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1
Madhyastha, Sadhana. "Design of circuit breakers for large area CMOS VLSI circuits." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59551.
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Large-area ICs require adequate defect-tolerance to achieve a reasonable yield. One concern is that the power distribution network is shared by a number of modules, and any single short between the supply (V$ sb{dd}$) and ground can disable all these modules. The object of this thesis is to evaluate the feasibility of incorporating circuit breakers in large area ICs, which provide protection against such defects by disconnecting the defective modules from the array. A critical analysis and comparison of MOS transistors and parasitic bipolar transistors as circuit breakers are carried out. It is shown that MOS transistors offer a better and a more practical solution than their bipolar counterparts. Several rules applicable to a MOS circuit breaker in a bulk CMOS process are defined and discussed. These rules, if strictly adhered to, are predicted to result in a design which is defect-tolerant, latch-up free and optimal in size. The design of a large MOS transistor, based on the Manhattan style of "waffle-iron" design is described. Results of two test chips provide the experimental validation of this design. The peak instantaneous current through the modules has to be known in order to realize a circuit breaker of optimal size. A preliminary analysis of a possible technique to estimate the magnitude of this worst case peak current for a CMOS combinational block is carried out. Finally a short discussion on the defect sensitivity of the power switch is presented.
2
Fletcher, R. G. "Power semiconductor devices in A.C. circuit protection." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/7921.
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POUILLY, Julien. "Multi-physical Simulations of High Voltage Circuit Breakers." Thesis, KTH, Energiteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-210221.
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This report is the outcome of a 6-month Master’s Thesis carried out at General Electric Grid Solutions in Villeurbanne within the LTDT team in the Circuit Breaker and Bay Development (CB2D) department of the Apparatus Research Center (ARC). It presents both the innovative methodology adopted and the results obtained along the project. The Master’s Thesis deals with high voltage circuit breakers and is focused on one project, which will be called CB2 for confidentiality reasons. The aim of the project is to design a new circuit breaker, the CB2, based on an existing circuit breaker, with a cost reduction of 25% in order to adapt the device to the Indian market. To do so, numerical simulations on a software platform called MC3 were implemented. Simulations are indeed quicker and much cheaper than real tests. MC3 is a 2D axisymmetric solver, thus it is necessary to calculate 2D equivalent sections and volumes of the circuit breaker. The first step of the project is to calibrate the MC3 tool for the original device, called CB1. Before implementing the tests on MC3, a mechanical study is led in order to study both the wear and the velocities in these different tests. The conclusion of the study asserted that the velocities are lower than expected on almost all of the tests, however, the levels of wear are sometimes critical. The calibration –comparison of the overpressure in the thermal volume – is carried out based on one parameter, the FRAC (fraction of the radiative flux involved in the ablation process); each default and arcing time is thus tested with two FRAC values: 0.8 and 1.1. The first step was invalidated due to the high wear of the circuit breaker. FRAC 1.1 shows more accurate results than FRAC 0.8. However, the pressure differentials are lower in all MC3 calculations than in real tests, which may be due to the high wear and low velocities (reduced by 3 m/s) compared to the old device. Finally, some modifications of the CB1’s geometry are recommended based on different studies in order to improve the design of CB2. Those modifications will be tested on MC3 by the next interns at ARC.Denna rapport är resultatet av en sex-månaders examensarbete utförd vid General Electric Grid Solutions i Villeurbanne, Frankrike, inom LTDT laget av Circuit Breaker Bay Development (CB2D) avdelningen som ingår i Apparatus Research Center (ARC). Både den innovativa metoden som använts och de resultat som uppnåtts under arbetets gång presenteras härmed. Examensarbetet behandlar högspänningsbrytare och är inriktad på ett projekt som kommer att kallas för CB2 av sekretesskäl. Syftet med projektet är att utforma en ny brytare, CB2, baserad på den befintliga brytaren CB1 med en kostnadsminskning på 25% för att anpassa enheten till den indiska marknaden. För att göra detta, numeriska simuleringar av strömbrytarens interna termomekaniska processer har genomförts på en programvara som kallas för MC3. Simuleringar är faktiskt snabbare och mycket billigare än riktiga tester. MC3 använder sig av 2D-rotationssymmetriska beräkningar, därför är det nödvändigt att avspegla flertalet 2D avsnitt i motsvarande mängd för att simulera strömbrytaren. Det första steget i projektet är att kalibrera MC3 verktyget på den ursprungliga enheten, strömbrytaren CB1, med sina välbeprövade parametrar. Innan simuleringsprocessen för CB2 genomförs på MC3 har en mekanisk studie inletts för att studera både slitaget och hastigheterna i den nya enheten. Slutsatsen av studien tillstyrker att hastigheterna blir lägre än väntat på nästan alla drivrutiner, dock kan slitagenivåerna bli kritiska. Simulationsprocessen för CB2 – nämligen en jämförelse av övertrycket i den termiska volymen - genomförs baserat på en varierande parameter, FRAC (fraktion av strålningsflödet som påverkar slitaget genom ablationsprocessen); varje tidsberoende verkan inom enheten har beräknats med två FRAC värden: 0,8 och 1,1. Ett första steg ansågs ogiltigt på grund av den höga slitaget av effektbrytaren, således FRAC 1,1 visar mer exakta resultat än FRAC 0,8. Däremot är tryckökningen lägre i alla MC3 beräkningar än i verkliga tester, vilket kan bero på den det höga slitaget och den låga hastigheterna (som minskar med 3 m/s) jämfört med den ursprungliga strömbrytaren. Slutligen har några specifika ändringar på CB1:s geometri föreslagits för att bättre utforma CB2, baserat på olika studier. Dessa modifikationer kommer att simuleras igen på MC3 plattformen av nästföljande praktikanter vid ARC.
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Taft, William T. (William Theodore). "Z-source circuit breakers in naval power systems." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122611.
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Thesis: Nav. E., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2019
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 97-100).
New power system components and control systems are required to facilitate the U.S. Navy's move to medium voltage direct current power (MVDC) systems on future vessels. Integrating the z-source circuit breaker into a "typical" naval MVDC power system requires understanding system dynamics that may cause the circuit breaker to inadvertently energize a circuit through regenerative turn-on of the thyristor. An electrically-scaled model and a simulation model are used to characterize voltage transients that could lead to this false triggering. The results of this experiment show that these transients are within the specifications of commercially available components. Limitations in the circuit breaker's protective capabilities during turn-on transients are identified and discussed. Potential topology modifications, control schemes, and power system arrangements that provide protection across the operating range are proposed for further investigation.
by William T. Taft.
Nav. E.
S.M.
Nav.E. Massachusetts Institute of Technology, Department of Mechanical Engineering
S.M. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science
5
Brookes, Ricky John. "Exploration of polymer replacements for SF6 in circuit breakers." Thesis, University of Liverpool, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526839.
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FILHO, JORGE AMON. "TRANSIENT RECOVERY VOLTAGE REQUIREMENTS FOR CIRCUIT BREAKERS: STUDY METHOD." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1986. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=9433@1.
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O trabalho desenvolvido estabelece uma metodologia de
estudo para a determinação dos requisitos de tensão de
restabelecimento transitória de disjuntores através de
simulações em computador digital com a utilização do
programa de cálculo de transitórios elétricos
Electromagnetic Transients Program (EMTP) de Bonneville
Power Administration (BPA).It is established in this paper a study method to determine the transient recovery voltage requirements for circuit breakers, by means of simulations in digital computer, using the Electromagnetic Transients Program (EMTP) de Bonneville Power Administration (BPA).
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Cwikowski, Oliver. "Synthetic testing of high voltage direct current circuit breakers." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/synthetic-testing-of-high-voltage-direct-current-circuit-breakers(2f15e62f-8b2c-4e29-884e-323b90af2d11).html.
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The UK is facing two major challenges in the development of its electricity network. First, two thirds of the existing power stations are expected to close by 2030. Second, is the requirement to reduce its CO2 emissions by 80% by 2050. Both of these challenges are significant in their own right. The fact that they are occurring at the same time, generates a significant amount of threats to the existing power system, but also provides many new opportunities. In order to meet both these challenges, significant amounts of offshore wind generation has been installed in the UK. For the wind generation with the longest connections to land, Voltage Source Converter (VSC) based High Voltage Direct Current (HVDC) transmission has to be used. Due to the high power rating of the offshore wind farms, compared to the limited transmission capacity of the links, a large number of point-to-point connections are required. This has lead to the concept of HVDC grids being proposed, in order to reduce the amount of installed assets required. HVDC grids are a new transmission environment and the fundamental question of how they will protect themselves must be answered. Several new technologies are under consideration to provide this protection, one of which is the HVDC circuit breaker. As HVDC circuit breakers are a new technology, they must be tested in a laboratory environment to prove their operation and improve their Technology Readiness Level (TRL). This thesis is concerned with how such HVDC circuit breakers are operated, rated, and tested in a laboratory environment. A review of the existing circuit breaker technologies is given, along with descriptions of several novel circuit breakers developed in this thesis. A standardized method of rating DC circuit breaker and their associated test circuit is developed. Mathematical analysis of several circuit breakers is derived from first principles and low power prototypes are developed to validate these design concepts. A high power test circuit is then constructed and a semiconductor circuit breaker is tested. The key learning outcomes from this testing are provided.
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Kwan, Stephen. "Computer simulation of arcs in gas-blast circuit-breakers." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243202.
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Garcia, Roberto Linan. "SFâ†6 decomposition under power arc and its degradation effects on superficial properties of insulating materials." Thesis, University of Salford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238773.
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Ennis, Michael Gerard. "Investigation of fundamental processes affecting the behaviour of electric arcs in electromagnetic interrupters." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318233.
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Yan, Jiu Dun. "Investigation of electric arcs in self-generated flow." Thesis, University of Liverpool, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367127.
