• Journal of Electrical Engineering and Technology
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• v.7 no.5
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• pp.778-783
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• 2012

The synthetic short-circuit making test to adequately stress the circuit breaker has been specified as the mandatory test duty in the IEC 62271-100. The purpose of this test is to give the maximum pre-arcing energy during making operation. And this requires the making operation with symmetrical short-circuit current that is established when the breakdown between contact gap occurs near the crest of the applied voltage. Also, if the interrupting chamber of circuit breakers is designed as the type of common enclosure or the operation is made by the gang operated mechanism that three-phase contacts are operated by one common mechanism, three-phase synthetic making test is basically required. Therefore, several testing laboratories have developed and proposed their own test circuits to properly evaluate the breaker performance. With these technical backgrounds, we have developed the new alternative three-phase making circuit.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.695-698
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• 2008

Self-blast circuit breakers utilize the energy dissipated by the arc itself to create the required conditions for arc quenching during the current zero. During the arcing period, high pressure, temperature and radiation of the arc could burn in pure SF6 gas and PTFE nozzle. Ablated nozzle shape and $SF_6$-PTFE mixture vapor affect the performance of an self-blast circuit breaker. After a number of tests, nozzle in circuit breaker is disassembled, a section of ablated nozzle is investigated precisely. Using computational fluid dynamics, the conservation equation for the gas and temperature, velocity and electric fields within breaker is solved. Before applying a section model, developed program is verified with experimental data. Performance of ablated nozzle shape is compared with original model through analysis program.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.6
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• pp.287-292
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• 2001

This paper deals with the configuration, operating principles, systematic calculation method of parameter and optimization method of test circuit for parallel current injection method, series voltage injection method and hybrid synthetic test method as the method for performance test of circuit breaker with extra high interrupting capacity. The test method depicted above is applied to short-circuit making and breaking test (operating sequence :Os CdOs, Od-CdOs) and out-of-phase tests(operating sequence :Os, CdOs) for performance test of the newly-developed 420kV, 50kA and 800kV 50kV puffer-type gas circuit-breaker according to IEC 60056 and IEC 60427. The testing results, evaluation of equivalence for test and analyzed results are also presented in this paper.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.7
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• pp.1199-1205
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• 2010

The recent power system is required to a large size of facilities and high power technology according to increasing power demand. However, it could lead to spoiling the beauty of city and environment problem. The miniaturized facilities with large capacity such as GIS have been required in recent power system. The GIS(Gas Insulated Substation) using the SF6 insulation gas enables to miniaturize facilities with large capacity with high insulation performance. However, the substation installed GIS has required to new design model which is different from the conventional substation. The TRV(Transient Recovery Voltage) analysis on simple circuit may applied by differential equation. However, in case of relatively complicated system, EMTP(Electro Magnetic Transients Program) mainly has been used to design and simulate for transient analysis. This paper mainly design the 22.9 kV GIS system and analyze the transient recovery voltage of main circuit breaker using EMTP/RV. It also enables to easily design the other substation installed GIS with same maker and voltage level because the proposed GIS model consists of separated modules such as busbar, circuit breaker, bushing, CT, PT etc. Eventually, it contributes to comfortably compare the interrupting performance of circuit breaker and system TRV corresponding to the substation system configuration.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.39-42
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• 2002

In this study, the computational heat transfer of the high-voltage vacuum circuit breaker was investigated. Higher normal current-ratings and stabilized thermal characteristics become more important in existing circuit breakers in order to satisfy market needs. Increases in current-ratings have an even greater effect on the Joule heating in the main circuit of the breakers. The thermal design must account for this increase in heat produced for the breaker to meet various temperature-rise limits set by industry standards. We are studying to enhance the normal current-ratings without major frame change of our present production models. As the method used in this research, we performed the computational analysis using the commercial Package, ICEPAK. We could get optimized thermal design suitable for 25% upgraded normal current-ratings through parametric study.

• Proceedings of the KIEE Conference
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• 2002.11a
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• pp.127-129
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• 2002

A new type of fiber-reinforced polymeric materials for the main body and the arc chamber of the low-voltage circuit breakers was developed. The tensile and the flectional strength of the three kinds of thermoplastic resins for the cover of MCCBs(Molded case circuit breakers) increase much higher than those made of BMC that has been used. In a high current-breaking test, an experimental MCCB with the new insulating material showed no-cracks on the bodies.

• Journal of the Korean Society of Safety
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• v.29 no.4
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• pp.54-60
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• 2014

This paper describes electric shock accidents on a 4.16 kV class circuit breaker for power plant. Electric shock accidents mostly involve damage of human life, in comparison with electrical fire, rate of human death tend to be higher in electric shock accidents. Specially, in a high voltage facilities rate of human death comprised about 43.7% by electric shock accidents. If electric shock accidents happen in a 4.16 kV class circuit breaker for power plant, then the power plant discontinue power production. Electric shock accidents in a power plant have a great ripple effect such as an electric power shortage. In this paper, we analyzed electric shock accidents on a 4.16 kV class circuit breaker for power plant. From the analysis results, we confirmed a cause of electric shock accidents on a 4.16 kV class circuit breaker, it happened by defect of interlock equipment or occurrence of breakdown between first feeder contactor and shielding plate. In order to reduce electric shock accidents on a 4.16 kV class circuit breaker, the power plant should consider improvement of interlock equipment and insulation of feeder contactor in circuit breaker.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.7
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• pp.105-113
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• 2011

The study about three-phase synthetic making test using DC power has been performed in order to increase the making test capacity on Vacuum Circuit Breaker. And, it made possible to solve the limitations that short-circuit testing facilities can not fulfill the testing requirements of VCB exceeding three-phase 36[kV] 31.5[kA]. By using DC power and high speed spark-gap switch, this method made the equivalence with the pre-arc that occurred during the making process under the fault condition of power system. As results, KERI(Korea Electrotechnology Research Institute) could have capacity to carry out type test for VCB under three-phase 52[kV] 40[kV], which satisfies the IEC Standard.

• Proceedings of the KIEE Conference
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• summer
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• pp.485-487
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• 2004

High-voltage gas-insulated circuit-breaker must interrupt short-circuit current successfully when breakdown occurs in electric power system. Among many test-duties, Basic Terminal fault T100a(BTF T100a) is the one of the severest duties because of its high DC component of short-circuit current. In this paper, we developed 245kV 50kA gas circuit breaker using control circuits to reduce DC component while interrupting short-circuit current, then got good performance through high-power tests in Korea Electrotechnology Research Institute(KERI) and KEMA

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.2
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• pp.190-195
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• 2013

Vacuum circuit breaker(VCB) has been widely used for interruption of load current and fault current for high voltage motor in the industrial field. Its arc extinguishing capability is excellent compared to other breakers. But it has the potential to cause multi reignition surge by high extinguishing capability. Surge voltage is generated by the opening and closing of VCB. Multi reignition surge of VCB is steep-fronted waveform. It may have a detrimental effect on the motor winding insulation. So, most of users install a protection device to limit steep-front waveform at the motor terminal or breaker side. So, most of users install a protection device at the motor terminal or breaker side. This protective device is surge absorber(SA) such as ZnO and RC type. In this study, we analyzed whether there is any effect when two type SA is applied to the VCB multi reignition surge. We confirmed that ZnO SA is slightly more effective than RC SA for reduction of multi reignition surge.