• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.8
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• pp.354-358
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• 2003

In this paper, insulations characteristics by temperature changes(＋50～-50[$^{\circ}C$]) of $SF_{6}$ gas in the experimental chamber were studied. From this result, at the low temperature, the breakdown voltage was increased with a drop of temperature and an increase of inner pressure in GIS. In addition the ability of insulation of liquid $SF_{6}$ was higher than that of the highly pressurized $SF_{6}$ gas. That is, with progress of low temperature, the main reason of breakdown was not liquefaction of $SF_{6}$ but rapid decrease of inner pressure. This study will come in greatly handy for the insulation design of GIS in a hard cold region

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.2
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• pp.95-101
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• 1999

The electron energy distributions function were analysed in sulIitur hexaflowide at E/N : 500~800(Td) for a case of non-equilibrium region in the nran electron energy. This papa- describes the electron transport characteristics in $ SF_6$ gas calculated for range of E/N values from 150~800(Td) by the Monte Carlo simulation and Boltzmann equation Irethod using a set of electron collision cross sectioos determined by the authors and the values of electron swarm parameters. The results gained that the value of an electron swarm parameter such as the electron drift velocity, the electron ionization or attachment coefficients, longitudinal and transverse diffusion coefficients agree with the experimental and theoretical for a range of E/N. The properties of electron avalanches in an electron energy non-equilibrium region.region.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.2
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• pp.85-90
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• 1998

This paper describes the breakdown characteristics of GIS by the free conducting particles under alternating voltage. If the conducting particles are present within the GIS, they can cause decrease in breakdown voltages. Various materials and sizes of free conducting particles were used to study the liftoff electric field and breakdown voltage. The measured lift-off electric fields were compared with the calculated ones for copper, steel and aluminium wire-type conducting particles. As an experimental result, it is shown that the breakdown voltages of the GIS chamber with conducting particles were lower than those without conducting particles, and were markedly dependent on the particle material and the particle sizes. Free conducting particles are important factor in particle-triggered breakdown of the GIS.he GIS.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.1
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• pp.75-81
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• 2000

This paper describes the partial discharge due to particles in $SF_6$ gas. A model GIS chamber was designed and manufactured. The partial discharge and breakdown phenomena due to the particles between electrodes were observed and partial discharge signals were detected, using an ultrasonic sensor. The analysis of the electric field by the states of the particle inserted between the electrodes, were also carried out. The partial discharge was observed at end while the particle was moving in $SF_6$ gas. The partial discharge in micro-gap grows to arc, and after all, it can cause a breakdown.The electric field strength was the highest in case that the particle was vertically attached on the conductor, and the lowest in case that it was horizontally attached on the enclosure.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1262-1263
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• 2011

Sulfur hexafluoride is the most commly used insulation gas in electrical systems. Gas insulated systems are widely used in the electric power industry for transmission and distribution of electrical energy. When $SF_6$ was first discovered, the potential application was only considered for insulation because of good dielectric properties. But the widespread use of $SF_6$ gas by electric power and other industries has led to increase concentrations of $SF_6$ gas in the atmosphere. This concern as to possible effects on global warming because $SF_6$ is a potent greenhouse gas. That's why firstly we studied uniform and nonuniform field property by mixing $SF_6$ and N2 gas. This paper presents the dielectric strength and insulating property for particle contamination under $SF_6/N_2$ mixtures. Two types of mixed gases(50% $SF_6$_50%$N_2$, 20% $SF_6$_80%$N_2$) were applied. We performed tests for the length and shape of particle. Test gas pressure is from 0.3 to 0.7 Mpa. The study was conducted to develop environment-friendly insulating material for GIS that can reduce $SF_6$ gas and make a design criteria for mixtures.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1403-1406
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• 2002

Environmental impact of human activities has become a great concern in most of the countries world-wide, and for years. It has recently focused on potential climate changes due to the increase of green house gases content in the atmosphere. One of these gases is $SF_6$, which is an essential material in electrical applications having excellent dielectric and arc-quenching properties. Though the actual contribution of $SF_6$ to global warming is negligible at present, the control of $SF_6$ emissions seems to be nevertheless imperative. Actually, it is listed in the Kyoto protocol that emissions should not only be duly reported but also the electrical industry which is now the major user of this gas must be able to show that it is possible to use this gas and at the same time preserve the environment. For the development of environmentally-benign electric power equipment and systems, novel gases or gas mixtures are strongly required as the alternatives of $SF_6$ gas. Until now, most research work is focused on the $SF_6/N_2$ mixed gas which is suitable for application in the electrical apparatus with slightly non-uniform fields. Recently, $SF_6/CO_2$ mixed gas also is expected to be promising as a $SF_6$ alternative, especially in highly non-uniform fields and in a gas-impregnated film insulation system. Including these results, the author reviews the research trend or reducing the environmental impact of $SF_6$ gas in this paper.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.4
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• pp.635-640
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• 2008

