• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.165-167
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• 1995

In this paper, the principle of the magnetic flux generation which influences the magnitude of the arc rotation in the interrupter of rotary arc type gas circuit breaker(GCB) is explained. The several factors making the phase difference between arc current and generated flux are analyzed and used to design and manufacture the rotary arc type model GCB. The magnetic flux density is calculated for the model GCB and the calculated result compared with that of the measured one.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.80-82
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• 1996

This paper deals with the effects of the volume of thermal expansion chamber on the interrupting performance in thermal expansion type 25.8kV 25kA gas circuit breaker. Model interrupters with 5 type thermal expansion chamber were designed and manufactured. Short-circuit tests were carried out for those model interrupters with 25kA breaking current. Pressure rise in the expansion chamber were measured and compared with the calculated one which was obtained from a self-developed program in our team. The analysis on the interrupting performance of each model interrupter has been done on the base of the short-circuit test results.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.160-163
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• 2003

This paper represent a test method for the reliability assessment on the indoor vacuum circuit breakers used in the distribution system by an accelerated life test. In order to guarantee the lifetime in service of the vacuum circuit breaker, additional test methods are suggested. Multiple closing-opening operation test under no load condition as a mechanical endurance test and a check of the quality in the vacuum interrupter are adopted to assure the long-term reliability of the vacuum circuit breaker.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.161-163
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• 1998

The interruption performance of EHV class gas circuit breakers critically depends on the flow conditions inside interrupter and the external circuit conditions. In case of puffer type gas circuit breakers the flow conditons are significantly influenced by arcing time. In this paper the calculated results of RRRV and pressure rise at current zero with varying arcing time are presented and the effect of arcing time on the thermal interruption performance of EHV class gas circuit breakers is analyzed.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.640-644
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• 1993

A mathematical arc model based on the integral method has been developed to study the arc behaviour of $SF_6$ Puffer circuit breakers during high current period. The interaction between the compression chamber and the arc interrupter plays a critical role in determining the arc behaviour. Computations have been carried out for the puffer circuit breaker of Noeske et al.[1]. The aerodynamic behaviour and electrical characteristics of the puffer circuit breaker have been investigated. In addition, the pressure rise in the compression chamber and arc voltage have been computed and the results compared with the available experimental results of Noeske et al.[1]. Special attention has been paid to the presence of the shock.

• 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.

• Transactions of the KSME C: Technology and Education
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• v.3 no.2
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• pp.141-148
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• 2015

In this study, the VCB(Vacuum Circuit Breaker) has been developed using the Recurdyn that is widely used on multibody dynamics analysis. The VCB consists of three main circuits with the VI(Vacuum Interrupter) and the main frame with the operating mechanism. This analytic model is validated by comparing the simulation results and the experimental results. Generally, in order to reliably cut off the breaking current, the opening speed of the VCB after contact separation has to be a 0.9~1.1m/s. Therefore, the study of the design parameters of the VCB is needed. To improve the opening velocity, Taguchi design method is applied to optimize the design parameters of a VCB with a lot of linkages. In addition, to evaluate the improvement of the operating characteristics, the simulation results are compared with the Recurdyn and experimental results with improved prototype sample.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2494-2499
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• 2007

Self-blast circuit breakers utilize the energy dissipated by the arc itself to create the required conditions for arc quenching during the current zero. The high-current simulation provides information about the mixing process of the hot PTFE cloud with $SF_6$ gas which is difficult to access for measurement. But it is also hard to simulate flow phenomenon because the flow in interrupter with high current, $SF_6$-PTFE mixture vapor and complex physical behavior including radiation, calculation of electric field. Using a commercial computational fluid dynamics(CFD) package, the conservation equation for the gas and temperature, velocity and electric fields within breaker can be solved. Results show good agreement between the predicted and measured pressure rise in the thermal chamber.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.11
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• pp.527-532
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• 2005

During the last ten years the new interruption techniques, which use the arc energy itself to increase the pressure inside a chamber by the PTFE nozzle ablation, have displaced the puffer circuit breakers due to reduced driving forces and better maintainability. In this paper, we have investigated the thermal flow characteristics inside a thermal puffer type gas circuit breaker by solving the Wavier-Stokes equations coupled with Maxwell's equations for considering all instabilities effects such as turbulence and Lorentz forces by transient arc plasmas. These relative inexpensive computer simulations might help the engineer research and design the new interrupter in order to downscale and uprating the GIS integral.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.804-806
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• 2003

In these days the Vacuum Circuit Breaker(VCB) is used in most medium voltage level because VCB has merits of simple structure, long life, free maintenance and environment friendly characteristics. Most of VCBs adopt mechanical spring drive mechanism to operate vacuum interrupter, but this mechanism is composed of many components and needs frequent maintenance works. In this paper, we study about the VCB drive mechanism with Permanent Magnet Actuator (PMA). Design methods and design flows about PMA are presented. The magnetic equivalent circuit is used for elementary and detailed design to determine the size of PMA. Finite Element Method (FEM) analysis is performed to evaluate the behavior characteristics of PMA in both static and transient state. Finally we manufacture sample PMA and verify FEM analysis through experiments.