Electrical field influence of metallic particles and inner voids on UHV AC GIS spacer

Gas insulated switchgear (GIS) has been widely applied in substation because of its high reliability and compactness. GIS spacers are critical components which influence the insulation level of GIS, playing supporting conductor, isolating chamber and electrical insulation roles. Defects in spacer like voids, metallic particles, protrusions or pits introduced during manufacturing, installation and operating process are considered to contribute to degradation of GIS. The defects are more likely to cause insulation failure when considering UHV AC GIS spacer. In this paper, a basic calculation model of a part of GIS was established using ANSYS with an epoxy spacer included. Two kinds of defects were studied. Metallic particles with different sizes sticking to or floating on the surface of spacer were simulated. The laws of electrical field distribution with size and position of metallic particles were summarized. Voids of different sizes were modeled in different positions in the epoxy body of spacer to investigate how they affect electrical field distribution. Results indicated that electrical field would be enhanced at the three point of epoxy, metal and SF
₆
for sticking particles. Floating particles would enhance electrical field of nearby surface of spacer. Sizes and positions hardly influenced the enhancement degrees of inner voids.