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Jeffery, Peter Andrew. "The motion of short circuit arcs in low-voltage current limiting miniature circuit breakers." Thesis, University of Southampton, 1999. https://eprints.soton.ac.uk/47620/.
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Investigations have been made into the effect of the Miniature Circuit Breaker configuration on the behaviour of short circuit arcs. A Flexible Test Apparatus was developed to recreate the operation of a MCB, igniting the arc between opening contacts. The short circuit fault was simulated using a capacitor discharge system, with a prospective peak current of 3.5 kA. A high-speed digital Arc Imaging System was used to record the arc behaviour. Analysis techniques have been developed that plot the individual trajectories of the anode and cathode root from the digital data. The time that each arc root remains in the contact region can be deduced and is defined as the arc root contact time. It is shown that the traditional arc voltage to measure arc contact times is not accurate. In the Arc Contact Time Investigation the contact material, contact geometry, arc runner configuration were varied. At 3m/s contact velocity silver graphite contacts and step geometry led to longer cathode root contact times. Cathode root motion was prevented by a corner on the arc runner. The polarity of connection affected the arc movement away from the contact region. Increasing the contact velocity reduced cathode root contact times, but did not guarantee arc movement away from the contact region. The Taguchi Method was applied to the Arc Behaviour Investigation. The contact material, contact geometry, arc chamber geometry, arc chamber material and arc chamber venting were varied. Tests were carried out at lOm/s contact velocity. The cathode root contact time, anode root contact times and let through energy were calculated. The arc voltage and current, arc root trajectory plots and selected arc images are presented. The cathode and anode root contact times were independent. Generally, the cathode root moved away from the contact region before the anode root. Lower let-though energies were recorded for open arc chamber vents. The arc failed to move from the contact region, when silver graphite contacts were used in combination with acrylic arc chamber, copper arc runners and choked arc chamber vents. The mobility of the arc is dominated by the cathode root, and can only run at high velocity if the electrode surface conditions promote oxide layer type emission. The arc is drawn between the contacts with metal vapour type emission dominating and is initially limited to low velocity. During the arc contact time the arc root interaction effects damage the oxide layer on the surrounding conductor surface. As the arc column length increases, deflection of the arc column by the self-blast magnetic field may cause a discontinuous jump, after which the arc may run at high velocity. Increasing the contact velocity and steel arc runner backing strips encourage a discontinuous jump away from the contact region. Deposition on the arc runner of silver and carbon discourages both discontinuous jumps and high velocity motion. Changes in geometry, restricting the arc chamber venting and the anode root commutation can reduce the cathode root velocity. When this occurs, the arc root interaction effects damage the oxide layer, and cause the arc to revert to metal vapour type emission. Additionally, the surface of the acrylic arc chamber is carbonised during prolonged arc contact times. The partial conducting path through the carbonised material further encourages the arc to remain in the contact region.
13
Boyd, Kimberley John Thomas. "Circuit breaker performance on overhead line disconnection." Thesis, Queensland University of Technology, 1992. https://eprints.qut.edu.au/36098/1/36098_Boyd_1992.pdf.
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In recent years, single break puffer type SF6 circuit breakers for use at high voltage have been developed for restrike-free operation on long transmission lines. In 1983, an SF6 circuit breaker classed as restrike-free installed on the Electricity Commission of New South Wales (ECNSW) 330 kV system restruck, resulting in a flashover on the system. This raised concerns that circuit breakers tested for restrike-free operation could restrike under certain conditions experienced in Australia. This suggested possible testing standard deficiencies.
A series of switching tests carried out on a 300 kV SF6 single break puffer type
circuit breaker installed on the Queensland Electricity Commission (QEC) 275 kV system did not reveal circuit breaker restriking. Additional switching tests
were performed on a 145 kV oil filled circuit breaker known to be restriking. System tests were simulated using the Electromagnetic Transients Program (EMTP) to examine worst case conditions. As a result, factors that could have an influence on the performance of a circuit
breaker and therefore could lead to restriking were identified. Deficiencies in the testing standards have been identified and changes recommended for
classifying circuit breakers to be used for long line disconnection duty.
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Nielsen, Torbjörn. "Electric arc-contact interaction in high current gasblast circuit breakers." Licentiate thesis, KTH, Mechanics, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1275.
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Tennakoon, Sarah Barbara. "DC thyristor circuit breakers : an investigation of current interruption ability." Thesis, University of Central Lancashire, 1986. http://clok.uclan.ac.uk/20873/.
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The aims of the project were to investigate DC Thyristor Circuit Breaker (TCB) current interruption and appraise the current interruption performance in simulated systems. A generalized analysis was developed which enabled succinct assessment of the current interruption performance of different thyristor circuit breaker configurations. A 250V, 60A DC Thyristor Circuit Breaker was analysed and a study of TCB-system interaction was made. A novel thyristor circuit breaker switching overvoltage control technique was also investigated. The project findings on TCB-system interaction demonstrated that practical thyristor circuit breaker selection and design must be done in conjunction with the system configuration and its parameters. The normalized and analytical approaches were found to be useful for determining TCB design criteria but computer simulation tools, such as SPICE, are necessary for predicting the full range of TCB current interruption.
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Li, Bo. "Long Run Incremental Cost Pricing for Use of Circuit Breakers." Thesis, University of Bath, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.527138.
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Dixon, Christopher Mark. "Modelling and simulation of physical processes occuring in circuit breakers." Thesis, University of Liverpool, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.544370.
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Hall, William Bewick. "Reduced energy requirement study for extra high voltage circuit breakers." Thesis, University of Sunderland, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268097.
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Phaniraj, Viruru. "Modeling of AC circuit breakers in the electromagnetic transients program." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/91057.
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The objective of this research project was to develop and implement a model for an A.C circuit breaker in the Electromagnetic Transients Program (EMTP). Various models for the arcing process were evaluated, and the modified Mayr equation was chosen for the model. Other equations were added to demonstrate the generality of the algorithm developed.
Since the Electromagnetic Transients Program was not designed to accommodate directly elements whose resistance varies with time, such as an electric arc, several strategies for interfacing the model with the program were studied. The compensation method was selected, and was used for interfacing the circuit breaker model with the program.
After implementation of the model, it was validated by comparing its performance with experimentally verified results reported previously. In order to render the model more practical, an auxiliary breaker parameter estimation routine was developed and tested.M.S.
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Zhang, Feng. "Circuit-breakers : optical technologies for probing neural signals and systems /." May be available electronically:, 2009. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Wang, W. "Contact erosion and nozzle ablation in gas blast circuit breakers." Thesis, University of Liverpool, 2018. http://livrepository.liverpool.ac.uk/3019489/.
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Zhou, Keming. "Computation of asymmetric fault current in complex power systems." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287924.
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Widener, Christopher. "Fault isolation in power electronic based distribution systems without circuit breakers." Thesis, The Florida State University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1559659.
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In the Future Renewable Electric Energy Distribution and Management (FREEDM) system, solid state Fault Isolation Devices (FIDs) are used to react to signals from a fault detection and location system to isolate faulted sections of a fault current limited power electronics based 12.47 kV distribution system. They accomplish this by interrupting fault currents, which in the FREEDM system are limited by Solid State Transformers (SST). However, as was expected, due to its silicon transistor technology, the developed FID prototype demonstrated rather high on-state losses during its operation. Therefore, it is necessary to perform comparison studies with alternative methods of sectionalizing faulted parts of the FREEDM grid. To respond to this need, a system study has been undertaken to explore an alternative fault isolation strategy, which instead of allowing fault currents to remain in the system uses the abilities of the SSTs to completely turn off fault currents. Once this turn-off has been accomplished, regular mechanical disconnects isolate the faulted section and the system is reenergized. Behavioral 3-phase PSCAD average-value SST models have been developed and are used in a representative model of the FREEDM Green Hub to demonstrate how this strategy would operate. Simulation data is presented that shows how the SSTs would react to fault situations, remove fault currents, and reenergize the system. The characteristic example system was constructed and parameterized allowing for sensitivity analyses to be performed. A comparison is made with the fault-current-breaking FID method of fault isolation currently in use and it is discussed how the presented approach can be used to evaluate future FREEDM fault isolation strategies.
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Dam, Quang Binh. "Operating strategies to preserve the adequacy of power systems circuit breakers." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28232.
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Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.Committee Chair: Meliopoulos, A. P. Sakis; Committee Member: Divan, Deepakraj M.; Committee Member: Harley, Ronald G.; Committee Member: Johnson, Ellis L.; Committee Member: Taylor, David G.
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Lund, Johan. "Assessment and modelling of switching technologies for application in HVDC-circuit breakers." Thesis, KTH, Elektroteknisk teori och konstruktion, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-53482.
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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 available. In this work three different DC-Circuit breaker topologies that show good potential in the medium voltage range has been modeled namely • Resonance Hybrid DC Circuit Breaker • Active Turn-off Hybrid DC Circuit Breaker • Snubbered Hybrid DC Breaker The three different breaker concepts has been analyzed and compared for their ability to limit short circuit current. The comparison shows that the Snubbered DC Circuit breaker has the best short circuit current limiting performance. The maximum short circuit current during the turn-off process is 20 % lower than for the other two DC breaker topologies which shows the aproximately the same sort circuit current limiting performance.
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Chaaraoui, Jamal Abdullatif. "Effects of high frequency arcing in SFâ†6 puffer interrupters from low inductive current switching." Thesis, University of Liverpool, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240706.
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El-Kholy, S. M. "Spectroscopic investigation of current zero arc properties." Thesis, University of Liverpool, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384300.
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Gustavsson, Niklas. "Evaluation and Simulation of Black-box Arc Models for High-Voltage Circuit-Breakers." Thesis, Linköping University, Department of Electrical Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2299.
