초고압 유입변압기 절연구조의 절연특성 향상에 관한 연구

Abstract

It is inevitably required to secure the service reliability of Extra High Voltage Oil-immersed Transformer by improving insulation design technology related to its insulation system such as turn-to-turn, section-to-section and creepage of solid insulators. Regarding the current industrial status in Korea, related research performance have been poorly activated since last long decades. And thus, due to the insufficient knowledges and experience with limited number of experts, most of Korean companies have been manufacturing high voltage power apparatus based on the insulation design program or standard drawing according to the technical licence with globally advanced leading industries. In this regards, this work is focused on the experimental study of dielectric strength of turn-to-turn, section-to-section and creepage of solid insulators. For this purpose, relevant test set-up for their breakdown experiments together with specimens have been designed and fabricated considering manufacturing process of commercial apparatus. With respect to turn-to-turn and section-to-section, the effect of mainly 3 design parameters have been under consideration: conductor roundness, insulation paper thickness and length of specimen. For the creepage of solid insulators, 3 parameters have been chosen: creepage distance, creepage shape and glued direction. Afterwards, related analysis based on the measurement in connection with their dielectric characteristics and partial discharge inception voltage have been systematically carried out. Throughout our works, in order to deduce the manufacturing cost of transformers, it could be pointed out that the type of insulation paper and related thickness should be chosen according to the purpose of insulation design. On the other hand, most of Korean industries have conventionally applied Weidmann reference without experimental verification or investigation on the dielectric characteristics of recent insulation materials used for extra high voltage oil-immersed transformer. In this respect, it is necessary to examine or ameliorate such traditional practices of industries based on our results.