• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.214-215
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• 1994

The VCB(Vacuum Circuit Breaker), which has been used in power distribution system, have prevented the performance of the phase modifying equipment (Condenser Bank and Shunt Reactor) and the important parts in the electric power system because of the transient voltage in opening and closing circuit. So, we developed the 25.8kV $SF_6$ gas GCB(GAS Circuit Breaker), which had the few occurance of the surge in opening & closing circuit and had the high reliability, based in our own technology.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1362-1364
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• 2000

This paper presents the control algorithm verification process for VCB (Vacuum Circuit Breaker) of Korean High Speed Train. In order to enhance the reliability of the control algorithm, the verification process must be performed. The verification is conducted by comparing the pre-designed control algorithm with the pre-planned scenario by simulation tools such as SDL and MSC. This verification process will be applied to the other control algorithms of various control units of Korean High Speed Train.

• 대한전기학회논문지
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• 제43권5호
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• pp.761-769
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• 1994

VCB (Vacuum Circuit Breaker), with the strong arc extinction capability in switching the source of an induction motor, occurs the severe switching surge voltage which can cause the breakdown or the deterioration of motor insulation. Therefore, a method which reduces surge voltage across motor windings is necessary. So, it is analyzed that fast-rise-time surges resulting from VCB switching operations give rise to severe voltage stress on turn insulation. Additionally, the switching surge simulation algorithms using EMTP are developed, and C, R values of surge suppressor minimizing the steep-fronted stress in winding insulation surges are calculated.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1603-1605
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• 1994

Recently, Gas Circuit Breakers are rapidly replacing Vacuum Circuit Breakers in the medium voltage switchgear. This is due to the improved performance of - GCB in interrupting capability, price, weight, size etc., while the countermeasure to suppress the switching surges of VCB has not been satisfactory. Intensive research works on the GCB have been conducted in the world widely since 1980. Nowadays it is well known that the thermal expansion type GCB can provide- better performance than puffer type in the distribution power system. KERI has conducted researches in the GCB rated at 25.8kV 25kA with Jinkwang Co. using the thermal expantion principle since 1993. In this paper, the calculated results of electric and magnetic fields for the model GCB are presented and analyzed. The effect of permanent magnet used to improve the interruption capabilty at the low current level is also investigated. The design parameters for the interrupter inspected through the short-circuit tests conducted at high power laboratory of KERI.

• 한국전기전자재료학회논문지
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• 제28권10호
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• pp.630-635
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• 2015

A vacuum Interrupter (VI), a core part that composes the breaking part of medium-voltage vacuum circuit breaker (VCB), has the excellent insulation performance and arc-extinguishing capability. $SF_6$ gas had been used for the external insulation of VIs since the dielectric strength of $SF_6$ gas is superior to that of other insulation gases. However, because of environmental problems related with global warming, a solid-insulated technology was recently researched. The functionally graded material (FGM), as changing spatially the distribution of the relative permittivity inside an insulator, can reduce the electric field stress at the specific region. Especially, the external insulation performance of the VI with the molded FGM insulator is greatly improved as compared with that of the existing VI or the VI with a new external shield. In this paper, the effectiveness of this FGM insulator is verified by the numerical simulation.

• 한국정보통신학회논문지
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• 제18권10호
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• pp.2503-2508
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• 2014

본 연구는 진공차단기 기계식 보조접점(MOC)의 구조적인 취약성을 해결하기 위해 전자식 센서 기술을 이용한 전자식 보조접점(EOC) 개발에 선행되어야할 센서의 선정 및 노이즈 시험에 관한 것으로, 기존 기계적 보조접점(MOC)에서 발생하는 반복적인 떨림 및 반동 현상에 의한 접점 오동작을 최소화하는 제품을 개발하는 것을 최종 목표로 하였다. 실험 결과, 차단기 투입 및 개방시 개방시의 써지전압 상승속도가 투입시 보다 4.2배 빠른 것으로 측정되었고, 소음크기는 각각 120dB, 110dB로 측정되었다. 상용주파과전압 60kV를 인가하였을 때 진공차단기 투입 및 개방시 센서에서 출력되는 파형은 일그러짐이 없이 정상적으로 동작됨을 알 수 있었다. 그리고 150kV $1.2{\times}50{\mu}s$의 충격파를 인가하였을 때 센서의 투입 및 개방측 출력접점의 전압파형이 일그러짐이 없이 정상상태를 유지하였으며, 2500A의 전류를 인가하였을 때 자계 잡음을 측정한 결과, 전압파형이 일그러짐이 없이 정상적으로 동작하였다.