can be used to produce TRIP steel tube, and it may serve as an important reference for the industrial production of TRIP steel tube.

  16. Safety aspects of unplanned shutdowns and trips

    International Nuclear Information System (INIS)

    The issue of unplanned shutdowns and trips is receiving increased attention worldwide in view of its importance to plant safety and availability. There exists significant variation in the number of forced shutdowns for nuclear power plants of the same type operating worldwide. The reduction of the frequency of these events will have safety benefits in terms of reducing the frequency of plant transients and the challenges to the safety systems, and the risks of possible incidents. This report provides an insight into the causes of unplanned shutdowns experienced in operating nuclear power plants worldwide, the good practices that have been found effective in minimizing their occurrence, and the measures that have been taken to reduce these events. Specific information on the experiences, approaches and practices of some countries in dealing with this issue is presented in Appendix A

  17. Open Design Architecture for Round Trip Engineering

    Science.gov (United States)

    Beličák, Miroslav; Pokorný, Jaroslav; Richta, Karel

    This chapter introduces a component design of application logic in special type of information system architecture called Open Design Architecture for Round Trip Engineering (ODARTE). This architecture supports model-driven development and integrates information system design with its executable form. It is possible to extract design anytime, modify it, and load back to change the activity and behavior of information system. In this approach, the application logic represents solely functionality and can be described either by sequential model of Windows Workflow Foundation or by UML activity or interaction diagrams. This approach allows creation of flexible and modifiable meta-design of application logic. Finally, an experimental simulation is shown demonstrating the effect of proposal which relates to pilot version of runtime environment for ODARTE support.

  18. User oriented trajectory search for trip recommendation

    KAUST Repository

    Shang, Shuo

    2012-01-01

    Trajectory sharing and searching have received significant attentions in recent years. In this paper, we propose and investigate a novel problem called User Oriented Trajectory Search (UOTS) for trip recommendation. In contrast to conventional trajectory search by locations (spatial domain only), we consider both spatial and textual domains in the new UOTS query. Given a trajectory data set, the query input contains a set of intended places given by the traveler and a set of textual attributes describing the traveler\\'s preference. If a trajectory is connecting/close to the specified query locations, and the textual attributes of the trajectory are similar to the traveler\\'e preference, it will be recommended to the traveler for reference. This type of queries can bring significant benefits to travelers in many popular applications such as trip planning and recommendation. There are two challenges in the UOTS problem, (i) how to constrain the searching range in two domains and (ii) how to schedule multiple query sources effectively. To overcome the challenges and answer the UOTS query efficiently, a novel collaborative searching approach is developed. Conceptually, the UOTS query processing is conducted in the spatial and textual domains alternately. A pair of upper and lower bounds are devised to constrain the searching range in two domains. In the meantime, a heuristic searching strategy based on priority ranking is adopted for scheduling the multiple query sources, which can further reduce the searching range and enhance the query efficiency notably. Furthermore, the devised collaborative searching approach can be extended to situations where the query locations are ordered. The performance of the proposed UOTS query is verified by extensive experiments based on real and synthetic trajectory data in road networks. © 2012 ACM.

  19. Self-consistent radiation-based simulation of electric arcs: II. Application to gas circuit breakers

    Science.gov (United States)

    Iordanidis, A. A.; Franck, C. M.

    2008-07-01

    An accurate and robust method for radiative heat transfer simulation for arc applications was presented in the previous paper (part I). In this paper a self-consistent mathematical model based on computational fluid dynamics and a rigorous radiative heat transfer model is described. The model is applied to simulate switching arcs in high voltage gas circuit breakers. The accuracy of the model is proven by comparison with experimental data for all arc modes. The ablation-controlled arc model is used to simulate high current PTFE arcs burning in cylindrical tubes. Model accuracy for the lower current arcs is evaluated using experimental data on the axially blown SF6 arc in steady state and arc resistance measurements close to current zero. The complete switching process with the arc going through all three phases is also simulated and compared with the experimental data from an industrial circuit breaker switching test.

  20. Arc-induced turbulent mixing in an SF6 circuit breaker model

    Science.gov (United States)

    Bini, Riccardo; Basse, Nils T.; Seeger, Martin

    2011-01-01

    Dielectric interruption performance of SF6 high-voltage gas circuit breakers depends on the temperature distribution of the gas during the post-arc phase. Understanding the details of the mixing process occurring inside the breaker during arcing is therefore fundamental for the design. Multiphysics simulations are nowadays used to predict the flow field and the energy distribution inside the interrupter during and after the arcing phase. In this paper we make use of an optical technique to observe the arc-induced SF6 mixing process inside a dedicated test device. We extract qualitative and quantitative information and we compare this with simulations to conclude on the suitability of the models used.

  1. Transient simulation of nozzle geometry change during ablation in high-voltage circuit breakers

    Science.gov (United States)

    Arabi, Sina; Trépanier, Jean-Yves; Camarero, Ricardo

    2015-02-01

    In high voltage circuit breakers, radiated heat from the electric arc is strongly absorbed by surrounding poly-tetra-fluro-ethylene (PTFE) parts and causes them to reach their vaporization temperature and ablate. Ablation deforms the PTFE parts, widens the throat and hence, changes the nozzle geometry. This paper presents a physical model coupling plasma flow simulation with erosion and movement of the PTFE walls to study this phenomena. The model is first applied and validated on a segmented tube case and on a model SF6 circuit breaker for which the experimental data is available. Then, the model is used to investigate the effect of the surface ablation on the nozzle geometry in a long-operation time.

  2. Transient simulation of nozzle geometry change during ablation in high-voltage circuit breakers

    International Nuclear Information System (INIS)

    In high voltage circuit breakers, radiated heat from the electric arc is strongly absorbed by surrounding poly-tetra-fluro-ethylene (PTFE) parts and causes them to reach their vaporization temperature and ablate. Ablation deforms the PTFE parts, widens the throat and hence, changes the nozzle geometry. This paper presents a physical model coupling plasma flow simulation with erosion and movement of the PTFE walls to study this phenomena. The model is first applied and validated on a segmented tube case and on a model SF6 circuit breaker for which the experimental data is available. Then, the model is used to investigate the effect of the surface ablation on the nozzle geometry in a long-operation time. (paper)

  3. Self-consistent radiation-based simulation of electric arcs: II. Application to gas circuit breakers

    International Nuclear Information System (INIS)

    An accurate and robust method for radiative heat transfer simulation for arc applications was presented in the previous paper (part I). In this paper a self-consistent mathematical model based on computational fluid dynamics and a rigorous radiative heat transfer model is described. The model is applied to simulate switching arcs in high voltage gas circuit breakers. The accuracy of the model is proven by comparison with experimental data for all arc modes. The ablation-controlled arc model is used to simulate high current PTFE arcs burning in cylindrical tubes. Model accuracy for the lower current arcs is evaluated using experimental data on the axially blown SF6 arc in steady state and arc resistance measurements close to current zero. The complete switching process with the arc going through all three phases is also simulated and compared with the experimental data from an industrial circuit breaker switching test

  4. Thermal radiation effect on the extinction properties of electric arcs in HV circuit breakers

    Directory of Open Access Journals (Sweden)

    Ziani Abderrahmane

    2009-01-01

    Full Text Available During the formation of the electric arc at the opening of a high voltage circuit breaker, the generated plasma will be the seat of a very important thermal exchange. Models founded only on conduction and convection thermal transfers don't reproduce the whole thermal exchanges that are governing the extinction process. This paper is devoted to the development of a model of the electric arc extinction in a high voltage circuit breaker taking in account the thermal radiation of the plasma, in addition to the conduction and convection phenomena. The Stefan-Boltzman equation is coupled with the heat equation, and both equations are solved simultaneously in order to follow the evolution of the arc voltage and the conductance of the thermal plasma. The obtained results are found in good agreement with experimental recordings.

  5. Research on the overload protection reliability of moulded case circuit-breakers and its test device

    Institute of Scientific and Technical Information of China (English)

    LI Kui; LU Jian-guo; WU Yi; QIN Zhi-jun; YAO Dong-mei

    2007-01-01

    This paper analyzed the reliability and put forward the reliability index of overload protection for moulded case circuit breaker. The success rate was adopted as its reliability index of overload protection. Based on the reliability index and the reliability level, the reliability examination plan was analyzed and a test device for the overload protection of moulded case circuit-breaker was developed. In the reliability test of overload protection, two power sources were used, which reduced the time of conversion and regulation between two different test currents in the overload protection test, which made the characteristic test more accurate. The test device was designed on the base of a Windows system, which made its operation simple and friendly.

  6. Effect of Circuit Breaker Shunt Resistance on Chaotic Ferroresonance in Voltage Transformer

    Directory of Open Access Journals (Sweden)

    RADMANESH, H.

    2010-08-01

    Full Text Available Ferroresonance or nonlinear resonance is a complex electrical phenomenon, which may cause over voltages and over currents in the electrical power system which endangers the system reliability and continuous safe operating. This paper studies the effect of circuit breaker shunt resistance on the control of chaotic ferroresonance in a voltage transformer. It is expected that this resistance generally can cause ferroresonance dropout. For confirmation this aspect Simulation has been done on a one phase voltage transformer rated 100VA, 275kV. The magnetization characteristic of the transformer is modeled by a single-value two-term polynomial with q=7. The simulation results reveal that considering the shunt resistance on the circuit breaker, exhibits a great mitigating effect on ferroresonance over voltages. Significant effect on the onset of chaos, the range of parameter values that may lead to chaos along with ferroresonance voltages has been obtained and presented.

  7. Dynamic analysis and design of a high voltage circuit breaker with spring operating mechanism

    International Nuclear Information System (INIS)

    Spring Operating Mechanism (SOM) is a dynamic system to open and close the circuit breaker in a voltage controlling system. For a high-speed action of opening and closing within a few mili-seconds, a SOM consists of many links, joints, chains, and cams. Thus, various dynamic characteristics are occurred, especially large contact forces between the cam and the roller, the shaft and the stopper. To save time and money for a new design of SOM system, analysis of the mechanism is necessary. In this paper, a multibody dynamic analysis and test technique was applied for a SOM to predict, estimate and validate forces occurring during the operation. For the multibody dynamic analysis, the ADAMS program was employed for 145kV circuit breaker with a SOM. For an accurate modeling, several components were sequentially added and the reliability of modeling was validated through the comparison with test data of opening and closing

  8. Investigation on critical breakdown electric field of hot carbon dioxide for gas circuit breaker applications

    Science.gov (United States)

    Sun, Hao; Rong, Mingzhe; Wu, Yi; Chen, Zhexin; Yang, Fei; Murphy, Anthony B.; Zhang, Hantian

    2015-02-01

    Sulfur hexafluoride (SF6) gas is widely used in high-voltage circuit breakers, but due to its high global warming potential, substitutes are being sought. CO2 has been investigated as a candidate based on its arc interruption performance. The hot gas in the circuit breaker after current zero, with a complicated species composition caused by the dissociation and many other reactions, will lead to the electrical breakdown, which is one of the major concerns in assessing the arc interruption performance. Despite this, little research has been reported on the dielectric strength of hot CO2. In this paper, the dielectric properties of hot CO2 related to the dielectric recovery phase of the circuit breaker were investigated in the temperature range from 300 to 4000 K and in the pressure range from 0.01 to 1.0 MPa. Under the assumptions of local thermodynamic equilibrium (LTE) and local chemical equilibrium (LCE), the equilibrium compositions of hot CO2 were obtained based on Gibbs free energy minimization. The cross sections for interactions between electrons and the species are presented. The critical reduced electric field strength of CO2 was determined by balancing electron generation and loss. These were evaluated using the electron energy distribution function (EEDF) derived from the two-term Boltzmann transport equation. The result indicates that unlike SF6 or air, in hot CO2 the reduced critical electric field strength does not change monotonically with increasing heavy-particle temperature from 300 to 4000 K. CO2 has a superior dielectric strength to pure SF6 above 2500 K at 0.5 MPa, which means it has the potential to improve the interruption performance of the circuit breakers, while reducing the global warming effect. Good agreement was found with published experimental results and calculations for CO2 at room temperature, and with previous calculations for hot CO2.

  9. A Novel Approach to Power Circuit Breaker Design for Replacement of SF6

    OpenAIRE

    D. J. Telfer; Spencer, J. W.; Jones, G. R.; J. E. Humphries

    2004-01-01

    This contribution explores the role of PTFE ablation in enhancing current interruption for various background gases in high voltage circuit breakers. An assessment of the current interruption capability has been made in terms of the arcing duration and the contact gap length at which critical arc extinction is achieved. These observations are supported by measurements of the magnitude of extinction and re-ignition voltage peaks. Most previous and other current experimental work on gas filled ...

  10. Investigation on critical breakdown electric field of hot carbon dioxide for gas circuit breaker applications

    International Nuclear Information System (INIS)

    Sulfur hexafluoride (SF6) gas is widely used in high-voltage circuit breakers, but due to its high global warming potential, substitutes are being sought. CO2 has been investigated as a candidate based on its arc interruption performance. The hot gas in the circuit breaker after current zero, with a complicated species composition caused by the dissociation and many other reactions, will lead to the electrical breakdown, which is one of the major concerns in assessing the arc interruption performance. Despite this, little research has been reported on the dielectric strength of hot CO2. In this paper, the dielectric properties of hot CO2 related to the dielectric recovery phase of the circuit breaker were investigated in the temperature range from 300 to 4000 K and in the pressure range from 0.01 to 1.0 MPa. Under the assumptions of local thermodynamic equilibrium (LTE) and local chemical equilibrium (LCE), the equilibrium compositions of hot CO2 were obtained based on Gibbs free energy minimization. The cross sections for interactions between electrons and the species are presented. The critical reduced electric field strength of CO2 was determined by balancing electron generation and loss. These were evaluated using the electron energy distribution function (EEDF) derived from the two-term Boltzmann transport equation. The result indicates that unlike SF6 or air, in hot CO2 the reduced critical electric field strength does not change monotonically with increasing heavy-particle temperature from 300 to 4000 K. CO2 has a superior dielectric strength to pure SF6 above 2500 K at 0.5 MPa, which means it has the potential to improve the interruption performance of the circuit breakers, while reducing the global warming effect. Good agreement was found with published experimental results and calculations for CO2 at room temperature, and with previous calculations for hot CO2. (paper)

  11. IMPROVEMENT OF TRANSIENT STABILITY OF POWER SYSTEM USING SOLID STATE CIRCUIT BREAKER

    OpenAIRE

    Kalai Murugan Amirthalingam; Raja Prabu Ramachandran

    2013-01-01

    The aim of this study is to use a solid state circuit breaker for the improvement of transient stability margin. Long distance AC transmission is often subject to stability problems, which limits the transmission capability. Interconnected power systems suffer from weakly damped swings between synchronous generator and sub systems. The development of modern power system has lead to an increasing complexity in the study of power system and also presents new challenges to power system stability...

  12. Detusking fence-breaker elephants as an approach in human-elephant conflict mitigation.

    Directory of Open Access Journals (Sweden)

    Matthew Mutinda

    Full Text Available Human-elephant conflict (HEC is a recurring problem that appears wherever the range of elephants and humans overlap. Different methods including the use of electric fences are used worldwide to mitigate this conflict. Nonetheless, elephants learn quickly that their tusks do not conduct electricity and use them to break down fences (fence-breakers.In Lewa Wildlife Conservancy, Kenya, destructive elephants (Loxodonta africana were monitored between 2010 and 2013. The fence-breaking rate reached four incidents (fence-breaking per elephant per 100 days. Ten bull males and 57 females were identified as fence-breakers. The bulls were involved in 85.07% and the females in 14.93% of incidents. The Kenya Wildlife Service approved detusking (partial cutting of tusks in four of the 10 fence-breakers as a way of preventing them from breaking down fences, thereby mitigating HEC in the Conservancy. The result of the detusking was a drastic six-fold reduction in damage to fences (range: 1.67 to 14.5 times less fence-breaking by the four worst fence-breaker elephants, because with trimmed tusks elephants lack the tools to break down fences. Detusking could not totally eliminate fence destruction because, despite lacking their tools, elephants can still destroy fences using their heads, bodies and trunks, albeit less effectively. On the other hand, apart from inherent aesthetic considerations, the detusking of elephants may have certain negative effects on factors such as elephants' social hierarchies, breeding, mate selection and their access to essential minerals and food.Elephant detusking seems to be effective in drastically reducing fence-breaking incidents, nonetheless its negative effects on behaviour, access to food and its aesthetical consequences still need to be further studied and investigated.

  13. An Experimental Investigation of Wind- and Mechanically Generated Short Wavelength Spilling Breakers

    Science.gov (United States)

    Diorio, J. D.; Liu, X.; Duncan, J. H.

    2006-11-01

    Short wavelength spilling breakers are studied in a wind wave tank that is 12.8 m long and 1.15 m wide and 0.91 m deep. The crest profile histories during breaking are measured with a photographic technique that employs a high-speed digital movie camera, a laser light sheet, and fluorescent dye. The photographic system is mounted on an instrument carriage that is set to move along the tank in phase with the crests of the breaking waves. In the first step in the experiment, breakers generated by the wind are measured at three wind speeds and three fetches at each wind speed. In the second step in the experiment, a mechanical wave maker is used without wind to generate a wave train consisting of a dominant wave and two unstable sidebands. The amplitudes and frequencies of these wave components are adjusted to create breakers at the various fetches and dominant wave frequencies found in the wind wave experiments. The similarities and differences between the ripple patterns at the crest during breaking between the wind wave and mechanical wave cases are discussed.

  14. A circuit breaker fuse system for the Wendelstein VII A ohmic heating circuit

    International Nuclear Information System (INIS)

    The ohmic heating circuit of the W VII A is to be operated in the initial phase of the experiment by means of a HVDC circuit breaker-fuse system satisfying current interrupting requirements of max. 15kA at max. 20kV every 3 minutes. Following on the work of J. Salge et al. a system was developed which consists of two slightly modified power breakers, a fast mechanical safety switch and a liquid-tamped exploding wire. The wire which has to be changed after each current interruption and the liquid (water) are designed as a prefabricated plastic cartridge which is inserted in a solid tube which withstands the explosion pressure and provides electric contact. This arrangement allows replacement times of a few times 10s. Under the given switching conditions the use of a helical wire yields explosion times of 1ms. With the available experimental devices currents of 16kA were interrupted a few hundred times at 22kV. The contacts of the circuit breaker pole thereby have to be replaced after approx. 300 operations. The choice of switchgear is explained, the design of the liquid-tamped fuse discussed and experience in operation reported

  15. Life testing of low-voltage air circuit breaker to assess age-related degradation

    International Nuclear Information System (INIS)

    This paper reports that a DS-416 low-voltage air circuit breaker manufactured by Westinghouse is mechanically cycled to identify age-related degradation in the various breaker subcomponents, specifically in the power-operated mechanism. This accelerated aging test is performed on one breaker unit for over 36 000 cycles. Three separate pole shafts, one with a 60-deg weld, one with a 120-deg weld, and one with a 180-deg weld in the third pole lever, are used to characterize cracking in the welds. In addition, during the testing, three different operating mechanisms and several other parts are replaced as they become inoperable. Among the seven welds on the pole shaft, welds 1 and 3 are found to be critical ones whose fracture can result in misalignment of the pole levers. This can lead to problems with the operating mechanism, including the burning of coils, excessive wear in certain parts, and overstressed linkages. Furthermore, the limiting service life of a number of subcomponents of the power-operated mechanism, including the operating mechanism itself, is assessed

  16. Fuzzy diagnostic system for oleo-pneumatic drive mechanism of high-voltage circuit breakers.

    Science.gov (United States)

    Nicolau, Viorel

    2013-01-01

    Many oil-based high-voltage circuit breakers are still in use in national power networks of developing countries, like those in Eastern Europe. Changing these breakers with new more reliable ones is not an easy task, due to their implementing costs. The acting device, called oleo-pneumatic mechanism (MOP), presents the highest fault rate from all components of circuit breaker. Therefore, online predictive diagnosis and early detection of the MOP fault tendencies are very important for their good functioning state. In this paper, fuzzy logic approach is used for the diagnosis of MOP-type drive mechanisms. Expert rules are generated to estimate the MOP functioning state, and a fuzzy system is proposed for predictive diagnosis. The fuzzy inputs give information about the number of starts and time of functioning per hour, in terms of short-term components, and their mean values. Several fuzzy systems were generated, using different sets of membership functions and rule bases, and their output performances are studied. Simulation results are presented based on an input data set, which contains hourly records of operating points for a time horizon of five years. The fuzzy systems work well, making an early detection of the MOP fault tendencies. PMID:24319349

  17. Measured turbulent mixing in a small-scale circuit breaker model.

    Science.gov (United States)

    Basse, N P T; Bini, R; Seeger, M

    2009-11-10

    The performance of high voltage gas circuit breakers depends on the temperature distribution of hot gas or plasma from the arc zone mixed with cold gas that is present, for example, in the exhausts and mixing volume. Understanding the details of the mixing process is imperative to estimate the temperature distribution within the entire breaker volume. Design studies rely on computational fluid dynamics (CFD) simulations to search for the best way to achieve satisfactory mixing. One key uncertainty in the CFD simulations is the role of turbulence in this process and how to properly account for it. To gain knowledge of the mixing process between hot and cold gases, we have constructed a simplified breaker geometry that is flexible and accessible to diagnostics. Apart from standard measurements of current and arc voltage, we measure pressure in the arc zone and the mixing volume. Further, the mixing volume is specially designed to be transparent, allowing us to make shadowgraphy measurements of the turbulent mixing during and after the arcing phase. We report on experiments performed in air at atmospheric pressure. PMID:19904340

  18. Fuzzy Diagnostic System for Oleo-Pneumatic Drive Mechanism of High-Voltage Circuit Breakers

    Directory of Open Access Journals (Sweden)

    Viorel Nicolau

    2013-01-01

    Full Text Available Many oil-based high-voltage circuit breakers are still in use in national power networks of developing countries, like those in Eastern Europe. Changing these breakers with new more reliable ones is not an easy task, due to their implementing costs. The acting device, called oleo-pneumatic mechanism (MOP, presents the highest fault rate from all components of circuit breaker. Therefore, online predictive diagnosis and early detection of the MOP fault tendencies are very important for their good functioning state. In this paper, fuzzy logic approach is used for the diagnosis of MOP-type drive mechanisms. Expert rules are generated to estimate the MOP functioning state, and a fuzzy system is proposed for predictive diagnosis. The fuzzy inputs give information about the number of starts and time of functioning per hour, in terms of short-term components, and their mean values. Several fuzzy systems were generated, using different sets of membership functions and rule bases, and their output performances are studied. Simulation results are presented based on an input data set, which contains hourly records of operating points for a time horizon of five years. The fuzzy systems work well, making an early detection of the MOP fault tendencies.

  19. IMPROVEMENT OF TRANSIENT STABILITY OF POWER SYSTEM USING SOLID STATE CIRCUIT BREAKER

    Directory of Open Access Journals (Sweden)

    Kalai Murugan Amirthalingam

    2013-01-01

    Full Text Available The aim of this study is to use a solid state circuit breaker for the improvement of transient stability margin. Long distance AC transmission is often subject to stability problems, which limits the transmission capability. Interconnected power systems suffer from weakly damped swings between synchronous generator and sub systems. The development of modern power system has lead to an increasing complexity in the study of power system and also presents new challenges to power system stability and in particular to the aspects of transient stability and small signal stability. Transient stability control plays a significant role in ensuring the stable operation of power systems in the event of large disturbances and faults and is thus a significant area of research. This study investigates the improvement of transient stability of a two area system, using Solid State Circuit Breaker which is capable of fast switching in case of faults and thus controlling the real and reactive power flows in a faulted transmission line. Simulations are carried out in Matlab/Simulink environment for two area system model with Solid State Circuit Breaker to analyze the effects of SSCB on transient stability performance of the system. From the simulation results, swing curves of the three phase faulted power system without SSCB gets increases monotonically and thus the system can be considered as unstable whereas the swing curves of the system with an SSCB reaches to a steady state.

  20. The Danish Curve Breaker Agreement model - a voluntary agreement to break the electricity consumption curve

    Energy Technology Data Exchange (ETDEWEB)

    Jarby, Christian (Public Sector Affairs, The Danish Electricity Saving Trust (Denmark)); Pagh Nielsen, Karen Marie (Alectia A/S (Denmark)); Fjordbak, Troels (IT Energy ApS (Denmark))

    2009-07-01

    Both the public and private company sectors are continually acquiring more electrically powered equipment. Consequently, electricity consumption has risen by more than 1% per year over the last 10 years in Denmark (Danish Energy Agency, 2008). Curve Breaker Agreements were introduced in Denmark in 2007 by The Danish Electricity Saving Trust, an independent institution led by a Board appointed by the Danish Ministry of Climate and Energy. The agreements commit organisations and companies signing the agreements to reduce their electricity consumption and 'break the rising electricity curve', typically over a 3-year period. This paper describes the Curve Breaker Agreement model and analyses the effectiveness of initiatives and solutions in different agreements. The analysis is based on empirical research covering 115 agreements concluded by 18 March 2009. The research also includes remotely metered electricity consumption data and interviews with agreeing partners. The results showed that agreements should be concluded at macro level. An important precondition of the agreement follow-up process is that both parties should be able to track the electricity consumption of an individual organisation on a website. 115 agreements have been concluded in about 2 years, and by December 2008 the list of signatories included one third of all Danish municipalities, government ministries and public sector institutions, as well as a number of large private companies. The latest survey of electricity consumption in the Danish public sector indicates that the consumption curve by signatories of Curve Breaker Agreements has generally been broken, and is heading lower.

  1. A Novel Approach to Power Circuit Breaker Design for Replacement of SF6

    Directory of Open Access Journals (Sweden)

    D. J. Telfer

    2004-01-01

    Full Text Available This contribution explores the role of PTFE ablation in enhancing current interruption for various background gases in high voltage circuit breakers. An assessment of the current interruption capability has been made in terms of the arcing duration and the contact gap length at which critical arc extinction is achieved. These observations are supported by measurements of the magnitude of extinction and re-ignition voltage peaks. Most previous and other current experimental work on gas filled circuit breaker design follows conventional wisdom in investigating arcing behaviours at elevated gas pressures (usually up to 6 bar. But in this work we concentrate on the effects of using low gas pressures (less than 1 bar in the presence of a close-fitting shield of ablatant polymer material (PTFE that surrounds the electrode assembly of an experimental high power circuit breaker. We demonstrate that for several different gases, arc extinction capability compares well under these conditions with SF6, suggesting that SF6 could be replaced entirely in this novel system by more environmentally friendly gases. Moreover, the critical contact gap lengths at extinction are only slightly greater than when using SF6 at 6 bar. Weight loss measurements from the ablatant shield suggest that a chemical puffer action is the most likely mechanism for achieving the observed arc extinctions in this system.

  2. Hydrodynamic characteristics and geometric properties of plunging and spilling breakers over impermeable slopes

    Science.gov (United States)

    Alagan Chella, Mayilvahanan; Bihs, Hans; Myrhaug, Dag; Muskulus, Michael

    2016-07-01

    The two-phase flow CFD model REEF3D has been used for modeling waves breaking over a sloping seabed for a spilling and a plunging breaker. This model is based on Reynolds-averaged Navier-Stokes (RANS) equations with the level set method (LSM) for the free surface and k-ω model for turbulence. First, the characteristics and geometric properties of plunging breaking waves with different offshore wave steepnesses over slopes are examined and discussed. The study further explores the hydrodynamic characteristics of spilling and plunging breakers in terms of the wave height evolution and attenuation, horizontal and vertical velocity, free surface profile evolution, and the geometric properties during the development of the breaking process. The numerical results show a good agreement with experimental data in terms of free surface elevation, horizontal and vertical velocity, wave envelope and turbulent intensity for the spilling and plunging breakers. Results of numerical simulations describing the physical flow characteristics such as the formation of the forward overturning water jet, air pocket, splash-up, and the secondary wave during the breaking process are presented for both cases. For both cases, the physical flow process is found to have similar flow features, but the breaking process occurs at significantly different scales.