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The task for this Master thesis was to evaluate different black-box arc models for circuit-breakers with the purpose of finding criteria for the breaking ability. A black-box model is a model that requires no knowledge from the user of the underlying physical processes. Black-box arc models have been used in circuit-breaker development for many years. Arc voltages from tests made in the High Power Laboratory in Ludvika were used for validation, along with the resistance calculated at current zero, R0, and 500 ns before current zero, R500.
Three different arc models were evaluated: Cassie-Mayr, KEMA and an arc model based on power calculations. The third model gave very good results and if the model is developed further, the breaking ability could easily be estimated.
The arc model based on power calculations could be improved by using better approximations of the quantities in the model, and by representing the current better. A further suggestion for the following work is to combine the second arc model tested, the KEMA model, with the model based on power calculations in order to estimate the KEMA model parameters.
The R0 and R500 values should also be calculated from more tests, in order to find a clear limit of the breaking ability.
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Pechrach, Kesorn. "Arc root commutation from the contact region in low contact velocity circuit breakers." Thesis, University of Southampton, 2003. https://eprints.soton.ac.uk/46530/.
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Circuit breakers are widely used in commercial and industrial installations for automatically switching off a short circuit current. Arc motion in low voltage (240VAC) high current (103-104 A.) circuit breakers is dominated by arc root mobility. This study provides a vital step in the development of a consistent arc structure and motion in circuit breakers operating at low contact opening velocity. The experimental investigations focus on the influence of the contact material, arc chamber material, contact velocity, power supply polarity, the gap behind the moving contact and the peak short circuit current level on the arc motion. The gas flows and gas composition effects are inspected. This thesis concentrates on the arc commutation at reduced contact opening velocity down to 1 m/s from a moving contact and in particular the point at which the arc root moves off from the contact region To investigate the arc root motion, the Flexible Test Apparatus (FTA) is used to simulate circuit breaker operation. The Arc Imaging System (AIS) is used to record series of the arc motion. New pressure transducers and a spectrometer are used to observe the gas flow and gas composition in the contact region. This data combination provides a new insight into the arc motion. The studies have observed that the gas flow in the region of the moving contact has been shown to affect the arc root mobility. The spectral emission from the arc gases confirms the presence of electronegative species. Experimental results are presented which include the measurements of pressures in the arc chamber, arc spectrum, and arc root motion. The interrelation of gas dynamic and magnetic forces is investigated further by developing relationships between electromagnetic forces and high temperature gas dynamic flows. New semi-empirical modelling is presented in terms of electrical and thermal energy transfer between the arc and the gas flow.
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YANG, JR-MING JIMMY. "A MARKET STABILIZATION MECHANISM - CIRCUIT BREAKER: THEORY AND EVIDENCE." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1054125077.
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Ma, Zhao. "Reactor current interruption by gas insulated switchgear." Thesis, Staffordshire University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.481658.
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Liu, J. "Modelling and simulation of air and SF6 switching arcs in high voltage circuit breakers." Thesis, University of Liverpool, 2016. http://livrepository.liverpool.ac.uk/3003675/.
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This thesis is concerned with the modelling of switching arcs in air in high voltage circuit breakers and with a comparative study of interruption capability of air and SF6 switching arcs. Emphasis is given to the identification of dominant energy transport processes for arc interruption and the material properties associated these processes. There have been renewed interests in air arcs because of its possible use in a mixture with other gases as a replacement for SF6 in circuit breakers for environment protection. Computer simulation of the switching air arc has been carried out using arc models based on laminar flow and on turbulent flow for the experimental set up of Fang et al [41] under DC current and that of Frind and Rich [66] for the current zero period. DC arc voltages predicted by arc model assuming laminar flow (LAM) are much lower than those measured. Thus, turbulence is introduced to account for additional power loss mechanism not included in the laminar flow model. Two turbulence models have been used to take into account of turbulence enhanced momentum and energy transport: the Prandtl mixing length model (PML) and the standard k-epsilon model or its modified version. For the DC air nozzle arc of Fang et al [41] the value of the turbulence parameter, c= 0.06, in PML has been chosen to match the predicted arc voltage with that measured at 1 kA DC and a stagnation pressure of 10 bar. PML can give satisfactory agreement with experiments over a DC current range from 250 A to 3 kA. When the standard k-epsilon model is used, the predict arc voltage is much higher than that measured indicating that turbulence cooling is too strong. One of the turbulence parameters of the standard k-epsilon model which controls the dissipation rate of turbulent kinetic energy is adjusted to match the predicted arc voltage with the experimentally measured arc voltage under the same discharge conditions as those for finding the value of c in PML. With this chosen value of 1 = 1.62, the modified k-epsilon model (MKE) gives similar results to those of PML. Three arc models (LAM, PML and MKE) are used to compute the critical rate of rise of recovery voltage (RRRV) for the air nozzle arc of Frind and Rich [66]. The presence of the shock inside the nozzle in the presence of the arc prevents the optimisation of the value of turbulence parameter for PML due to numerical convergence problems. RRRV predicted by PML and LAM are much lower than the experimental value. MKE with 1 = 1.65 is successful in predicting satisfactorily the RRRV at di/dt= 13.5 A/μs for several stagnation pressures. However, it has been found that a single value of 1 chosen for one value of di/dt cannot give satisfactory prediction of RRRV for other values of di/dt. A comparative computational study of SF6 and air switching arcs based on MKE has been carried out for the experimental conditions of Frind and Rich [66] for di/dt= 13.5A/μs at several stagnation pressures. Under the same discharge conditions RRRV of SF6 switching arc is one order of magnitude higher than that of air switching arc. Such large difference in the interruption capabilities of SF6 and air is due to the different dominant energy transport processes responsible for the arc cooling during current zero period. Two material properties of the arc plasma, the product of density and specific heat at constant pressure (ρCP) and that of density and enthalpy (ρh) are responsible for the distinctive arc features for SF6 and air. SF6 switching arc has a distinctive arc core surrounded by a thin region with steep temperature gradient. Under the same discharge conditions as those of SF6 air switching arc has no distinctive core structure. Its radial temperature profile is very broad and arc radius is much bigger than that of SF6. Such broad radial temperature profile of air arc is due to the peaks of turbulent thermal conductivity at 4,000 K and 7,000 K produced by the corresponding peaks of the material property of ρCP of air. For SF6 ρCP has a peak just below 4,000 K, which ensures rapid temperature decay above 4,000 K and a gentle temperature tail below 4,000 K. In comparison with SF6 under the same pressure difference across the nozzle the velocity inside air arc is much higher than that of SF6. With ρh of air being greater than that of SF6 for temperature higher than 7,000 K together with higher velocity enthalpy transport capability of air arc is much higher than that of SF6. Energy balance calculation for the current carrying core indicates that after the breakdown of quasi-steady state turbulent thermal conduction is the dominant energy transport process for SF6 while for air arc axial convection is dominant. As a consequence the rates of decay of arc temperature and arc radius for air arc a few microseconds before current zero are much slower than those of SF6, thus resulting in a large difference between RRRVs for the two gases under the same discharge conditions. To find an alternative arc quenching gas with similar interruption capability to that of SF6 one should aim at ρCP and ρh of the alternative gas with similar features to those of SF6.
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Camps, George David. "The development of a methodology to determine the maintenance strategy for high voltage circuit breakers." Thesis, University of Strathclyde, 2010. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=14438.
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Corona, Erick (Erick Gustavo). "Analysis of asset health : an approach to monitoring and diagnostics for medium voltage circuit breakers." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/80994.
Full textAbstract:
Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division; in conjunction with the Leaders for Global Operations Program at MIT, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 85-88).
The Medium Voltage Electric Industry is a very conservative and risk adverse sector that has undergone very little change in the past 30 years when compared to other technologically dependent activities; this reality is rapidly shifting. The advent of cost-effective and reliable telecommunications, coupled with the drastic price decrease of wireless communication and sensing technologies, are steering the industry towards an information based era that is generically known as smart-grid. With an emphasis on medium voltage circuit breakers, the purpose of this thesis was to identify sensor technology and analytics that will allow electric utilities in North America-primarily the United States-to assess the health of their equipment and utilize this information for maintenance operational decisions. The main areas of research included in this work were the market context for medium voltage circuit breaker Monitoring & Diagnostics solutions, the financial justification for such applications, and the technical merit of multiple sensor technologies and associated analytics. The findings of this research helped support the development of an advanced Monitoring and Diagnostics kit currently deployed at a customer site as part of a pilot demonstration program. The prototype system provides real-time monitoring and trending information for six reactor-switching 15 kV circuit breakers. The completion of this thesis, and successful development of the advanced Monitoring and Diagnostics kit, was the result of the collaborative effort of a small interdisciplinary team assembled to identify smart-grid opportunities in the medium voltage space. This work took place at ABB's Medium Voltage Headquarters in the United States.
by Erick Corona.
S.M.
M.B.A.
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Wang, Hao. "Turbulent switching arcs and influence of design parameters on performance of auto-expansion circuit breakers." Thesis, University of Liverpool, 2014. http://livrepository.liverpool.ac.uk/2003400/.