New gas mixtures are now finding applications such as interrupting media for high-voltage circuit breakers. These mixtures consist of a high content of carbon tetrafluoride($CF_4$) added to sulfur hexafluoride($SF_6$). Nowdays $SF_6$ has been established for the use in gas insulated substations due to its high insulation withstand level and good arc quenching capability. At this paper Breakdown characteristics were investigated for $SF_6/CF_4$ mixtures when AC voltage and standard lightning impulse voltage(LI) was applied in a needle-plane electrodes. And partial discharge(PD) experiments were carried out in the test chamber which was made in needle-plane electrode. And ${\Phi}$-Q-N distribution of partial discharge signals was analyzed. The total pressure of the $SF_6/CF_4$ mixtures was varied within the range of 0.1-0.5 Mpa in the test chamber. The breakdown voltage in needle-plane electrode displayed N shape characteristics for increasing the content of $SF_6$ at positive impulse voltage and the PD inception voltage was increased slightly when pressure of $SF_6/CF_4$ Mixtures was increased. Maximum PD inception voltage is showed in 80% SF6/20%$CF_4$.

• KEPCO Journal on Electric Power and Energy
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• v.8 no.1
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• pp.37-41
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• 2022

Because sulfur hexafluoride(SF₆) is classified as one of the six major greenhouse gases, SF₆ handling in power plant such as recovery, purification, and reuse is considered to be important. KEPCO has focused to develop the advanced recovery and purification technology of SF₆ reuse. SF₆ analysis includes the on-site analyses and on-line analyzer; i.e., (1) on-site analysis has an error rate of ±0.5% and (2) on-line analysis has an error rate of ±0.1%, which is possible to adjust operating conditions and to make the work more conveniently by analyzing SF₆ concentration before and after purification step. This paper presents an online analysis method in the SF₆ purification and reuse system. In addition, the analysis results and quality guarantees for each section of the analysis system were presented.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.365-368
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• 2002

The design of industrial arc plasma systems is still largely based on trial and error although the situation is rapidly improving because of the available computational power at a cost which is still fast coming down. The desire to predict the behavior of arc plasma system, thus reducing the development cost, has been the motivation of arc research. To interrupt fault current, the most enormous duty of a circuit breaker, is achieved by separating two contacts in a interruption medium, $SF_{6}$ gas or air etc., and arc plasma is inevitably established between the contacts. The arc must be controlled and interrupted at an appropriate current zero. In order to analyze arc behavior in $SF_{6}$ gas circuit breakers, a numerical calculation method combined with flow field and electromagnetic field has been developed. The method has been applied to model arc generated in the Aachen nozzle and compared the results with the experimental results. Next, we have simulated the unsteady flow characteristics to be induced by arcing of AC cycle, and conformed that the method can predict arc behavior in account of thermal transport to $SF_{6}$ gas around the arc, such as increase of arc voltage near current zero and dependency of arc radius on arc current to maintain constant arc current density.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1354-1355
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• 2008

교류 펄스전압을 이용한 글라이딩 아크 플라즈마를 이용하여 PFCs(Perfluoro compounds) 가스의 일종인 $CF_4$ $SF_6$, $NF_3$를 가스분해하는 연구를 실시하였다. 반응기 양전극 사이에 인가되는 전압은 10kV로 고정하고 각각의 가스의 유량을 조절하여 분해한후 FT-IR을 통해 각각의 가스의 분해율과 분해후 가스내 성분을 스펙트럼을 이용하여 분석하였다. 유량이 낮아질수록 분해율은 좋아졌고 $SF_6$와 $NF_3$의 경우 99%이상의 높은 분해율에 도달하였을 뿐 아니라 대표적인 난분해 가스로 손꼽히는 $CF_4$의 경우 82%이상의 분해율을 확인하였다.