  3. REVIEW AND PROSPECT OF HIGH STRENGTH LOW ALLOY TRIP STEEL

    Institute of Scientific and Technical Information of China (English)

    L. Li; P. Wollants; Y.L. He; B.C. De Cooman; X.C. Wei; Z.Y. Xu

    2003-01-01

    Research status of high strength low alloy TRIP (transformation induced plasticity)steels for automobile structural parts is briefly described. Composition and microstructure factors especially the morphology, size and volume fraction of retained austenite,which largely influence the strength and ductility of the steel, are reviewed and discussed one after another. Modelling of the inter-critical annealing and martempering processes as well as the designing of the TRIP steel aided by commercial software are introduced. Some special aspects of the dynamic mechanical properties of TRIP steel are firstly reported.

  4. Peer Pressure Road Trip 2012 - A Report

    Science.gov (United States)

    Popnoe, Olivia

    2012-10-01

    Each year since 2005 the Angelo State University SPS ``Peer Pressure Team'' has travelled for a week in May to promote physics and other sciences for grades K-12. This year, the Peer Pressure Team visited schools in West Texas and New Mexico. This was the first year the team has traveled outside of Texas, inspired by the SPS 2012 theme ``Physics Beyond Borders.'' The purpose of the Road Tours is to encourage an interest in science in children in grades K-12 and give experience in presenting and explaining physics to the undergraduate volunteers. The schools attended are carefully selected based on socioeconomic need and an underrepresentation in physics, as well as other sciences. During this week, the Peer Pressure Team saw about 1,500 students over 10 shows. Surveys were given to teachers post-demonstration to have students complete and return so the Team could gauge the effectiveness of the outreach program. In addition, the surveys allow the Team to determine which demonstrations had the most impact. We present the details of this year's road trip with the results and analysis of the survey data.

  5. You Can't Reach for the Stars if You are Tripping Over the Ground! (Preventing Slips, Trips, and Falls)

    Science.gov (United States)

    Miller, Darcy; Raysich, Mark; Kirkland, Mary

    2016-01-01

    Although there are very few mishaps related to ground, vehicle or payload processing at the Kennedy Space Center (KSC), employees have experienced a significant number of injuries due to slips, trips, and falls outside of performing flight processing operations. Slips, trips, and falls are major causes of occupational injuries at KSC, the National Aeronautics and Space Administration (NASA), and in general industry. To help KSC employees avoid these injuries, and allow them to be fully productive, KSC launched an initiative in 2013 to reduce slips, trips, and falls. This initiative is based on a four-part model focusing on DATA analysis, HAZARD awareness, PREVENTIVE methods, and BALANCE.

  6. [August 1992 trip report : Kirwin NWR and Rainwater Basin WMD

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This trip report evaluates the current years farming and grazing results for Kirwin National Wildlife Refuge and Rainwater Basin Wetland Management District.

  7. Analisis Sympathetic Trip pada Penyulang Ungasan-Bali Resort, Bali

    Directory of Open Access Journals (Sweden)

    Cakasana Alif Bathamantri

    2012-09-01

    Full Text Available Sistem pengaman dalam tenaga listrik dimaksudkan untuk melokalisir gangguan agar tidak meluas sesuai dengan cakupan daerah pengaman. Salah satu kegagalan pengaman melokalisir gangguan disebut sympathetic trip yaitu kegagalan rele pada penyulang 20 kV di gardu induk dimana penyulang yang tidak terganggu, akan ikut trip dengan penyulang yang terganggu. Dalam tugas akhir ini akan dibahas mengenai analisa penyebab terjadinya peristiwa sympathetic trip pada penyulang Ungasan-Bali Resort 20kV di Bali karena di tempat inilah tercatat sering terjadi gangguan sympathetic trip. Besarnya arus kapasitif, setting ground fault relay dan koordinasi rele pengaman semua akan di analisa pada tugas akhir ini. Untuk analisa koordinasi rele, perhitungan dilakukan menggunakan program ETAP 7.0.

  8. Probabilistic determination of neutronic trip setpoints at Cernavoda NPP, Romania

    International Nuclear Information System (INIS)

    This paper describes the methodology used for probabilistic determination of the Regional Overpower tripsetpoints at Cernavoda Nuclear Power Plant Unit 1 (a CANDU project). The shutdown systems use in-core flux detectors to protect against local power increases that can lead to fuel dryout and melting. These flux detectors are spread throughout the reactor core and are assigned to 3 independent trip channels per shutdown systems. The design criteria is that each shutdown system must trip the reactor with a confidence of 98% on a 2 of 2 logic, i.e. assuming the best trip channel unavailable. Parameter considered in the calculation of the trip-setpoints (TSP) are affected by random and systematic error. The probabilistic approach described here was developed by AECL specialists and allows error margins of ∼ 10%, lower than the deterministic margin of 15-20%.(author)

  9. Hawaii Longline Fishery Trip Expenditure (2004 to present)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This is a time-series dataset of trip expenditure data for the Hawaii-based longline fleet for the period August 2004 to present. The data collection includes 10...

  10. Customer satisfaction with individual shopping trip experiences in grocery retailing

    DEFF Research Database (Denmark)

    Esbjerg, Lars; Grunert, Klaus G; Jensen, Birger Boutrup;

    individual shopping trips is a prerequisite for developing customer loyalty. However, there is surprisingly little research focusing on satisfaction with individual shopping trips. On the contrary, satisfaction is normally conceptualised and studied as an overall evaluation of a given retailer based on all...... mechanisms may be at work than in other retail settings such as themed flagship stores, which are visited less regularly and are oriented more towards creating hedonic shopping experiences. This paper develops a conceptual framework for analysing customer satisfaction with individual shopping trip...... experiences in grocery retailing. The framework makes at least two important contributions to the literature. First, it focuses on customer satisfaction with individual shopping trips whereas previous research and theoretical frameworks have addressed either overall satisfaction with the retailer, service...

  11. [July 1999 trip report : Kirwin National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report summarizes a trip to Kirwin National Wildlife Refuge in 1999. It provides general background on the refuge, and reviews recreational activities, habitat...

  12. On-line condition monitoring systems for high voltage circuit breakers : a collaborative research project 1997-2001

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    A three year field project was initiated to review and evaluate the state of the art in on-line conditioning monitoring technology for a high voltage (240 kV SF6) circuit breaker located at Dorsey Converter Station. The ELF breaker is a three independent pole design which allows for three separate monitoring systems. This project involved the installation of a different type of monitoring system on each phase and incorporated many types of transducers. Each monitoring system measured the same basic parameters including contact travel, 'a' and 'b' auxiliary contacts, phase currents, coil currents, heater and pump current, plus SF6/CF4 pressure and temperature. Over the entire monitoring period the breaker was operated over 700 times at rated voltage and an additional 300 times during maintenance. Temperature conditions ranged from -35 to +30 degrees C. The use of on-line monitoring provided many valuable results and enhanced the knowledge base for the apparatus under the test. It was determined that on-line monitoring of HV circuit breakers has potential, but installation has to be considered carefully. Monitoring systems can offer improvement in the understanding of how circuit breakers work and provide input into RCM programs. However, monitoring systems themselves are subject to failure and require maintenance and attention. 2 refs., 2 tabs., 7 figs.

  13. The life test of a DC circuit breaker of tokamak device JT-60 for a nuclear fusion research

    International Nuclear Information System (INIS)

    In the Tokamak devices for nuclear fusion research, the construction of the current transformer circuits having plasma as the secondary circuit and the change of the primary circuit current are necessary for generating current in the plasma. This is considered to be fairly difficult in practice if conventional methods using capacitor discharge and iron core coils are employed. Considering such circumstances, it was decided for JT-60 to use an air-core current transformer coil and to employ the method of storing energy in the form of current in the coil inductance instead of a capacitor. For this reason, a DC circuit breaker is required to interrupt coil current. The authors improved an AV vacuum breaker, which had been developed as the vacuum breaker of longitudinal magnetic field type applying a magnetic field in parallel with an arc, to get the one for DC circuit for the purpose of applying it to JT-60. In this paper, the operational characteristic of the DC breaker is described, the construction and function of the life test circuit is explained, and the test results are reported. Finally, interruptions of 10,000 times at 20 kA were carried out. It is successful that the restrike of arc occurring during tens of milli-seconds after interruptions was improved to 0.05% or less for 10,000 times operations. Further, it was found that the generation of arc restrike can be reduced practically to zero with two breakers in series. (Wakatsuki, Y.)

  14. My trip to Britain,my greatest inspiration

    Institute of Scientific and Technical Information of China (English)

    陈嘉瑜

    2015-01-01

    During a summer vacation I went to Britain to visit our sister school there with the teachers and students delegation in our school for a cross-cultural communication trip and we stayed there for about a month.What I saw and experienced during the trip broadened my horizon and had a great effect on me and it’s really a wonderful and unforgettable experience in my life.

  15. Systematic comparison of trip distribution laws and models

    OpenAIRE

    Lenormand, Maxime; Bassolas, Aleix; Ramasco, José J.

    2015-01-01

    Trip distribution laws are basic for the travel demand characterization needed in transport and urban planning. Several approaches have been considered in the last years. One of them is the so-called gravity law, in which the number of trips is assumed to be related to the population at origin and destination and to decrease with the distance. The mathematical expression of this law resembles Newton's law of gravity, which explains its name. Another popular approach is inspired by the theory ...

  16. Modelling leisure day trips between Berlin and its surrounding

    OpenAIRE

    Beuck, Ulrike

    2005-01-01

    The paper describes the development, application and validation of a quantitative spatial model for leisure day trips from Berlin into the surrounding regions. Leisure activities can contribute substantially to the economies of rural regions like the surroundings of Berlin, but these activities are also often very sensitive to environmental quality, which is usually negatively affected by the traffic caused by the leisure travelers...A model of the spatial distribution of leisure day trips ca...

  17. Systematic comparison of trip distribution laws and models

    OpenAIRE

    Lenormand, Maxime; Bassolas, Aleix; José J. Ramasco

    2016-01-01

    Trip distribution laws are basic for the travel demand characterization needed in transport and urban planning. Several approaches have been considered in the last years. One of them is the so-called gravity law, in which the number of trips is assumed to be related to the population at origin and destination and to decrease with the distance. The mathematical expression of this law resembles Newton's law of gravity, which explains its name. Another popular approach is inspired by the theory ...

  18. Accommodation of the spinal cat to a tripping perturbation

    Directory of Open Access Journals (Sweden)

    ReggieEdgerton

    2012-05-01

    Full Text Available Adult cats with a complete spinal cord transection at T12-T13 can relearn over a period of days-to-weeks how to generate full weight-bearing stepping on a treadmill or standing ability if trained specifically for that task. In the present study, we assessed short-term (msec-min adaptations by repetitively imposing a mechanical perturbation on the hindlimb of chronic spinal cats by placing a rod in the path of the leg during the swing phase to trigger a tripping response. The kinematics and EMG were recorded during control (10 steps, trip (1 to 60 steps with various patterns and then release (without any tripping stimulus, 10 to 20 steps sequences. Our data show that the activation patterns and kinematics of the hindlimb in the step cycle immediately following the initial trip (mechanosensory stimulation of the dorsal surface of the paw was modified in a way that increased the probability of avoiding the obstacle in the subsequent step. This indicates that the spinal sensorimotor circuitry reprogrammed the trajectory of the swing following a perturbation prior to the initiation of the swing phase of the subsequent step, in effect “attempting” to avoid the re-occurrence of the perturbation. The average height of the release steps was elevated compared to control regardless of the pattern and the length of the trip sequences. In addition, the average impact force on the tripping rod tended to be lower with repeated exposure to the tripping stimulus. EMG recordings suggest that the semitendinosus, a primary knee flexor, was a major contributor to the adaptive tripping response. These results demonstrate that the lumbosacral locomotor circuitry can modulate the activation patterns of the hindlimb motor pools within the time frame of single step in a manner that tends to minimize repeated perturbations. Furthermore, these adaptations remained evident for a number of steps after removal of the mechanosensory stimulation.

  19. A Field Trip without Buses: Connecting Your Students to Scientists through a Virtual Visit

    Science.gov (United States)

    Adedokun, Omolola; Parker, Loran Carleton; Loizzo, Jamie; Burgess, Wilella; Robinson, J. Paul

    2011-01-01

    One school offers zipTrips as an alternative to actual field trips taken outside of school. ZipTrips are web- and broadcast-delivered electronic field trips that include online videos, lesson plans, and a live, 45-minute interactive program consisting of four core components: an in-studio audience, live interaction with scientists, prerecorded…

  20. Field Trips Put Chemistry in Context for Non-Science Majors

    Science.gov (United States)

    Peterman, Keith E.

    2008-01-01

    Field trips can provide excellent real-world learning situations for students in non-science major chemistry courses. The field trips described in this article are accessible, most trips can be completed within a scheduled three-hour laboratory time period, and they can be conducted at minimal cost. These field trips significantly enhanced student…

  1. Language Travel or Language Tourism: Have Educational Trips Changed So Much?

    Science.gov (United States)

    Laborda, Jesus Garcia

    2007-01-01

    This article points out the changes in organization, students and language learning that language trips, as contrasted with educational trips (of which language trips are a subgroup) have gone through in the last years. The article emphasizes the need to differentiate between language trips and language tourism based on issues of additional…

  2. Development and formability analysis of TRIP seamless steel tube

    Institute of Scientific and Technical Information of China (English)

    Zhang Zicheng; Zhu Fuxian

    2014-01-01

    In this paper,the production technology of transformation induced plasticity (TRIP) steel was first introduced into the steel tube manufacture field to produce the steel tubes with high strength and plasticity. The TRIP seamless steel tubes with the microstructure of ferrite,bainite,retained austenite and a little martensite were successfully fabricated using a cold-drawn steel tube with two-stage heat treatment technique and continu-ous heat treatment process,respectively. The ring tensile test and cold bend test were carried out to study the formability of the newly developed TRIP seamless steel tube. The results showed that the TRIP seamless steel tubes have a good cold formability,and they are available to be used in the tube hydroforming process. In ad-dition,the equipment of continuous heat treatment developed in the current study can be used to produce TRIP steel tube,and it may serve as an important reference for the industrial production of TRIP steel tube.

  3. Round trip landing missions to the asteroid Eros, 1981 opportunity

    Science.gov (United States)

    Zambo, G. A.

    1971-01-01

    A comprehensive, Del V (magnitude of impulsive velocity-change vector) study of short staytime (0 to 30 days), short total trip time (10 to 160 days) round trip landing missions (fast missions) is presented. The characteristics of the following selected round trip landing missions are described: mission A (fast mission) with 120-day total trip time, 0-day stay-time, and 73,000-fps total mission Del V; mission B (opposition class) with 380-day total trip time, 0-day staytime, and 52,000-fps total mission Del V; and mission C (conjuction class) with 540-day total trip time, 175-day staytime, and 39,000-fps total mission Del V. A study of large-tank Agena, chemical propulsion stage (CPS), and nuclear stage was conducted. A payload of 5000 pounds was assumed. The propulsion requirements for mission A were found to be two large-tank Agenas and ten CPSs (or alternatively, two large-tank Agenas and five nuclear stages) while mission B required two large-tank Agenas and two CPSs. Mission C can be performed with one large-tank Agena and one CPS.

  4. Analysis of the Unexpected HANARO Trip History(1996 - 2005)

    International Nuclear Information System (INIS)

    Since its first criticality in February 1995, the HANARO has been utilized for nuclear fuel and material irradiation tests, radioisotope production, neutron beam applications, neutron activation analyses, and a neutron transmutation doping, etc. In the early HANARO operations, the unexpected reactor trip occurred frequently during a power ascension test which was one of the reactor performance tests. They were most due to a system problem and an operator's error. Some cases originated from an experimenter error and the failure of an electric power supply. To reduce the unexpected reactor trips due to system problems, the neutron power measuring system was improved. A retraining of the operators was performed to reduce the human errors. When the reactor power increases, the reactor is tripped in the case that the difference of the neutron and thermal power is larger than 3 MW. To prevent a reactor trip by the thermal and neutron power mismatch, the neutron power is calibrated during an increasing power when the neutron power and thermal power differences are above 1.5MW. In this paper, the cases of unexpected reactor trips are analyzed from 1996 to 2005 and the efforts to reduce the unexpected reactor trips and their effects are described

  5. Hybrid intelligent monironing systems for thermal power plant trips

    Science.gov (United States)

    Barsoum, Nader; Ismail, Firas Basim

    2012-11-01

    Steam boiler is one of the main equipment in thermal power plants. If the steam boiler trips it may lead to entire shutdown of the plant, which is economically burdensome. Early boiler trips monitoring is crucial to maintain normal and safe operational conditions. In the present work two artificial intelligent monitoring systems specialized in boiler trips have been proposed and coded within the MATLAB environment. The training and validation of the two systems has been performed using real operational data captured from the plant control system of selected power plant. An integrated plant data preparation framework for seven boiler trips with related operational variables has been proposed for IMSs data analysis. The first IMS represents the use of pure Artificial Neural Network system for boiler trip detection. All seven boiler trips under consideration have been detected by IMSs before or at the same time of the plant control system. The second IMS represents the use of Genetic Algorithms and Artificial Neural Networks as a hybrid intelligent system. A slightly lower root mean square error was observed in the second system which reveals that the hybrid intelligent system performed better than the pure neural network system. Also, the optimal selection of the most influencing variables performed successfully by the hybrid intelligent system.

  6. User Oriented Trajectory Search for Trip Recommendation

    KAUST Repository

    Ding, Ruogu

    2012-09-08

    Trajectory sharing and searching have received significant attention in recent years. In this thesis, we propose and investigate the methods to find and recommend the best trajectory to the traveler, and mainly focus on a novel technique named User Oriented Trajectory Search (UOTS) query processing. In contrast to conventional trajectory search by locations (spatial domain only), we consider both spatial and textual domains in the new UOTS query. Given a trajectory data set, the query input contains a set of intended places given by the traveler and a set of textual attributes describing the traveler’s preference. If a trajectory is connecting/close to the specified query locations, and the textual attributes of the trajectory are similar to the traveler’s preference, it will be recommended to the traveler. This type of queries can enable many popular applications such as trip planning and recommendation. There are two challenges in UOTS query processing, (i) how to constrain the searching range in two domains and (ii) how to schedule multiple query sources effectively. To overcome the challenges and answer the UOTS query efficiently, a novel collaborative searching approach is developed. Conceptually, the UOTS query processing is conducted in the spatial and textual domains alternately. A pair of upper and lower bounds are devised to constrain the searching range in two domains. In the meantime, a heuristic searching strategy based on priority ranking is adopted for scheduling the multiple query sources, which can further reduce the searching range and enhance the query efficiency notably. Furthermore, the devised collaborative searching approach can be extended to situations where the query locations are or- dered. Extensive experiments are conducted on both real and synthetic trajectory data in road networks. Our approach is verified to be effective in reducing both CPU time and disk I/O time.

  7. User Oriented Trajectory Search for Trip Recommendation

    KAUST Repository

    Ding, Ruogu

    2012-07-08

    Trajectory sharing and searching have received significant attention in recent years. In this thesis, we propose and investigate the methods to find and recommend the best trajectory to the traveler, and mainly focus on a novel technique named User Oriented Trajectory Search (UOTS) query processing. In contrast to conventional trajectory search by locations (spatial domain only), we consider both spatial and textual domains in the new UOTS query. Given a trajectory data set, the query input contains a set of intended places given by the traveler and a set of textual attributes describing the traveler’s preference. If a trajectory is connecting/close to the specified query locations, and the textual attributes of the trajectory are similar to the traveler’s preference, it will be recommended to the traveler. This type of queries can enable many popular applications such as trip planning and recommendation. There are two challenges in UOTS query processing, (i) how to constrain the searching range in two domains and (ii) how to schedule multiple query sources effectively. To overcome the challenges and answer the UOTS query efficiently, a novel collaborative searching approach is developed. Conceptually, the UOTS query processing is conducted in the spatial and textual domains alternately. A pair of upper and lower bounds are devised to constrain the searching range in two domains. In the meantime, a heuristic searching strategy based on priority ranking is adopted for scheduling the multiple query sources, which can further reduce the searching range and enhance the query efficiency notably. Furthermore, the devised collaborative searching approach can be extended to situations where the query locations are ordered. Extensive experiments are conducted on both real and synthetic trajectory data in road networks. Our approach is verified to be effective in reducing both CPU time and disk I/O time.

  8. "Report to the Legislature on": The Implementation of the Special Education Reimbursement ("Circuit Breaker") Program. Line-Item 7061-0012

    Science.gov (United States)

    Massachusetts Department of Education, 2008

    2008-01-01

    This paper reports on the implementation of the Special Education Reimbursement ("Circuit Breaker") Program. Fiscal Year 2007 is the fourth year implementing the Circuit Breaker reimbursement program which provides additional state support for students with disabilities. School districts are eligible for a reimbursement of eligible costs of…

  9. Simulation of SLF Interrupting Performance for SF6 Gas Circuit Breaker based on Serially Connected 3 Arc Models

    Science.gov (United States)

    Koshizuka, Tadashi; Shinkai, Takeshi; Udagawa, Keisuke; Kawano, Hiromichi

    This paper shows the simulation of SLF interrupting performances for SF6 gas circuit breakers. From the measurements using 300kV-SF6 gas model circuit breakers, it was shown that the extinction peak voltages were varying with arcing times. But, the current values at the extinction peak were the same. To simulate the SLF interrupting performances for the circuit breakers, serially connected 3 arc models were used. Cassie arc model and two Mayr arc models were serially connected. In this arc model, the Cassie model simulates the high current arc. One of the Mayr arc model (Mayr model 1) simulates the arc around the voltage extinction peak. And the other Mayr arc model simulates the arc around current zero. In this model, arc voltage of the Cassie model and arc power loss of the Mayr model 1 are only estimated from the experiments. It was good agreement with the measurements and simulations.

  10. Study and field verification of the effects of removing closing resistors from 500 kV circuit breakers

    International Nuclear Information System (INIS)

    Closing resistors in EHV circuit breakers are frequently used to reduce switching transients on lines thus preventing flashovers during line energization. Maintenance and failures of such closing resistors can be costly and reduce transmission system reliability. For these reasons, APS conducted an investigation into the technical feasibility of operating its 500 kV without closing resistors. This paper describes study results of removing closing resistors from 500 kV breakers in a system which employs older technology silicon carbide type surge arresters. The paper also describes results of field tests of the expected flashover rates calculated in the study. These field tests involve repeatedly energizing a 258 mile 500 kV line using a breaker in which the closing resistors are disabled. Transient overvoltages captured during the tests are compared with predicted overvoltages. The study concludes that closing resistors may be removed from the subject system without unacceptable consequences

  11. Air blast circuit breaker noise and hearing loss: a multifactorial model for risk assessment.

    Science.gov (United States)

    McBride, D I; Williams, S

    2000-04-01

    The assessment of the risk to hearing from impulse noise exposure may be a problem for the occupational physician because existing legislative and international noise exposure standards deal primarily with continuous noise, and are not valid in excess of the peak exposure limit of 200 pa (140 dB). Noise exposure in excess of this level, for example that due to firearms, is frequently perceived as harmful, but this is not necessarily the case, as impulse noise standards do, in fact, allow exposure with a maximum in the order of 6.3 kPa (170 dB). To illustrate this, a cross-sectional group of electrical transmission workers have been studied who were exposed to significant levels of impulse noise from air blast circuit breakers and firearms. Important hearing loss factors have been identified by means of a specially designed questionnaire. Using the Health & Safety Executive definition, the risk of hearing loss was determined by calculating prevalence odds ratios (ORs) for exposure to these factors. The OR for those with fewer than eight unprotected air blast circuit breaker exposures was 2.27 (95% confidence interval (CI), 1.01-5.08), whilst for those with more than eight exposures the OR was 2.10 (95% CI, 0.97-4.54). For firearm exposure, ORs of 1.61 (95% CI, 0.95-2.74) were noted in the medium exposure group and 2.05 (95% CI, 1.08-3.86) in the high exposure group. When all the factors were included in the model, the most significant factor was age. The study gives support to the impulse noise exposure criteria, confirming the borderline risk from air blast circuit breaker noise exposure and the relative safety of moderate gunfire exposure. PMID:10912360

  12. Dielectric recovery in a high-voltage circuit breaker in SF6

    Science.gov (United States)

    Seeger, M.; Schwinne, M.; Bini, R.; Mahdizadeh, N.; Votteler, T.

    2012-10-01

    The dielectric recovery in high-voltage circuit breakers after interruption of high-current amplitudes was investigated experimentally in a test device. Various current amplitudes were tested, which cover a typical range of practical interest. Simulations with computational fluid dynamics together with electric field simulations allowed one to deduce the physical parameters in the region where the breakdown was decided. A leader inception model using these parameters explains under which condition leader inception occurs; causing breakdown of the gap. Based on this model scaling laws for leader inception are given.

  13. Simulation of arc-electrode interaction using sheath modelling in SF6 circuit-breakers

    Science.gov (United States)

    Maruzewski, P.; Martin, A.; Reggio, M.; Trépanier, J.-Y.

    2002-05-01

    The transition layer, or sheath, located at the interface between the electrode and the electric arc plasma in circuit-breaker arcs is modelled and integrated into software for the simulation of arcs. The sheath model includes the equation of the continuity of electrons, the generalized Ohm's law and the equation of conservation of total energy. The latter equation takes into account Joule heating, the radiation from the arc and phenomena on the surface of the electrode such as thermionic and radiative cooling by thermal emission. The resulting arc model can predict electrode and arc temperatures simultaneously.

  14. El uso de los "ice breakers" en la orientación de las asignaturas

    OpenAIRE

    Galván Vallina, Joaquín; Gutiérrez Duarte, María Victoria

    2012-01-01

    El proceso de renovación pedagógica que ha supuesto el Espacio Europeo de Educación Superior (EEES) conduce a una nueva orientación en el desarrollo de las asignaturas. Con arreglo a estos planteamientos, se ha desarrollado el uso de los Ice Breakers (actividades para romper el hielo) con el objetivo de que el alumno se integre en la dinámica de la asignatura, superando la desconfianza y el recelo iniciales que se presentan ante una materia nueva y/o un grupo nuevo de compañeros de clase. En ...

  15. Condition based maintenance of gas circuit breaker using synchronous switching control

    International Nuclear Information System (INIS)

    CBM(Condition Based Maintenance) attracts the attention as a resolution of the request for the maintenance cost reduction of power electrical equipments. CBM is to maintain the necessary contents at the optimum timing. This maintenance timing is planed according to the trend of equipments condition information. Especially at the highly reliable equipments like a GIS(Gas Insulated Switchgear), it is expected to optimize the maintenance period. We describe the applicable CBM of GCB (Gas Circuit Breaker) using the operation time data that are the control one of the Synchronous Switching Controller. (author)

  16. Optical fiber imaging for high speed plasma motion diagnostics: applied to low voltage circuit breakers.

    Science.gov (United States)

    McBride, J W; Balestrero, A; Ghezzi, L; Tribulato, G; Cross, K J

    2010-05-01

    An integrated portable measurement system is described for the study of high speed and high temperature unsteady plasma flows such as those found in the vicinity of high current switching arcs. An array of optical fibers allows the formation of low spatial resolution images, with a maximum capture rate of 1 x 10(6) images per second (1 MHz), with 8 bit intensity resolution. Novel software techniques are reported to allow imaging of the arc; and to measure arc trajectories. Results are presented on high current (2 kA) discharge events in a model test fixture and on the application to a commercial low voltage circuit breaker. PMID:20515174

  17. A novel advanced glycation endproducts breaker restores cardiovascular dysfunctions in experimental diabetic rats

    Institute of Scientific and Technical Information of China (English)

    GangCHENG; Li-liWANG; Hong-yingLIU; HaoCUI; Ying-linCAO; SongLI

    2005-01-01

    AIM The formation of advanced glycation endproducts (AGEs) on connective tissue and matrix components leads to increases in collagen crosslinkingthat contributes to aortic and myocardial stiffness in normal aging and which occurs at an accelerated rate in diabetes. In this study, we examined the effects of a novel AGEs breaker, C36, on cardiovascular dysfunctions in experimental diabetic rats. METHODS and RESULTS Male Wiatar rats were made diabetic by i.p. injection of 70mg/kg streptozotocin. After 12 weeks of diabetes, the animals were randomly divided into 4 groups (n=8-11),

  18. Simulation of the Effects of Several Factors on Arc Plasma Behavior in Low Voltage Circuit Breaker

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Taking into account the properties of the arc plasma and the electromagnetic, heat and radiative phenomena, commercial computational fluid dynamics software PHOENICS has been adapted and modified to develop the three-dimensional magneto-hydrodynamic (MHD)model of arc in a low voltage circuit breaker. The effects of the arc ignition location, venting size and gassing material on arc behavior have been investigated. The analysis of the results show that the arc velocity accelerates with the increase in the distance between arc ignition location and of the venting size, and the existence of the gassing material is beneficial to improving the arc voltage and reducing the arc temperature.