Full textAbstract:
Turbulence enhanced momentum and energy transport is an important mechanism in shaping the flow and temperature field of low current turbulent SF6 (Sulfur-hexafluoride) arcs burning in a nozzle. It is a factor that largely determines the prediction accuracy of the interruption capability of high voltage circuit breakers. Previous study [81] has shown that for SF6 arcs the parameters in the Prandtl mixing length model and the two equation k-ε model must be adjusted to bring agreement between prediction and measurement. The experimental observation [109] of steep temperature or density gradient exists at the arc edge, where turbulence is usually strongest. The density gradient can be regarded as a result of temperature gradient when the pressure difference across the low current arc column is small. In previous studies of turbulence models, the effects of large density or temperature gradient have not been considered. In the present work the k-ε model is modified to take into account the effect of the presence of steep local temperature gradient. The model is first applied to the steady state SF6 nozzle arcs in the current range from 100 A to 1800 A. The performance of the modified turbulence model is assessed by a comparison of the predicted and measured radial temperature profiles at different currents and its behaviours with another two most commonly used turbulence models, the Prandtl mixing length model and the k-ε model. The relevant turbulence parameters of the Prandtl mixing length model are adjusted according to the different nozzle shapes with different values and it has been found that its applicability is limited. The modified k-ε model, which is modified to take into account the effect of large temperature gradient with all default coefficients, can make reasonable prediction for turbulent arcs in the Aachen nozzle [67, 108] under direct current conditions. The model is then applied to the transient nozzle arcs in a GE nozzle [86] and the Campbell nozzle [85]. Finally, a real puffer-type circuit breaker of 252 kV has been used to verify this model. The predicted arc voltage and pressure agree reasonably well with the measurements at both high and low current levels, justifying the applicability of the modified k-ε turbulence model. The auto-expansion circuit breaker is a relatively new interruption technique, which creates the required fast gas flow at current zero using the energy dissipated by the arc itself. A design study has been carried out for a prototype 245 kV auto-expansion circuit breaker at 50 Hz, in order to investigate the influence of key design parameters in terms of arcing conditions at the current zero phase and the critical RRRV (Rate of Rise of Recovery Voltage). Auxiliary nozzle with different lengths, and the severity of leakage from the expansion volume have been implemented for testing the influence of design parameters in an auto-expansion circuit breaker. PC-based arc modelling taking account the effect of nozzle ablation and the mixing process of PTFE vapour with SF6 has been made for auxiliary nozzle investigation. For the effect of leakage, various sizes of a leakage hole are specified on the valve of the expansion volume. The critical RRRV values for the Ref. Case and the its modifications are used for comparison of its interruption capability in order to estimate the influence of these key design parameters. The solution of all of the equations in the arc models is based on a commercial computational fluid dynamics package, PHOENICS. PHOENICS has been extensively used at the University of Liverpool to model the arc behaviours since 1992. Before using PHOENICS to simulate the arc behaviour in this thesis some conditions need to be resolved. These are related with the choice of turbulence model, the computational domain size for electric field, and the influence of the Lorentz force. The differential models for reported works in the thesis is implemented into PHOENICS version 3.6.1. All boundary conditions which are treated as sources terms are discussed in Section 2.3.
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Westerlund, Per. "Condition measuring and lifetime modelling of disconnectors, circuit breakers and other electrical power transmission equipment." Doctoral thesis, KTH, Elektroteknisk teori och konstruktion, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-214984.
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The supply of electricity is important in modern society, so the outages of the electric grid should be few and short, especially for the transmission grid. A summary of the history of the Swedish electrical system is presented. The objective is to be able to plan the maintenance better by following the condition of the equipment. The risk matrix can be used to choose which component to be maintained. The risk matrix is improved by adding a dimension, the uncertainty of the probability. The risk can be reduced along any dimension: better measurements, preventive maintenance or more redundancy. The number of dimensions can be reduced to two by following iso-risk lines calculated for the beta distribution. This thesis lists twenty surveys about circuit breakers and disconnectors, with statistics about the failures and the lifetime. It also presents about forty condition-measuring methods for circuit breakers and disconnectors, mostly applicable to the electric contacts and the mechanical parts. A method for scheduling thermography based on analysis of variance of the current is tried. Its aim is to reduce the uncertainty of thermography and it is able to explain two thirds of the variation using the time of the day, the day of the week and the week number as explanatory variables. However, the main problem remains as the current is in general too low. A system with IR sensors has been installed at the nine contacts of six disconnectors with the purpose of avoiding outages for maintenance if the contacts are in a good condition. The measured temperatures are sent by radio and regressed against the square of the current, the best exponent found. The coefficient of determination $R^2$ is high, greater than 0.9. The higher the regression coefficient is, the more heat is produced at the contact. So this ranks the different contacts. Finally a framework for lifetime modelling and condition measuring is presented. Lifetime modelling consists in associating a distribution of time to failure with each subpopulation. Condition measuring means measuring a parameter and estimating its value in the future. If it exceeds a threshold, maintenance should be carried out. The effect of maintenance of the contacts is shown for four disconnectors. An extension of the risk matrix with uncertainty, a survey of statistics and condition monitoring methods, a system with IR sensors at contacts, a thermography scheduling method and a framework for lifetime modelling and condition measuring are presented. They can improve the planning of outages for maintenance. Finally a framework for lifetime modelling and condition measuring is presented. Lifetime modelling consists in associating a distribution of time to failure with each subpopulation. Condition measuring means measuring a parameter and estimating its value in the future. If it exceeds a threshold, maintenance should be carried out. The effect of maintenance of the contacts is shown for four disconnectors. An extension of the risk matrix with uncertainty, a survey of statistics and condition monitoring methods, a system with IR sensors at contacts, a thermography scheduling method and a framework for lifetime modelling and condition measuring are presented. They can improve the planning of outages for maintenance.Elförsörjningen är viktig i det moderna samhället, så avbrotten bör vara få och korta, särskilt i stamnätet. En kortfattad historik över det svenska elsystemet presenteras. Målet är att kunna planera avbrotten för underhåll bättre genom att veta mera om apparaternas skick. Det är svårt att planera avbrott för underhåll och utbyggnad. Riskmatrisen är verktyg för att välja vad som ska underhållas och den kan förbättras genom att lägga till en dimension, sannolikhetens osäkerhet. Risken kan minskas längs med varje dimension: bättre mätningar, förebyggande underhåll och mer redundans. Antalet dimensioner kan igen bli två genom att följa linjer med samma risk, som är beräknade för betafördelningen. Denna avhandling tar upp tjugo studier av fel i brytare och frånskiljare med data om felorsak och livslängd. Den har också en översikt av ett fyrtiotal olika metoder för tillståndsmätningar för brytare och frånskiljare, som huvudsakligen rör de elektriska kontakterna och de mekaniska delarna. Ett system med IR sensorer har installerats på de nio kontakterna på sex frånskiljare. Målet är att minska antalet avbrott för underhåll genom att skatta skicket när frånskiljarna är i drift. De uppmätta temperaturerna tas emot genom radio och behandlas genom regression mot kvadraten av strömmen, då den bästa exponenten för strömmen visade sig vara 2,0. Förklaringsfaktorn $R^2$ är hög, över 0,9. För varje kontakt ger det en regressionskoefficient. Ju högre koefficienten är, desto mer värme utvecklas det i kontakten, vilket kan leda till skador på materialet. Koefficienterna ger en rangordning av frånskiljarna. Systemet kan också användas för att minska eller öka den tillåtna strömmen baserat på skicket. Slutligen förklaras ett ramverk för livslängdsmodellering och tillståndsmätning. Livslängdsmodellering innebär att koppla en fördelning för tiden till fel med varje delpopulation. Med tillståndsmätning avses att mäta en parameter och skatta dess värde i framtiden. Om den överskrider en tröskel, måste apparaten underhållas. Effekten av underhåll visas för fyra frånskiljare. En utveckling av riskmatrisen med osäkerheten, en sammanställning av statistik och metoder för tillståndsövervakning, ett system med IR-sensor vid kontakerna, en metod för termografiplanering och ett ramverk för livslängdsmodellering och tillståndsmätningar presenteras. De kan förbättra avbrottsplaneringen.
El suministro de energía eléctrica es importante en la sociedad moderna. Por eso los cortes eléctricos deben ser poco frecuentes y de poca duración, sobre todo en la red de transmisión. Esta tesis resume la historia del sistema eléctrico sueco. El objetivo es planificar los cortes mejor siguiendo la condición de los aparatos. La matriz de riesgo se utiliza muchas veces para escoger en qué aparatos debería realizarse mantenimiento. Esta matriz se puede mejorar añadiendo una dimensión: la incertidumbre de la probabilidad. El riesgo puede ser disminuido siguiendo cada una de las tres dimensiones: mejores mediciones, mantenimiento preventivo y mayor redundancia. El número de dimensiones puede reducirse siguiendo líneas del mismo riesgo calculadas para la distribución beta. Esta tesis presenta veinte estudios de fallos en interruptores y seccionadores con datos sobre la causa y el tiempo hasta la avería. Contiene también una visión general de cuarenta métodos para medir la condición de seccionadores e interruptores, aplicables en su mayoría a los contactos eléctricos y los componentes mecánicos. Se ha instalado un sistema con sensores infrarrojos en los seis contactos de nueve seccionadores. El objetivo es disminuir los cortes de servicio para mantenimiento, estimando la condición con el seccionador en servicio. Las temperaturas son transmitidas por radio y se hace una regresión con el cuadrado de la corriente, ya que el mejor exponente de la corriente resultó ser 2,0. $R^2$ alcanza un valor de 0,9 indicando un buen ajuste de los datos por parte del modelo. Existe un coeficiente de regresión para cada contacto y este sirve para ordenar los contactos según la necesidad de mantenimiento, ya que cuanto mayor sea el coeficiente más calor se produce en el contacto. Finalmente se explica que el modelado de tiempo hasta la avería consiste en asignar una distribución estadística a cada equipo. La monitorización del estado consiste en medir y estimar un parámetro y luego predecir su valor en el futuro. Si va a sobrepasar un cierto límite, el equipo necesitará de mantenimiento. Se presenta el efecto de mantenimiento de cuatro seccionadores. Un desarrollo de la matriz de riesgo, un conjunto de estadísticas y métodos de monitoreo de condición, un sistema de sensores IR situados cerca de los contactos, en método de planificación de termografía y un concepto para explicar la modelización de tiempo hasta la avería y de la monitorización de la condición han sido presentados y hace posible una mejor planificación de los cortes de servicio.
QC 20170928
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Çoban, Abdulkerim Levent. "A low-voltage high-resolution audio delta-sigma modulator." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/15514.
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Hibbert, Mark Stanley Bruce. "Distribution system transient recovery voltage." Thesis, Queensland University of Technology, 1995. https://eprints.qut.edu.au/36237/1/36237_Hibbert_1995.pdf.
