• Proceedings of the KSME Conference
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• 2001.11b
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• pp.523-528
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• 2001

There are many difficult problems in analyzing the flow characteristics in a high voltage circuit breaker such as shock wave and complex geometries, which may be either static or in relative motion. Although a variety of mesh generation techniques are now available, the generation of meshes around complicated, multicomponent geometries like a gas circuit breaker is still a tedious and difficult task for the computational fluid dynamics. This paper presents the computational method for analyzing the compressible flow fields in a high voltage gas circuit breaker using the Cartesian cut-cell method based on the CFD-CAD integration, which can achieve the accurate representation of the geometry designed by a CAD tools. The technique is frequently satisfied, and it will be almost universally so in the future, as the CFD-CAD traffic increases.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.305-310
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• 2001

This paper presents the computational method for analyzing the compressible flow fields in a high voltage gas circuit breaker. There are many difficult problems in analyzing the gas flow in GCB due to complex geometry, moving boundary, shock wave and so on. In particular, the distortion problem of the grid due to the movement of moving parts can be worked out by the fixed grid technique. Numerical simulations are based on a fully implicit finite volume method of the compressible Reynolds-averaged Navier-Stokes equations to obtain the pressure, density, and velocity through the entire interruption process. The presented method is applied to the real circuit breaker model and the pressure in front of the piston is good agreement with the experimental one.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.91-94
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• 2002

It is important to develop new effective technologies for increasing the interruption capacity and reducing the size of a GCB (Gas Circuit Breaker). It is not easy to test the real GCB model in practice as in theory. Therefore, a simulation tool based on a CFD (Computational Fluid Dynamics) algorithm has been developed to facilitate an optimization of the interrupter. But the choice of grid is not at all trivial in the complicated geometries like a GCB. In this paper, we have applied a CFD-CAD integration using Cartesian cut-cell method, which is one of the grid generation techniques for dealing with complex and multi-component geometries.

• Proceedings of the KIEE Conference
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• summer
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• pp.1100-1102
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• 2004

열팽창 방식의 가스차단기는 아크 에너지 자체를 이용하여 압력상승을 얻고, 상승된 압력을 이용하여 전류 영점 부근에서 아크 방향으로의 유동을 형성하여 아크를 소호한다. 대전류 구간에서 노즐 폐색현상이 일어나면 노즐 용삭이 크게 일어나며 용삭된 노즐 물질은 팽창실의 압력과 온도를 상승시키게 된다. 따라서 차단 특성해석을 위해서는 노즐 용삭에 의한 압력 상승해석이 필요하다. 본 논문에서는 아크에너지에 따른 노즐 용삭비를 이용하여 용삭되는 노즐량을 계산하고, 이로 인한 back flow현상을 고려한 해석 방법을 제안한다. 개발된 프로그램을 제작한 차단부 모델에 적용한 결과, 열팽창실의 압력상승치는 시험결과와 잘 일치함을 확인하였다.

• 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.

• 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.

• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.22-24
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• 2006

This paper presents the prediction method of small current interruption Performance for EHV gas circuit breakers. The FVFLIC method is used for the gas flow analysis and the FEM for the electric field analysis. Then, the dielectric withstanding voltage is evaluated by the empirical formulation or Streamer theory. By comparing the calculated dielectric strength with the test result. it is found that both methods show good prediction capability for the small current interruption performance. Especially, when both methods predict the same interrupting performance, the prediction is in accordance with the experimental result.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.8
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• pp.384-391
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• 2001

The insulation strength between contacts after current interruption to the transient recovery voltage i.e., the dielectric recovery strength should be estimated for the evaluation of the small capacitive current interruption capability. Many authors have used theoretical and semi-experimental approaches to evaluate the transient breakdown voltage after the current interruption. Moreover, an empirical equation, which is obtained from a series of tests, has been used to estimated the dielectric recovery strength. Un this paper, the theoretical method which is generated from the streamer theory has been applied to real circuit breakers in order to evaluated the interruption capability. The results of analysis have been compared with the test results and the reliability has been investigated.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.94-96
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• 1997

A mathematical model (hybrid arc model) for arc behaviour in an $SF_6$ puffer gas-blast circuit-breaker has been developed. It has adopted the advantages of integral method and differential method. The method has been applied to model puffer circuit breaker of Noeske et al and good agreement of critical RRRV(Ratio of Rise of Recovery Voltage) has been obtained. Axial or radial distributions of temperature, electric field and arc radius are also presented and analyzed.

• 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.