  19. Hv-dc circuit breaker for 20 kA, 12 kV and its protection system

    International Nuclear Information System (INIS)

    Plasma physics experiments require hv-dc circuit breakers to reproducibly commutate large dc currents at a preset time from an opening interrupter into resistor which is connected in parallel to the interrupter. The normal operating conditions of the interrupter are comparable to those of short circuit interruptions at large repetition rates. Therefore, the interrupter needs a fast and reliable protection system which prevents damage to the interrupter in the case of a malfunction. The hv-dc circuit breaker and its protection system, as it is used with the stellarator experiment 'Wendelstein VII', is described. (orig.)

  20. Power nanosecond pulse shaping by means of RCD-generators with peaking circuits based on diode current breakers

    CERN Document Server

    Grekhov, I V; Korotkov, S V; Stepanyants, A L; Khristyuk, D V

    2002-01-01

    One considered the basic principles to design nanosecond region generators based on reverse-connected dynistos (RCD) with diode current breaker base output peaking circuits. Paper presents the results of experimental investigation in intense generator based on RCD, peaking pulsed transformer and high-voltage diode breaker from a set of series-connected drift diodes with abrupt reset. Generator at 1 kHz frequency commutates voltage pulses with approx 45 kV amplitude, approx 50 ns duration and approx 10 ns rise front to 25 ohm load

  1. Power nanosecond pulse shaping by means of RCD-generators with peaking circuits based on diode current breakers

    International Nuclear Information System (INIS)

    One considered the basic principles to design nanosecond region generators based on reverse-connected dynistos (RCD) with diode current breaker base output peaking circuits. Paper presents the results of experimental investigation in intense generator based on RCD, peaking pulsed transformer and high-voltage diode breaker from a set of series-connected drift diodes with abrupt reset. Generator at 1 kHz frequency commutates voltage pulses with ∼ 45 kV amplitude, ∼ 50 ns duration and ∼ 10 ns rise front to 25 ohm load

  2. Proposal to negotiate, without competitive tendering, a contract for the maintenance of three 420 kV circuit breakers

    CERN Document Server

    2000-01-01

    This document concerns the award of a contract for the maintenance, by the manufacturer, of three 420 kV circuit breakers. The Finance Committee is invited to agree to the negotiation of a contract, without competitive tendering, with SCHNEIDER ITALY (IT) (formerly NUOVA MAGRINI GALILEO), the manufacturer of the equipment, for the maintenance of three 420 kV circuit breakers for a total amount of 490 000 Swiss francs, not subject to revision. The firm has indicated the following distribution by country of the contract value covered by this adjudication proposal: IT?100%.

  3. Field Trips and Their Effect on Student Achievement and Attitudes: A Comparison of Physical versus Virtual Field Trips to the Indian River Lagoon

    Science.gov (United States)

    Garner, Lesley C.; Gallo, Michael A.

    2005-01-01

    This study examined the effect of physical and virtual field trips on undergraduate, nonscience majors. No significant differences were seen in achievement, attitudes, learning styles, interactions between field trip and learning styles, or students' ability to answer questions at different levels. Results imply that both field trips promote…

  4. The return trip is felt shorter only postdictively: A psychophysiological study of the return trip effect [corrected].

    Directory of Open Access Journals (Sweden)

    Ryosuke Ozawa

    Full Text Available The return trip often seems shorter than the outward trip even when the distance and actual time are identical. To date, studies on the return trip effect have failed to confirm its existence in a situation that is ecologically valid in terms of environment and duration. In addition, physiological influences as part of fundamental timing mechanisms in daily activities have not been investigated in the time perception literature. The present study compared round-trip and non-round-trip conditions in an ecological situation. Time estimation in real time and postdictive estimation were used to clarify the situations where the return trip effect occurs. Autonomic nervous system activity was evaluated from the electrocardiogram using the Lorenz plot to demonstrate the relationship between time perception and physiological indices. The results suggest that the return trip effect is caused only postdictively. Electrocardiographic analysis revealed that the two experimental conditions induced different responses in the autonomic nervous system, particularly in sympathetic nervous function, and that parasympathetic function correlated with postdictive timing. To account for the main findings, the discrepancy between the two time estimates is discussed in the light of timing strategies, i.e., prospective and retrospective timing, which reflect different emphasis on attention and memory processes. Also each timing method, i.e., the verbal estimation, production or comparative judgment, has different characteristics such as the quantification of duration in time units or knowledge of the target duration, which may be responsible for the discrepancy. The relationship between postdictive time estimation and the parasympathetic nervous system is also discussed.

  5. Understanding intra-urban trip patterns from taxi trajectory data

    Science.gov (United States)

    Liu, Yu; Kang, Chaogui; Gao, Song; Xiao, Yu; Tian, Yuan

    2012-10-01

    Intra-urban human mobility is investigated by means of taxi trajectory data that are collected in Shanghai, China, where taxis play an important role in urban transportation. From the taxi trajectories, approximately 1.5 million trips of anonymous customers are extracted on seven consecutive days. The globally spatio-temporal patterns of trips exhibit a significant daily regularity. Since each trip can be viewed as a displacement in the random walk model, the distributions of the distance and direction of the extracted trips are investigated in this research. The direction distribution shows an NEE-SWW-dominant direction, and the distance distribution can be well fitted by an exponentially truncated power law, with the scaling exponent β = 1.2 ± 0.15. The observed patterns are attributed to the geographical heterogeneity of the study area, which makes the spatial distribution of trajectory stops to be non-uniform. We thus construct a model that integrates both the geographical heterogeneity and distance decay effect, to interpret the observed patterns. Our Monte Carlo simulation results closely match to the observed patterns and thus validate the proposed model. According to the proposed model, in a single-core urban area, the geographical heterogeneity and distance decay effect improve each other when influencing human mobility patterns. Geographical heterogeneity leads to a faster observed decay, and the distance decay effect makes the spatial distribution of trips more concentrated.

  6. Evidence, explanations, and recommendations for teachers' field trip strategies

    Science.gov (United States)

    Rebar, Bryan

    Field trips are well recognized by researchers as an educational approach with the potential to complement and enhance classroom science teaching by exposing students to unique activities, resources, and content in informal settings. The following investigation addresses teachers' field trip practices in three related manuscripts: (1) A study examining the details of teachers' pedagogical strategies intended to facilitate connections between students' experiences and the school curricula while visiting an aquarium; (2) A study documenting and describing sources of knowledge that teachers draw from when leading field trips to an aquarium; (3) A position paper that reviews and summarizes research on effective pedagogical strategies for field trips. Together these three pieces address key questions regarding teachers' practices on field trips: (1) What strategies are teachers employing (and not employing) during self-guided field trips to facilitate learning tied to the class curriculum? (2) What sources of knowledge do teachers utilize when leading field trips? (3) How can teachers be better prepared to lead trips that promote learning? The Oregon Coast Aquarium served as the field trip site for teachers included in this study. The setting suited these questions because the aquarium serves tens of thousands of students on field trips each year but provides no targeted programming for these students as they explore the exhibits. In other words, the teachers who lead field trips assume much of the responsibility for facilitating students' experience. In order to describe and characterize teachers' strategies to link students' experiences to the curriculum, a number of teachers (26) were observed as they led their students' visit to the public spaces of the aquarium. Artifacts, such as worksheets, used during the visit were collected for analysis as well. Subsequently, all teachers were surveyed regarding their use of the field trip and their sources of knowledge for

  7. Deliberation of arc plasma characteristics according to experimental results in a typical gas circuit-breaker

    International Nuclear Information System (INIS)

    One of the industrial plasma applications is in the gas circuit breakers (GCB) and switching processes. During GCB operation and opening of its two contacts, current flows through of the inter-electrode medium (generally SF6 or its mixture) and electric arc forms from the plasma that has been created between the contacts. The electric arc is a self-sustained discharge having low voltage drop and able to support great amplitudes of current. The technical basis of circuit breaker is: initiating arc plasma, flowing a large current, cooling it effectively to avoid re-ignition, and finally the transition from a well-conducting medium into insulating gas space in a very short time interval. In other words, for a successful interruption we need to know about power brought to the arc and that of removed. In this paper an attempt has been made to study, characterize and understand some arc behaviors such as arc conductance and its changes according to recorded current and voltage traces experimentally. From physical point of view, there are different phenomena that affect on arc behavior. According to methodology used here, we tried to understand some of arc behavior from experimental results and finally we extract some arc parameters. (author)

  8. New device for measuring post-arc currents in circuit breakers

    Science.gov (United States)

    Vokurka, V.; Ackermann, U.; Schade, E.

    1987-06-01

    This paper describes a new technique for measuring post-arc currents in circuit breakers. The measurements are performed with a specially designed current monitor. In contrast to commonly used current monitors saturation of the core of the transformer at high pulses of current is prevented by shunting the turns of the transformer by antiparallel fast-recovery diodes. This new device offers several advantages in comparison to other known techniques for post-arc measurements: there is no galvanic coupling to the network, the system is easy to handle, and the costs of the components are low. The two post-arc-current monitors (PACM) described have a sensitivity of 0.1 V/A and 10 mV/A, and are linear within 1% in the range of ±4 and ±100 A, respectively. The first PACM has an upper cutoff frequency of 18 MHz, the second one 3.8 MHz and are designed for sinusoidal fault currents of 6.3 kA and 56 kA, respectively, at a frequency of 50 Hz. Examples of applications to axially blown arcs in SF6 and to vacuum circuit breakers are presented.

  9. Function and operation of the Doublet III E-coil vacuum breaker system

    International Nuclear Information System (INIS)

    The ohmic heating system for the Doublet III fusion research device at General Atomic is required to provide the voltage for the initial breakdown phase (there is no preionization) along with the energy to drive the plasma current to a value of 2.5 MA or greater. This requires a peak one turn voltage of 250 volts (16 kV across coil terminals) and a magnetic flux swing of 5 volt-seconds (peak coil current of 110 kA). This voltage and flux swing is accomplished by reverse biasing the ohmic heating coil (E-coil) where, upon reaching a value of 110 ka the coil current is interrupted and commutated into a RC network producing 16 kV across the coil. The interrruption of the E-coil current is accomplished by the use of an array of vacuum circuit breakers (VCB's) and a counter plus network. A description is given of the ohmic heating circuit and the performance of the vacuum circuit breaker array and its counter pulse system

  10. Study on the Mathematical Model of Dielectric Recovery Characteristics in High Voltage SF6 Circuit Breaker

    Science.gov (United States)

    Lin, Xin; Wang, Feiming; Xu, Jianyuan; Xia, Yalong; Liu, Weidong

    2016-03-01

    According to the stream theory, this paper proposes a mathematical model of the dielectric recovery characteristic based on the two-temperature ionization equilibrium equation. Taking the dynamic variation of charged particle's ionization and attachment into account, this model can be used in collaboration with the Coulomb collision model, which gives the relationship of the heavy particle temperature and electron temperature to calculate the electron density and temperature under different pressure and electric field conditions, so as to deliver the breakdown electric field strength under different pressure conditions. Meanwhile an experiment loop of the circuit breaker has been built to measure the breakdown voltage. It is shown that calculated results are in conformity with experiment results on the whole while results based on the stream criterion are larger than experiment results. This indicates that the mathematical model proposed here is more accurate for calculating the dielectric recovery characteristic, it is derived from the stream model with some improvement and refinement and has great significance for increasing the simulation accuracy of circuit breaker's interruption characteristic. supported by Science and Technology Project of State Grid Corporation of China (No. GY17201200063), National Natural Science Foundation of China (No. 51277123), Basic Research Project of Liaoning Key Laboratory of Education Department (LZ2015055)

  11. Surface Degradation of Ag/W Circuit Breaker Contacts During Standardized UL Testing

    Science.gov (United States)

    Yu, Haibo; Sun, Yu; Kesim, M. Tumerkan; Harmon, Jason; Potter, Jonathan; Alpay, S. Pamir; Aindow, Mark

    2015-09-01

    The near-surface microstructure of Ag/W contacts from 120 V, 30 A commercial circuit breakers in the as-manufactured condition and after standardized UL overload/temperature-rise, endurance, and short-circuit testing have been investigated using a combination of x-ray diffraction, scanning electron microscopy, energy-dispersive x-ray spectroscopy, focused ion beam milling, and transmission electron microscopy. The as-manufactured contacts comprised three constituents: sintered Ag/W composite particles with fine-grained Ag and coarse-grained W, coarse-grained pockets of Ag infiltrate, and a nano-crystalline surface Ag layer. There are also WO3 and Ag2O phases at the surface. After UL overload/temperature-rise testing, there is Ag loss giving a porous W-rich layer at the contact surface. In addition to binary oxides, we observe the formation of Ag2WO4. After UL endurance testing, material is swept across the surface by the breaker action giving a W-rich eroded porous surface on one side and a build-up of mixed oxides on the other. After UL short-circuit testing, a W crust forms due to melting and re-solidification of W and vaporization of Ag, and mid-plane cracks form due to the severe thermal gradients. There is a strong correlation between the observed microstructural features and the contact resistance measurements obtained from these samples.

  12. Study of a circuit-breaker arc with self-generated flow

    International Nuclear Information System (INIS)

    This study concerns the operation of a circuit breaker with self-generated flow. This article deals with the first phase of operation, corresponding to the energy transfer between arc and gas and to the pressure rise. The experimental study is devoted to measurements of current, arc voltage, and pressure variations in N/sub 2/ and SF/sub 6/. For currents of the order of 10 kA the mean measured electric field is about 32 V/cm in SF/sub 6/ and 36 V/cm in N/sub 2/. Through a bibliographical study and a modeling approach of the interruption arc, an analysis of the role of the different mechanisms of energy transfer between the arc and SF/sub 6/ has been conducted. With a 10 kA pulse, about 80 percent of the transfer is due to convection and the rest to radiation from the arc. This transfer results in an overpressure of nearly 1 bar in SF/sub 6/ and 2 bar in N/sub 2/. It appears that the operation of this type of circuit breaker is limited to high currents; for currents below 7 kA the overpressure is lower than 0.5 bar, which does not provide efficient blowing at current zero

  13. Mathematical models of pre-arcing and arcing phenomena in vacuum circuit breakers

    International Nuclear Information System (INIS)

    The main aim of this paper is to show that properties of electrical contact materials are responsible for the metallic vapour pressure at contact closure. Dynamic phenomena accompanying electrical contacts closure in vacuum circuit breakers are considered as consecutive stages, including breakdown, touch, penetration, restitution, bridging and arcing at bouncing. The hybrid mathematical model is elaborated to describe dynamics of the arc and forces acting in contact gap. It includes experimental oscillograms of current, voltage and contact displacement and nonlinear equations for arc, anode and cathode temperature fields and contact motion. Experiments are carried out using a standard vacuum circuit breaker with laser sensors for measurement of contact gap. The special difference path method techniques was applied to take into account oscillations of a fixed contact. The axisymmetrical Stefan problem with two free boundaries corresponding to melting and evaporation interfaces is solved to find dynamics of contact evaporation. It is shown theoretically and confirmed experimentally that in the range of high current the force of metallic vapour pressure at arcing in vacuum is comparable with magnetic repulsion force and should be taken into consideration. Two mechanisms of vapour pressure formation and evolution are discussed, which occur due to explosion of micro-asperities at contact touch or due to arcing after bridge rupture at contact bouncing. (author)

  14. Quench protection system using a novel d.c. circuit breaker for LHD

    International Nuclear Information System (INIS)

    The Large Helical Device (LHD) has 12 superconducting coils that are strongly coupled with each other. The rating currents of these coils are from 13 to 32 kA and total magnetically stored energy reached 1.6 GJ. These coils are excited by six d.c. power supplies and each coil current is controlled with high accuracy to make a magnetic surface required for various plasma experiments. At the same time, it is required that these power supplies discharge the stored energy quickly when coil quench is detected. This paper introduces the quench protection circuit installed in the power supplies. For this system, a 30 kA and 2 kV class d.c. current breaker using the parallel connection of a small vacuum circuit breaker and power fuse is developed. Also, the best discharge resistor set, that dumps stored energy in the wide operation range of the LHD without changing connection, is found using numerical simulation. To confirm the reliability of quench protection and operation delay, operating tests are done using an actual quench protection system and power supply. In this test, more than 400 shots for three deference power systems are finished without any operation failure. (orig.)

  15. Experimental study on PTFE ablation in high voltage circuit-breakers

    International Nuclear Information System (INIS)

    The average surface ablation of poly-tetra-fluro-ethylene (PTFE) nozzles in high voltage circuit-breakers was investigated experimentally by means of the specific ablation. Experiments were done with a test device in the current and arcing time range of 2-40 kArms and 5-17 ms, respectively. This allowed determining the dependences of the specific PTFE ablation on current and arcing time. Additionally, the specific PTFE nozzle ablation in commercial high voltage circuit-breakers was analysed in a broad range of current amplitudes and arcing times. For understanding the results more in detail, experiments with a small scale test device were performed. The different experiments yielded consistent values for the PTFE ablation. The ablation depends mainly on the total arc energy. The total ablation is given by the ablation of walls surrounding the arc and by the ablation in regions where plasma from the arc cools down. Different specific ablation values can be observed for the axial blown arc mode and the ablation controlled arc mode

  16. Development of a test for water-in-oil emulsion breakers

    International Nuclear Information System (INIS)

    Studies have been conducted on the breaking of water-in-oil emulsions to develop a standard test for emulsion breaking agents, to test commercial products, and to understand the physics of emulsions. A review of the literature on the physics of emulsification is presented, showing the effects on emulsion formation of polar and asphaltene compounds in the oil. Nine basic test methods and several variations of each were developed, with successive tests developed to solve problems noted with earlier tests. The tests had to have a high degree of repeatability, aspects of the test methods had to be analogous to the sea and the practical application of emulsion breaking agents, and the test results had to relate to physical understanding of phenomena. Once a basic test was established, a series of studies was conducted to examine optimal time of shaking, the possibility of substituting settling time for shaking time, the relationship between energy of shaking and demuslfier effectiveness, and the effects of water to oil ratios. The studies show that a test for emulsion breakers can be developed to yield consistent results which are not entirely dependent on the shaking methods or vessels. The critical factor is the stability of the emulsion being tested, since unstable emulsions will show anomalous results. Other major factors are the type of emulsion breaker being tested and the determination of endpoint. 17 refs. 17 figs., 18 tabs

  17. TRIBES - A CPC (Core Protection Calculator)/CEAC (Control Element Assembly Calculator) TRIp Buffer Expert System

    International Nuclear Information System (INIS)

    This paper discusses the development of a small IBM personal computer based expert system to diagnose reactor trips initiated by the Core Protection Calculator, CPC, and the Control Element Assembly Calculator, CEAC. The expert system interprets information from trip buffers created by the CPC and CEAC to determine the reason for the reactor trip. A trip buffer consists of a number of numeric point IDs and their values at the time of the CPC or CEAC channel trip. An expert system approach was chosen because trip buffer interpretation requires a CPC expert to determine the cause of a trip, the knowledge is amenable to formulation in rules and the justification subsystem of an expert system allows a novice user to follow the program's logic to the trip conclusion. The TRIp Buffer Expert System, TRIBES, inference engine is written in TURBO-PROLOG

  18. Potential conflict between TRIPS and GATT concerning parallel importation of drugs and possible solution to prevent undesirable market segmentation.

    Science.gov (United States)

    Lo, Chang-Fa

    2011-01-01

    From international perspective, parallel importation, especially with respect to drugs, has to do with the exhaustion principle in Article 6 of the TRIPS Agreement and the general exception in Article XX of the GATT 1994. Issues concerning the TRIPS Agreement have been constant topics of discussion. However, parallel importation in relation to the general rules of the GATT 1994 as well as to its exceptions provided in Article XX was not seriously discussed. In the view of the paper, there is a conflict between the provisions in these two agreements. The paper explains such conflict and tries to propose a method of interpretation to resolve the conflict between GATT Article XX and TRIPS Article 6 concerning parallel importation for the purpose of reducing the possible undesirable market segmentation in pharmaceutical sector. The method suggested in the paper is a proper application of good faith principle in the Vienna Convention to interpret GATT Article XX, so that there could be some flexibility for those prohibitions of parallel importation which have positive effect on international trade. PMID:24505847

  19. Microstructure characterization of Friction Stir Spot Welded TRIP steel

    DEFF Research Database (Denmark)

    Lomholt, Trine Colding; Adachi, Yoshitaka; Peterson, Jeremy;

    2012-01-01

    Transformation Induced Plasticity (TRIP) steels have not yet been successfully joined by any welding technique. It is desirable to search for a suitable welding technique that opens up for full usability of TRIP steels. In this study, the potential of joining TRIP steel with Friction Stir Spot...... Welding (FSSW) is investigated. The aim of the study is to investigate whether acceptable welds can be produced, and additionally, to obtain an understanding of the microstructural changes during welding. The microstructure was investigated with a combination of microscopical techniques with the aim of...... identifying the transformations occurring during welding. Reflected light microscopy, scanning electron microscopy, and electron backscatter diffraction were among the methods applied for detailed investigations. The microstructure adjacent to the welds can generally be subdivided in two thermo...

  20. Mechanical and Microstructural Characterization of an Aluminum Bearing Trip Steel

    Science.gov (United States)

    Monsalve, Alberto; Guzmán, Alexis; De Barbieri, Flavio; Artigas, Alfredo; Carvajal, Linton; Bustos, Oscar; Garza-Montes-de Oca, Nelson F.; Colás, Rafael

    2016-03-01

    The mechanical properties and microstructural characteristics of a steel able to sustain the TRIP-effect were studied. The material was prepared by taking in mind the partial substitution of silicon by aluminum following a processing route that included hot forging, hot and cold rolling, intercritical annealing, and a final bainitic isothermal treatment. The mechanical properties that were obtained resulted to be above those of commercial a 780 TRIP steel. The TRIP phenomenon was confirmed by the change in retained austenite before and after deforming the steel; X-ray diffraction was used to evaluate the volume content of retained austenite. Formability of the steel under study can be rationalized in terms of the texture developed in the material.

  1. Microstructure and Mechanical Properties of High Manganese TRIP Steel

    Institute of Scientific and Technical Information of China (English)

    ZHAO Jin-long; XI Yan; SHI Wen; LI Lin

    2012-01-01

    Microstructure evolution and mechanical properties of newly designed 0.1C-6Mn-0.5Si-1Al TRIP-aided steels under different annealing conditions and the effects of matrix microstructure before intercritical annealing on the final microstructure were studied by means of X-ray diffraction(XRD),scanning electron microcopy(SEM),dilatometric simulation,optical microstructure(OM) and tensile testing in this work.The experimental results indicate that the TRIP steel with Mn of 6% could form a considerable amount of retained austenite with good TRIP effect after a simple intercritical annealing treatment,and the matrix microstructure before intercritical annealing treatment can greatly affect the final microstructure.The original microstructure of the ferritic matrix steel was eliminated,while annealed martensite was remained from the martensite matrix steel under the same intercritical annealing conditions

  2. Mechanical and Microstructural Characterization of an Aluminum Bearing Trip Steel

    Science.gov (United States)

    Monsalve, Alberto; Guzmán, Alexis; De Barbieri, Flavio; Artigas, Alfredo; Carvajal, Linton; Bustos, Oscar; Garza-Montes-de Oca, Nelson F.; Colás, Rafael

    2016-06-01

    The mechanical properties and microstructural characteristics of a steel able to sustain the TRIP-effect were studied. The material was prepared by taking in mind the partial substitution of silicon by aluminum following a processing route that included hot forging, hot and cold rolling, intercritical annealing, and a final bainitic isothermal treatment. The mechanical properties that were obtained resulted to be above those of commercial a 780 TRIP steel. The TRIP phenomenon was confirmed by the change in retained austenite before and after deforming the steel; X-ray diffraction was used to evaluate the volume content of retained austenite. Formability of the steel under study can be rationalized in terms of the texture developed in the material.

  3. Are short daily trips compensated by higher leisure mobility?

    DEFF Research Database (Denmark)

    Næss, Petter

    2006-01-01

    Studies in several cities have shown that inner-city residents travel shorter distances and use cars less for local transport than suburbanites do. However, according to some authors, a low daily amount of travel is likely to be compensated through more extensive leisure mobility at weekends and on...... holidays. On the basis of a study of residential location and travel in the Copenhagen metropolitan area, this paper addresses the phenomenon of compensatory travel. For travel within ‘weekend trip distance’ from the residence, inner-city living appears to have a certain compensatory effect in the form of...... a higher frequency of medium-distance leisure trips. Probably, this reflects a shortage of nature in the immediate surroundings of the dwelling as well as less leisure time tied to gardening and house maintenance. These compensatory trips imply a slight reduction of the transport-reducing effect of...

  4. Transforming an Exposure trip to Botanical Expedition: Introducing Ecological Research thru Exposure Trip in an Eco-tourism Site

    Directory of Open Access Journals (Sweden)

    Bernardo C. Lunar

    2014-10-01

    Full Text Available – Fieldtrips can be considered as one of the three avenues through which science can be taught - through formal classroom teaching, practical work and field trips. An exposure trip at Bangkong Kahoy Valley Field Study Center was arranged for a class of BS Biology and BS Education students enrolled in Ecology Course. This approach purposefully transformed the usual exposure trip from being a casual site visit into a focused and productive learning experience. This transformation from exposure trip to a botanical expedition has exceeded the initial activity goals. Rather than a day off from learning, the time spent at the study center has been a meaningful opportunity to engage students in an active ecological research project while delivering valuable science content. Employing the descriptive survey design, the learning gains of the students were assessed and students were directed to do a guided reflection writing using the ORID Model of Focused Conversation. The learning gains and reflections of the students confirmed that students can collaboratively develop focused research questions, make meaning from a variety of sources, carry out a vegetation analysis and conduct surveys on socio-economic status, plant resource utilization and ecotourism assessment of the host community. As students prepared for their trip and synthesized their learning afterward, they were able to come up with very impressive and scientifically sound research outputs.

  5. The development of cause analysis system for CPCS trip using the rule-base deduction

    International Nuclear Information System (INIS)

    The Core Protection Calculator System(CPCS) was developed to initiate a Reactor Trip under the circumstance of certain transients by Combustion Engineering Company. The major function of the CPCS is to generate contact outputs for the Departure from Nucleate Boiling Ratio(DNBR) Trip and Local Power Density(LPD) Trip. But in CPCS the trip causes can not be identified, only trip status is displayed. It may take much time and efforts for plant operator to analyse the trip causes of CPCS. So, the Cause Analysis System for CPCS(CASCPCS) has been developed using the rule-base deduction method to aid the operators in Nuclear Power Plant

  6. Medium voltage SF6 switch rooms with switch breakers; Cubiculos de media tensao em SF6 com disjuntores

    Energy Technology Data Exchange (ETDEWEB)

    Matias, Marcos [Schneider Electric Brasil, Sao Paulo, SP (Brazil)

    1999-07-01

    This paper describes the technology using SF6 as breaking gas and the application in medium and high voltage switch rooms. The paper also describes the metal clad panel, the ring main unit, the medium voltage, and the panel saw and circuit breakers with SF6.

  7. Transient Recovery Voltages at the Main 132kV Line Bay GIS Circuit Breaker in a Windfarm

    DEFF Research Database (Denmark)

    Arana Aristi, Iván; Okholm, J.; Holbøll, Joachim

    2011-01-01

    This paper presents the results of investigations of the Transient Recovery Voltage (TRV) across the terminals of the main 132kV Line Bay GIS circuit breaker (GIS CB) for Walney 2, second phase of the Walney Offshore Wind Farm. Several simulations were performed where the influence of different...

  8. Transient Studies in Large Offshore Wind Farms, Tak-ing Into Account Network/Circuit Breaker Interaction

    DEFF Research Database (Denmark)

    Glasdam, Jakob; Bak, Claus Leth; Hjerrild, Jesper; Arana Aristi, Iván

    2011-01-01

    ensure reliable switching operations. Transient measurement results in an OWF are compared with simulation results in PSCAD EMTDC and DigSILENT Power Factory, where a user-defined model of the vacuum circuit breaker (VCB) is included, capable of simulating multiple prestrikes during the closing operation...... simulation results, whereas little improvement is found in DigSILENT....