Full textAbstract:
In recent years the use of small pole-mounted circuit breakers has increased due to advances in distribution system automation technology. This increased use has given rise to concern over the transient recovery voltage stresses imposed on circuit breakers and reclosers located in distribution feeder environments. A survey of the available literature has revealed that little work has been carried out in this area. This report details an investigation into the transient recovery voltage
experienced in distribution feeder environments. Fault interruption tests were carried out using a pole-mounted recloser located on an 11 kV distribution feeder in the South East Queensland Electricity Corporation's network. The measured transient recovery voltage responses were used as the basis for comparison with computer simulation results. A computer model was developed that adequately represents the inherent transient recovery voltage response of the distribution system. This model was used to carry out simulations to fully characterise distribution system transient recovery voltage parameters.
Fonnulae were established that enable transient recovery voltage parameters to be calculated for any given distribution system. This report concludes that the transient recovery voltage experienced in distribution feeder environments can be either significantly lower, or in some cases significantly more severe, than the
requirements specified in current standards. This report recommends that:- 1. Standards committees give consideration to the adoption of a four parameter envelope with no delay line, for the specification of distribution feeder transient recovery voltage, and that
2. The rate of rise of transient recovery voltage specified in standards, is increased in proportion
to increases in the rated breaking capacity, for pole-mounted reclosers intended for use on feeders in the distribution system.
3. Circuit breaker manufacturers give consideration to the development of pole-mounted reclosers
with breaking capacities rated at 1 kA, designed for transient recovery voltage responses
consistent with their application in distribution feeders at distances greater than 10 km from
substations.
4. Purchasers of pole-mounted reclosers intended for use in distribuion feeder environments, give
consideration to specifying TRV requirements in accordance with the findings of this study.
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Pei, Yuqing. "Computer simulation of fundamental processes in high voltage circuit breakers based on an automated modelling platform." Thesis, University of Liverpool, 2014. http://livrepository.liverpool.ac.uk/2007107/.
Full textAbstract:
Auto-expansion circuit breakers utilize the arc’s energy to generate the flow conditions required for current interruption. The operation of this type of circuit breaker is extremely complex and its interruption capability depends on the whole arcing history as well as a number of geometric factors. On the other hand, circuit breaker development based on test is extremely expensive and time consuming. The accumulated understanding of the underlying physical processes so far enables arc models be used as a tool for optimum design of switchgear product such as high voltage circuit breakers. For academic research, there is often a need to study the performance of a newly developed arc model by inspecting the distribution of relevant physical quantities during a simulation and their sensitivity to model parameters in an efficient and convenient approach. However the effective use of computer simulation by design engineers has been hindered by the complexity encountered in model implementation. This thesis presents the development and structure of an automated simulation tool, the Integrated Simulation and Evaluation Environment (ISEE), for the arcing process in gas-blast circuit breakers. The functionalities of ISEE are identified and developed based on the experience in real product design, which include visual creation and definition of components, automatic setup of arc models based on a commercial CFD software package as equation solver, simulation task management, and visualization of computational results in “real-time” mode. This is the first automated simulation platform in the community of switching arc simulation. Using ISEE as the simulation tool, different designs of auto-expansion circuit breakers have been investigated to reveal the fundamental characteristics of the arcing process under different test duties. Before attempting to investigate the capability of an auto-expansion circuit breaker, the fundamental issue of determining the turbulence parameter of the Prandtl mixing length model is addressed. Previous studies on turbulence arcs were mostly concerned with simple converging-diverging nozzles. There has been little work on real circuit breaker nozzles. In order to calibrate the turbulence parameter, real arcing conditions including interrupting currents, contact travels, and transient recovery voltages of two commercial circuit breakers, with rated voltage of 145 kV and 245 kV, have been used together with the geometry of the circuit breakers to calibrate the range of the turbulence parameter. The effect of nozzle ablation has been considered. All together 6 cases have been used for three circuit breakers with each pair of cases corresponding to a success and failure in its thermal recovery process. It has been found that a single parameter of 0.35 is applicable to all three circuit breakers with an auxiliary nozzle and a main nozzle of converge-flat throat-diverge shape. It must be noted that this value is obtained with the definition of thermal radius introduced in Chapter 3 and the assumption that the parameter linearly changes with the interrupting current from 0.05 at 15 kA to 0.35 at current zero. Using the calibrated turbulence model, a computational study of the thermal interruption performance of a 145 kV, 60 Hz auto-expansion circuit breaker with different arc durations has been carried out in Chapter 4. The relation between pressure peak and current peak in the auto-expansion circuit breaker is discussed. It has been found that a larger average mass flux in the main nozzle indicates a better interruption environment, enabling the circuit breaker to withstand a larger rate of rise of recovery voltage after current zero. Another important finding is that the auxiliary nozzle plays an important role in an auto-expansion circuit breaker both at the high current phase and during the current zero period. Therefore, the proper design and use of an auxiliary nozzle is a key factor to enhance the thermal interruption capability of high voltage auto-expansion circuit breakers. In Chapter 5 of the thesis, the transient pressure variation in auto-expansion circuit breakers was studied. The pressure variation has an extremely complex pattern and the pressure changes in different ways depending on the location in the arcing chamber. It is shown, for the first time, that the time lag between the current peak and pressure peak in the expansion volume can be explained by using an energy flow rate balance method, that is flow reversal occurs when the enthalpy exhaustion rate from the contact space equals the electrical power input. Following the flow reversal, a high enthalpy flow rate from the expansion volume into the contact gap first occurs for a short while (1 ms), which is followed by a high mass flow rate of relatively cool gas at less than 2000 K. This high mass flow rate causes a surplus in mass flow rate into the contact gap and results in the last temporary pressure peak in the contact space before the pressure and flow field finally settle down for arc quenching at current zero. The pressure change under different conditions, i.e. different arc durations, different current levels and different length of the heating channel, has also been studied in details. In summary the present research leads to original findings in three aspects of the operation of auto-expansion circuit breakers, i.e. the calibration of the turbulence parameter for the Prandtl mixing length model, interruption performance with different arc durations, and the transient pressure variation in the arcing process. The results are expected to provide useful information for the optimum design of auto-expansion circuit breakers.
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Magnusson, Jesper. "On the design of hybrid DC-breakers consisting of a mechanical switch and semiconductor devices." Licentiate thesis, KTH, Elektroteknisk teori och konstruktion, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-164524.
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The interest of using direct current in networks for both transmission and distribution of power is increasing due to the higher efficiency compared to the alternating current used today. As no natural zero crossings exist in direct current, the interruption of fault currents becomes a challenge. Several circuit breaker topologies have been proposed to fulfill the requirements for DC grids. One such topology is the hybrid DC-breaker consisting of three parallel branches: a mechanical switch, a semiconductor branch, and a metal oxide varistor. The current interruption in the hybrid DC-breaker is made in three steps. A mechanical switch carries the nominal current with low losses during normal operation. When the breaker is tripped to interrupt the current, the mechanical switch is opened and commutates the current into the semiconductor branch. This branch will then conduct the current as the mechanical switch regains its voltage withstand. The semiconductors turn off and force the current into the varistor branch where the magnetic energy is absorbed and the current is forced to zero. This thesis is based on simulations and experiments to obtain design rules for such a DC-breaker. It has been shown that several aspects needs to be considered. Simulations are performed with several different models to obtain the requirements of each of the components in the DC-breaker. First of all, the choice of the semiconductor is important. There are a number of components available in the market, but typically they are optimized for fast switching applications like inverters rather than circuit breaker applications that only requires one single switching. Due to the high current and voltage ratings and the easy control, the IGBT seems to be the best choice among the commercially available components. Simulations on the mechanical switch show that there is an optimal combination of opening time and arc voltage of the to obtain a successful commutation into the semiconductor branch. The actuator is a key component since a relatively low increase in performance of the actuator drive circuit, significantly decreases the requirement of the other components in the DC-breaker. A significant part of the work has been put on the voltage transient during the turn-off of the semiconductor. As the current is forced into the varistor branch, the stray inductance in that loop will result in an over-voltage due to the high current derivative. A new type of snubber has been investigated using another varistor mounted close to the semiconductor. It has been shown that the function of the varistor snubber can be divided into two regions depending on the ratio between the snubber and the main varistor. If the ratio is high enough, the energy absorbed in the snubber varistor is only a few percent of the total energy.Intresset för att använda likström i både transmission och distribution av elkraft har ökat tack vare en högre verkningsgrad och lägre förluster. En begränsande faktor för utbyggnad av likströmsnät är utvecklingen av brytare för likström. Svårigheten att bryta en likström jämfört med växelström är att det saknas en naturlig nollgenomgång där strömmen kan brytas. För att tvinga fram en nollgenomgång kan man använda en hybrid brytare som består av tre parallella grenar: en mekanisk switch, en gren med krafthalvledarkomponenter och en gren med en varistor. Hybridbrytaren bryter en ström i tre steg. I normalfallet leder den mekaniska kontakten strömmen för att hålla nere de elektriska förlusterna. När strömmen ska brytas öppnas den mekaniska kontakten och strömmen kommuteras över till krafthalvledargrenen. När krafthalvledaren stängs av, trycks strömmen över till den tredje grenen där varistorn begränsar spänningen över brytaren och absorberar den magnetiska energi som finns lagrad i nätet. Strömmen avtar och när systemet är avmagnetiserat når strömmen noll. Denna avhandling sammanfattar ett arbete att med hjälp av simuleringar och experiment få fram designparametrar för en sådan brytare. Flera simuleringsmodeller har av använts för att få fram designkriterier för de olika komponenterna i hybridbrytaren. Ett första steg är att välja krafthalvledarkomponent. Dessa komponenter är främst utvecklade för omvandling mellan lik- och växelström där de slås av och på i korta intervall. En brytartillämpning skiljer sig markant från detta eftersom strömmen bara behöver brytas enstaka gånger vilket ändrar kraven på komponenten. Enkelheten i att kontrollera komponenten tillsammans med dess höga ström- och spänningstålighet gör IGBTn till det bästa valet bland de kommersiellt tillgängliga komponenterna. Simuleringar visar att en optimal design av den mekaniska switchen är en kombination av snabbhet och ljusbågsspänning. En nyckelkomponent är den snabba aktuatorn som driver switchen. En relativt liten förbättring av drivkretsen kan leda till minskade krav och därmed kostnader på övriga komponenter i brytaren. En stor del av arbetet har lagts på att studera den transienta överspänningen då krafthalvledarkomponenten bryter strömmen. Den höga strömderivatan medför att även små ströinduktanser leder till relativt stora överspänningar som riskerar att skada brytaren. En ny typ av snubberkrets, bestående av en mindre varistor som monteras nära krafthalvledaren, har föreslagits. På detta sätt separeras överspänningsskyddet från absorptionen av den magnetiska energin. Experiment och simuleringar visar att om spänningsförhållandet mellan de två varistorerna är tillräckligt stort absorberas endast ett par procent av energin i snubbern.
