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Insulation Characteristics for a Conduction-Cooled HTS SMES
천현권,윤문수,백승명,김상현 한국초전도.저온공학회 2005 한국초전도저온공학회논문지 Vol.7 No.2
Toward the practical applications, on operation of conduction-cooled HTS SMES at temperatures well below 77 K should be investigated, in order to take advantage of a greater critical current density of HTS and considerably reduce the size and weight of the system. Recently, research and development concerning application of the conduction-cooled HTS SMES that is easily movement are actively progressing in Korea. Electrical insulation under cryogenic temperature is a key and an important element in the application of this apparatus. However, the behaviors of insulators for cryogenic conditions in air or vacuum are virtually unknown. Therefore, this work focuses on the breakdown and flashover phenomenology of dielectrics exposed in vacuum for temperatures ranging from room temperature to cryogenic temperature. Firstly, we summary the insulation factors of the magnet for HTS SMES. And a surface flashover as well as volume breakdown in air and vacuum has been investigated with two kind insulators. Finally, we will discuss applications for the HTS SMES including aging studies on model coils exposed in vacuum at cryogenic temperature.
Breakdown Characteristics and Survival Probability of Turn-to-Turn Models for a HTS Transformer
천현권,백승명,성기철,김상현,김해종 한국초전도.저온공학회 2005 한국초전도저온공학회논문지 Vol.7 No.2
Breakdown characteristics and survival probability of turn-to-turn models were investigated under ac and impulse voltage at 77K. For experiments, two test electrode models were fabricated: One is point contact model and the other is surface contact model. Both are made of copper wrapped by 0.025mm thick polyimide film(Kapton). The experimental results were analyzed statistically using Weibull distribution in order to examine the wrapping number effects on voltage-time characteristics under ac voltage as well as under impulse voltage in LN2. Also survival analysis were performed according to the Kaplan-Meier method. The breakdown voltages of surface contact model are lower than that of point contact model, because the contact area of surface contact model is wider than that of point contact model. Besides, the shape parameter of point contact model is a little bit larger than that of surface contact model. The time to breakdown t50 is decreased as the applied voltage is increased, and the lifetime indices slightly are increased as the number of layers is increased. According to the increasing applied voltage and decreasing wrapping number, the survival probability is increased.
천현권,최재형,곽동순,김해종,성기철,윤문수,김상현,Cheon Hyeon-Gweon,Choi Jae-Hyeong,Kwag Dong-Soon,Kim Hae-Jong,Seong Ki-Chul,Yun Mun-Soo,Kim Sang-Hyun 한국전기전자재료학회 2006 전기전자재료학회논문지 Vol.19 No.6
Toward the practical applications, on operation of conduction-cooled HTS SMES at temperatures well below 77 K should be investigated, in order to take advantage of a greater critical current density of HTS and considerably reduce the size and weight of the system. Recently, research and development concerning application of the conduction-cooled HTS SMES that is easily movement are actively progressing in Korea. Electrical insulation under cryogenic temperature is a key and an important element in the application of this apparatus. Using multi wrapped copper by Polyimide film for HTS SMES, the breakdown characteristics of models for turn-to-turn, that is surface contact model, were investigated under ac and impulse voltage at 77 K. A material that is Polyimide film (Kapton) 0.025 mm thickness is used for multi wrapping of the electrode. Statistical analysis of the results using Weibull distribution to examine the wrapping number effects on breakdown voltage under at and impulse voltage in $LN_2$ was carried.
곽동순,천현권,김해종,조전욱,정순용,김상현,Kwag, Dong-Soon,Cheon, Hyeon-Gweon,Kim, Hae-Jong,Cho, Jeon-Wook,Chung, Soon-Yong,Kim, Sang-Hyun 한국전기전자재료학회 2005 전기전자재료학회논문지 Vol.18 No.10
For the insulation design of a high temperature superconducting(HTS) cable, three kinds of design method were proposed, which used AC and impulse withstand voltage and partial discharge inception strength. However, the designed insulation thickness by AC and impulse could not be applied to cable fabrication process due to much low electrical breakdown strength. The effect of the multi-layered insulation paper was not considered on the previous insulation design and the insulation thickness by partial discharge inception strength could be applied only. In this paper, the electrical breakdown characteristic, which considered the effect of multi-layered of LPP, was investigated to design the insulation thickness.