  9. Support information for slips, trips and falls from height offshore

    International Nuclear Information System (INIS)

    This document contains support information for the Slips, Trips and Falls from Height Offshore Final Report produced by BOMEL for the Health and Safety Executive's Offshore Division (BOMEL Reference C919/05/171R Rev B). The project was requested in response to a concern that slips, trips and falls from height (STFS) consistently account for a significant proportion of all accidents offshore. The work has provided a detailed understanding of the factors which influence the likelihood of STFs and presents a strategy to reduce such accidents offshore. An important part of the strategy is guidance to enable a practical assessment of STF risk. (author)

  10. What drives people? Analyzing leisure-shopping trip decisions making

    OpenAIRE

    DE CEUNYNCK, Tim; KUSUMASTUTI, Diana; HANNES, Els; JANSSENS, Davy; Wets, Geert

    2011-01-01

    Because of the strong increase in the number of leisure-shopping trips, a shift towards more sustainable leisure-shopping behaviour is desirable. This can be attained by having a better insight into people’s reasoning in choosing a transport mode and shopping location for this type of activities. Thus, this paper highlights individuals’ leisure-trip decision-making processes. The uniqueness of this study is the use of a large sample group, consisting of 221 respondents. A Computer-Based Causa...

  11. Bake hardening behavior of TRIP and DP steels

    Institute of Scientific and Technical Information of China (English)

    Jicheng Zhang; Renyu Fu; Mei Zhang; Rendong Liu; Xicheng Wei; Lin Li

    2008-01-01

    The bake hardening (BH) behavior of transformation-induced plasticity (TRIP) and dual-phase (DP) steels after different prestrains was studied. The experimental results indicate that TRIP steel exhibits good BH ability while DP steel does not, and prestrain displays a strong effect on the BH values of both steels. The comparison of microstructures of the two steels showed that the hard second phase in the matrix might be harmful to the BH ability. For deformed specimens, baking resulted in a loss of uniform elongation, but there was no obvious decrease in uniform elongation for unprestrained specimens.

  12. Incremento del porcentaje de breakers que pasan la calibración magnética en la linea FA Maggard para Schneider Electric

    OpenAIRE

    Gamboa Corzas, Ramón

    2005-01-01

    El objetivo principal de este trabajo consistió en incrementar el porcentaje de breakers que pasan la prueba de calibración magnética en la linea de ensamble de breakers FA Maggard en la empresa Schneider Electric. El problema principal es que el porcentaje de breakers que pasan la calibración magnética en esta línea ha sido tan solo del 80% en los meses de mayo, junio y julio del 2005, ocasionando por consecuencia una eficiencia del 60%, un retrabajo de 76 hrs. mensuales y ...

  13. Resolved Photon Processes

    OpenAIRE

    Godbole, RM

    1998-01-01

    After giving a very brief introduction to the resolved photon processes, I will summarise the latest experimental information from HERA, on resolved photon contribution to large pt jet production as well as to direct photon production. I will point out the interesting role that resolved photon processes can play in increasing our understanding of the dynamics of the Quarkonium production. I will then discuss the newer information on the parton content of virtual photons as well as the kt dist...

  14. Systematic comparison of trip distribution laws and models

    CERN Document Server

    Lenormand, Maxime; Ramasco, José J

    2016-01-01

    Trip distribution laws are basic for the travel demand characterization needed in transport and urban planning. Several approaches have been considered in the last years. One of them is the so-called gravity law, in which the number of trips is assumed to be related to the population at origin and destination and to decrease with the distance. The mathematical expression of this law resembles Newton's law of gravity, which explains its name. Another popular approach is inspired by the theory of intervening opportunities and it has been concreted into the so-called radiation models. Individuals are supposed to travel until they find a job opportunity, so the population and jobs spatial distributions naturally lead to a trip flow network. In this paper, we perform a thorough comparison between the gravity and the radiation approaches in their ability at estimating commuting flows. We test the gravity and the radiation laws against empirical trip data at different scales and coming from different countries. Diff...

  15. Geïntegreerde trips- en spintbestrijding in chrysant

    NARCIS (Netherlands)

    Beerling, E.A.M.; Berg, van den D.

    2008-01-01

    Raspportage van vierjarig project (2001-2004) waarbij op semi-praktijkschaal in proefkassen werd onderzocht wat de werkelijke bijdrage van natuurlijke vijanden en biologische middelen aan de bestrijding van trips en spint in chrysant is. Op basis hiervan werd geprobeerd zinvolle geïntegreerde bestri

  16. A model for sustainable short-term international medical trips.

    Science.gov (United States)

    Suchdev, Parminder; Ahrens, Kym; Click, Eleanor; Macklin, Lori; Evangelista, Doris; Graham, Elinor

    2007-01-01

    The health status of many people in developing countries is often dismal compared with the norms in industrialized countries. Increasingly, medical practitioners in the United States and other industrialized countries have become interested in global health issues, an interest that often takes the form of short-term international medical trips. We discuss several ethical issues associated with participation in such trips and use our experiences in developing the Children's Health International Medical Project of Seattle (CHIMPS) to outline and illustrate a set of 7 guiding principles for making these trips. CHIMPS is a resident-run, faculty-supported international medical program founded in 2002 by pediatric residents at the University of Washington in Seattle. Members of CHIMPS work with a rural community in El Salvador to support ongoing public health interventions there and provide sustainable medical care in collaboration with the community and a local nongovernmental organization. The 7 principles developed as a result of this work-mission, collaboration, education, service, teamwork, sustainability, and evaluation-can be used as a model for health practitioners as they develop or select international medical trips. The importance of partnering with the community and working within the existing medical and public health infrastructure is emphasized. Many of the challenges of doing international medical work can be overcome when efforts are guided by a few specific principles, such as those we have outlined. PMID:17660105

  17. At the Crossroads: Notes from a Trip to the Philippines

    OpenAIRE

    Schirmer, Daniel Boone

    1990-01-01

    Report of 1990 Philippines trip in preparation for the upcoming 1991 vote in the Philippine Senate to reject or renew the treaty between the Philippines and the United States regarding U.S. military bases. A conference, and subsequent travel around the country revealed the explosive growth of anti-bases sentiment.

  18. Solving touristic trip planning problem by using taboo search approach

    Directory of Open Access Journals (Sweden)

    Kadri Sylejmani

    2011-09-01

    Full Text Available In this paper, we introduce an algorithm that automatically plans a touristic trip by considering some hard and soft constrains. Opening and closing hours of POIs, trip duration and trip allocated budget represent the hard constraints, while the satisfaction factors of the POIs and travelling distance in the trip are considered as soft constraints. We use the soft constraints to evaluate the generated solution of the algorithm. The algorithm is developed by utilizing the taboo search method as a meta heuristic. The operators of Swap, Insert and Delete are used to explore the search space. The Swap and Insert operator are used in each iteration of the algorithm loop, while the Delete operator is used whenever the algorithm tends to enter in an endless cycle. The algorithm is developed by using Java programming language, while the data repositories are created in the XML format. The algorithm is tested with 40 instances of POIs of the city of Vienna. Various entry parameters of the algorithm are used to test its performance. The results gained are discussed and compared in respect to the optimal solution.

  19. The Scope of Gene Patent Protection and the TRIPS Agreement

    DEFF Research Database (Denmark)

    Sommer, Tine

    2007-01-01

    The Scope of Gene Patent Protection and the TRIPS Agreement - An Exclusively Nondiscriminatory Approach?   Gene patenting in Europe has provoked much debate both before and since the adoption of Directive 98/44/EC on the legal protection of biotechnological inventions. Some of the major points of...

  20. Record breakers

    CERN Multimedia

    Antonella Del Rosso

    2012-01-01

    In the sixties, CERN’s Fellows were but a handful of about 50 young experimentalists present on site to complete their training. Today, their number has increased to a record-breaking 500. They come from many different fields and are spread across CERN’s different activity areas.   “Diversifying the Fellowship programme has been the key theme in recent years,” comments James Purvis, Head of the Recruitment, Programmes and Monitoring group in the HR Department. “In particular, the 2005 five-yearly review introduced the notion of ‘senior’ and ‘junior’ Fellowships, broadening the target audience to include those with Bachelor-level qualifications.” Diversification made CERN’s Fellowship programme attractive to a wider audience but the number of Fellows on site could not have increased so much without the support of EU-funded projects, which were instrumental in the growth of the programme. ...

  1. Balloon Breakers

    OpenAIRE

    González Rodríguez, Jesús

    2011-01-01

    El objetivo de este PFC es crear un videojuego en 3D basado en el clásico "Pang!". El juego se divide en niveles donde el jugador debe controlar a un personaje sobre una superficie rectangular donde aparecen burbujas (o bolas), cubos y animales (pájaros carpintero y cangrejos ermitaños). El jugador pasa de nivel cuando todas las bolas hayan sido destruidas, bien por el mismo jugador o por los animales. El jugador pierde una vida cuando sea alcanzado por una bola o un animal o bien cuand...

  2. CNMI, American Samoa, and Guam Small Boat Fishery Trip Expenditure (2009 to present)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This is a time-series dataset of trip expenditure data including actual fishing trip expenses, input usage, and input prices, for boat-based reef fish, bottomfish,...

  3. Theoretical and experimental study of a dual-flow circuit breaker nozzle flow

    Science.gov (United States)

    Dearborn, J. B.; Nagamatsu, H. T.; Rumsey, C. I.

    1983-07-01

    The performance of the high power gas blast circuit breakers to interrupt high power depends on the arc quenching near current zero. The cooling of the arc is governed by the cold flow field through the nozzle. Thus, a finite element type of computer program was developed to determine the axisymmetric cold field for dual-flow arc interrupter nozzle configurations of different throat radii and various gap spacings between the dual-flow nozzles using SF6 or air as the high pressure gas. The axial flow acceleration in the stagnation and sonic regions present in the are interrupter nozzles has been examined in the flow field calculations. Experimental data obtained for a 4 deg conical nozzle correlated well with the computed results.

  4. New Breakdown Electric Field Calculation for SF6 High Voltage Circuit Breaker Applications

    Science.gov (United States)

    Robin-Jouan, Ph.; Yousfi, M.

    2007-12-01

    The critical electric fields of hot SF6 are calculated including both electron and ion kinetics in wide ranges of temperature and pressure, namely from 300 K up to 4000 K and 2 atmospheres up to 32 atmospheres respectively. Based on solving a multi-term electron Boltzmann equation the calculations use improved electron-gas collision cross sections for twelve SF6 dissociation products with a particular emphasis on the electron-vibrating molecule interactions. The ion kinetics is also considered and its role on the critical field becomes non negligible as the temperature is above 2000 K. These critical fields are then used in hydrodynamics simulations which correctly predict the circuit breaker behaviours observed in the case of breaking tests.

  5. Study of switching electric circuits with DC hybrid breaker, one stage

    Science.gov (United States)

    Niculescu, T.; Marcu, M.; Popescu, F. G.

    2016-06-01

    The paper presents a method of extinguishing the electric arc that occurs between the contacts of direct current breakers. The method consists of using an LC type extinguishing group to be optimally sized. From this point of view is presented a theoretical approach to the phenomena that occurs immediately after disconnecting the load and the specific diagrams are drawn. Using these, the elements extinguishing group we can choose. At the second part of the paper there is presented an analyses of the circuit switching process by decomposing the process in particular time sequences. For every time interval there was conceived a numerical simulation model in MATLAB-SIMULINK medium which integrates the characteristic differential equation and plots the capacitor voltage variation diagram and the circuit dumping current diagram.

  6. Plasma circuit breaker in a magnetic field as a high-power ion flux generator

    International Nuclear Information System (INIS)

    It is ascertained that plasma circuit breaker (PCB) in the external magnetic field of acute-anguled geometry in the mode when PCB serves as inductive storage loading is a natural magnetoizolated diode. Using PCB as an ion emitter and as a high-voltage generator it proved possible in case of full electron magnetiuzation to attain the maximum efficiency of the storage. The density of ion current evaluated by the measured energy density for 30 J/cm2 thermocouple and by the energy of 1.5 MeV constitutes 100 A/cm2. The given method of ion generation is very effective when high ion currents with a high energy are required

  7. The Impact Of Surface Shape Of Chip-Breaker On Machined Surface

    Science.gov (United States)

    Šajgalík, Michal; Czán, Andrej; Martinček, Juraj; Varga, Daniel; Hemžský, Pavel; Pitela, David

    2015-12-01

    Machined surface is one of the most used indicators of workpiece quality. But machined surface is influenced by several factors such as cutting parameters, cutting material, shape of cutting tool or cutting insert, micro-structure of machined material and other known as technological parameters. By improving of these parameters, we can improve machined surface. In the machining, there is important to identify the characteristics of main product of these processes - workpiece, but also the byproduct - the chip. Size and shape of chip has impact on lifetime of cutting tools and its inappropriate form can influence the machine functionality and lifetime, too. This article deals with elimination of long chip created when machining of shaft in automotive industry and with impact of shape of chip-breaker on shape of chip in various cutting conditions based on production requirements.

  8. Current commutation from a fast-response circuit breaker to shunting conductor

    International Nuclear Information System (INIS)

    Reasons of failures of fast response circuit breakers (FRCB) at multistage commutation of current in the circuit with an inductive storage ring are considered, when the current commutation in the shunting conductor (SC) is not completed. The commutation mode has been determined by five dimensional parameters: commutation current, stray inductance of the circuit, rate of voltage growth across the FRCB, initial resistance of SC and characteristic power contribution. The existence of two critical current densities is stated: the first one is related to the rate of voltage growth on the FRCB and the second one is associated with the ultimate maximum voltage developed by FRCB. The obtained calculation estimations permit to determine the current density upper boundary in SC above which the commutation is impossible

  9. Design and construction of thyristor DC circuit breakers for alcator C-MOD

    International Nuclear Information System (INIS)

    This paper reports on the detailed design of the Alcator C-MOD thyristor DC circuit breakers which required extensive simulation and careful consideration of parasitic elements as well as device recovery and turn-on limitations. The circuit uses up to 12 parallel paths to carry pulsed currents as high as 50 kA. Maximum interrupting voltages of 2 kV are supported by devices rated 4.4 kV. Each SCR is shunted by a diode in series with an air core decoupling reactor. The counterpulse capacitor is discharged though 1 or 2 SCRs and utilizes a pulse forming network to quickly reduce the main SCR current to zero, then provide an relatively low and stable reverse voltage during the commutation interval. All devices are mounted with radial symmetry. The diode reactors are subject to modest forces under normal conditions but large lateral forces when adjacent paths are lost

  10. Influencing Factors of Breaking Capacity of Double-Break Vacuum Circuit Breakers

    Directory of Open Access Journals (Sweden)

    Shengwen Shu

    2013-06-01

    Full Text Available Using a series arrangement of two vacuum interrupters (VIs has been proved to be an effective way of developing higher voltage vacuum circuit breakers (VCBs, which are known as double-break VCBs. The uniform distribution of the transient recovery voltage (TRV across each VI is very critical for the breaking capacity of double-break VCBs. In this paper, the TRV distribution characteristics of double-break VCBs was studied by the synthetic test and the PSCAD/EMTDC simulation based on a vacuum arc interruption model. The results show that the bias of the TRV distribution ratio is caused by the stray capacitance and the imbalanced post arc plasma characteristic in each VI, which is consistent with the theoretical analysis. Moreover, the negative effect of grading capacitors was discussed. The results show that it is advisable to limit the value of grading capacitors to those ranges which can guarantee sufficiently improve the voltage distribution.

  11. Swirling flow and its influence on dc arcs in a duo-flow hybrid circuit breaker

    International Nuclear Information System (INIS)

    The effects of swirling flow on the behaviour of dc SF6 arcs in a duo-flow nozzle are computationally investigated in the electric current range 3-7 kA. A swirling flow is produced by the interaction of the magnetic field of a current-carrying coil and the plasma. Results show that a strong swirling flow is generated in regions where a large radial current density exists as a result of the conducting arc column rapidly changing its radial dimension. The presence of the swirling flow reduces the axis pressure, modifies the arc shape and slightly lowers the arc voltage (2-5%) in comparison with the case without considering the swirling flow. The different natures of swirling flows in a plasma jet/arc heater and in a hybrid circuit breaker are also discussed.

  12. New Breakdown Electric Field Calculation for SF6 High Voltage Circuit Breaker Applications

    Institute of Scientific and Technical Information of China (English)

    Ph.ROBIN-JOUAN; M.YOUSFI

    2007-01-01

    The critical electric fields of hot SF6 are calculated including both electron and ion kinetics in wide ranges of temperature and pressure,namely from 300 K up to 4000 K and 2 atmospheres up to 32 atmospheres respectively.Based on solving a multi-term electron Boltzmann equation the calculations use improved electron-gas collision cross sections for twelve SF6 dissociation products with a particular emphasis on the electron-vibrating molecule interactions.The ion kinetics is also considered and its role on the critical field becomes non negligible as the temperature is above 2000 K.These critical fields are then used in hydrodynamics simulations which correctly predict the circuit breaker behaviours observed in the case of breaking tests.

  13. Transient studies in large offshore wind farms, taking into account network/circuit breaker interaction

    Energy Technology Data Exchange (ETDEWEB)

    Glasdam, Jakob; Hjerrild, Jesper; Arana, Ivan [DONG Energy Power A/S, Fredericia (Denmark); Bak, Claus Leth [Aalborg Univ. (Denmark). Inst. of Energy Technology

    2011-07-01

    Switching overvoltages (SOV) are considered a possible source of experienced component failures in existing offshore wind farms (OWFs). The inclusion of sufficiently accurate and validated models of the main components in the OWF in the simulation tool is therefore an important issue in order to ensure reliable switching operations. Transient measurement results in an OWF are compared with simulation results in PSCAD EMTDC and DigSILENT Power Factory, where a user-defined model of the vacuum circuit breaker (VCB) is included, capable of simulating multiple prestrikes during the closing operation. An analysis of the switching transients that might occur in an OWF will be made on basis of the validated model and the importance of the inclusion of a sufficient accurate representation of the VCB in the simulation tool will be described. The inclusion of the VCB model in PSCAD greatly improves the simulation results, whereas little improvement is found in DigSILENT. (orig.)

  14. New Breakdown Electric Field Calculation for SF6 High Voltage Circuit Breaker Applications

    International Nuclear Information System (INIS)

    The critical electric fields of hot SF6 are calculated including both electron and ion kinetics in wide ranges of temperature and pressure, namely from 300 K up to 4000 K and 2 atmospheres up to 32 atmospheres respectively. Based on solving a multi-term electron Boltzmann equation the calculations use improved electron-gas collision cross sections for twelve SF6 dissociation products with a particular emphasis on the electron-vibrating molecule interactions. The ion kinetics is also considered and its role on the critical field becomes non negligible as the temperature is above 2000 K. These critical fields are then used in hydrodynamics simulations which correctly predict the circuit breaker behaviours observed in the case of breaking tests

  15. Transient Studies in Large Offshore Wind Farms, Employing Detailed Circuit Breaker Representation

    DEFF Research Database (Denmark)

    Glasdam, Jakob Bærholm; Bak, Claus Leth; Hjerrild, Jesper

    2012-01-01

    order to ensure reliable switching operations. Transient measurement results in an OWF are compared with simulation results in PSCAD EMTDC and DigSILENT Power Factory. A user-defined model of the vacuum circuit breaker (VCB) is included in both tools, capable of simulating multiple prestrikes during the......Switching overvoltages (SOV) are considered a possible source of component failures experienced in existing offshore wind farms (OWFs). The inclusion of sufficiently accurate and validated models of the main electrical components in the OWF in the simulation tool is therefore an important issue in...... closing operation. An analysis of the switching transients that might occur in OWFs will be made on the basis of the validated model, and the importance of the inclusion of a sufficiently accurate representation of the VCB in the simulation tool will be described. The inclusion of the VCB model in PSCAD...

  16. Study on Restrike Phenomena for 40.5-kV Vacuum Circuit Breakers

    Institute of Scientific and Technical Information of China (English)

    Yan Jing; Ma Zhiying

    2006-01-01

    When interrupting short circuit fault by 40.5-Kv vacuum circuit breakers, it is significant to eliminate multiple restrike phenomena, which occur frequently and result in high overvoltage and even interruption failure. A synthetic circuit that can supply a DC recovery voltage after current zero was used to study multiple restrike phenomena in switching. Some key factors including breaking current, clearance between open contacts, electrode structure and contact material, which may affect restrike characteristics, were studied. Under various clearances, the statistical probability of restrike was obtained. As a result, the best scope of clearance between open contacts was found. The performance of CuCrS0/50 and CuCr75/25 material were compared. Two kinds of electrode structures, namely 1/2 coil structure and cup-shaped axial magnetic structure, were tested. After a high-current interruption, conditioning effect was realized and the probability ofrestrike decreased.

  17. A Heuristic for Locating Electric Vehicle Charging Stations for Trip Chains

    DEFF Research Database (Denmark)

    Wen, Min; Røpke, Stefan

    We present the problem of locating a limited number of electric vehiclecharging stations for a given set of trip chains, each of which consistsof a series of linked short trips and is represented by a sequence ofintervening stops along the trip chain. The objective of this problemis to maximize t...... number of trip chains that can be completed by the electric vehicle without running out of battery. A mixed-integer programmingformulation as well as a heuristic for solving this problemwill be presented....

  18. Numerical modeling of high-voltage circuit breaker arcs and their interraction with the power system

    Science.gov (United States)

    Orama, Lionel R.

    In this work the interaction between series connected gas and vacuum circuit breaker arcs has been studied. The breakdown phenomena in vacuum interrupters during the post arc current period have been of special interest. Numerical models of gas and vacuum arcs were developed in the form of black box models. Especially, the vacuum post arc model was implemented by combining the existing transition model with an ion density function and expressions for the breakdown mechanisms. The test series studied reflect that for electric fields on the order of 10sp7V/m over the anode, the breakdown of the vacuum gap can result from a combination of both thermal and electrical stresses. For a particular vacuum device, the vacuum model helps to find the interruption limits of the electric field and power density over the anode. The series connection of gas and vacuum interrupters always performs better than the single gas device. Moreover, to take advantage of the good characteristics of both devices, the time between the current zero crossing in each interrupter can be changed. This current zero synchronization is controlled by changing the capacitance in parallel to the gas device. This gas/vacuum interrupter is suitable for interruption of very stressful short circuits in which the product of the dI/dt before current zero and the dV/dt after current zero is very high. Also, a single SF6 interrupter can be replaced by an air circuit breaker of the same voltage rating in series with a vacuum device without compromising the good performance of the SF6 device. Conceptually, a series connected vacuum device can be used for high voltage applications with equal distribution of electrical stresses between the individual interrupters. The equalization can be made by a sequential opening of the individual contact pairs, beginning with the interruptors that are closer to ground potential. This could eliminate the use of grading capacitors.

  19. Inhibition of aggregation of amyloid peptides by beta-sheet breaker peptides and their binding affinity.

    Science.gov (United States)

    Viet, Man Hoang; Ngo, Son Tung; Lam, Nguyen Sy; Li, Mai Suan

    2011-06-01

    The effects of beta-sheet breaker peptides KLVFF and LPFFD on the oligomerization of amyloid peptides were studied by all-atom simulations. It was found that LPFFD interferes the aggregation of Aβ(16-22) peptides to a greater extent than does KLVFF. Using the molecular mechanics-Poisson-Boltzmann surface area (MM-PBSA) method, we found that the former binds more strongly to Aβ(16-22). Therefore, by simulations, we have clarified the relationship between aggregation rates and binding affinity: the stronger the ligand binding, the slower the oligomerization process. The binding affinity of pentapeptides to full-length peptide Aβ(1-40) and its mature fibrils has been considered using the Autodock and MM-PBSA methods. The hydrophobic interaction between ligands and receptors plays a more important role for association than does hydrogen bonding. The influence of beta-sheet breaker peptides on the secondary structures of monomer Aβ(1-40) was studied in detail, and it turns out that, in their presence, the total beta-sheet content can be enhanced. However, the aggregation can be slowed because the beta-content is reduced in fibril-prone regions. Both pentapeptides strongly bind to monomer Aβ(1-40), as well as to mature fibrils, but KLVFF displays a lower binding affinity than LPFFD. Our findings are in accord with earlier experiments that both of these peptides can serve as prominent inhibitors. In addition, we predict that LPFFD inhibits/degrades the fibrillogenesis of full-length amyloid peptides better than KLVFF. This is probably related to a difference in their total hydrophobicities in that the higher the hydrophobicity, the lower the inhibitory capacity. The GROMOS96 43a1 force field with explicit water and the force field proposed by Morris et al. (Morris et al. J. Comput. Chem. 1998, 19, 1639 ) were employed for all-atom molecular dynamics simulations and Autodock experiments, respectively. PMID:21563780

  20. 49 CFR 236.531 - Trip arm; height and distance from rail.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Trip arm; height and distance from rail. 236.531... Train Stop, Train Control and Cab Signal Systems Rules and Instructions; Roadway § 236.531 Trip arm; height and distance from rail. Trip arm of automatic train stop device when in the stop position shall...

  1. Questionnaire-based person trip visualization and its integration to quantitative measurements in Myanmar

    Science.gov (United States)

    Kimijiama, S.; Nagai, M.

    2016-06-01

    With telecommunication development in Myanmar, person trip survey is supposed to shift from conversational questionnaire to GPS survey. Integration of both historical questionnaire data to GPS survey and visualizing them are very important to evaluate chronological trip changes with socio-economic and environmental events. The objectives of this paper are to: (a) visualize questionnaire-based person trip data, (b) compare the errors between questionnaire and GPS data sets with respect to sex and age and (c) assess the trip behaviour in time-series. Totally, 345 individual respondents were selected through random stratification to assess person trip using a questionnaire and GPS survey for each. Conversion of trip information such as a destination from the questionnaires was conducted by using GIS. The results show that errors between the two data sets in the number of trips, total trip distance and total trip duration are 25.5%, 33.2% and 37.2%, respectively. The smaller errors are found among working-age females mainly employed with the project-related activities generated by foreign investment. The trip distant was yearly increased. The study concluded that visualization of questionnaire-based person trip data and integrating them to current quantitative measurements are very useful to explore historical trip changes and understand impacts from socio-economic events.

  2. Multiple Stages of Weekend Field Trips To Expose Students to Nature: Emphasis on Discovery and Awareness.

    Science.gov (United States)

    Krupa, James J.

    2002-01-01

    Describes the three stages of a field trip and reviews stage 1, weekend field trips, which focuses on an organism's morphology, behavior, and ecology. Presents activities on salamanders, small mammals, fish, birds, and bats. Explains the difficulties of weekend trips. (YDS)

  3. Nuevos atrayentes de trips ayudan a los agricultores en el control de plagas

    NARCIS (Netherlands)

    Tol, van R.W.H.M.; Kogel, de W.J.; Teulon, D.

    2007-01-01

    Los trips constituyen una plaga importante que afecta a muchos cultivos diferentes. El año pasado se probaron con éxito, en situaciones prácticas, aromas atrayentes de trips de las flores y trips de la cebolla. El producto, que estará a disposición de los cultivadores en junio, resultó efectivo en t

  4. Scaled photographs of surf over the full range of breaker sizes on the north shore of Oahu and Jaws, Maui, Hawaiian Islands (NODC Accession 0001753)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Digital surf photographs were scaled using surfers as height benchmarks to estimate the size of the breakers. Historical databases for surf height in Hawaii are...