QC 20150420
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Wong, Toh Ming. "Computer Simulation and Visualisation of Complex Systems: Arcs and Hot Gas Flow in Auto-expansion Circuit Breakers." Thesis, University of Liverpool, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.490814.
Full textAbstract:
Auto-expansion circuit breakers (also known as the self-blast circuit breakers) are an advanced generation of high voltage switchgear. This type of circuit breaker uses the arc's energy to generate a high pressure SOurce in the expansion volume (also known as the heating chamber) to create the required thermal and aerodynamic conditions for interrupting the circuit at a current zero. Ablation of the arc confining nozzle at high current is the main mechanism for pressurisation of the expansion volume. The operation of such a breaker is extremely complex and its performance depends on the whole arcing history as well as a number of geometrical factors characterising the geometry of the interrupter. It is a complex system with inter-related mechanical parts (moving pistons, valves, ablating nozzles, and moving contact) and physical processes (radiation, thermodynamics, aerodynamics, turbulence and ablation of solid materials). The relationship between all the constituent parts and physical processes gives rise to the collective behaviour of the whole system. Computer simulation of the arcing process in such a breaker has been carried out in the present work. Because of the very high power level encountered in such a breaker the arc interacts intensely with its surroundings. The objective of the work is to establish a computer model to simulate the whole arcing process, validate the model and then perform an extensive analysis of system behaviour to extract useful information for the optimisation design of such devices. The history of circuit breaker development, fundamental aspects related to the operation of high voltage circuit breakers, and history of computer modelling of switching arcs are first reviewed in chapter I, which provides an overall background picture for the present work. The mathematical description of the important physical processes is then given in chapter 2 which includes the governing equations for arc flow, the modelling of radiation and turbulence, the calculation of nozzle ablation, and the computation of electrical and magnetic fields for Lorentz force and Ohmic heating. The temperature and pressure encountered in computer simulation of the autoexpansion circuit breaker arc covers a wide range, from 300K to possibly 40, OOOK and from atmospheric pressure to 100 bar. The material and transport properties of the mixture of the working gas and ablated nozzle vapour are highly non-linear functions of plasma parameters. Thus a robust computational fluid dynamics (CFO) solver is essential. In the present work, a commercial CFO package, PHOENICS, is used for the simulation. The practically important issues, such as the implementation of the arc model with input of material properties into the solver, the specification of initial and boundary conditions, the approximate of the circuit breaker geometry, and choice of time step and control of convergence, are discussed in chapter 3. In the operation of an ABB auto-expansion circuit breaker, there are a number of mechanical parts that move with time during an operation process. The operation of over pressure valves, with one of them attached to the moving piston, has to be correctly modelled. This is detailed in chapter 4 where validation of the numerical meth~ ' ods is provided by comparing the prediction with analytical results from isentropic compression and also with measurement from ABB. Results show that the proposed numerical scheme can satisfactorily model the valve operation and the piston movement. Typical results of the gas flow in such a circuit breaker without the presence of an arc (no-load operation) are presented and discussed. In chapter 5 the operation of the ABB breaker under specified arcing current is then simulated for almost a whole arcing period. Results indicate that Lorentz force has a profound effect on the flow field as well as the arc shape. Detailed energy and mass balance calculation is performed for the arcing space and also for the expansion volume, which clearly shows the importance of radiation transfer, convection at different nozzle exits and the change of energy and mass storage at different instants in the arcing process. It is also shown that the pressurisation of the expansion volume is due to the influx of thermal energy, not the mass influx. The predicted arc voltage overally agrees with the test results within 15% for all three cases simulated with different breaker geometry. The predicted pressure at current zero is within 10% of the test results. On the whole the prediction is considered satisfactory in consideration of the approximations that have been introduced in the geometry and radiation model. It has been found that for the auto-expansion circuit breaker the pressure in the arcing space can fluctuate rapidly in the period shortly before the thermal recovery period. Pressure fluctuation with several bars around the current zero period results in a scatter of thermal interruption and dielectric recovery performances. Large pressure variation is therefore not desirable. Optimisation of design parameters is necessary in order to avoid pressure variation and to ensure maximum pressure and lowest temperature possible in the arcing voll!-me. A systematic study of the mechanisms responsible for the pressure fluctuation is therefore carried out in chapter 6. It has been found that the evolution of pressure and temperature fields in the arcing space around current zero depend on the supply rate of gas from the expansion volume and the exhaustion rate at the nozzle exits. Thus, an optimum design is directly linked with the design of the expansion volume and the link channel between the arcing space and the expansion volume. A systematic study of the influence of various design parameters is also carried out to identify the most influencing parameter, which is the dimension of the channel link. Based on the knowledge and understanding derived from this study a new design has been simulated which produces very promising result in smoothing the pressure fluctuation in the arcing space. Pressure and temperature fields at current zero depend on the whole arcing history as well as the contact movement which determines the gas exhaust passage. Arcing processes with different arcing time (altogether three cases with different arcing times) are finally performed to assess the efficiency of the new design. In all cases it has been shown that with the addition of a buffer volume the pressure smoothly changes in the period approaching the final current zero. In summary, the three objectives stated in chapter 1 have all been achieved by the work presented in chapters 2 to 6. Nevertheless, there are still several aspects of the model that need to be improved. This is discussed in the final chapter.
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Fradinho, Bastos Ivan. "Marketing Introduction Plan for the New Generation of Sustainable Circuit Breakers LTA 420 kV : A real-life case for implementation at Hitachi ABB Power Grids." Thesis, KTH, Kemiteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-297294.
Full textAbstract:
En strömbrytare är en säkerhetsanordning som är utformad för att bryta strömmen om ett problem uppstår. Det finns ett flertal olika typer av brytare beroende vilket spänningsområde som avses. Brytare för lågspänning används för hushållsapparater, medan högspänningstyper används för överföring av spänning i elnätet. Högspänningsbrytare använder idag svavelhexafluorid (SF6)-gas, som ett isolerande medium för att släcka den elektriska ljusbåge som bildas när strömmen bryts. SF6 är dock problematiskt för miljön, då dess globala uppvärmningspotential (GWP) är 23 500 gånger högre jämfört med koldioxid (CO2). Företaget Hitachi ABB Power Grids har utvecklat AirPlus™-tekniken som ersätter SF6-gasen med en koldioxidbaserad gasblandning. Examensarbetet fokuserade på att utvärdera möjligheten att minska användningen av SF6 genom AirPlus™-tekniken och hur tekniken skulle kunna en introduceras på marknaden. Slutligen så utvecklades en strategi för hur detta skulle kunna ske. Studien innefattar den bakomliggande informationsinhämtningen och analysen av data, marknadsutvärdering och utvecklingen av marknadsstrategin. Detta utfördes genom att utvärdera AirPlus™-tekniken och dess konkurrenter, samt genom en kvalitativ och kvantitativ analys av implementeringen av LTA 420 kV-brytaren på marknaden. Sammanfattningsvis så visar studien att marknadsintroduktionen av strömbrytaren LTA 420 kV är genomförbar. Även om koldioxid tekniskt inte har samma prestanda som SF6, är tekniken fortfarande bra och ger starka kundfördelar: GWP minskar med över 99,9%, användningen överensstämmer med miljöregler, den ger lägre ägandekostnader, färre kontroller, lägre kostnad för hantering av koldioxidgasen, och fungerar väl vid extremt låga temperaturer. De viktigaste utmaningarna för Hitachi ABB Power Grids relaterar till konkurrensen på marknaden. Det är därför tillrådligt att företaget arbetar med en effektiv marknadsintroduktion för att säkerställa en stor marknadsandel.A circuit breaker is a safety device designed to interrupt power if a problem is detected. There are several kinds of circuit breakers for different applications. Low-voltage circuit breakers are used for household appliances, while high-voltage types are used for transmission networks. High-voltage circuit breakers use sulfur hexafluoride (SF6) gas as an insulating medium, which extinguishes the electric arc that is formed when power is cut. However, it is a huge hazard for the environment, as its global warming potential (GWP) is 23,500 times higher than that of CO2 gas. The company Hitachi ABB Power Grids developed the AirPlus™ technology, which replaces the SF6 gas with a carbon dioxide (CO2) based gas mixture. The presented degree project has evaluated the feasibility of reducing the use of SF6 through the AirPlus™ technology and then developed a strategy for the company Hitachi ABB Power Grids for the market introduction of the eco-efficient LTA 420 kV circuit breaker. This study covers the background research, market evaluation, and market strategy. It was done through research about the AirPlus™ technology and its competitors, so as qualitative and quantitative analysis of the LTA 420 kV circuit breaker implementation in the market. In conclusion, the study shows that the market introduction of the LTA 420 kV circuit breaker is feasible. Although CO2 is not as good an insulation medium as SF6, it is still good and presents strong customer benefits: GWP reduced by over 99.9%, compliance with new regulations, lower cost of ownership, fewer regulatory controls, reduced cost of handling the gas, and well-functioning at extremely low temperatures. The main concerns for Hitachi ABB Power Grids are related to market competition. Thus, it is advisable that the company works on an effective market introduction to assure a large market share.
