• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.846_846
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• 2009

노즐의 용삭은 초고압 가스 차단기의 압력 상승에 중요한 역할을 한다. 기존의 연구는 총 아크 에너지와 용삭량과의 관계에 집중되어 왔으며 아크 에너지 대신 전류의 제곱등을 사용하기도 했다. 본 논문에서는 반복 시험을 통해 노즐 용삭 특성을 구하였으며, 이를 통해 아크의 전류, 전압과 용삭량과의 상관관계를 구하였다. 또한 계단형 노즐을 사용하여 노즐 반지름과 용삭량과의 관계에 대해서도 살펴보았다.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1772-1774
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• 2004

Because the physics occurring during an interruption process is not well known, it is not easy to analyze the characteristics of a self-blast circuit breaker neither theoretically nor experimentally. Fortunately the available computational power and the numerical method improved recently make it possible to predict an interruption process as precisely and fast as possible. Therefore many researches using computational methods have been done for the interruption process of interrupters and applied to extend the information such as thermal and dielectric reignition. In this paper, we have simulated the interruption process of SF6 self-blast circuit breakers with the arc plasma during the fault interruption of a 10 kA current. The CFD program used here is coupled with the electromagnetic field analysis, the radiation model and the effects of turbulence. Through this work, we have get further information about the thermal performance as well as the behavior of the arc. The results have been compared with the measured arc voltage.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2076-2079
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• 1999

This paper describes the analysis results on the PT ferroresonance at 154 kV GIS (gas Insulated substation by EMTP (Electro-magnetic Transient Program). We had simulated the PT ferroresonance between a potential transformer(PT) and an open circuit breaker's grading capacitance. The ferroresonance leads to very large power frequency overvoltages on PT bus and subsequent insulation failure. The large power can be supplied to the PT by the high voltage on the opened circuit due to the grading capacitance and equivalent capacitance of the buses during the ferroresonance. The damping circuit connected on the secondary winding were considered in the model. The actual countermeasure include a saturable inductor and a resistor series-mounted, but the 2 ohms of damping resistance was used in the computational model.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1665-1667
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• 2003

Recently, a breaking capacity increases with breaking method using gas pressure from ablation materials in low voltage circuit breakers. In this paper, we investigated arc quenching materials with spectroscopic method. Especially, Hydrogen spectrum was investigated because its dielectric characteristics are better than other gases. We selected two arc quenching materials, UP and PA6, that use in circuit breakers. They had hydrogen spectrums, but PA6 was better than UP in the qualitative aspect.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.3
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• pp.129-134
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• 2004

To analyze the performance of the gas circuit breaker(GCB), the flow field variables such as temperature, pressure and density should be evaluated accurately In the puffer chamber of puffer type GCB, the pressure rise may Exceed 20 bar and in this range of high pressure, $SF_6$ gas deviates the ideal gas property. Therefore, the real gas property of $SF_6$ should be taken into consideration for the accurate analysis of flow field. This paper presents the analysis technique of cold gas flow in GCB employing the real gas state equation of SF6. The FVFLIC method is Employed to solve the axisymmetric Euler equation. To reduce the computational effort of real gas state equation, the relationship between density and pressure is approximated by the polynomial at the temperature of 300K. The proposed method is applied to the test GCB model and simulation results show good agreement with the experimental ones.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.104-108
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• 1997

The puffer type GCB(gas circuit breaker) has been widely used in modern transmission power system. Understanding the motion of cold $SF_6$ gas flow is essential for the better design of those GCB's. For this purpose, a program using the so-called FLIC(Fluid-In-Cell) method has been developed and applied to a puffer type GCB. The calculated results are compared with those from the measurement and the computation by commercial CFD (Computational Fluid Dynamics) package 'RAMPANT' and show fairly good agreement.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.12
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• pp.36-46
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• 2008