  5. Using GIS for planning field trips: In-situ assessment of Geopoints for field trips with mobile devices

    Science.gov (United States)

    Böhm, Sarah; Kisser, Thomas; Ditter, Raimund

    2016-04-01

    Up to now no application is existing for collecting data via mobile devices using a geographical information system referring to the evaluation of Geopoints. Classified in different geographical topics a Geopark can be rated for suitability of Geopoints for field trips. The systematically acquisition of the suitability of Geopoints is necessary, especially when doing field trips with lower grade students who see a physical-geographic phenomenon for the first time. For this reason, the development of such an application is an invention for easy handling evaluations of Geopoints on the basis of commonly valid criteria like esthetic attraction, interestingness, and pithiness (Streifinger 2010). Collecting data provides the opportunity of receiving information of particularly suitable Geopoints out of the sight from students, tourists and others. One solution for collecting data in a simple and intuitive form is Survey123 for ArcGIS (http://survey123.esri.com/#/). You can create surveys using an ArcGIS Online organizational account and download your own survey or surveys "that may have been shared with you" (https://itunes.apple.com/us/app/survey-123-for-arcgis/id993015031?mt=8) on your mobile device. "Once a form is downloaded, you will be able to start collecting data."(https://itunes.apple.com/us/app/survey-123-for-arcgis/id993015031?mt=8) Free of cost and use while disconnected the application can easily be used via mobile device on field trips. On a 3-day field trip which is held three times per year in the Geopark Bergstraße-Odenwald Survey123 is being used to evaluate the suitability of different Geopoints for different topics (geology, soils, vegetation, climate). With every field trip about 25 students take part in the survey and evaluate each Geopoint at the route. So, over the time, the docents know exactly which Geopoints suites perfect for teaching geology for example, and why it suites that good. The field trip is organized in an innovative way. Before

  6. Secrecy from Resolvability

    CERN Document Server

    Bloch, Matthieu R

    2011-01-01

    We investigate an approach to physical-layer security based on the premise that the coding mechanism for secrecy over noisy channels is fundamentally tied to the notion of resolvability. Instead of considering capacity-based constructions, which associate to each message a sub-code whose rate approaches the capacity of the eavesdropper's channel, we consider resolvability-based constructions, which associate to each message a sub-code whose rate is beyond the resolvability of the eavesdropper's channel. We provide evidence that resolvability is a more powerful and perhaps more fundamental coding mechanism for secrecy by developing results that hold for strong secrecy metrics and arbitrary channels. Specifically, we show that, at least for binary symmetric wiretap channels, random capacity-based constructions fail to approach the strong secrecy capacity while resolvability-based constructions achieve it. We then obtain the secrecy-capacity region of arbitrary broadcast channels with confidential messages and a...

  7. An Engineering Process for Automatic Seismic Trip System Implementation

    International Nuclear Information System (INIS)

    To cope with potential seismic risks of catastrophic earthquakes, an Automatic Seismic Trip System (ASTS) is being developed for the operating nuclear power plants in Korea. The ASTS is designed to automatically trip the reactor upon an occurrence of the Safe Shutdown Earthquake (SSE) at the plant site. By the end of 2012, the ASTS will have been installed at all twenty (20) nuclear power plants currently under operation in Korea as of 2010. The system must be designed and constructed so that it not only ensures a highly reliable reactor trip upon the SSE but also minimizes a spurious trip during normal operation and maintenance. Since the ASTS is designed for the currently operating plants, the system design must consider different reactor types, including the Pressurized Water Reactor (PWR) and the Pressurized Heavy Water Reactor (PHWR), and easy operation and maintenance as well. This paper presents an engineering process for the design and implementation of the ASTS for the nuclear power plants. The presentation is mainly focused on the application of a systematic design process and a rigorous verification process for the various nuclear power plants. The systematic design process is based on the concepts of modularization and standardization. For the systematic design, the ASTS is functionally divided into three separate modules consisting of a sensor module, a trip logic module, and a trip actuation module. Rigorous verification is applied to the hardware qualification and the software verification. Environmental, seismic, and EMI qualifications are included in hardware verification. Strict software verification is also performed through the entire life cycle for software development. Even though the ASTS is not designed as a safety-related Class 1E system per the requirement of ANS-51.1, the intent of safety related design standards are applied, to the extent practical, to the hardware qualification and software verification. Application of this engineering

  8. Using a Field Trip Inventory to Determine If Listening to Elementary School Students' Conversations, While on a Zoo Field Trip, Enhances Preservice Teachers' Abilities to Plan Zoo Field Trips

    Science.gov (United States)

    Patrick, Patricia; Mathews, Cathy; Tunnicliffe, Sue Dale

    2013-01-01

    This study investigated whether listening to spontaneous conversations of elementary students and their teachers/chaperones, while they were visiting a zoo, affected preservice elementary teachers' conceptions about planning a field trip to the zoo. One hundred five preservice elementary teachers designed field trips prior to and after…

  9. Numerical simulation of temperature fluctuation reduction by a vortex breaker in an elbow pipe with thermal stratification

    International Nuclear Information System (INIS)

    Highlights: • Thermal stratification can cause thermal fatigue in an elbow pipe. • Temperature fluctuations were modeled by large-eddy simulation. • Temperature fluctuations can be reduced by fixing a vortex breaker. - Abstract: Thermal fluctuations in an elbow pipe with thermal stratification can readily lead to thermal fatigue in a nuclear power plant, and hence have attracted considerable attention in nuclear engineering and technology. This work describes a mathematical model for the study of the mechanism of heat transfer in an elbow pipe with thermal stratification. The temperature fluctuations of the fluid are modeled by means of large eddy simulations on the FLUENT platform. The numerical results show that temperature fluctuations in the elbow pipe can be reduced by fixing a vortex breaker in the upper straight pipe

  10. Babcock and Wilcox Owners' Group program: Trip reduction and transient response improvement

    International Nuclear Information System (INIS)

    In 1985, the average trip frequency for the industry was 4.3 trips per plant per year while Babcock ampersand Wilcox (B ampersand W)-designed plants had 4.5 trips. In early 1986, the B ampersand W Owners' Group (B ampersand WOG) established goals to reduce trip frequency and improve posttrip transient response. Through the recommendations of the B ampersand WOG Trip Reduction and Transient Response Improvement Program (TR/TRIP) and other utility initiatives, the trip frequency for the B ampersand WOG plants has been on a progressive downward trend and has been consistently below the industry average since 1986. The successful results in trip reduction for the B ampersand WOG plants are shown. The B ampersand WOG has implemented several programs that have resulted in fewer trips per plant. This success can be attributed to the following: (1) a comprehensive program to evaluate each trip and transient for root-cause determination, define corrective actions, share information, and peer reviews; (2) a broad program to review systems and components that contribute to trips and transients, identify specific recommendations to correct deficiencies, utility commitment to implementation, conduct internal monitoring and indirectly exert peer pressure; (3) an awareness of the goals at all levels in the organization coupled with strong executive-level involvement; and (4) timely implementation of recommendations

  11. The Big Trip and Wheeler-DeWitt equation

    CERN Document Server

    Yurov, Artyom V; Yurov, Valerian A

    2012-01-01

    Of all the possible ways to describe the behavior of the universe that has undergone a big trip the Wheeler-DeWitt equation should be the most accurate -- provided, of course, that we employ the correct formulation. In this article we start by discussing the standard formulation introduced by Gonz\\'alez-D\\'iaz and Jimenez-Madrid, and show that it allows for a simple yet efficient method of the solution's generation, which is based on the Moutard transformation. Next, by shedding the unnecessary restrictions, imposed on aforementioned standard formulation we introduce a more general form of the Wheeler-DeWitt equation. One immediate prediction of this new formula is that for the universe the probability to emerge right after the big trip in a state with $w=w_0$ will be maximal if and only if $w_0=-1/3$.

  12. 10 years after implementation of TRIPS obligations in India.

    Science.gov (United States)

    Pawar, Mahesh D

    2015-01-01

    The Patent (Amendment) Act of 2005 enforced after TRIPS raises many issues which hinder growth of Indian pharma companies. To tackle this, Indian pharma companies doubled their R&D expenditure and became significant players in global generic drug market. Indian pharmaceutical companies, which predominantly focused on import-oriented market, shifted to research-based approach by signing various agreements with MNCs that led to M&A and technology transfer. At the same time growth in R&D activities increased ANDA and DMF filing in the USA and Europe. Companies also kept their social responsibility by selling medicines at affordable price to patients. This paper highlights the changing business scenario of Indian pharmaceutical companies to counteract various issues evolved from new patent regime after TRIPS. PMID:26030078

  13. Analysis of reactor trips originating in balance of plant systems

    Energy Technology Data Exchange (ETDEWEB)

    Stetson, F.T.; Gallagher, D.W.; Le, P.T.; Ebert, M.W. (Science Applications International Corp., McLean, VA (USA))

    1990-09-01

    This report documents the results of an analysis of balance-of-plant (BOP) related reactor trips at commercial US nuclear power plants of a 5-year period, from January 1, 1984, through December 31, 1988. The study was performed for the Plant Systems Branch, Office of Nuclear Reactor Regulation, US Nuclear Regulatory Commission. The objectives of the study were: to improve the level of understanding of BOP-related challenges to safety systems by identifying and categorizing such events; to prepare a computerized data base of BOP-related reactor trip events and use the data base to identify trends and patterns in the population of these events; to investigate the risk implications of BOP events that challenge safety systems; and to provide recommendations on how to address BOP-related concerns in regulatory context. 18 refs., 2 figs., 27 tabs.

  14. Microstructure Evolution during Friction Stir Spot Welding of TRIP steel

    DEFF Research Database (Denmark)

    Lomholt, Trine Colding

    Transformation Induced Plasticity (TRIP) steels have been developed for automotive applications due to the excellent high strength and formability. The microstructure of TRIP steels is a complex mixture of various microstructural constituents; ferrite, bainite, martensite and retained austenite...... deteriorating the uniform elongation. The unique deformation properties can be exploited in automotive applications for crash resistant parts due to the high energy absorption, thus improving passenger safety. Furthermore, the high strength and good formability permits the application of thinner sheet material...... Stir Spot Welding (FSSW) is investigated. The aim of the study is to assess whether high quality welds can be produced and, in particular, to obtain an understanding of the microstructural changes during welding. The microstructure of the welded samples was investigated by means of reflected light...

  15. Analysis of reactor trips originating in balance of plant systems

    International Nuclear Information System (INIS)

    This report documents the results of an analysis of balance-of-plant (BOP) related reactor trips at commercial US nuclear power plants of a 5-year period, from January 1, 1984, through December 31, 1988. The study was performed for the Plant Systems Branch, Office of Nuclear Reactor Regulation, US Nuclear Regulatory Commission. The objectives of the study were: to improve the level of understanding of BOP-related challenges to safety systems by identifying and categorizing such events; to prepare a computerized data base of BOP-related reactor trip events and use the data base to identify trends and patterns in the population of these events; to investigate the risk implications of BOP events that challenge safety systems; and to provide recommendations on how to address BOP-related concerns in regulatory context. 18 refs., 2 figs., 27 tabs

  16. Visiting the USSR: a trip of a lifetime.

    Science.gov (United States)

    Brown, Geraldine

    2012-01-01

    To Russia, who me? That is actually how it all began. A decade or more ago, I had the opportunity to visit what was then known as the Union of Soviet Socialist Republics (USSR), Russia. Although, this place held high priority on my list of places to go, I never thought such a trip was within my reach. This idea was quite fascinating to me because of the events that did happen there, including the Russian space ship Sputnik and the dog, the high stepping military officers, Red Square and the St. Basil's Cathedral. After reading a lot about Russia, I thought it would be great to see a clean place, where it was unlawful to throw paper on the streets, and ride in public transportation such as the buses, taxis and the subway system, which were immaculately clean. It was an exciting trip, one, I will always remember, but would be a difficult adjustment to make, to live. PMID:22774358

  17. Prediction of the mechanical behaviour of TRIP steel

    OpenAIRE

    Perdahcioglu, E.S.; Geijselaers, H.J.M.; Tekkaya, A. E.; Hirt, G.

    2011-01-01

    TRIP steel typically contains four different phases, ferrite, bainite, austenite and martensite. During deformation the metastable retained austenite tends to transform to stable martensite. The accompanying transformation strain has a beneficial effect on the ductility of the steel during forming. By changing the alloy composition, the rolling procedure and the thermal processing of the steel, a wide range of different morphologies and microstructures can be obtained. Interesting parameters ...

  18. Are short daily trips compensated by higher leisure mobility?

    OpenAIRE

    Petter Næss

    2006-01-01

    Studies in several cities have shown that inner-city residents travel shorter distances and use cars less for local transport than suburbanites do. However, according to some authors, a low daily amount of travel is likely to be compensated through more extensive leisure mobility at weekends and on holidays. On the basis of a study of residential location and travel in the Copenhagen metropolitan area, this paper addresses the phenomenon of compensatory travel. For travel within ‘weekend trip...

  19. EFFECT OF CHEMICAL COMPOSITION ON RETAINED AUSTENITE IN TRIP STEEL

    Institute of Scientific and Technical Information of China (English)

    Y. Chen; X. Chen; Q.F. Wang; G.L. Yuan; C.Y. Li; X.Y. Li; Y.X. Wang

    2002-01-01

    The systematic chemical compositions including common C, Si, Mn, Al, and micro- alloying elements of Ti and Nb were designed for high volume fraction of retained austenite as much as possible. The thermo-cycle experiments were conducted by using Gleeble 2000 thermo-dynamic test machine for finding the appropriate composition. The experimental results showed that chemical composition had a significant effect on retained austenite, and the appropriate compositions were determined for commercial production of TRIP steels.

  20. Marketing a destination: Case of CreateTrips and Mexico

    OpenAIRE

    Tiainen, Johanna; Korvenpää, Emmi

    2015-01-01

    This thesis concentrates on Finnish people travelling to Mexico. Firstly, the writers conduct a quantitative research, a questionnaire, that studies Finnish people’s thoughts and presumptions about Mexico. Secondly, they create mobile travel guides of four different destinations. The questionnaire concentrates on the people’s point of view, asking what people think about Mexico, on what kind of trip would they go it they travel there, how long it would last and so on. The questionnaire also h...

  1. The Use of trips Flexibilities by Emerging Countries.

    OpenAIRE

    Amélie Robine

    2007-01-01

    The patent law has been harmonized at the international level in 1994 by the Agreement on Trade- Related Aspects of Intellectual Property Rights (trips). In practice, this text requires all member States of the World Trade Organization (wto) to recognize the patentability in all industrial sectors. A pharmaceutical patent shall then be granted for any pharmaceutical invention insofar as it fulfills all three criteria for patentability: novelty, inventive step and industrial application. Thus,...

  2. Meaningful Field Trip in Education of Renewable Energy Technologies

    OpenAIRE

    Hasan Said Tortop

    2013-01-01

    Renewable energy sources, in terms of countries‟ obtaining their energy needs from clean and without harming the environment is becoming increasingly important. This situation also requires improving the quality of science education will be given in this field. In this activity, in a field trip to the center for the renewable energy resources technologies, the application of learning cycle model appropriate for constructivist approach is shown. In the example of solar chimney activity accordi...

  3. Equilibrium analysis of trip chains in congested networks

    OpenAIRE

    Heydecker, B.

    2004-01-01

    In this paper, we develop a model of travel in a chain of trips joining several locations througha congested network. We develop a microscopic analysis of individual benefits obtained byspending time at each of the locations and costs incurred through travel between them. This iscombined with a macroscopic equilibrium model of travel during congested peak periods toshow how individuals? travel choices are influenced by the congestion that result fromcorresponding choices made by others. We sh...

  4. A turbine trip transient analyses with TRAC-BF1

    International Nuclear Information System (INIS)

    This paper reports a turbine trip transient analysis for a BWR/5 nuclear power plant performed with TRAC-BF1 code, a well-known best-estimate code used for transient analyses of boiling water reactors. The work undertook an evaluation of several safety parameters, such as dome pressure rise, maximum temperature in the fuel, maximum reactor power, total reactivity, and others. 2 refs., 7 figs., 3 tabs

  5. Bicycle-Sharing System Analysis and Trip Prediction

    OpenAIRE

    Zhang, Jiawei; Pan, Xiao; Li, Moyin; Yu, Philip S.

    2016-01-01

    Bicycle-sharing systems, which can provide shared bike usage services for the public, have been launched in many big cities. In bicycle-sharing systems, people can borrow and return bikes at any stations in the service region very conveniently. Therefore, bicycle-sharing systems are normally used as a short-distance trip supplement for private vehicles as well as regular public transportation. Meanwhile, for stations located at different places in the service region, the bike usages can be qu...

  6. Investigation on critical breakdown electric field of hot sulfur hexafluoride/carbon tetrafluoride mixtures for high voltage circuit breaker applications

    Science.gov (United States)

    Wang, Weizong; Murphy, Anthony B.; Rong, Mingzhe; Looe, Hui M.; Spencer, Joseph W.

    2013-09-01

    Sulfur hexafluoride (SF6) gas, widely used in high-voltage circuit breakers, has a high global warming potential and hence substitutes are being sought. The use of a mixture of carbon tetrafluoride (CF4) and SF6 is examined here. It is known that this reduces the breakdown voltage at room temperature. However, the electrical breakdown in a circuit breaker after arc interruption occurs in a hot gas environment, with a complicated species composition because of the occurrence of dissociation and other reactions. The likelihood of breakdown depends on the electron interactions with all these species. The critical reduced electric field strength (the field at which breakdown can occur, relative to the number density) of hot SF6/CF4 mixtures corresponding to the dielectric recovery phase of a high voltage circuit breaker is calculated in the temperature range from 300 K to 3500 K. The equilibrium compositions of hot SF6/CF4 mixtures under different mixing fractions were determined based on Gibbs free energy minimization. Full sets of improved cross sections for interactions between electrons and the species present are presented. The critical reduced electric field strength of these mixtures was obtained by balancing electron generation and loss mechanisms. These were evaluated using the electron energy distribution function derived from the Boltzmann transport equation under the two-term approximation. The result indicates that critical electric field strength decreases with increasing heavy-particle temperature from 1500 to 3500 K. Good agreement was found between calculations for pure hot SF6 and pure hot CF4 and experimental results and previous calculations. The addition of CF4 to SF6 was found to increase the critical reduced electric field strength for temperatures above 1500 K, indicating the potential of replacing SF6 by SF6/CF4 mixtures in high-voltage circuit breakers.

  7. Chelation: A Fundamental Mechanism of Action of AGE Inhibitors, AGE Breakers, and Other Inhibitors of Diabetes Complications

    OpenAIRE

    Nagai, Ryoji; Murray, David B.; Metz, Thomas O.; Baynes, John W.

    2012-01-01

    This article outlines evidence that advanced glycation end product (AGE) inhibitors and breakers act primarily as chelators, inhibiting metal-catalyzed oxidation reactions that catalyze AGE formation. We then present evidence that chelation is the most likely mechanism by which ACE inhibitors, angiotensin receptor blockers, and aldose reductase inhibitors inhibit AGE formation in diabetes. Finally, we note several recent studies demonstrating therapeutic benefits of chelators for diabetic car...

  8. NRC Information No. 88-42: Circuit breaker failures due to loose charging spring motor mounting bolts

    International Nuclear Information System (INIS)

    There are two emergency diesel generators (EDGs) at North Anna Unit 2 (H and J). On May 19, 1988, following completion of scheduled preventive maintenance, the ''J'' EDG failed to pick up and carry the required load during preoperational testing. The licensee then shut down the ''J'' EDG and performed unplanned corrective maintenance. The licensee's technical specifications require that the operable EDG be tested within 24 hours if the inoperable EDG is inoperable due to any cause other than preplanned preventive maintenance or testing; thus, because of the unplanned maintenance on the ''J'' EDG the licensee tested the ''H'' EDG. During this test, the ''J'' EDG output circuit breaker (ITE Type 5HK) failed to close. The licensee's investigation determined that the ''H'' EDG output breaker closing spring had not been charged because the charging spring motor mounting bolts had become loose, allowing the motor to become detached from the frame. A similar occurrence was previously reported by Philadelphia Electric Company (the Limerick Units 1 and 2 licensee) on August 27, 1984. During an EDG preoperational test, the charging spring motor of a BBC Brown Boveri, Inc. 5HK breaker failed to perform its intended function. The licensee determined that three out of four horizontal charging spring motor mounting bolts had loosened, allowing the charging spring motor to rotate. Loose charging spring motor mounting bolts may be a generic concern. Because of changes in corporate name, mergers etc., circuit breakers similar to those discussed may indicate manufacture by ITE, ITE Imperial, Gould, Brown Boveri, or a combination thereof

  9. Inhibition of Cu-amyloid-β by using bifunctional peptides with β-sheet breaker and chelator moieties.

    Science.gov (United States)

    Jensen, Madeleine; Canning, Anne; Chiha, Sabri; Bouquerel, Pierre; Pedersen, Jeppe Trudslev; Østergaard, Jesper; Cuvillier, Olivier; Sasaki, Isabelle; Hureau, Christelle; Faller, Peter

    2012-04-16

    Breaking the mold: Inhibition of toxic amyloid-β (Aβ) aggregates and disruption of Cu-Aβ with subsequent redox-silencing of Cu have been considered promising strategies against Alzheimer's disease. The design and proof of concept of simple peptides containing a Cu-chelating/redox-silencing unit and an Aβ-aggregation inhibition unit (β-sheet breaker) is described (see scheme). PMID:22422637

  10. Investigation on no-load mechanical endurance and electrical degradation of a circuit breaker model under short circuit current interruption

    OpenAIRE

    Suwanasri, Thanapong

    2006-01-01

    The demand on reducing circuit breaker failure, extending service life, increasing equipment reliability and lowering the related operating and maintenance costs are nowadays of prime importance for the electricity supply network. According to statistics, the major failure mode is originated from operating mechanism, whereas interrupter has the highest percentage of failure in high voltage component. Thus, the method to facilitate the assessment of internal mechanical conditions by using comm...

  11. Understanding Social Learning Behaviors via a Virtual Field Trip

    Directory of Open Access Journals (Sweden)

    Xin Bai

    2014-06-01

    Full Text Available This is a multidisciplinary study investigating how a virtual rather than face-to-face field trip can be conducted in a real-world setting and how students respond to such a social learning opportunity. Our participants followed a story of a stroke patient at her virtual home and in a virtual hospital via a teaching vignette. They were then given a new case and got on a virtual trip via a multiuser virtual environment. They played the roles of patients, relatives, doctors, or nurses, experiencing the emotional, physical, or social impacts those stakeholders may go through. Our study finds the overall participation of the Virtual Group is 50% more than the Text Group. Although the Virtual Group generates much more nodes in total, they focused much less on knowledge sharing and comparing than the Text Group (46 vs. 67, but more on other higher-level aspects of social interactions, such as knowledge discovery (57 vs. 42, co-construction (66 vs. 39, testing and modification (58 vs. 24 and application of newly constructed meaning (60 vs. 16. Analysis of students’ virtual field activities and in-depth discussions of important issues implied are included to help understand social learning behaviors during a virtual field trip. Sustainability of such systems is discussed.

  12. Properties and application of TRIP-steel in sheet metal forming

    Energy Technology Data Exchange (ETDEWEB)

    Doege, E.; Kulp, S.; Sunderkoetter, C. [Dept. of Sheet Metal Forming, Inst. for Metal Forming and Metal Forming Machine Tools, Univ. of Hannover (Germany)

    2002-07-01

    A further development of dual-phase-steels are represented by TRIP (transformation induced plasticity) -steels. TRIP-steels contain austenite, which is metastable at room temperature. It transforms to martensite during straining (TRIP effect). This process improves the strength-ductility balance of these steels. Two types of TRIP-steels, low alloyed (L-TRIP) and high alloyed (H-TRIP), can be applied in sheet forming processes and exhibit different forming characteristics. Basing on results of uniaxial tensile tests and the evaluation of Young's modulus the forming limits in deep drawing processes and the component properties of deep drawn parts are discussed. The Young's modulus decreases significantly with increasing pre-strain, especially demonstrated for the L-TRIP material TRIP700. Forming limit curves determined at different forming temperatures indicate its influence on the forming limits. Martensite transformation is suppressed at a temperature of approximately T = 200 C and therefore the major strain {phi}{sub 1} decreases significantly. For the investigated stainless steel AISI304 (H-TRIP) different lubricant types in comparison to chlorinated paraffins have been tested. Lubricants consisting of sulphur additives led to good forming conditions in forming processes, even better than lubricants based on chlorinated paraffins. The evaluation of component properties, compared between L-TRIP and H-TRIP, was done based on the analysis of springback and dent resistance. The L-TRIP material TRIP700 shows higher springback angles than AISI304 resulting from higher yield strength and decreased Young's modulus, resulting from the forming process. The dent resistance of TRIP-steel was exemplarily demonstrated for AISI304. Uniaxial pre-strained sheet specimen were analysed to show the dent resistance depending on dent depth. During elastic denting prestrain has no influence on dent resistance. Further increasing dent depth lead to increased dent forces

  13. Functional characterization of Trip10 in cancer cell growth and survival

    Directory of Open Access Journals (Sweden)

    Yan Pearlly S

    2011-02-01

    Full Text Available Abstract Background The Cdc42-interacting protein-4, Trip10 (also known as CIP4, is a multi-domain adaptor protein involved in diverse cellular processes, which functions in a tissue-specific and cell lineage-specific manner. We previously found that Trip10 is highly expressed in estrogen receptor-expressing (ER+ breast cancer cells. Estrogen receptor depletion reduced Trip10 expression by progressively increasing DNA methylation. We hypothesized that Trip10 functions as a tumor suppressor and may be involved in the malignancy of ER-negative (ER- breast cancer. To test this hypothesis and evaluate whether Trip10 is epigenetically regulated by DNA methylation in other cancers, we evaluated DNA methylation of Trip10 in liver cancer, brain tumor, ovarian cancer, and breast cancer. Methods We applied methylation-specific polymerase chain reaction and bisulfite sequencing to determine the DNA methylation of Trip10 in various cancer cell lines and tumor specimens. We also overexpressed Trip10 to observe its effect on colony formation and in vivo tumorigenesis. Results We found that Trip10 is hypermethylated in brain tumor and breast cancer, but hypomethylated in liver cancer. Overexpressed Trip10 was associated with endogenous Cdc42 and huntingtin in IMR-32 brain tumor cells and CP70 ovarian cancer cells. However, overexpression of Trip10 promoted colony formation in IMR-32 cells and tumorigenesis in mice inoculated with IMR-32 cells, whereas overexpressed Trip10 substantially suppressed colony formation in CP70 cells and tumorigenesis in mice inoculated with CP70 cells. Conclusions Trip10 regulates cancer cell growth and death in a cancer type-specific manner. Differential DNA methylation of Trip10 can either promote cell survival or cell death in a cell type-dependent manner.

  14. Technical-economic evaluation of the utilization of closing resistor in CEMIG extra-high voltage circuit breakers

    Energy Technology Data Exchange (ETDEWEB)

    Rocha, Angelica C.O.; Pinto, Roberto del Giudice R.; Teixeira, Jose Cleber; Fonseca, Rodrigo Assuncao; F. Junior, Sebastiao V. [Companhia Energetica de Minas Gerais (CEMIG), Belo Horizonte, MG (Brazil)

    1994-12-31

    This paper presents the technical and economic studies performed by CEMIG, Companhia Energetica de Minas Gerais, Brazil, concerning the use of closing resistor in its extra-high voltage (EHV) breakers. The analysis emphasizes the advantages which could be achieved with the elimination of the resistor as far as costs and reliability are concerned. This evaluation was motivated by two 500 kV breaker failures resulting from the breakdown of the closing resistor operation mechanism. These occurrences resulted in operative restriction for CEMIG EHV system. The analysis demanded a review of the capability criteria of silicon carbide (Si C) gap arresters, which are still greatly used in CEMIG EHV System, and of the procedures to be applied when carrying out the transient studies. The investigation resulted in the prompt removal of closing resistors from circuit breakers in CEMIG extra-high voltage system generating an economy of approximately U$ 840,00 and an improvement in safety and system reliability. (author) 13 refs., 4 figs., 1 tab.

  15. 基于MATLAB仿真的缓冲器对断路器分闸特性影响研究%Simulation Study on the Influence of Multi-orifice Hydraulic Buffer on Opening Characteristics of High Voltage Circuit Breaker Based on MATLAB

    Institute of Scientific and Technical Information of China (English)

    余明星; 赵伟涛

    2015-01-01

    为研究用于弹簧操动机构中的排孔式液压缓冲器结构参数对高压断路器分闸特性的影响,文中以排孔式缓冲器工作原理为基础建立了缓冲过程的数学模型,应用MATLAB对数学模型进行仿真求解。仿真所得曲线与试验曲线相吻合,证明了仿真的准确性,并依此为依据,仿真得到缓冲器在不同阻尼孔直径、不同阻尼孔位置、不同活塞与缸体配合间隙以及不同分闸弹簧刚度下对断路器分闸特性的影响,该研究为设计出满足断路器分合特性的缓冲器提供了理论指导。%In order to investigate the influence of structure parameters of multi-orifice hydraulic buffer which used in the spring operating mechanism of high voltage circuit breaker to the opening operation , in this paper, a mathematical model of cushioning process based on buffer working principle is established. Then simulate and solve such mathematical model by MATLAB. First of all , to verify the simulation accuracy, the simulation and experimental curves are compared and analyzed. Then on this basis, through numerical simulation, it is found that the diameter and the spacing interval of damped orifice, the clearance between piston and cylinder block, and the stiffness of trip spring would influence the opening operation of circuit breaker. This study provides the theoretical guidance for designing and optimizing the performance of hydraulic buffer.