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Matsumura, Toshiro, Tomohiro Aritake, Yasunobu Yokomizu, Hirotaka Shimizu, and Norimitsu Murayama. "Performances of small fault current limiting breaker model with high Tc Superconductor." IEEE, 2005. http://hdl.handle.net/2237/6791.
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Rainbird, Paul L. "Prediction of temperature rise in low voltage high current electrical switchboards." Thesis, Queensland University of Technology, 1990. https://eprints.qut.edu.au/36452/1/36452_Rainbird_1990.pdf.
Full textAbstract:
At present, the electrical switchboard designer us ually
constructs a full-scale prototype and tests it at rated
current to ascertain its temperature rise performance, under
simulated normal operating conditions. Temperatures are then
reduced by application of one or several techniques including
modification of the switchboard design.
Steady-state temperature rise within an electrical
switchboard is attained when t he Joule heat generated by
electrical losses is exactly balanced by the heat l ost by
cooling. The basic factors affecting this heat balance in
electrical switchboards are r eviewed in this thesis . Also,
the available empirical and computer based techniques which
have been used to predict the temperature rise of electrical
components such as cables, busbars, and circuit breakers as
well as electrical switchboards containing these components,
are discussed in detail.
In view of the time and expense of development testing using
techniques such as the above, this thesis introduces the
concept of representing · the electrical switchboard heat
transfer processes of radiation, convection, conduction, and
natural ventilation by thermal equivalent resistances which
are analogous to resistances in electric field theory. It is
shown how thermal equivalent resistance circuits of
individual switchboard components enable evaluation of their
temperature rise and power loss performance The temperature rise experiments and the deve l opment of
thermal equivalent resistance circuits for a 400 A moulded
case circuit breaker and a 1600 A medi um voltage air circuit
breaker , for a wide range of unenclosed and enc losed
opera t ing conditions, are descr ibed and analysed .
This thesis also presents the results of tests performed on a
number of typical switchboard ventilators to quantify in real
terms t heir ability to remove internally generated Joule heat
from within electrical switchboards by natural ventilation.
This analysis required the construction of a ventilator
experimental test rig which is used to accurately simulate
the actual operating conditions of a ventilator in nn
electrical switchboard. The visualisation of the air flow
patterns through these ventilators is also investigated.
In line with the above described experiments, tests are
performed on a full-scale electrical switchboard to determine
its temperature rise and power loss performance for various
ventilation configurations . From the measurement of the
small differential pressure drops across the switchboard
ventilators and internal components , the major obstructions
to natura l ventilation and convection air flow within the
switchboard are identified .
To conduct these experiments on the switchboard, an automatic
testing system was developed. This system, using a HP85
personal computer, digital multifunction meter, process datal
ogger, pneumatic scanning box, digital micromanometer, and a
special IEEE 488 input/output device, enables the
automatic measurement, logging , and processing of electrical
switch board experimental test data.
This thesis also describes a computer program d e veloped by
Van Leersum (16, 17) which has been used in the prediction of
temperature rise o f simple non-vented heated enclos ures
containing electronic equipment. A joint collaborative
pro j ect between the Queensland University of Technology and
the CSIRO's Division of Energy Technology was established to
examine t he possibility of adapting this computer program,
b a s~d upon the results of the t emperature rise tests on
switchboard components d e scribed herein, so as to predict the
t ~mperature r ise performance of vent i l ated enclosures such as
electrica l switchboards.
Simulations using this computer program are performed on both
an idealised switchboard enclosure and a full-scale
electrical switchboard over a wide range of operating
conditions . Comparisons with experimental results revealed
that the computer program could predict temperature rises to
an accuracy of ±6 percent.
It is concluded that although computer programs of this type
are new to the electrical switchboard manufacturing industry
in Australia and indeed throughout the world, their
application in commercial switchboard design is justified in
terms of both accuracy of temperature rise prediction and
economic benefit
development testing
i n
of
that costly and time
low voltage high current
switchboards is not requi red.
consuming
electrica
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Westerlund, Per. "Condition measuring and lifetime modelling of electrical power transmission equipment." Licentiate thesis, KTH, Elektroteknisk teori och konstruktion, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-167136.
Full textAbstract:
The electric grid is important in modern society, so the outages should be few. The transmission grid should have a real high availability, since it transports electrical energy across the country. Then, it is difficult to plan outages for maintenance and installation. This thesis lists twenty surveys about failures of circuit breakers and disconnectors, with data about the cause and the lifetime. It also contains a survey of about forty condition-measuring methods for circuit breakers and disconnectors, mostly applicable to the electric contacts and the mechanical parts. As there is no published method to monitor the electric contacts at voltages around 400 kV, a system with IR sensors has been installed at the nine contacts of six disconnectors. The purpose is to avoid outages for maintenance by estimating the condition of the contacts while the disconnectors are still connected to high voltage. The measured temperatures are collected by radio and regressed against the square of the current, since the best exponent for the current was found to be 2.0. The coefficient of determination $R^2$ is high, greater than 0.9. This gives for each contact a regression coefficient, which can serve as an estimate of the condition of the contact. The higher the coefficient is, the more heat is produced at the contact, which can damage the material. This enables a ranking of the different contacts and shows which the worst ones are. This coefficient can also give a dynamic rating of the disconnector.Elnätet är viktigt i det moderna samhället, så antalet avbrott bör vara lågt. Särskilt stamnätet bör ha en särskilt hög tillgänglighet, då det transporterar elektrisk energi tvärsöver landet. Då blir det svårt att planera avbrott för underhåll och utbyggnad. Denna avhandling tar upp tjugo studier av fel i brytare och frånskiljare med data om felorsak och livslängd. Den har också en översikt av ett fyrtiotal olika metoder för tillståndsmätningar för brytare och frånskiljare, som huvudsakligen rör de elektriska kontakterna och de mekaniska delarna. Eftersom det inte finns någon beskriven metod för att övervaka elektriska kontakter för spänningar på runt 400 kV, har ett system med IR sensorer installerats på de nio kontakterna på sex frånskiljare. Målet är att minska antalet avbrott för underhåll genom att skatta skicket hos kontakterna, när frånskiljarna fortfarande är kopplade till högspänning. De uppmätta temperaturerna tas emot genom radio och behandlas genom regression mot kvadraten av strömmen, då den bästa exponenten för strömmen visade sig vara 2,0. Förklaringsfaktorn $R^2$ är hög, över 0,9. För varje kontakt ger det en regressionskoefficient, som blir en skattning av kontaktens skick. Ju högre koefficienten är, desto mer värme utvecklas det i kontakten, vilket kan leda till skador på materialet. Kontakternas olika koefficienter ger en rankordning dem och därmed en möjlighet att prioritera vilken frånskiljare som ska underhållas först. Systemet kan också användas för att minska eller öka den tillåtna strömmen baserat på skicket.
QC 20150522
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Beddard, Antony James. "Factors affecting the reliability of VSC-HVDC for the connection of offshore windfarms." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/factors-affecting-the-reliability-of-vschvdc-for-the-connection-of-offshore-windfarms(ed389e21-7795-49bf-b2fa-9deaed36ede1).html.
Full textAbstract:
The UK Government has identified that nearly 15% of the UK’s electricity generation must come from offshore wind by 2020. The reliability of the offshore windfarms and their electrical transmission systems is critical for their feasibility. Offshore windfarms located more than 50-100km from shore, including most Round 3 offshore windfarms, are likely to employ Voltage Source Converter (VSC) High Voltage Direct Current (HVDC) transmission schemes. This thesis studies factors which affect the reliability of VSC-HVDC transmission schemes, in respect to availability, protection, and system modelling. The expected availability of VSC-HVDC systems is a key factor in determining if Round 3 offshore windfarms are technically and economically viable. Due to the lack of publications in this area, this thesis analyses the energy availability of a radial and a Multi-Terminal (MT) VSC-HVDC system, using component reliability indices derived from academic and industrial documentation, and examining the influence of each component on the system’s energy availability. An economic assessment of different VSC-HVDC schemes is undertaken, highlighting the overall potential cost savings of HVDC grids. The connection of offshore windfarms to a MT HVDC system offers other potential benefits, in comparison to an equivalent radial system, including a reduction in the volume of assets and enhanced operational flexibility. However, without suitable HVDC circuit breakers, a large MT HVDC system would be unviable. In this thesis, a review of potential HVDC circuit breaker topologies and HVDC protection strategies is conducted. A HVDC circuit breaker topology, which addresses some of the limitations of the existing designs, was developed in this thesis, for which a UK patent application was filed. Accurate simulation models are required to give a high degree of confidence in the expected system behaviour. Modular Multi-level Converters (MMCs) are the preferred HVDC converter topology, however modelling MMCs in Electromagnetic Transient (EMT) simulation programs has presented a number of challenges. This has resulted in the development of new modelling techniques, for which the published validating literature is limited. In this thesis these techniques are compared in terms of accuracy and simulation speed and a set of modelling recommendations are presented. Cable models are the other main DC component which, upon analysis, is found to have a significant impact on the overall model’s simulation results and simulation time. A set of modelling recommendations are also presented for the leading cable models. Using the modelling recommendations to select suitable MMC models, radial and MT EMT MMC-HVDC models for the connection of typical Round 3 windfarms are developed in this thesis. These models are used to analyse the steady-state and transient performance of the connections, including their compliance to the GB grid code for AC disturbances and reactive power requirements. Furthermore, the MT model is used to investigate the effect of MT control strategies on the internal MMC quantities.