This paper is to study on the Construction of Test circuit and Unification of Experiment Method for high voltage gas-insulated load switch using high power testing system The high power testing system is a equipment to verify electrical and mechanical performance on electrical product. The system consist of short-circuit generator, back-up breaker, making switch, impedance, high voltage transformer, low voltage transformer, measuring and protection system, etc. Using this system, we can test related to high power, for example, short-time current test, active load Current test, magnetizing Current test, capacitive current test, closed loop current test, etc. Standards of high voltage gas-insulated load switch that is in use domestic distribution line are ES 5925-0002, IEC 60265-1, IEC 62271-1 and IEEE C 37.74, etc. In this paper, we standardized on the test procedure, organization of test circuit and analysis of measured data prescribed many difference standards, and applied this test method to 600[MVA] high power testing system. So that we can test the load switch satisfied standards.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1181-1187
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• 2015

Sulfur hexafluoride (SF₆) gas is used widely in electric power equipment such as Gas Insulated Switchgear (GIS), Gas Insulation transmission Line (GIL), and Gas Circuit Breaker (GCB). But applications of SF₆ should be restricted because SF6 gas is one of the greenhouse effect gases. To reduce use of SF₆ gas, a study on eco-friendly alternative insulation medium is needed. In this paper, we investigated lightning impulse (LI) breakdown of dry-air which is attracting attention as an ecofriendly alternative gas and the LI breakdown of hybrid insulation combined with dry-air and solid insulation (Room-Temperature Vulcanizing Silicone Rubber-RTV SIR) and dry-air in inhomogeneous fields according to gap distance and pressure. The experiment results showed that the LI breakdown strength of hybrid insulation system was higher than that of dry-air insulation system. It was verified that the development of technology related to eco-friendly power apparatus compact such GIS, GCB and GIL can be used as basic research data.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.5
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• pp.242-248
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• 2002

It is important to develop new effective technologies to increase the interruption capacity and to reduce the size of a UB(Gas Circuit Breakers). Major design parameters such as nozzle geometries and interrupting chamber dimensions affect the cooling of the arc and the breaking performance. But it is not easy to test real GCB model in practice as in theory. Therefore, a simulation tool based on a computational fluid dynamics(CFD) algorithm has been developed to facilitate an optimization of the interrupter. Special attention has been paid to the supersonic flow phenomena between contacts and the observation of hat-gas flow for estimating the breaking performance. However, there are many difficult problems in calculating the flow characteristics in a GCB such as shock wave and complex geometries, which may be either static or in relative motion. Although a number of mesh generation techniques are now available, the generation of meshes around complicated, multi-component geometries like a GCB is still a tedious and difficult task for the computational fluid dynamics. This paper presents the CFD program using CFB-CAD integration technique based on Cartesian cut-cell method, which could reduce researcher's efforts to generate the mesh and achieve the accurate representation of the geometry designed by a CAD tools.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.480-480
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• 2008

Vacuum circuit breaker(VCB) is now emerging as an alternative of gas circuit breaker(GCB) which uses SF6 gas as insulating material whose dielectric strength is outstanding. But we have to reduce SF6 gas because SF6 gas is one of greenhouse gas and efforts to reduce greenhouse gas are now trend of the world. Therefore, we can say VCB is the optimal alternative of GCB because vacuum is environmentally friendly. The vacuum interrupter is the core part of VCB to interrupt arcing current. There are mainly two methods to extinguish arc. One is radial magnetic field (RMF) method and the other is axial magnetic field (AMF) method. We deals with RMF method in this paper. Compared with AMP, RMF arc quenching method has different principle to extinguish arc. In case of RMF method, pinch effect is much larger than AMF method. Because of pinch effect RMF type contact electrodes have the single large spot which is severly damaged and melted while AMF type contact electrodes have small and multiple spots which are slightly damaged and melted. To prevent contact electrode being damaged and melted from high temperature-arc, RMF method uses Lorentz force to move arc. In this paper we calculated and compared the arc driving force of two cases and we analyzed the force acting on each part of arc by means of commercial finite element method software Maxwell 3D. They have 3petals and we considered two cases. One is the case when fixed(upper) and movable(lower) contacts are in mirror arrangement (Case 1). The other is the case when one of two contacts (movable contact) is revolved at maximum angle as possible as it can be (Case 2). And at each case above, we analyzed arc driving force at two positions, position 1 is the closest to the center of contact and position 2 is near the edge of petal on fixed contact. As a result we could find that Case 2 generated stronger arc driving force than Case 1 at position 1. But at position 2 Case 1 generated stronger arc driving force than Case 2. This simulation method can contribute to optimizing spiral-type electrode designs in a view of arc driving force.