  16. Pre-trip vs. post-trip destination image variations: A case of inbound tourists to Tanzania

    OpenAIRE

    Jani, Dev; Nguni, Winnie

    2016-01-01

    Despite the conceptual indications of destination image to vary with factors like travel status and tourist behaviour, there are few studies that have empirically researched the variations in destination image particularly in emerging destinations like those in Africa. This study aimed at testing the variation of pre- and post trip destination image held by inbound travellers to Tanzania. Four hypotheses were defined to test variation of destination image with travel status, destination famil...

  17. Current identification in vacuum circuit breakers as a least squares problem*

    Directory of Open Access Journals (Sweden)

    Ghezzi Luca

    2013-01-01

    Full Text Available In this work, a magnetostatic inverse problem is solved, in order to reconstruct the electric current distribution inside high voltage, vacuum circuit breakers from measurements of the outside magnetic field. The (rectangular final algebraic linear system is solved in the least square sense, by involving a regularized singular value decomposition of the system matrix. An approximated distribution of the electric current is thus returned, without the theoretical problem which is encountered with optical methods of matching light to temperature and finally to current density. The feasibility is justified from the computational point of view as the (industrial goal is to evaluate whether, or to what extent in terms of accuracy, a given experimental set-up (number and noise level of sensors is adequate to work as a “magnetic camera” for a given circuit breaker. Dans cet article, on résout un problème inverse magnétostatique pour déterminer la distribution du courant électrique dans le vide d’un disjoncteur à haute tension à partir des mesures du champ magnétique extérieur. Le système algébrique (rectangulaire final est résolu au sens des moindres carrés en faisant appel à une décomposition en valeurs singulières regularisée de la matrice du système. On obtient ainsi une approximation de la distribution du courant électrique sans le problème théorique propre des méthodes optiques qui est celui de relier la lumière à la température et donc à la densité du courant. La faisabilité est justifiée d’un point de vue numérique car le but (industriel est d’évaluer si, ou à quelle précision, un dispositif expérimental donné (nombre et seuil limite de bruit des senseurs peut travailler comme une “caméra magnétique” pour un certain disjoncteur.

  18. Spreading Geodiversity awareness in schools through field trips and ICT

    Science.gov (United States)

    Magagna, Alessandra; Giardino, Marco; Ferrero, Elena

    2014-05-01

    Geodiversity, unlike Biodiversity, is not a topic included in the Italian schools curriculum. Nevertheless, Geomorphology is taught at all levels, and it seems to be the right tool for introducing the students to the concepts related to Geodiversity. In this context, a research on the use of field trips and Information and Communication Technologies (ICT) is being carried out for spreading the value of Geodiversity in Secondary Schools. Relevant international literature states that field trips are effective didactic tools for Earth Science education, because they stimulate an active learning process and allow students to appreciate the geological complexity of an area. On the other side, ICT allow students to get knowledge about the variety of landforms of their own territory by staying indoor, using virtual field trips and free software like Google Earth, Google Maps, Bing etc. In order to connect the two strategies, an innovative educational project is proposed here; it involves both the indoor and the outdoor activities, by enhancing a critical approach to the complexity of geological processes. As a starting point, a multimedia product on 20 Italian geological tours, designed for analyzing Geodiversity at a regional scale, has been tested with teachers and students, in order to understand its effectiveness by using it solely indoor. In a second phase, teachers and students have been proposed to compare and integrate indoor and outdoor activities to approach Geodiversity directly at a local scale, by means of targeted field trips. For achieving this goal, during the field trips, students used their mobile devices (smartphone and tablet) equipped with free and/or open source applications (Epicollect, Trimble Outdoor Navigator). These tools allow to track field trips, to gather data (geomorphological observations and related photographs), and to elaborate them in the laboratory; a process useful for reasoning on concepts such as spatial and temporal scales and for

  19. Predictive Process Optimization for Fracture Ductility in Automotive TRIP Steels

    Science.gov (United States)

    Gong, Jiadong

    In light of the emerging challenges in the automotive industry of meeting new energy-saving and environment-friendly requirements imposed by both the government and the society, the auto makers have been working relentlessly to reduce the weight of automobiles. While steel makers pushed out a variety of novel Advanced High Strength Steels (AHSS) to serve this market with new needs, TRIP (Transformation Induced Plasticity) steels is one of the most promising materials for auto-body due to its exceptional combination of strength and formability. However, current commercial automotive TRIP steels demonstrate relatively low hole-expansion (HE) capability, which is critical in stretch forming of various auto parts. This shortcoming on ductility has been causing fracture issues in the forming process and limits the wider applications of this steel. The kinetic theory of martensitic transformations and associated transformation plasticity is applied to the optimization of transformation stability for enhanced mechanical properties in a class of high strength galvannealed TRIP steel. This research leverages newly developed characterization and simulation capabilities, supporting computational design of high-performance steels exploiting optimized transformation plasticity for desired mechanical behaviors, especially for the hole-expansion ductility. The microstructure of the automotive TRIP sheet steels was investigated, using advanced tomographic characterization including nanoscale Local Electrode Atom Probe (LEAP) microanalysis. The microstructural basis of austenite stability, the austenite carbon concentration in particular, was quantified and correlated with measured fracture ductility through transformation plasticity constitutive laws. Plastic flow stability for enhanced local fracture ductility at high strength is sought to maintain high hole-expansion ductility, through quantifying the optimal stability and the heat-treatment process to achieve it. An additional

  20. Small break LOCA analysis for RCP trip strategy for YGN 3 and 4 emergency procedure guidelines

    International Nuclear Information System (INIS)

    A continued operation of RCPs during a certain small break LOCA may increase unnecessary inventory loss from the RCS causing a severe core uncovery which might lead to a fuel failure. After TMI-2 accident, the CEOG developed RCP trip strategy called 'Trip-Two/Leave-Two' (T2/L2) in response to NRC requests and incorporated it in the generic EPG for CE plants. The T2/L2 RCP trip strategy consists of tripping the first two RCPs on low RCS pressure and then tripping the remaining two RCPs if a LOCA has occurred. This analysis determines the RCP trip setpoint and demonstrates the safe operational aspects of RCP trip strategy during a small break LOCA for YGN 3 and 4. The trip setpoint of the first two RCPs for YGN 3 and 4 is calculated to be 1775 psia in pressurizer pressure based on the limiting small break LOCA with 0.15 ft2 break size in the hot leg. The analysis results show that YGN 3 and 4 can maintain the core coolability even if the operator fails to trip the second two RCPs or trips at worst time. Also, the YGN 3 and 4 RCP trip strategy demonstrates that both the 10 CFR 50.46 requirements on PCT and the ANSI standards 58.8 requirements on operator action time can be satisfied with enough margin. Therefore, it is concluded that the T2/L2 RCP trip strategy with a trip setpoint of 1775 psia for YGN 3 and 4 can provide improved operator guidance for the RCP operation during accidents. 11 figs., 4 tabs., 9 refs. (Author)

  1. Factors that influence learning during a scientific field trip in a natural environment

    Science.gov (United States)

    Orion, Nir; Hofstein, Avi

    This study deals with the educational effectiveness of field trips. The main purpose was to obtain insight concerning factors that might influence the ability of students to learn during a scientific field trip in a natural environment. The research was conducted in the context of a 1-day geologic field trip by 296 students in Grades 9 through 11 in high schools in Israel. The study combined qualitative and quantitative research methods. Data were collected from three different sources (student, teacher, and outside observer) in three stages (before, after, and during the field trip). Using observations and questionnaires we investigated: a) the nature of student learning during the field trip, b) student attitudes toward the field trip, and c) changes in student knowledge and attitudes after the field trip. Our findings suggest that the educational effectiveness of a field trip is controlled by two major factors: the field trip quality and the Novelty space (or Familiarity Index). The educational quality of a field trip is determined by its structure, learning materials, and teaching method, and the ability to direct learning to a concrete interaction with the environment. The novelty space consists of three prefield variables: cognitive, psychological, and geographic. The learning performance of students whose Novelty Space was reduced before the field trip was significantly higher than that of students whose Novelty Space had not been so reduced. Thus, the former group gained significantly higher achievement and attitude levels. It is suggested that a field trip should occur early in the concrete part of the curriculum, and should be preceded by a relatively short preparatory unit that focuses on increasing familiarity with the learning setting of the field trip, thereby limiting the Novelty Space factors.Received: 23 March 1993; Revised: 24 January 1994;

  2. Field trips and their effect on student achievement in and attitudes toward science: A comparison of a physical versus a virtual field trip to the Indian River Lagoon

    Science.gov (United States)

    Garner, Lesley Cochran

    The purpose of this study was to determine the effect of physical and virtual field trips on students' achievement in estuarine ecology and their attitudes toward science. The study also assessed the effect of students' learning styles, the interaction between group membership and learning styles, and the effect of group membership on students' ability to answer questions at different levels of Bloom's (1956) taxonomy. Working with a convenient sample of 67 freshmen and sophomore non-science majors, students were randomly assigned to one of two treatment groups (physical, n = 32 and virtual, n = 35). Prior to treatment, students' learning styles were determined, students were pre-assessed on the two targeted measures, and all students attended four consecutive, in-class, 75-minute lectures on estuarine ecology and the Indian River Lagoon (IRL). Pre-assessed data indicated no significant differences between the groups on the two dependent measures. On the weekend following the lecture series, the physical field trip group engaged in a set of predetermined activities at the IRL for 2 hours in the morning. Later that afternoon, the virtual field trip group participated in a 2-hour virtual trip to the IRL that exactly matched the physical field trip activities. This virtual trip incorporated the CD-ROM The Living Lagoon: An Electronic Field Trip. Following each trip, students were post-assessed using the same pre-assessment instruments. MANCOVA results indicated no significant differences on all research factors (i.e., group membership, learning style, and group-learning style interaction). Data analysis also revealed that there was no significant effect of group membership on students' ability to answer questions at different levels of Bloom's taxonomy. These findings imply that educators can integrate virtual field trips that are structured in the same manner as their corresponding physical field trips without significantly impacting student achievement or attitudes.

  3. Simulation and Experimental Analysis of Arc Motion Characteristics in Air Circuit Breaker

    Science.gov (United States)

    Niu, Chunping; Ding, Juwen; Wu, Yi; Yang, Fei; Dong, Delong; Fan, Xingyu; Rong, Mingzhe

    2016-03-01

    In this paper, to simulate the arc motion in an air circuit breaker (ACB), a three-dimensional magneto-hydrodynamic (MHD) model is developed, considering the influence of thermal radiation, the change of physical parameters of arc plasma and the nonlinear characteristic of ferromagnetic material. The distributions of pressure, temperature, gas flow and current density of arc plasma in the arc region are calculated. The simulation results show some phenomena which discourage arc interruption, such as back commutation and arc burning at the back of the splitter plate. To verify the simulation model, the arc motion is studied experimentally. The influences of the material and position of the innermost barrier plate are analyzed mainly. It proved that the model developed in this paper can efficiently simulate the arc motion. The results indicate that the insulation barrier plate close to the top of the splitter plate is conducive to the arc splitting, which leads to the significant increase of the arc voltage, so it is better for arc interruption. The research can provide methods and references to the optimization of ACB design. supported by National Key Basic Research Program of China (973 Program) (Nos. 2015CB251002, 6132620303), National Natural Science Foundation of China (Nos. 51221005, 51377128, 51577144), and the Fundamental Research Funds for the Central Universities, China

  4. Transient Response Simulation of Downstream Thermofluid Field in a Gas Circuit Breaker during Current Interruption

    Science.gov (United States)

    Nishiyama, Hideya; Hamada, Katsuhisa; Uchii, Toshiyuki; Kawano, Hiromichi; Tanaka, Yasunori

    A transient response of SF6 thermofluid field inside the exhaust tube in a Gas Circuit Breaker under high temperature, high pressure and high velocity conditions is analyzed by taking compressible effect and some realistic processes into account related to the available experimental data of GCB test facility. Furthermore, computational simulation is conducted to clarify the effective cooling process of SF6 hot gas flow inside the exhaust tube for transient time to avoid the SF6 hot gas breakdown near exhaust tube exit after the arc current interruption. It is found that the SF6 hot gas flow can be effectively cooled down for the rough inside wall of exhaust tube due to the separation of SF6 hot gas flow from the inside wall and also active mixing with upstream cold gas. The effect of roughness pattern on the real time thermofluid field of SF6 hot gas flow and possible breakdown region are also clarified. Finally, the computed temperature in GCB shows the good agreement with the available experimental data for smooth surface of exhaust tube.

  5. The Voltage Distribution Characteristics of a Hybrid Circuit Breaker During High Current Interruption

    International Nuclear Information System (INIS)

    Hybrid circuit breaker (HCB) technology based on a vacuum interrupter and a SF6 interrupter in series has become a new research direction because of the low-carbon requirements for high voltage switches. The vacuum interrupter has an excellent ability to deal with the steep rising part of the transient recovery voltage (TRV), while the SF6 interrupter can withstand the peak part of the voltage easily. An HCB can take advantage of the interrupters in the current interruption process. In this study, an HCB model based on the vacuum ion diffusion equations, ion density equation, and modified Cassie-Mayr arc equation is explored. A simulation platform is constructed by using a set of software called the alternative transient program (ATP). An HCB prototype is also designed, and the short circuit current is interrupted by the HCB under different action sequences of contacts. The voltage distribution of the HCB is analyzed through simulations and tests. The results demonstrate that if the vacuum interrupter withstands the initial TRV and interrupts the post-arc current first, then the recovery speed of the dielectric strength of the SF6 interrupter will be fast. The voltage distribution between two interrupters is determined by their post-arc resistance, which happens after current-zero, and subsequently, it is determined by the capacitive impedance after the post-arc current decays to zero. (plasma technology)

  6. Numerical Study on Arc Plasma Behavior During Arc Commutation Process in Direct Current Circuit Breaker

    International Nuclear Information System (INIS)

    This paper focuses on the numerical investigation of arc plasma behavior during arc commutation process in a medium-voltage direct current circuit breaker (DCCB) contact system. A three-dimensional magneto-hydrodynamic (MHD) model of air arc plasma in the contact system of a DCCB is developed, based on commercial software FLUENT. Coupled electromagnetic and gas dynamic interactions are considered as usual, and a thin layer of nonlinear electrical resistance elements is used to represent the voltage drop of plasma sheath and the formation of new arc root. The distributions of pressure, temperature, gas flow and current density of arc plasma in arc region are calculated. The simulation results indicate that the pressure distribution related to the contact system has a strong effect on the arc commutation process, arising from the change of electrical conductivity in the arc root region. In DCCB contact system, the pressure of arc root region will be concentrated and higher if the space above the moving contact is enclosed, which is not good for arc root commutation. However, when the region is opened, the pressure distribution would be lower and more evenly, which is favorable for the arc root commutation.

  7. Calculation of Nozzle Ablation During Arcing Period in an SF6 Auto-Expansion Circuit Breaker

    Science.gov (United States)

    Zhang, Junmin; Lu, Chunrong; Guan, Yonggang; Liu, Weidong

    2016-05-01

    The nozzle ablation process is described as two phases of heat and ablation in the interruption for an SF6 circuit breaker in this paper. Their mathematical models are established with the Fourier heat conduction differential equation respectively. The masses of nozzle ablation with different arc durations and arc currents are calculated through the model of the nozzle ablation combined with an MHD (magneto-hydrodynamic) arc model. The time of the temperature rise on the inner surface of the nozzle under a given energy flux and of reaching the pyrolysis temperature under different energy fluxes is respectively analyzed. The relations between the mass of nozzle ablation and breaking current and arc duration are obtained. The result shows that the absorbing energy process before the nozzle ablation can be neglected under the condition of the energy flux entering into nozzle q > 109 W/m2. The ablation is the severest during the high-current phase and the ablation mass increases rapidly with the breaking current and with arc duration respectively. supported by National Natural Science Foundation of China (Nos. 51177005 and 51477004)

  8. Simulation and Experimental Study of Arc Column Expansion After Ignition in Low-Voltage Circuit Breakers

    Institute of Scientific and Technical Information of China (English)

    MA Qiang; RONG Mingzhe; WU Yi; XU Tiejun; SUN Zhiqiang

    2008-01-01

    The dynamicprocess of arc pressure and corresponding arc column expansion, which is the main feature after arc ignition and has a significant effect on the breaking behaviour of low -voltage circuit breakers, is studied. By constructing a three dimensional mathematical model of air arc plasma and adopting the Control Volume Method, the parameters of arc plasma including temperature and pressure axe obtained. The variations of pressure field and temperature field with time are simulated. The result indicates that there are six stages for the process of arc column expansion according to the variation of pressure in arc chamber. In the first stage, the maximal pressure locates in the region close to cathode, and in the second stage the maximal pressure shifts to the region close to the anode. In the third stage, the pressure difference between the middle of arc column and the ambient gas is very large, so the arc column begins to expand apparently. In the fourth stage, the pressure wave propagates towards both ends and the maximal pressure appears at the two ends when the pressure wave reaches both sidewalls. In the fifth stage, the pressure wave is reflected and collides in the middle of the arc chamber. In the last stage, the propagation and reflection of pressure wave will repeat several times until a steady burning state is reached. In addition, the experimental results of arc column expansion, corresponding to the arc pressure variation, are presented to verify the simulation results.

  9. Speckle measurements of density and temperature profiles in a model gas circuit breaker

    International Nuclear Information System (INIS)

    Speckle imaging was used to measure the density and temperature distribution in the arc zone of a model high voltage circuit breaker during the high current phase and under conditions simulating those present during current-zero crossings (current-zero-like arc); the arc was stabilized by a transonic, axial flow of synthetic air. A single probe beam was used; thus, accurate reconstruction was only possible for axially symmetric gas flows and arc channels. The displacement of speckles with respect to a reference image was converted to a line-of-sight integrated deflection angle, which was in turn converted into an axially symmetric refractive index distribution using a multistep process that made use of the inverse Radon transform. The Gladstone–Dale relation, which gives the index of refraction as a function of density, was extended to high temperatures by taking into account dissociation and ionization processes. The temperature and density were determined uniquely by assuming that the pressure distribution in the case of cold gas flow (in the absence of an arc) is not modified significantly by the arc. The electric conductivity distribution was calculated from the temperature profile and compared to measurements of the arc voltage and to previous results published in the literature for similar experimental conditions. (paper)

  10. Ohmic heating dc circuit breakers with liquid-metal plasma valves

    International Nuclear Information System (INIS)

    The ohmic heating circuits of Tokamaks and Stellarators now under construction or in the planning state require circuit breakers which can interrupt currents as high as 250kA against voltages of up to 50kV after conducting the current for as long as a few seconds (not necessarily in this parameter combination). In order to satisfy these upcoming needs, Hughes Research Laboratories (HRL) is developing a switch module whith a 35kA interrupting capability, based on the 'liquid-metal plasma valve' (LMPV). Higher current ratings will be achieved by paralleling several modules. This modular approach will satisfy the needs of different ohmic heating circuits and will permit more economical testing. Current interruption is achieved by forced commutation of the LMPVs. These valves are vacuum arc devices, using a mercury (or other liquid-metal) vapor plasma to provide the current conduction medium without causing appreciable electrode erosion. Conduction for arbitrarily long times without discharge-voltage losses can be achieved by using a mechanical bypass switch (MBS) to carry the current for most of the conduction time, the LMPV taking over the current from the MBS just long enough for the MBS to deionize. A relatively simple, reasonably priced mechanical switch can be employed for this purpose with very little contact erosion, and hence, with long life

  11. Speckle measurements of density and temperature profiles in a model gas circuit breaker

    Science.gov (United States)

    Stoller, P. C.; Panousis, E.; Carstensen, J.; Doiron, C. B.; Färber, R.

    2015-01-01

    Speckle imaging was used to measure the density and temperature distribution in the arc zone of a model high voltage circuit breaker during the high current phase and under conditions simulating those present during current-zero crossings (current-zero-like arc); the arc was stabilized by a transonic, axial flow of synthetic air. A single probe beam was used; thus, accurate reconstruction was only possible for axially symmetric gas flows and arc channels. The displacement of speckles with respect to a reference image was converted to a line-of-sight integrated deflection angle, which was in turn converted into an axially symmetric refractive index distribution using a multistep process that made use of the inverse Radon transform. The Gladstone-Dale relation, which gives the index of refraction as a function of density, was extended to high temperatures by taking into account dissociation and ionization processes. The temperature and density were determined uniquely by assuming that the pressure distribution in the case of cold gas flow (in the absence of an arc) is not modified significantly by the arc. The electric conductivity distribution was calculated from the temperature profile and compared to measurements of the arc voltage and to previous results published in the literature for similar experimental conditions.

  12. Influence of Copper Vapor on Low-Voltage Circuit Breaker Arcs During Stationary and Moving States

    Institute of Scientific and Technical Information of China (English)

    MA Qiang; RONG Mingzhe; WU Yi; XU Tiejun; SUN Zhiqiang

    2008-01-01

    The influence of copper vapor on the low-voltage circuit breaker arcs is studied. A three-dimensional (3-D) magnetohydrodynamics(MHD) model of arc motion under the effect of external magnetic field is built up. By adopting the commercial computational fluid dynamics (CFD) package FLUENT based on control-volume method, the above MHD model is solved. For the mediums of air-1% Cu and air-10% Cu, the distributions of stationary temperature, pressure, electrical potential and the arc motion processes are compared with those of a pure air arc. The copper vapor diffusion process in the arc chamber and the distribution of copper vapor mass concentration are also simulated. The results shows that the copper vapor has a cooling effect on the arc plasma and can decrease the stationary voltage as well. Moreover, the presence of copper vapor can decelerate the arc motion in the quenching chambers. The maximal copper vapor concentration locates behind the arc root because of the existence of a "double vortex" near the electrodes.

  13. Identification Trouble Valve Destruction On Hidroulic Press Breaker Model MPV.1620 ''DAVY-ITALlA''

    International Nuclear Information System (INIS)

    To 'utility instalation examination and operation test, how long capacity to appear on the severaly valve.Torned valve on hidroulic press breaker is three sample: The first directional control valve type. 4 WE 10 H 32 / CE 24 N 9 Z4. Coil: Hydronorma GZ . 63-4 -A. 476. 24VDC, 1,46 A. For two and three is boll spriral spring valve Process operation explanation a short is oil lubrication to pump from reception center tank in to directional control valve then distributed. anything to boll spiral spring valve continued to hidroulic piston for pressed the sample job / plate thickness maximum = 16 mm with to different corner model, maximum press = 160 bar.Hindrance principle is to utilize operation test, hidroulic piston movement botom-up is smothly 0 whereas botom-down went no smoothly. Operation test property to utilize repeated resutls of the aqua. Hindrance / broken the fist estimate that the hole oil works at the directional control valve to threadbore hidroulic piston, wherever preasure not maximum to manometer indicate = 0 bar, at the moment to utilize operation. The second on the boll spiral spring valve no maximum, then to utilize servise detail and to utilize operation test againt. The results from operation test to concende destruction at the boll spiral spring valve, wherever after over houling to appear boll massive place position possessed spring wire> 3 mm to twist of couse preasure to press hidroulic piston no maximum because from leaking

  14. Vacuum interrupter, high reliability component of distribution switches, circuit breakers and contactors

    Institute of Scientific and Technical Information of China (English)

    SLADE Paul G.; LI Wang-pei; MAYO Stephen; SMITH R.Kirkland; TAYLOR Erik D.

    2007-01-01

    The use of vacuum interrupters (VIs) as the current interruption component for switches, circuit breakers, reclosers and contactors operating at distribution voltages has escalated since their introduction in the mid-1950's. This electrical product has developed a dominating position for switching and protecting distribution circuits. VIs are even being introduced into switching products operating at transmission voltages. Among the reasons for the VI's popularity are its compactness, its range of application, its low cost, its superb electrical and mechanical life and its ease of application. Its major advantage is its well-established reliability. In this paper we show how this reliability has been achieved by design, by mechanical life testing and by electrical performance testing. We introduce the "sealed for life" concept for the VI's integrity. We discuss this in terms of what is meant by a practical leak rate for VIs with a life of over 30 years. We show that a simple high voltage withstand test is an easy and effective method for monitoring the long-term vacuum integrity. Finally we evaluate the need for routine inspection of this electrical product when it is used in adverse ambient environments.

  15. Calculation of Nozzle Ablation During Arcing Period in an SF6 Auto-Expansion Circuit Breaker

    Institute of Scientific and Technical Information of China (English)

    ZHANG Junmin; LU Chunrong; GUAN Yonggang; LIU Weidong

    2016-01-01

    The nozzle ablation process is described as two phases of heat and ablation in the interruption for an SF6 circuit breaker in this paper.Their mathematical models are established with the Fourier heat conduction differential equation respectively.The masses of nozzle ablation with different arc durations and arc currents are calculated through the model of the nozzle ablation combined with an MHD (magneto-hydrodynamic) arc model.The time of the temperature rise on the inner surface of the nozzle under a given energy flux and of reaching the pyrolysis temperature under different energy fluxes is respectively analyzed.The relations between the mass of nozzle ablation and breaking current and arc duration are obtained.The result shows that the absorbing energy process before the nozzle ablation can be neglected under the condition of the energy flux entering into nozzle q > 109 W/m2.The ablation is the severest during the high-current phase and the ablation mass increases rapidly with the breaking current and with arc duration respectively.

  16. Improving Transient Recovery voltage of circuit breaker using Fault Current Limiter

    Directory of Open Access Journals (Sweden)

    Amir Heidary

    2012-12-01

    Full Text Available This study investigates influence of Fault Current Limiter (FCL on short-circuits current level of substation bus bar splitter circuit breaker and its TRV. An approach for TRV evaluation is developed and applied for proposed power system as shown in this study. FCL circuit is connected to the power system in order to limit TRV. The limiter circuit consists of two equal windings which are turned around unique magnetic core. One of the windings is connected in series with the power system network and the other is connected to the network via series capacitor and power electronic switches. During normal operating condition, both tyristors are in on state and current of the primary and secondary windings are equal. This causes zero impedance of the limiter. During fault, faults current cause the power electronic switch to turn off which increases the limiter impedance. By increasing the limiter impedance, amplitude of TRV decreases substantially. The novel method presented in this study is a cheap and successful scheme.

  17. Transient Studies in Large Offshore Wind Farms Employing Detailed Circuit Breaker Representation

    Directory of Open Access Journals (Sweden)

    Jesper Hjerrild

    2012-07-01

    Full Text Available Switching overvoltages (SOV are considered a possible source of component failures experienced in existing offshore wind farms (OWFs. The inclusion of sufficiently accurate and validated models of the main electrical components in the OWF in the simulation tool is therefore an important issue in order to ensure reliable switching operations. Transient measurement results in an OWF are compared with simulation results in PSCAD EMTDC and DigSILENT Power Factory. A user-defined model of the vacuum circuit breaker (VCB is included in both tools, capable of simulating multiple prestrikes during the closing operation. An analysis of the switching transients that might occur in OWFs will be made on the basis of the validated model, and the importance of the inclusion of a sufficiently accurate representation of the VCB in the simulation tool will be described. The inclusion of the VCB model in PSCAD greatly improves the simulation results, whereas little improvement is found in DigSILENT. Based on the transient study it is found that the simulated SOV can be up to 60% higher at the sending end when using the detailed VCB representation compared to the built-in switch, which emphasises the need for accurate representation of the VCB for energisation studies.