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Bissal, Ara. "Modeling and Verification of Ultra-Fast Electro-Mechanical Actuators for HVDC Breakers." Doctoral thesis, KTH, Elektroteknisk teori och konstruktion, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-162921.
Full textAbstract:
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 ultra-fast electro-mechanical actuator systems suitable for such HVDC breakers.Initially, holistic multi-physics and hybrid models with different levels of complexity and computation time were developed to simulate the entire switch. These models were validated by laboratory experiments. Following a generalized analysis, in depth investigations involving simulations complemented with experiments were carried out on two of the sub-components of the switch: the ultra-fast actuator and the damper. The actuator efficiency, final speed, peak current, and maximum force were explored for different design data.The results show that models with different levels of complexity should be used to model the entire switch based on the magnitude of the impulsive forces. Deformations in the form of bending or elongation may deteriorate the efficiency of the actuator losing as much as 35%. If that cannot be avoided, then the developed first order hybrid model should be used since it can simulate the behavior of the mechanical switch with a very good accuracy. Otherwise, a model comprising of an electric circuit coupled to an electromagnetic FEM model with a simple mechanics model, is sufficient.It has been shown that using a housing made of magnetic material such as Permedyn, can boost the efficiency of an actuator by as much as 80%. In light of further optimizing the ultra-fast actuator, a robust optimization algorithm was developed and parallelized. In total, 20520 FEM models were computed successfully for a total simulation time of 7 weeks. One output from this optimization was that a capacitance of 2 mF, a charging voltage of 1100 V and 40 turns yields the highest efficiency (15%) if the desired velocity is between 10 m/s and 12 m/s.The performed studies on the passive magnetic damper showed that the Halbach arrangement gives a damping force that is two and a half times larger than oppositely oriented axially magnetized magnets. Furthermore, the 2D optimization model showed that a copper thickness of 1.5 mm and an iron tube that is 2 mm thick is the optimum damper configuration.QC 20150422
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Ferro, Federica. "Leveraging a service oriented architecture for automatic retrieval and processing of fault recordings to obtain information for maintenance of circuit breakers." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254407.
Full textAbstract:
Maintenance of power system components is fundamental to ensure high qualityoperations and avoid malfunctioning. Given the crucial role of the circuitbreakers (CBs) in ensuring quality of the power systems operations, this thesisworks on the implementation of an automatic retrieval and processing offault recordings with the aim compute quantities relevant for maintenance andpreventive maintenance of the CBs. For the scope, a service oriented architecture(SOA) is developed on top of the power system and connected with twoapplications able to automatically retrieve, decode and use fault recordingsto obtain indicators on the health of the CBs. Even if the lack of a commonmetadata for fault recordings does not permit generalizations on the topic, theproject shows that the resulting layered architecture composed of power system,SOA and applications, allows to automatically obtain indicators on thestate of the CBs and consequently to improve maintenance of the analyzedarea of the substation.Underhåll av strömkomponenter är grundläggande för att säkerställa högkvalitativaoperationer och undvika funktionsfel. Med tanke på den avgörande rollsom strömbrytare (CBs) har för att säkerställa kvaliteten på ställverkoperationerna,så fokuserar avhandlingen på genomförandet av en automatisk hämtningoch behandling av felinspelningar med syftet att beräkna kvantiteter somär relevanta för underhåll och förebyggande underhåll av CBs. För omfattningen,en serviceorienterad arkitektur (SOA) är utvecklad ovanpå elsystemet ochkopplat till två applikationer som automatiskt kan hämta, avkoda och användafelinspelningar för att få indikatorer på hälsan hos CBs. Även om bristenpå en gemensam metadata för felinspelningar inte tillåter generaliseringar avmetoden, så visar projektet att den resulterande arkitekturen som består avkraftsystem, SOA och applikationer, möjliggör att automatiskt få indikatorerpå tillståndet hos CBs och följaktligen förbättra underhållet av kraftverketsanalyserade område.
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Bonkarev, Maxim [Verfasser], and Harald [Akademischer Betreuer] Schwarz. "Concept analysis for High-Voltage Direct-Current circuit breakers for application in a network of HVDC transmission / Maxim Bonkarev ; Betreuer: Harald Schwarz." Cottbus : BTU Cottbus - Senftenberg, 2015. http://d-nb.info/1114283959/34.
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Zhong, Linlin. "Influence of copper contamination on thermophysical, radiation, and dielectric breakdown properties of CO2-N2 mixtures as replacement of SF6 in circuit breakers." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30114/document.
Full textAbstract:
La thèse porte sur les propriétés thermodynamiques, de transport, de diffusion de rayonnement, et diélectriques des mélanges CO2-N2 contaminés par du cuivre, pour des températures de 300 - 30,000 K et des pressions 0.1 - 16 bar. Les motivations de ce travail ainsi qu'un état de l'art sur le remplacement du SF6 et l'influence des vapeurs métalliques dans de tels dispositifs sont présentés dans le chapitre 1. Le chapitre 2 étudie les compositions à l'équilibre calculées à partir de la méthode de minimisation de l'énergie libre de Gibbs, en considérant la présence de phases condensées dans le plasma. A partir de ces compositions, nous présentons les propriétés thermodynamiques comme la densité de masse, l'enthalpie et la chaleur spécifiques à pressions constante. Les corrections de Virial et Debye-Hückel sont prises en compte pour tenir compte de l'effet des ions et des hautes pressions. Dans le chapitre 3, les coefficients de transport (conductivité électrique, viscosité, et conductivité thermique) et les coefficients de diffusion combinés (coefficients de diffusion ordinaires combinés, ceux liés au champ électrique, aux gradients de pression et de température) sont calculés selon la théorie de Chapman-Enskog. Les intégrales de collision nécessaires au calcul de ces coefficients sont obtenues pour les interactions neutre-neutre et neutre-ion à partir d'un potentiel de Lennard-Jones modifié. Dans le chapitre 4, les coefficients d'émission nette (CEN) sont calculés en considérant le rayonnement des raies atomiques, du continuum atomique, des raies moléculaires et du continuum moléculaire. Les élargissements en pression des raies (élargissements de Van der Waals et de résonance), les élargissements Stark, et l'élargissement sont pris en compte dans la détermination d'un facteur de fuite qui permet de simplifier le calcul du coefficient d'émission des raies. Le rayonnement du continuum atomique tient compte de l'attachement radiatif, de la recombinaison radiative et du Bremsstrahlung. Dans le chapitre 5, les propriétés diélectriques de claquage (incluant la fonction de distribution d'énergie des EEDF), le coefficient réduit d'ionisation réduit, le coefficient réduit d'attachement électronique, le coefficient effectif réduit d'ionisation, et le champ critique réduit) du gaz chaud ont été calculés sur la base de l'approximation à deux termes de l'équation de Boltzmann. Les interactions, incluant les collisions élastiques, excitation, ionisation et attachement entre électrons et espèces neutres sont pris en compte dans la résolution de l'équation de Boltzmann. Les sections efficaces d'ionisation de Cu2 et CuO non disponibles dans la littérature ont été calcules selon la méthode DM. La conclusion des travaux et leurs perspectives sont présentés dans le chapitreSulfur hexafluoride (SF6) is a greenhouse gas designated by the Kyoto Protocol because of its extremely high global warming potential (GWP). CO2, N2, and their mixtures have the potential to replace SF6 in certain applications, such as circuit breakers. In these electric apparatus, copper vapour resulting from the heating of electrodes can modify the characteristics of arc plasmas, which must be taken into account when setting up physical models. This dissertation, therefore, investigates the thermodynamic, transport, diffusion, radiation, and dielectric breakdown properties of CO2-N2 mixtures contaminated by copper at temperatures of 300 - 30,000 K and pressures of 0.1 - 16 bar. The equilibrium compositions are calculated using the minimization of Gibbs free energy with consideration of condensed species. Copper vapour is found to condense at temperatures below 3000 K. Based on the compositions, the thermodynamic properties, including mass density, specific enthalpy, and specific heat at constant enthalpy, are determined according to their definitions. The Debye-Hückel corrections are also considered in the calculation of compositions and thermodynamic properties. The transport coefficients (including electrical conductivity, viscosity, thermal conductivity) and combined diffusion coefficients (including the combined ordinary diffusion coefficient, combined electric field diffusion coefficient, combined temperature diffusion coefficient and combined pressure diffusion coefficient) are calculated based on the Chapman-Enskog theory. The newly developed Lennard-Jones like phenomenological model potential is adopted to describe the neutral-neutral and neutral-ion interactions in determining collision integrals. The net emission coefficients (NEC) of gas mixtures are calculated with considering atomic lines and continuum and molecular bands and continuum. The pressure broadening (Van der Waals broadening and the resonance broadening), Stark broadening, and Doppler broadening are taken into account in the determination of escape factors. The continuum radiation of atoms is described by radiative attachment, radiative recombination, and Bremsstrahlung. The dielectric breakdown properties (including EEDF, reduced ionization coefficient, reduced electron attachment coefficient, reduced effective ionization coefficient, and reduced critical electric field strength) of hot gas mixtures are calculated based on the two-term approximation of the Boltzmann equation. The interactions, including elastic, excitation, ionization and attachment collisions, between electrons and neutral species are taken into account in solving the Boltzmann equation. The ionization cross sections of Cu2 and CuO which are unavailable in literatures are calculated using the DM method. Compared with SF6-Cu mixtures, CO2-N2-Cu mixtures present much different thermophysical, radiation, and dielectric breakdown properties. As an arc quenching gas, CO2-N2-Cu mixtures have lower ??Cp and thermal conductivity at low temperatures but present higher ??Cp, thermal conductivity, and NEC in the medium temperature range. As an insulating medium, the hot CO2-N2-Cu mixtures have much poorer dielectric strength below 2000 K, whereas above 2000 K, they present better dielectric breakdown performance than SF6-Cu mixtures