Analysis and Experimental Study of an Internal Discharge Fault in a 220kV GIS

This paper presents an analysis of a discharge fault in the busbar of a 220kV Gas Insulated Switchgear (GIS) device. Firstly, through decomposition product energy spectrum analysis, partial discharge tests, and CST 3D electromagnetic simulation, it was found that there were no significant defects in the insulation bushing of the faulty phase. Based on the comprehensive results of on-site maintenance and return-to-factory tests, the root cause was identified as an eccentric installation of the shielding cover, which came into contact with the conductor. During operation, continuous vibration led to friction and the generation of metallic powder. Once a sufficient quantity accumulated and drifted into the high electric field region of the gas chamber, flashover occurred. Based on this, the paper proposes control measures for assembly quality, factory acceptance, and handover testing of GIS equipment.