  18. The Influence of Contact Space on Arc Commutation Process in Air Circuit Breaker

    Science.gov (United States)

    Niu, Chunping; Ding, Juwen; Yang, Fei; Dong, Delong; Rong, Mingzhe; Xu, Dan

    2016-05-01

    In this paper, a 3D magneto-hydrodynamic (MHD) arc simulation model is applied to analyze the arc motion during current interruption in a certain air circuit breaker (ACB). The distributions of pressure, temperature, gas flow and current density of the arc plasma in the arc region are calculated, and the factors influencing the commutation process are analyzed according to the calculated results. Based on the airflow in the arc chamber, the causes of arc commutation asynchrony and the back commutation are investigated. It indicates that a reasonable contact space design is crucial to a successful arc commutation process. To verify the simulation results, the influence of contact space on arc voltage and arc commutation is tested. This research can provide methods and references to the optimization of ACB design. supported by National Key Basic Research Program of China (973 Program) (Nos. 2015CB251002, 6132620303) and National Natural Science Foundation of China (Nos. 51221005, 51377128, 51577144), and Science and Technology Project Through Grid State Corporation (No. SGSNKYOOKJJS1501564)

  19. Insulation co-ordination aspects for power stations with generator circuit-breakers

    International Nuclear Information System (INIS)

    The generator circuit-breaker (gen. c.b.) located between the generator and the step-up transformer, is now being applied world-wide. It has become a recognized electrical component of power stations which is largely due to economical advantages and increased power station availability. Technical protection considerations for power stations have always been the reason for discussion and the object of improvement. With the use of a gen. c.b., some points of view need to be considered anew. Not only the protection system in case of fault conditions will be influenced, but also the insulation co-ordination philosophy. Below the results of some calculations concerning expected overvoltages are presented. These calculations are based on a transformer rated 264/15.5kV, 220 MVA. But the results are transferable to other power plants. Some measurements carried out on a transformer of the same rating complement the calculations. The findings may contribute to an improvement in insulation co-ordination and protection of the electrical system generator--step-up transformer

  20. Improvement of failure protection for high voltage side circuit breaker of 220 kV transformer%220kV变压器高压侧断路器失灵保护的改进

    Institute of Scientific and Technical Information of China (English)

    郑春生

    2016-01-01

    Failure protection of Shengli Oilfield 220 kV substation main transformer circuit breaker, its typical configuration cannot effectively isolate the fault point, in some atypical failure,the main transformer for a long time by the impact of short-circuit current,seriously affect the power system stability and safety. The failure protection action nodes and mother difference protection action nodes and the corresponding non electric starter relay series, when startup failure protection, the corresponding node closed, start relay, to direct trip-ping of main transformer with three side of the switch. Using this improved scheme, 3 of Shengli Oilfield 220 kV substation main transformer failure protection has been improved, reduces the possibility of 220 kV Main Transformer be impact by the fault current, guarantee the safe and stable operation of power grids.%胜利油田220 kV变电站主变断路器失灵保护中的典型配置不能有效隔离故障点,在一些非典型故障中,会使主变长时间受到短路电流冲击,严重影响电力系统稳定性和安全性.为此,将失灵保护动作节点和母差保护动作节点与相应的非电量启动继电器串联,当失灵保护启动时,相应节点闭合,启动继电器,进而直接跳开主变三侧开关.应用此改进方案,对胜利油田3座220 kV变电站的主变失灵保护进行了完善,降低了220 kV主变压器受到故障电流冲击的可能性,保障了电网安全、稳定运行.

  1. Active commuting to school in Portuguese adolescents: Using PALMS to detect trips

    DEFF Research Database (Denmark)

    Pizarro, Andreia Nogueira; Schipperijn, Jasper; Andersen, Henriette Bondo;

    2016-01-01

    Abstract The declining levels of physical activity (PA) have led to active commuting to school (ACS) being seen as a key strategy to increase PA levels in school-aged children. In Portugal, no data exists on the patterns of this behavior, an essential step for developing evidence-based and...... effective interventions. The purpose of this study is to explore the travel to school behavior using an objective methodology. Methods 155 adolescents (mean age 15.9±1.1 years) wore an accelerometer and a GPS for 7 consecutive days. Home and school addresses were geocoded to identify home-school trips. The...... web-based tool PALMS was used to combine GPS and accelerometer data, categorize Moderate to Vigorous Physical Activity (MVPA) and classify trip mode of home-school trips into: walking, bicycling or vehicle. Results 609 trips were identified as home-school trips. Walking was the most frequent trip mode...

  2. Development of RPS trip logic based on PLD technology

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jong Gyun; Lee, Dong Young [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-08-15

    The majority of instrumentation and control (I and C) systems in today's nuclear power plants (NPPs) are based on analog technology. Thus, most existing I and C systems now face obsolescence problems. Existing NPPs have difficulty in repairing and replacing devices and boards during maintenance because manufacturers no longer produce the analog devices and boards used in the implemented I and C systems. Therefore, existing NPPs are replacing the obsolete analog I and C systems with advanced digital systems. New NPPs are also adopting digital I and C systems because the economic efficiencies and usability of the systems are higher than the analog I and C systems. Digital I and C systems are based on two technologies: a microprocessor based system in which software programs manage the required functions and a programmable logic device (PLD) based system in which programmable logic devices, such as field programmable gate arrays, manage the required functions. PLD based systems provide higher levels of performance compared with microprocessor based systems because PLD systems can process the data in parallel while microprocessor based systems process the data sequentially. In this research, a bistable trip logic in a reactor protection system (RPS) was developed using very high speed integrated circuits hardware description language (VHDL), which is a hardware description language used in electronic design to describe the behavior of the digital system. Functional verifications were also performed in order to verify that the bistable trip logic was designed correctly and satisfied the required specifications. For the functional verification, a random testing technique was adopted to generate test inputs for the bistable trip logic.

  3. Implementing virtual field trips in the curriculum of geography students

    Science.gov (United States)

    Steegen, An; Verstraeten, Gert; Martens, Lotte

    2016-04-01

    Current online geospatial databases and tools offer many opportunities in geoscience education. On the one hand a variety of geoscientific topics and regions can be studied without traditional fieldwork, and on the other hand, field-based learning activities can be prepared or post-processed. In this research, the use of Virtual Field Trips (VFTs) in Google EarthTM is studied. In the framework of geomorphology courses, undergraduate geography students were given VFTs as developed by the lecturers or had to develop VFTs themselves, after visiting a study area. Maps, photographs, GPS-tracks, literature and other spatial information were integrated in the VFTs. The effect of VFTs on learning outcomes, on the insight in the horizontal and vertical relationships between the spatially varying topics, and motivation were measured. Results confirm that students are positive about the use of VFTs. They indicate that VFTs significantly improve their mental map of the study area, whereby horizontal relationships were strengthened. Also the additional information in some VFTs proved to have positive effects on studying and structuring the learning content. Students also appreciated to work independently with the VFTs and saw possibilities for integrating various geoscientific topics. However, there are also some constraints in working with VFTs. It was clear from the study that VFTs have to be embedded in the curriculum as students do not use or develop VFTs spontaneously. Indeed, it takes a lot of time to develop a VFT, and students also appreciate a variety in work forms. Also some technical difficulties on sufficient wireless internet access and flexible work spaces have to be encountered. Besides this, curricula developers should be aware that VFTs are an interesting tool additionally to field trips, but that they cannot replace the field trips.

  4. Arizona Geology Trip - February 25-28, 2008

    Science.gov (United States)

    Thomas, Gretchen A.; Ross, Amy J.

    2008-01-01

    A variety of hardware developers, crew, mission planners, and headquarters personnel traveled to Gila Bend, Arizona, in February 2008 for a CxP Lunar Surface Systems Team geology experience. Participating in this field trip were the CxP Space Suit System (EC5) leads: Thomas (PLSS) and Ross (PGS), who presented the activities and findings learned from being in the field during this KC. As for the design of a new spacesuit system, this allowed the engineers to understand the demands this type of activity will have on NASA's hardware, systems, and planning efforts. The engineers also experienced the methods and tools required for lunar surface activity.

  5. Effect of Thermomechanical Processing on Microstructures of TRIP Steel

    Institute of Scientific and Technical Information of China (English)

    TANG Zheng-you; DING Hua; DU Lin-xiu; DING Hao; ZHANG Xin

    2007-01-01

    In order to control retained austenite, the effect of hot deformation in the intercritical region on the microstructure of hot-rolled transformation-induced plasticity (TRIP) steel was studied on a Gleeble 1500 hot simulator. Compressive strains varying in amounts from 0 to 60% were imposed in the intercritical region, and effects on the formation of polygonal ferrite, carbide-free bainite and retained austenite were determined. With increasing the hot deformation amount and the ferrite content and decreasing the carbide-free bainite content, the volume fraction of retained austenite decreases. Increased dislocation density, grain refinement of ferrite and carbon enrichment are the main factors which control retained austenite stability.

  6. Study of nuclear power plant stability. Trip criteria

    International Nuclear Information System (INIS)

    The influence that nuclear power plants and high voltage power systems have on each other when confronted by disturbances in the offsite network may lead, due to dynamic effects, to plant trip. It is therefore necessary to study the disturbances in the network and the effects on plant equipment by means of dynamic simulations which evaluate the unit protection system and the auxiliary services so as to obtain maximum unit availability without jeopardizing its safety. These studies can be conducted since there are models and software tools capable of simulating dynamic behaviour of the electric system, including the excitation systems and specific speed governors obtainment of valid. (author)

  7. Harvesting Collective Trend Observations from Large Scale Study Trips

    DEFF Research Database (Denmark)

    Eriksen, Kaare; Ovesen, Nis

    2014-01-01

    To enhance industrial design students’ decoding and understanding of the technological possibilities and the diversity of needs and preferences in different cultures it is not unusual to arrange study trips where such students acquire a broader view to strengthen their professional skills and...... numbers of students to the annual Milan Design Week and the Milan fair ‘I Saloni’ in Italy. The present paper describes and evaluates the method, the theory behind it, the practical execution of the trend registration, the results from the activities and future perspectives....

  8. A 3D virtual geology field trip in Unity

    OpenAIRE

    Minocha, Shailey; Argles, Thomas; Richardson, Brian; Burden, David

    2013-01-01

    As a part of The OpenScience Laboratory, (http://www.open.ac.uk/openscience/), an initiative of The Open University (OU), UK and The Wolfson Foundation, we (OU and Daden http://www.daden.co.uk) are developing a 3D simulation of a Geology field trip based around Skiddaw in the Lake District, using the Unity 3D software. We are using digital data and imagery to reconstruct the landscape faithfully enough to provide a real sense of presence for the user. The primary objective of developing an au...

  9. Pig herd monitoring and undesirable tripping and stepping prevention

    DEFF Research Database (Denmark)

    Gronskyte, Ruta; Clemmensen, Line Katrine Harder; Hviid, Marchen Sonja;

    2015-01-01

    at the slaughterhouse and identify undesirable events such as pigs tripping or stepping on each other. In this paper, we monitor pig behavior in color videos recorded during unloading from transportation trucks. We monitor the movement of a pig herd where the pigs enter and leave a surveyed area. The...... machines is 93% of all frames. The sensitivity of the model is 93.5% with 90% specificity and 6.5% false alarm rate. The radial lens distortion and camera position required for convenient surveillance make the recordings highly distorted. Therefore, we also propose a new approach to correct lens and...

  10. Design of Thermo Mechanicaln Processing and Transformation Behaviour of Bulk Si-Mn Trip Steel

    OpenAIRE

    J. Zrnik; Mamuzić, I.; Lukaš, P.; Muransky, O.; Jenčuš, P.; Novy, Z.

    2006-01-01

    In the last decade, a lot of effort has been paid to optimising the thermomechanical processing of TRIP steels that stands for transformation induced plasticity. The precise characterization of the resulting multiphase microstructure of low alloyed TRIP steels is of great importance for the interpretation and optimisation of their mechanical properties. The results obtained in situ neutron diffraction laboratory experiment concerning the austenite to ferrite transformation in Si-Mn bulk TRIP ...

  11. Linking Geographic Information Systems and Trip Reduction: Success and Failure in a Pilot Application

    OpenAIRE

    Burns, Elizabeth K.

    1993-01-01

    Travel demand management policies are the focus of a national debate on ways to limit the growth of local highway congestion and improve urban air quality (Bae, 1993; Orski, 1989). One innovative approach, trip reduction programs, requires changes in individual travel behavior, usually in journey to work trips. While precise local goals and requirements vary, major trip reduction programs focus on large employers who must persuade drive-alone employees to increase vehicle occupancy, limit mil...

  12. Constraint Programming Formulation for the Elevator Trip Origin-Destination Matrix Estimation Problem

    OpenAIRE

    Kuusinen, Juha-Matti; Malapert, Arnaud

    2014-01-01

    We present a constraint programming formulation for the elevator trip origin-destination matrix estimation problem, and propose different approaches to solve the problem. An elevator trip consists of successive stops in one direction of travel with passengers inside the elevator. It can be defined as a directed network, where the nodes correspond to the stops on the trip, and the arcs to the possible origins and destinations of the passengers boarding and alighting at the stops. The goal is t...

  13. Does ignoring multidestination trips in the travel cost method cause a systematic bias?

    OpenAIRE

    Kuosmanen, Timo; Nillesen, Eleonora; Wesseler, Justus

    2004-01-01

    The present paper demonstrates that treating multidestination trips (MDT) as single‐destination trips does not involve any systematic upward or downward bias in consumer surplus (CS) estimates because the direct negative effect of a price increase (treating MDT as a single‐destination trip) is offset by a shift in the estimated demand curve. Still, ignoring MDT can greatly underestimate or overestimate the CS. In addition, we demonstrate that there is a sound theoretical basis for using prefe...

  14. The Research of TRIP Protocol Based on Soft-switching Technology

    OpenAIRE

    Ya-qin Fan; Kai-bo Zhang; Chao Sun

    2010-01-01

    This article makes a comparison through the TRIP agreement in different soft switching network, we find that the TRIP protocol in the improved network performs better than the old, and the performance of the network topology changes very sensitive, it fully describes that the TRIP agreement mechanism is adapt to the improved soft-switching networks, it is so necessary to improve the original soft-switching network that it can better adapt to changes in network topology, achieve the separation...

  15. Fuel cladding integrity analysis during beam trip transients for China lead-based demonstration reactor

    International Nuclear Information System (INIS)

    Highlights: • Beam trip effect on Accelerator Driven sub-critical System (ADS) is remained a critical issue on ADS reactor technology. • The CFD model of fuel pin of China Lead-based Demonstration Reactor (CLEAR-III) was established. • The thermal hydraulic behaviors of fuel pin during beam trip transient of CLEAR-III were studied. • The thermal stress variation of fuel cladding during beam trip transient of CLEAR-III was evaluated. • Results reveal that beam trip effect on fuel cladding is so small that can be neglected. - Abstract: Frequent beam trips as experienced in the existing high-power proton accelerators may cause thermal fatigue in Accelerator-Driven System (ADS) components, which may lead to degradation of their structural integrity and reduction of their lifetime. In this paper, we focus on the strength and integrity of fuel cladding during the beam trip transients of China Lead-based Demonstration Reactor (CLEAR-III). Typical frequent beam trips and fuel burn-up are addressed to investigate the acceptable beam trip frequency limitation. Correspondingly, the variation magnitude of temperature and thermal stress of fuel cladding are simulated by ANSYS code. Besides, the behavior of cladding material T91 under irradiation, creep and Lead Bismuth Eutectic (LBE) corrosion conditions has been discussed. It shows that beam trips have little influence on the cladding integrity and the acceptable beam trip frequency of the fuel cladding within 10 s of the beam trip time duration is more than 2.5 × 105 times per year, consequently the CLEAR-III’s fuel claddings are expected to have a good resistance to the thermal–mechanical effects induced by beam trips

  16. A data mining approach for trip time prediction in mass transit companies

    OpenAIRE

    Moreira, João M., 1964-; Alípio Jorge; Jorge Freire Sousa; Carlos Soares

    2005-01-01

    In this paper we discuss how trip time prediction can beuseful for operational optimization in mass transit companies and howdata mining techniques can be used to improve results. Firstly, we an-alyze which departments need trip time prediction and when. Secondly,we review related work and thirdly we present the analysis of trip timeover a particular path. We proceed by presenting experimental resultsconducted on real data with the forecasting techniques we found mostadequate, and conclude by...

  17. Numerical Prediction on the Thermal Interrupting Capability of HV SF6 Gas Circuit Breakers%Numerical Prediction on the Thermal Interrupting Capability of HV SF6Gas Circuit Breakers

    Institute of Scientific and Technical Information of China (English)

    MU Jingwei; GUO Jin; DENG Xiang'e

    2013-01-01

    The design technology for HV SF6 gas circuit breakers is very demanding.A numerical method for prediction of the thermal interruption capability of SF6 gas circuit breakers is established based on the two-dimensional magneto-hydrodynamic (MHD) model and a commercial CFD(computational fluid dynamics) software,FLUENT.Nozzle ablation effect is considered by introducing an independent mass conservation equation for the ablated material to the overall conservation equations of mass,momentum,and energy.The ohmic heating and the radiation of the electric arc are considered in the model by adding relevant source terms.To predict the thermal interruption capability,the arc conductance 200 ns before current zero is used as an indicator.The CFD model is applied for the high current arcing phase,and Mayr arc model is used near the current zero period.The arc conductance at 200 ns before current zero(G200) for various arcing periods are computed by the present method.It shows that there exist a limit of the G200.For those whose arcing periods are within the arcing window,the related G200 are below the limit,therefore result a successful current interruption,and vice versa.The validation of the developed computer simulation tool is therefore verified.The numerical prediction by the simulation tool is verified by the direct interrupting test of 550 kV gas circuit breaker (GCB).The developed computer simulation tool was applied in the design of a 550 kV GCB.Significant benefits have been achieved in terms of both the cost saving and shorten of the development cycle.

  18. Teachers as Secondary Players: Involvement in Field Trips to Natural Environments

    Science.gov (United States)

    Alon, Nirit Lavie; Tal, Tali

    2016-07-01

    This study focused on field trips to natural environments where the teacher plays a secondary role alongside a professional guide. We investigated teachers' and field trip guides' views of the teacher's role, the teacher's actual function on the field trip, and the relationship between them. We observed field trips, interviewed teachers and guides, and administered questionnaires. We found different levels of teacher involvement, ranging from mainly supervising and giving technical help, to high involvement especially in the cognitive domain and sometimes in the social domain. Analysis of students' self-reported outcomes showed that the more students believe their teachers are involved, the higher the self-reported learning outcomes.

  19. Effect of Aluminum and Silicon on Transformation Induced Plasticity of the TRIP Steel

    Institute of Scientific and Technical Information of China (English)

    Lin LI; B.C. De Cooman; P. Wollants; Yanlin HE; Xiaodong ZHOU

    2004-01-01

    With the sublattice model, equilibrium compositions of ferrite (α) and austenite (γ) phases, as well as the volume percent of austenite (γ) at 780℃ in different TRIP steels were calculated. Concentration profiles of carbon, Mn, Al and Si in the steels were also estimated under the lattice fixed frame of reference so as to understand the complex mechanical behavior of TRIP steels after different isothermal bainitic transformation treatments. The effect of Si and Mn on transformation induced plasticity (TRIP) was discussed according to thermodynamic and kinetic analyses. It is recognized that Al also induces phase transformation in the steels but its TRIP effect is not as strong as that of Si.

  20. The E3 ubiquitin ligase activity of Trip12 is essential for mouse embryogenesis.

    Directory of Open Access Journals (Sweden)

    Masashi Kajiro

    Full Text Available Protein ubiquitination is a post-translational protein modification that regulates many biological conditions. Trip12 is a HECT-type E3 ubiquitin ligase that ubiquitinates ARF and APP-BP1. However, the significance of Trip12 in vivo is largely unknown. Here we show that the ubiquitin ligase activity of Trip12 is indispensable for mouse embryogenesis. A homozygous mutation in Trip12 (Trip12(mt/mt that disrupts the ubiquitin ligase activity resulted in embryonic lethality in the middle stage of development. Trip12(mt/mt embryos exhibited growth arrest and increased expression of the negative cell cycle regulator p16. In contrast, Trip12(mt/mt ES cells were viable. They had decreased proliferation, but maintained both the undifferentiated state and the ability to differentiate. Trip12(mt/mt ES cells had increased levels of the BAF57 protein (a component of the SWI/SNF chromatin remodeling complex and altered gene expression patterns. These data suggest that Trip12 is involved in global gene expression and plays an important role in mouse development.

  1. Numerical and experimental investigation of the TRIP strain

    International Nuclear Information System (INIS)

    In the first part a comprehensive experimental program is presented involving differential thermo-analyses (DTA) as well as dilatation tests under various non-proportional mechanical as well as thermal loading paths with the objective to measure the additional inelastic strain contribution due to transformation induced plasticity (TRIP). A maraging steel exhibiting complete martensitic transformation in a temperature interval ranging from around 150 oC down to about 70 oC is chosen as an appropriate testing material, since its comparatively low martensite start temperature (MS) facilitates measuring and precludes undesirable creep effects. A concept on how to isolate the TRIP strain contribution from the overall strain monitored by the multiaxial testing device is discussed. Particular attention is paid to the evolution of the martensite fraction during transformation and its dependence on the type and the magnitude of the applied mechanical load. The second part deals with the numerical simulation of the thermo-mechanical material behavior using an elastic predictor - radial return algorithm based on the underlying thermodynamic principles as the starting point. A user supplied subroutine has been developed that provides a commercial finite element solver with the proper material response to a given strain increment. The behavior of a three dimensional unit cell consisting of a regular array of cubic elements, each representing a single, arbitrarily oriented grain of a polycrystal is investigated. The good agreement of the numerical results with the experimental data backs the notion of a transformation related backstress is proposed. Refs. 3 (author)

  2. Transforming the radiological interpretation process: the SCAR TRIP initiative

    Science.gov (United States)

    Andriole, Katherine P.; Morin, Richard L.; Arenson, Ronald L.; Carrino, John A.; Erickson, Bradley J.; Horii, Steven C.; Piraino, David W.; Reiner, Bruce I.; Seibert, James A.; Siegel, Eliot L.

    2004-04-01

    The Society for Computer Applications in Radiology (SCAR) Transforming the Radiological Interpretation Process (TRIP) Initiative aims to spearhead research, education, and discovery of innovative solutions to address the problem of information and image data overload. The initiative will foster inter-disciplinary research on technological, environmental and human factors to better manage and exploit the massive amounts of data. TRIP will focus on the following basic objectives: improving the efficiency of interpretation of large data sets, improving the timeliness and effectiveness of communication, and decreasing medical errors. The ultimate goal of the initiative is to improve the quality and safety of patient care. Interdisciplinary research into several broad areas will be necessary to make progress in managing the ever-increasing volume of data. The six concepts involved include: human perception, image processing and computer-aided detection (CAD), visualization, navigation and usability, databases and integration, and evaluation and validation of methods and performance. The result of this transformation will affect several key processes in radiology, including image interpretation; communication of imaging results; workflow and efficiency within the health care enterprise; diagnostic accuracy and a reduction in medical errors; and, ultimately, the overall quality of care.

  3. Effective Lesson Planning: Field Trips in the Science Curriculum

    Science.gov (United States)

    Rieger, C. R.

    2010-10-01

    Science field trips can positively impact and motivate students. However, if a field trip is not executed properly, with appropriate preparation and follow-up reinforcement, it can result in a loss of valuable educational time and promote misconceptions in the students. This study was undertaken to determine if a classroom lesson before an out-of-the-classroom activity would affect learner gain more or less than a lesson after the activity. The study was based on the immersive theater movie ``Earth's Wild Ride'' coupled with a teacher-led Power Point lesson. The participants in the study were students in a sixth grade physical science class. The order of lessons showed no detectable effect on final learner outcomes. Based on pre- and post-testing, improvement in mean learning gain came from the teacher-led lesson independent of the movie. The visit to the immersive theater, however, had significant positive effects that did not show up in the quantitative results of the testing.

  4. Sensitivity of Peach Bottom turbine trip test calculations using RETRAN

    International Nuclear Information System (INIS)

    Fast acting power increase transients are required to test the one-dimensional reactor kinetics used in RETRAN. In addition, methods used to model the steam separator, down comer, steam lines and feedback from turbine control valves, feedwater and recirculation flow control can be tested using the Peach Bottom benchmarks. Gulf States Utilities (GSU) performed simulations of the three Peach Bottom turbine trip tests. These calculations were performed using RETRAN02/MOD4, with kinetics data generated by the GSU's CASMO1/SIMULATE-E/SIMTRAN models. The Peach Bottom tests were held at low power conditions for which reactor vessel pressure and enthalpy distribution data was unavailable. During the computer program benchmark process, it was found that the results showed a large sensitivity to the reactor conditions used to initialize RETRAN. Many other sensitivities were observed such as turbine trip induced pressure wave impact on overall results. Timing and magnitude of the pressure waves were found to be affected by the use of equilibrium or non-equilibrium models, by distribution of separator inertia and by distribution of pressure losses through core and separators. The timing and magnitude of these pressure waves has a significant effect on the peak power and heat flux

  5. Obtaining a TRIP microstructure by thermomechanical treatment without isothermal holding

    Science.gov (United States)

    Masek, B.; Jirkova, H.; Kucerova, L.; F-X Wagner, M.

    2016-03-01

    The contemporary development of technological processes for the production of modern multiphase steels can be characterized by the need for precise control of their technological parameters. The design of modern technological processes that allow sophisticated microstructures to be obtained usually cannot be carried out on real production equipment for technical as well as economical reasons. Therefore, new processes and test devices are continuously being developed to make it possible to simulate and model thermomechanical treatments on small specimens with precise control and monitoring of process parameters. A simulator for experimental modelling of thermomechanical processes has been developed at the University of West Bohemia. In this paper, to demonstrate the feasibility of simulating thermomechanical treatments with this setup on a lab scale, we discuss the thermomechanical treatment of TRIP steels without isothermal holding - a processing route that is difficult to handle and thus poses several technological as well as economic problems. The realistic processing of wire rolling with different cooling strategies is tested on the TRIP CMnSiNb steel. Our results show that the processing route without isothermal holding allows to obtain multiphase microstructures with a tensile strength of up to 835 MPa and a ductility A5mm = 25%.

  6. C16, a novel advanced glycation endproduct breaker, restores cardiovascular dysfunction in experimental diabetic rats

    Institute of Scientific and Technical Information of China (English)

    Gang CHENG; Li-li WANG; Wen-sheng QU; Long LONG; Hao CUI; Hong-ying LIU; Ying-lin CAO; Song LI

    2005-01-01

    Aim: Advanced glycation endproducts (AGE) have been implicated in the pathogenesis of diabetic complications, including diabetic cardiovascular dysfunction.3-[2-(4-Bromo-phenyl)- 1-methyl-2-oxo-ethyl]-4,5,6,7-tetrahydro-benzothiazol-3-ium bromide (C16), a novel AGE breaker, was investigated for its effects on the development of cardiovascular disease in diabetic rats. Methods: Rats that had streptozotocin-induced diabetes for 12 weeks were divided into groups receiving C16 or vehicle by gavage. Results: In hemodynamic studies of the left ventricle,C16 treatment (25 or 50 mg/kg) for 4 weeks resulted in a significant increase in left ventricular systolic pressure, +dp/dtmax, and -dp/dtmax as compared with vehicletreated diabetic rats. Furthermore, in hemodynamic studies of the cardiovascular system, C16 (12.5, 25, or 50 mg/kg) treatment for 4 weeks resulted in a dosedependent and significant increase in cardiac output, a reduction of total peripheral resistance, and an increase in systemic arterial compliance when compared with vehicle-treated diabetic rats. Biochemical studies showed that C16 treatment also resulted in a significant decrease in immunoglobulin G-red blood cell surface crosslink content and an increase in collagen solubility. Morphological and immunohistochemical examinations indicated that C 16 was able to prevent increases of the collagen type Ⅲ/Ⅰ ratio in the aorta and decrease the accumulation of AGE in the aorta. Conclusion: C16 has the ability to reduce AGE accumulation in tissues in vivo, and can restore diabetes-associated cardiovascular disorders in rats. This provides a potential therapeutic approach for cardiovascular disease associated with diabetes and aging in humans.

  7. Simulation of the Process of Arc Energy-Effect in High Voltage Auto-Expansion SF6 Circuit Breaker

    Institute of Scientific and Technical Information of China (English)

    Rong Mingzhe; Yang Qian; Fan Chunduo

    2005-01-01

    A new magnetic hydro-dynamics (MHD) model of arc in H.V. auto-expansion SF6circuit breaker that takes into consideration nozzle ablation due to both radiation and thermal conduction is presented in this paper. The effect of PTFE (polytetrafluorethylene) vapor is considered in the mass, momentum and energy conservation equations of the constructed model. Then,the gas flow fields with and without conduction considered are simulated. By comparing the aforementioned two results, it is indicated that the arc's maximal temperature with conduction considered is 90 percent of that without considering conduction.

