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Lee, Hongseok,Mo, Young Kyu,Lee, Onyou,Kim, Junil,Bang, Seungmin,Kang, Jong O,Nam, Seokho,Kang, Hyoungku The Korea Institute of Applied Superconductivity a 2015 한국초전도저온공학회논문지 Vol.17 No.1
High voltage superconducting apparatuses have been developed presently around the world under AC and DC sources. In order to improve electrical reliability of superconducting apparatuses with AC and DC networks, a study on the DC as well as the AC electrical breakdown characteristics of cryogenic insulations should be conducted for developing a high voltage superconducting apparatus. Recently, a sub-cooled liquid nitrogen cooling system is known to be promising method for developing a high voltage superconducting apparatus. A sub-cooled liquid nitrogen cooling system uses gaseous nitrogen to control the pressure and enhance the dielectric characteristics. However, the dielectric characteristics of gaseous nitrogen are not enough to satisfy the grade of insulation for a high voltage superconducting apparatus. In this case, the application of solid insulating barriers is regarded as an effective method to reinforce the dielectric characteristics of a high voltage superconducting apparatus. In this paper, it is dealt with a barrier effect on the DC and AC dielectric characteristics of gaseous nitrogen with respect to the position and number of solid insulating barriers. As results, the DC and AC electrical breakdown characteristics by various barrier effects is verified.
Creepage Discharge Characteristics of Solid Insulation Materials for Superconducting Power Cable
Lee, Onyou,Jeong, Minkyung,Jeon, Sangsu,Lee, Hongseok,Hong, Jonggi,Kang, Hyoungku Institute of Electrical and Electronics Engineers 2018 IEEE transactions on applied superconductivity Vol.28 No.3
<P>Solid insulation materials need to be robust in terms of both mechanical and electrical performance for application in a high-voltage superconducting apparatus. It is known that creepage discharge characteristics of solid insulation materials are inferior to their electrical breakdown characteristics with penetration. Therefore, electrical breakdown accidents in a superconducting apparatus could occur as a form of creepage discharge rather than electrical breakdown with penetration. In this study, we conduct dielectric experiments on the penetration and creepage discharge characteristics of epoxy resin and polypropylene laminated paper under cryogenic temperature by using three kinds of electrode systems. The first is for creepage discharge experiments along the surfaces of solid insulation materials in liquid nitrogen. The second is for creepage discharge experiments across the interface between two different solid insulation materials making contact in liquid nitrogen. The third is for experiments of electrical breakdown with penetration on solid insulation materials in liquid nitrogen. Dielectric experiments are conducted with an absolute pressure of 0.1 MPa under alternating current and lightning impulse voltages. Experimental results for electrical breakdown characteristics of solid insulation materials with penetration are compared with the creepage discharge characteristics on the surface and interfaces between solid insulation materials. Moreover, the criteria for electric field intensities at creepage discharge voltages in various conditions are deduced as empirical formulas.</P>
이온유(Onyou Lee),이홍석(Hongseok Lee),전상수(Sangsu Jeon),정민경(Minkyung Jeong),강형구(Hyoungku Kang) 대한전기학회 2018 전기학회논문지 P Vol.67 No.2
Social infrastructure such as production, transportation, gas, and electrical facilities would be degraded according to time and those facilities might need more maintenances, repairing, and management as time goes by. Especially, in the case of a power transformer, it is important to diagnose the transformer in order to avoid malfunction and failure because they could cause enormous damage. The economic as well as technical aspects of a transformer management must be considered while it is operated. Therefore, the concept of asset management should be applied as an advanced method of transformer management. Asset management refers to a series of processes to make a plan of maintenance and conservation of a power transformer considering the soundness, investment cost, and importance of equipment. It is important to apply the asset management considering calculation of a lifetime loss. In this paper, the lifetime loss calculation method of asset management for a power transformer is suggested.
A study on the barrier effect with respect to the condition of solid insulation materials in GN2
Hongseok Lee,Young Kyu Moa,Onyou Lee,Junil Kim,Seungmin Bang,Jong O Kang,Seokho Nam,Hyoungku Kang 한국초전도.저온공학회 2015 한국초전도저온공학회논문지 Vol.17 No.1
High voltage superconducting apparatuses have been developed presently around the world under AC and DC sources. In orderto improve electrical reliability of superconducting apparatuses with AC and DC networks, a study on the DC as well as the ACelectrical breakdown characteristics of cryogenic insulations should be conducted for developing a high voltage superconductingapparatus. Recently, a sub-cooled liquid nitrogen cooling system is known to be promising method for developing a high voltagesuperconducting apparatus. A sub-cooled liquid nitrogen cooling system uses gaseous nitrogen to control the pressure and enhancethe dielectric characteristics. However, the dielectric characteristics of gaseous nitrogen are not enough to satisfy the grade ofinsulation for a high voltage superconducting apparatus. In this case, the application of solid insulating barriers is regarded as aneffective method to reinforce the dielectric characteristics of a high voltage superconducting apparatus. In this paper, it is dealt witha barrier effect on the DC and AC dielectric characteristics of gaseous nitrogen with respect to the position and number of solidinsulating barriers. As results, the DC and AC electrical breakdown characteristics by various barrier effects is verified.