Development of Partial Discharge Sensing Device for Epoxy Resin Bushing

Abstract

For the electric power equipment and the cables, prevention of accident is very important. And in substations, a lot of solid insulations using epoxy resin are introduced into cubicle-type switchgears because of its high insulation reliability and down-sizing ability. We know a phenomenon that partial discharge occur when electric installation have degraded. When void or crack exist in the polymer insulating materials or interface of conductor, partial discharge is caused and finally results in breakdown. In recent years, the feature is seen in the partial discharge generated in the epoxy resin before and after the progress of electric tree by our research. Electro-magnetic wave spectra radiated from partial discharge have specific frequency region from 200MHz to 450MHz. We developed the sensing device that can detect the electric discharge by receiving the signal by mobile antenna. We proved the performance of this equipment in operating substations; As a result, partial discharge in epoxy resin was detected by electro-magnetic wave. And then, we removed epoxy resin bushing from the cubicle and measured partial discharge by discharging current, we confirmed that presumed level is correct.