  8. The Media as an Image Maker/Breaker: The Case of Tina Modotti and Its Literary Representation

    OpenAIRE

    Alvarez, Araceli

    2000-01-01

    The Media as an Image Maker/Breaker: The Case of Tina Modotti and Its Literary Representation Araceli Alvarez (ABSTRACT) This thesis examines the role the media played in shaping Tina Modotti's public image during the 1920s in Mexico and the representation of this image in the novel Tinísima by Elena Poniatowska. In Chapter I, the present study tackles also the issues behind the press attitude in relation to the Mexican political situation and the communist influence during t...

  9. Field Experiments on 10 kV Switching Shunt Capacitor Banks Using Ordinary and Phase-Controlled Vacuum Circuit Breakers

    OpenAIRE

    Wenxia Sima; Mi Zou; Qing Yang; Ming Yang; Licheng Li

    2016-01-01

    During the switching on/off of shunt capacitor banks in substations, vacuum circuit breakers (VCBs) are required to switch off or to switch on the capacitive current. Therefore, the VCBs have to be operated under a harsh condition to ensure the reliability of the equipment. This study presents a complete comparison study of ordinary and phase-controlled VCBs on switching 10 kV shunt capacitor banks. An analytical analysis for switching 10 kV shunt capacitor banks is presented on the basis of ...

  10. Power ion beam production in a magnetic-insulated diode placed in a circuit with an inductive storage with a plasmoerosion circuit breaker

    International Nuclear Information System (INIS)

    Consideration is given to results of experimental studies of modes of operation of plasma current breaker and magnetic insulated diode, placed parallel in a circuit with inductive storage and microsecond generator, as well as parameters of high-power ion beam, generated in gas-filled diode. Magnetic field of mirror configuration, which enabled to locate the gas-filled diode dose to breaking region was used for decrease of electrodynamic plasma transfer. It is shown that time delay (of the order of ten and more) of power maximum in gas-filled diode with respect to power maximum in plasma breaker is observed when using passive plasma source on anode

  11. 6.9-kV, 63-kA metal-clad switchgear with vacuum circuit breakers for nuclear power plants

    International Nuclear Information System (INIS)

    Based on data of a series of in-house tests made so far and on performance in the field, Toshiba Corporation has developed a metal-clad switchgear with vacuum circuit breakers for nuclear power plants. Metal-clad switchgear for nuclear power plants are required to have high reliability and large capacities. This paper describes results of a series of reliability tests made on the vacuum circuit breaker and resistance to earthquakes of the metal-clad switchgear required for use in a nuclear power plant. 4 refs

  12. Diagnosis technique for the detection of mechanical faults in power breakers; Tecnica de diagnostico para la deteccion de fallas mecanicas en interruptores de potencia

    Energy Technology Data Exchange (ETDEWEB)

    Linan, Roberto; Perez, Marciano; Estrada, J. Manuel [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1996-12-31

    This article reports a non-invasive diagnosis technique for the detection of mechanical faults in power breakers, supporting it with the recording and analysis of vibration signals of the equipment under test. Also, an assessment of four breakers using this technique is presented. [Espanol] En el presente articulo se reporta una tecnica de diagnostico no invasiva para detectar fallas mecanicas en interruptores de potencia, apoyandose en el registro y analisis de senales de vibracion del equipo bajo prueba. Asimismo, se presenta la evaluacion de cuatro interruptores usando esta tecnica.

  13. Summary of CIGRE 13.06 Working Group world wide reliability data and maintenence cost data on high voltage circuit breakers above 63 kV

    Energy Technology Data Exchange (ETDEWEB)

    Colombo, E.; Dialynas, E.; Heising, C.; Janssen, A.; Lanz, W.

    1995-06-01

    A summary is given of the most significant reliability data and maintenance cost data from the two CIGRE 13.06 Working Group world wide reliability surveys of the reliabilityof high voltage circuit breakers 63 kV and above. The first enquiry covered the years 1974 thru 1977 and included all interrupting technologies. The second enquiry covered the years 1988 thru 1991 and only included single pressure SF6 breakers. A description is given of the scope and objectives of the CIGRE 13.06 Working Group. A brief description is given of some of the highlights from their studies.

  14. Fatigue strength of TRIP-aided bainitic sheet steels; TRIP gata beinaito gohan no hiro kyodo tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Sugimoto, K.; Kobayashi, M.; Inoue, K.; Sun, X. [Shinshu Univ., Nagano (Japan). Faculty of Education] Soshiroda, T. [Kobe Steel Ltd. (Japan)

    1998-08-01

    Fatigue strength and crack initiation-propagation behavior of TRIP-aided bainitic sheet steels which are associated with the transformation-induced plasticity (TRIP) of retained austenite were investigated for the automotive applications. The steels composing of bainitic ferrite lath matrix and the retained austenite films completed the highest fatigue limit of several high-strength dual-phase type and bainitic type of steels. The threshold value of the stress intensity factor range ({Delta}K{sub th}) was lower than those of the other dual-phase type of steels, although the crack propagation rate at a high stress intensity factor range agreed well with those of the other steels. It was concluded that the retained austenite films suppressed a micro-crack initiation and propagation in the matrix and a long crack propagation due to (stress relaxation) and (block effect) resulting from the strain-induced transformation, because the mean interfilm space of retained austenite is smaller than a plastic zone of crack tip. 18 refs., 9 figs., 2 tabs.

  15. Influence of original microstructure on the transformation behavior and mechanical properties of ultra-high-strength TRIP-aided steel

    Science.gov (United States)

    Yin, Hong-xiang; Zhao, Ai-min; Zhao, Zheng-zhi; Li, Xiao; Li, Shuang-jiao; Hu, Han-jiang; Xia, Wei-guang

    2015-03-01

    The transformation behavior and tensile properties of an ultra-high-strength transformation-induced plasticity (TRIP) steel (0.2C-2.0Si-1.8Mn) were investigated by different heat treatments for automobile applications. The results show that F-TRIP steel, a traditional TRIP steel containing as-cold-rolled ferrite and pearlite as the original microstructure, consists of equiaxed grains of intercritical ferrite surrounded by discrete particles of M/RA and B. In contrast, M-TRIP steel, a modified TRIP-aided steel with martensite as the original microstructure, containing full martensite as the original microstructure is comprised of lath-shaped grains of ferrite separated by lath-shaped martensite/retained austenite and bainite. Most of the austenite in F-TRIP steel is granular, while the austenite in M-TRIP steel is lath-shaped. The volume fraction of the retained austenite as well as its carbon content is lower in F-TRIP steel than in M-TRIP steel, and austenite grains in M-TRIP steel are much finer than those in F-TRIP steel. Therefore, M-TRIP steel was concluded to have a higher austenite stability, resulting in a lower transformation rate and consequently contributing to a higher elongation compared to F-TRIP steel. Work hardening behavior is also discussed for both types of steel.

  16. 14 CFR 372.25 - Tariffs to be filed for charter trips.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Tariffs to be filed for charter trips. 372... § 372.25 Tariffs to be filed for charter trips. Effective October 1, 1972, a charter operator shall not... on file with the Department a currently effective tariff showing all rates, fares, and charges...

  17. Forest Field Trips among High School Science Teachers in the Southern Piedmont

    Science.gov (United States)

    McCabe, Shannon M.; Munsell, John F.; Seiler, John R.

    2014-01-01

    Students benefit in many ways by taking field trips to forests. Improved academic performance, increased participation in outdoor recreation, and a better grasp of natural resources management are some of the advantages. However, trips are not easy for teachers to organize and lead. Declining budgets, on-campus schedules, and standards of learning…

  18. Study Abroad Field Trip Improves Test Performance through Engagement and New Social Networks

    Science.gov (United States)

    Houser, Chris; Brannstrom, Christian; Quiring, Steven M.; Lemmons, Kelly K.

    2011-01-01

    Although study abroad trips provide an opportunity for affective and cognitive learning, it is largely assumed that they improve learning outcomes. The purpose of this study is to determine whether a study abroad field trip improved cognitive learning by comparing test performance between the study abroad participants (n = 20) and their peers who…

  19. Anything Can Happen out There: A Holistic Approach to Field Trips

    Science.gov (United States)

    Plutino, Alessia

    2016-01-01

    This paper looks back at an academic-led language field trip project, now in its third year, involving ab-initio students of Italian at the University of Southampton. It considers the role of academic-led field trips in Modern Languages (ML) and it explores the underlying pedagogical approaches that were adopted to enhance students' engagement,…

  20. 49 CFR 236.560 - Contact element, mechanical trip type; location with respect to rail.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Contact element, mechanical trip type; location with respect to rail. 236.560 Section 236.560 Transportation Other Regulations Relating to... Instructions; Locomotives § 236.560 Contact element, mechanical trip type; location with respect to...

  1. 50 CFR 660.332 - Open access daily trip limit (DTL) fishery for sablefish.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Open access daily trip limit (DTL) fishery... COAST STATES West Coast Groundfish-Open Access Fisheries § 660.332 Open access daily trip limit (DTL) fishery for sablefish. (a) Open access DTL fisheries both north and south of 36° N. lat. Open...

  2. Modelling mode choice in short trips - shifting from car to bicycle

    DEFF Research Database (Denmark)

    Halldórsdóttir, Katrín; Christensen, Linda; Jensen, Thomas Christian;

    2011-01-01

    relevance of the cost for short trips. Expectedly, the selection of bicycle as mode for short trips is positively related to owning a bicycle and negatively linked to owning one or more cars. Urban density has also positive correlation with the selection of sustainable transport modes....

  3. Testing of the TriP Chip Running at 132 nsec Using a Modified AFE Board

    International Nuclear Information System (INIS)

    In this note we describe the first set of tests done with a sample of TriP chips that were mounted on a modified AFE board. The modifications consisted of different firmware and the replacement of one power supply switch. The board used was a standard AFEIc board (red type) on which new MCMs (MCMIIs) were mounted. The new MCMs were designed to support the TriP and emulate the SVX for readout when mounted on an AFEIc board. The TriP and the MCMs are described in Ref. [1]. Two versions of the MCMII were designed and built: one (MCMIIb) supports two TriP chips wirebonded directly to the MCM substrate. The other, (MCMIIc) supports one TriP which can be either wirebonded directly or packaged into a standard TQFP surface mount package. Due to space constraints, this MCM can support only 1 TriP. We tested 6 TriP chips on 3 different MCMIIb (MCMIIb-1, MCMIIb-2 and MCMIIb-3) and 2 other TriPs were tested on MCMIIc, one of them with an unpackaged TriP (MCMIIc-1) and the other with a packaged TriP (MCMIIc-2). A set of 10 programable internal registers control the TriP operation, the description of these registers can be found in [1]. Table 1 shows the values used for the tests described in this note. In Ref. [1] there is a description of the signals that are needed to operate the TriP chip. We implemented in a Field Programable Gate Array (FPGA), also part of the MCM, a set of shift registers that allow us to download via the 1553 interface to the AFE board, any desired timing for the signals that the FPGA has to send to the TriP chip. These registers are run with a 121.21 MHz clock (which is 16x the crossing clock and phase locked to it), which means that each bit corresponds to a time interval of 8.25 nsec. Finer control of timing is possible, but this changing the programing of the FPGA and recompiling. The bits downloaded to these shift registers inside the TriP are listed in Table 2

  4. Multiple Objects Tracking Using CAMShift Algorithm and Implementation of Trip Wire

    Directory of Open Access Journals (Sweden)

    Shirish Halbe

    2013-05-01

    Full Text Available In this paper we represent Security application which is developed using concepts of Video Analytics. User can draw Trip wire on video stream with help of Mouse Callback events. Using this application user can restrict any area of total video scene. Direction selection for tripping is also a choice of a user. If any undesired moving object cross this drawn trip wire then motion of this moving object is getting detected and also tracked. If object crosses trip wire in the same direction as that of user selected then Alarm Indication will appear on that moving object. OpenCV library functions are used for motion detection and motion tracking. CAMShift algorithm is implemented for tracking. An experimental result shows Motion detection, Motion Tracking and drawn trip wire on video.

  5. An integrative conceptual framework for analyzing customer satisfaction with shopping trip experiences in grocery retailing

    DEFF Research Database (Denmark)

    Esbjerg, Lars; Jensen, Birger Boutrup; Bech-Larsen, Tino;

    2012-01-01

    Grocery retailers aim to satisfy customers, and because grocery shopping trips are frequently recurring, they must do socontinuously. Surprisingly, little research has addressed satisfaction with individual grocery shopping trips. This article therefore develops a conceptual framework for analyzing...... customer satisfaction with individual grocery shopping trip experiences within a overall ‘disconfirmation of expectations model’ of customer satisfaction. The contribution of the framework is twofold. First, by focusing on satisfaction with individual grocery shopping trips, previous research on...... satisfaction is extended to a context marked by frequently recurring, often tedious and routine activities. Understanding what causes satisfaction/dissatisfaction with individual shopping trips is required to explain overall, cumulative satisfaction with a retailer, which has been the focus of prior research...

  6. Highly Scalable Trip Grouping for Large Scale Collective Transportation Systems

    DEFF Research Database (Denmark)

    Gidofalvi, Gyozo; Pedersen, Torben Bach; Risch, Tore;

    2008-01-01

    techniques and support input rates that can be orders of magnitude larger. The following three contributions make the grouping algorithms scalable. First, the basic grouping algorithm is expressed as a continuous stream query in a data stream management system to allow for a very large flow of requests......Transportation-related problems, like road congestion, parking, and pollution, are increasing in most cities. In order to reduce traffic, recent work has proposed methods for vehicle sharing, for example for sharing cabs by grouping "closeby" cab requests and thus minimizing transportation cost and...... utilizing cab space. However, the methods published so far do not scale to large data volumes, which is necessary to facilitate large-scale collective transportation systems, e.g., ride-sharing systems for large cities. This paper presents highly scalable trip grouping algorithms, which generalize previous...

  7. Microprocessor tester for the treat upgrade reactor trip system

    International Nuclear Information System (INIS)

    The upgrading of the Transient Reactor Test (TREAT) Facility at ANL-Idaho has been designed to provide additional experimental capabilities for the study of core disruptive accident (CDA) phenomena. In addition, a programmable Automated Reactor Control System (ARCS) will permit high-power transients up to 11,000 MW having a controlled reactor period of from 15 to 0.1 sec. These modifications to the core neutronics will improve simulation of LMFBR accident conditions. Finally, a sophisticated, multiply-redundant safety system, the Reactor Trip System (RTS), will provide safe operation for both steady state and transient production operating modes. To insure that this complex safety system is functioning properly, a Dedicated Microprocessor Tester (DMT) has been implemented to perform a thorough checkout of the RTS prior to all TREAT operations

  8. Vehicle Routing Problem with Backhaul, Multiple Trips and Time Window

    Directory of Open Access Journals (Sweden)

    Johan Oscar Ong

    2011-01-01

    Full Text Available Transportation planning is one of the important components to increase efficiency and effectiveness in the supply chain system. Good planning will give a saving in total cost of the supply chain. This paper develops the new VRP variants’, VRP with backhauls, multiple trips, and time window (VRPBMTTW along with its problem solving techniques by using Ant Colony Optimization (ACO and Sequential Insertion as initial solution algorithm. ACO is modified by adding the decoding process in order to determine the number of vehicles, total duration time, and range of duration time regardless of checking capacity constraint and time window. This algorithm is tested by using set of random data and verified as well as analyzed its parameter changing’s. The computational results for hypothetical data with 50% backhaul and mix time windows are reported.

  9. How travellers’ schedule their trips under uncertain travel times

    DEFF Research Database (Denmark)

    Hjorth, Katrine

    Travel times play an important role when people decide where, when and how much to travel. But travel times are not always predictable from the traveller’s point of view: They may vary from day to day due to demand fluctuations, weather conditions, accidents and other unforeseen events that cause...... road capacity to decrease. We refer to this uncertainty as travel time variability (TTV). TTV is likely to affect how travellers schedule their trips, since it affects their probability of arriving late at their destination. We would like to account for TTV in traffic models and cost-benefit analyses......, but in practice there are limits to the kinds of behaviour that can be accommodated in such applications. For that reason, we are not solely interested in explaining travellers’ behaviour, but also in whether this behaviour can be approximated by behavioural models that are simple enough to be applied...

  10. Microstructure Evolution during Friction Stir Spot Welding of TRIP Steel

    DEFF Research Database (Denmark)

    Lomholt, Trine Colding; Pantleon, Karen; Somers, Marcel A. J.

    2010-01-01

    In this study, the feasibility of friction stir spot welding of TRIP steel is investigated. In addition to manufacturing successful welds, the present study aims at a fundamental understanding of the mechanisms occurring at the (sub)micron scale during friction stir spot welding. As one of the main...... parameters to control friction stir welding, the influence of the rotational speed of the tool was investigated. Three different rotational speeds (500 rpm, 1000 rpm and 1500 rpm, respectively) were applied. The microstructure of the welded samples was investigated with reflected light microscopy, scanning...... electron microscopy, and electron backscatter diffraction. Microhardness measurements and lap-shear tensile tests completed the investigations of the welded samples and allow evaluation of the quality of the welds....

  11. Primary circulating pump trip transient analysis for 500 MWe PHWR

    International Nuclear Information System (INIS)

    The 500 MWe Indian pressurised heavy water (PHWR) incorporates many new features as compared to the earlier 220 MWe PHWRs. To evaluate the new design features like primary heat transport (PHT) system configuration with two loops, four primary circulating pumps (PCPs) and four passes through core, addition of a pressuriser (surge tank) in the PHT system along with feed/bleed system and their safety related implications, simulation model development and transient analysis studies are necessary. The paper deals with the details of the mathematical model for PHT system and parametric study on one PCP trip transient analysis with set/step back. The studies were carried out after including the proposed new SGPC program similar to 220 MWe PHWR, which gives a 48 kg/cm2 maximum SG pressure setpoint at zero power, without changing the 100% power set pressure

  12. Development of INSTEC(INformation System of Trip Event Cases)

    International Nuclear Information System (INIS)

    In this research, we established an incident analysis procedure based on the concept of interaction between plant components and developed INSTEC(INformation System of Trip Event Cases) which can manage data obtained as the result of incident analysis. The analysis procedure is consisted of the following steps; reconfiguration of incident context, identification of the paths and contents of the interaction between plant components, identification of unit event obstructing normal plant operation, identification of possible erroneous actions, decision of error modes, identification of likely causes, summarization of analysis results. INSTEC was developed to effectively present the result of incident analysis. This system offers the analyzed information such as analysis results of human error cases, operating issues and problems, recommendations to prevent a similar incident, etc. 24 tabs., 18 figs., 10 refs. (Author)

  13. Impact of radial external magnetic field on plasma deformation during contact opening in SF6 circuit breakers

    Science.gov (United States)

    Abbasi, V.; Gholami, A.; Niayesh, K.

    2012-10-01

    A three-dimensional (3D) transient model is developed to investigate plasma current deformation driven by internal and external magnetic fields and their influences on arc stability in a circuit breaker. The 3D distribution of electric current density is obtained by solving the current continuity equation along with the generalized Ohm's law in the presence of an external magnetic field, while the magnetic field induced by the current flowing through the arc column is calculated by the magnetic vector potential equation. The applied external field imposes a rotational electromagnetic force on the arc and influences the plasma current deformation, which is discussed in this paper. In SF6 circuit breakers when gas interacts with the arc column, the fundamental equations such as Ampere's law, Ohm's law, turbulence model, transport equations of mass, momentum, and energy of plasma flow have to be coupled for analysing the phenomenon. The coupled interactions between the arc and the plasma flow are described within the framework of magnetohydrodynamic equations in conjunction with a K-ɛ turbulence model. Simulations are focused on sausage and kink instabilities in the plasma (these phenomena are related to the electromagnetic field distribution and define the plasma deformations). The 3D simulation reveals the relation between plasma current deformation and instability phenomena, which affects the arc stability during the operation. Plasma current deformation is a consequence of coupling between electromagnetic forces (resulting from internal and radial external magnetic fields) and the plasma flow that are described in the simulations.

  14. A comparative study of arc behaviour in an auto-expansion circuit breaker with different arc durations

    International Nuclear Information System (INIS)

    A computational study of the thermal interruption performance of a 145 kV, 60 Hz auto-expansion circuit breaker has been carried out. The pressure peak in the expansion volume has a delay of 2.8–3.4 ms with reference to the current peak when the arc duration varies. A reasonable indicator of the interruption environment is the average mass flux in the main nozzle. The short arc duration case (12.25 ms) is the most difficult case with the lowest critical rate of rise of recovery voltage (RRRV) of 10 kV µs−1, just above the initial system applied RRRV of 9 kV µs−1. This is a result of an insufficient gas flow cross sectional area between the live contact and the main nozzle to develop rapid gas flow for arc cooling. The auxiliary nozzle plays two roles. It provides blockage in the high current phase to reduce gas exhaustion from the main nozzle into the hollow contact; after current zero the hollow contact shares a considerable portion of the system recovery voltage, especially for the short arc duration case (36%). Therefore the proper design and use of an auxiliary nozzle is key to enhancing the thermal interruption capability of high voltage auto-expansion circuit breakers. (paper)

  15. Sheath expansion and plasma dynamics in the presence of electrode evaporation: Application to a vacuum circuit breaker

    International Nuclear Information System (INIS)

    During the postarc dielectric recovery phase in a vacuum circuit breaker, a cathode sheath forms and expels the plasma from the electrode gap. The success or failure of current breaking depends on how efficiently the plasma is expelled from the electrode gap. The sheath expansion in the postarc phase can be compared to sheath expansion in plasma immersion ion implantation except that collisions between charged particles and atoms generated by electrode evaporation may become important in a vacuum circuit breaker. In this paper, we show that electrode evaporation plays a significant role in the dynamics of the sheath expansion in this context not only because charged particle transport is no longer collisionless but also because the neutral flow due to evaporation and temperature gradients may push the plasma toward one of the electrodes. Using a hybrid model of the nonequilibrium postarc plasma and cathode sheath coupled with a direct simulation Monte Carlo method to describe collisions between heavy species, we present a parametric study of the sheath and plasma dynamics and of the time needed for the sheath to expel the plasma from the gap for different values of plasma density and electrode temperatures at the beginning of the postarc phase. This work constitutes a preliminary step toward understanding and quantifying the risk of current breaking failure of a vacuum arc.

  16. Impact of radial external magnetic field on plasma deformation during contact opening in SF6 circuit breakers

    International Nuclear Information System (INIS)

    A three-dimensional (3D) transient model is developed to investigate plasma current deformation driven by internal and external magnetic fields and their influences on arc stability in a circuit breaker. The 3D distribution of electric current density is obtained by solving the current continuity equation along with the generalized Ohm's law in the presence of an external magnetic field, while the magnetic field induced by the current flowing through the arc column is calculated by the magnetic vector potential equation. The applied external field imposes a rotational electromagnetic force on the arc and influences the plasma current deformation, which is discussed in this paper. In SF6 circuit breakers when gas interacts with the arc column, the fundamental equations such as Ampere's law, Ohm's law, turbulence model, transport equations of mass, momentum, and energy of plasma flow have to be coupled for analysing the phenomenon. The coupled interactions between the arc and the plasma flow are described within the framework of magnetohydrodynamic equations in conjunction with a K-ε turbulence model. Simulations are focused on sausage and kink instabilities in the plasma (these phenomena are related to the electromagnetic field distribution and define the plasma deformations). The 3D simulation reveals the relation between plasma current deformation and instability phenomena, which affects the arc stability during the operation. Plasma current deformation is a consequence of coupling between electromagnetic forces (resulting from internal and radial external magnetic fields) and the plasma flow that are described in the simulations.

  17. Approach for electrodynamic force for compensation in low voltage circuit breaker WP 630-1.2 type

    Institute of Scientific and Technical Information of China (English)

    LU Na; XU L.J.; Miedzi(n)ski B.

    2007-01-01

    Undesirable repulsive force between contact members due to both a current path shrink near a real contact area and/or so-called pinch effect is particularly onerous for power switch applications, and results in either contact floating or bouncing which are associated with an electric arc following contact welding. This problem is of great importance for any circuit breaker especially for compact low voltage vacuum circuit breakers. To avoid contact floating at closure and during any inrush current under short circuit conditions, the electrodynamic repulsive force can be employed successfully if we use a special compensation system flexibly combined with the contact itself. However to select and design the compensation system properly, its efficiency has to be known. This paper presents an approach to obtain the electrodynamic force value depending on different shaped (rectangular,square, circle and arch) copper plates used in the compensator by using ANSYS for current values 40 kA RMS. Curve-fitting was done according to the calculating results, the optimization designing of compensation unit is based on them.

  18. Resolvability in Circulant Graphs

    Institute of Scientific and Technical Information of China (English)

    Muhammad SALMAN; Imran JAVAID; Muhammad Anwar CHAUDHRY

    2012-01-01

    A set W of the vertices of a connected graph G is called a resolving set for G if for every two distinct vertices u,v ∈ V(G) there is a vertex w ∈ W such that d(u,w) ≠ d(v,w).A resolving set of minimum cardinality is called a metric basis for G and the number of vertices in a metric basis is called the metric dimension of G,denoted by dim(G).For a vertex u of G and a subset S of V(G),the distance between u and S is the number mins∈s d(u,s).A k-partition H ={S1,S2,...,Sk} of V(G) is called a resolving partition if for every two distinct vertices u,v ∈ V(G) there is a set Si in Π such that d(u,Si) ≠ d(v,Si).The minimum k for which there is a resolving k-partition of V(G) is called the partition dimension of G,denoted by pd(G).The circulant graph is a graph with vertex set Zn,an additive group ofintegers modulo n,and two vertices labeled i and j adjacent if and only if i - j (mod n) ∈ C,where C C Zn has the property that C =-C and 0(∈) C.The circulant graph is denoted by Xn,△ where A =|C|.In this paper,we study the metric dimension of a family of circulant graphs Xn,3 with connection set C ={1,-n/2,n - 1} and prove that dim(Xn,3) is independent of choice of n by showing that 3 for all n =0 (mod 4),dim(X,n,3) ={ 4 for all n =2 (mod 4).We also study the partition dimension of a family of circulant graphs Xn,4 with connection set C ={±1,±2} and prove that pd(Xn,4) is independent of choice of n and show that pd(X5,4) =5 and 3 forall odd n≥9,pd(Xn,4) ={ 4 for all even n ≥ 6 and n =7.

  19. Dual Brushless Resolver Rate Sensor

    Science.gov (United States)

    Howard, David E. (Inventor)

    1997-01-01

    A resolver rate sensor is disclosed in which dual brushless resolvers are mechanically coupled to the same output shaft. Diverse inputs are provided to each resolver by providing the first resolver with a DC input and the second resolver with an AC sinusoidal input. A trigonometric identity in which the sum of the squares of the sin and cosine components equal one is used to advantage in providing a sensor of increased accuracy. The first resolver may have a fixed or variable DC input to permit dynamic adjustment of resolver sensitivity thus permitting a wide range of coverage. In one embodiment of the invention the outputs of the first resolver are directly inputted into two separate multipliers and the outputs of the second resolver are inputted into the two separate multipliers, after being demodulated in a pair of demodulator circuits. The multiplied signals are then added in an adder circuit to provide a directional sensitive output. In another embodiment the outputs from the first resolver is modulated in separate modulator circuits and the output from the modulator circuits are used to excite the second resolver. The outputs from the second resolver are demodulated in separate demodulator circuit and added in an adder circuit to provide a direction sensitive rate output.

  20. The effect of an advanced glycation end-product crosslink breaker and exercise training on vascular function in older individuals: a randomized factorial design trial.

    NARCIS (Netherlands)

    Oudegeest-Sander, M.H.; Olde Rikkert, M.G.M.; Smits, P.; Thijssen, D.H.J.; Dijk, A.P.J. van; Levine, B.D.; Hopman, M.T.E.

    2013-01-01

    Aging leads to accumulation of irreversible advanced glycation end-products (AGEs), contributing to vascular stiffening and endothelial dysfunction. When combined with the AGE-crosslink breaker Alagebrium, exercise training reverses cardiovascular aging in experimental animals. This study is the fir