Through-Hole Spacer Design for a ±550 kV DC GIS

Designing through-hole spacers for ±550 kV DC gas-insulated switchgear (GIS) demands critical multi-physics optimization to simultaneously mitigate detrimental surface charge accumulation and ensure robust mechanical integrity. To address this challenge, the effects of the size, shape, and position of through-holes on the surface charge and surface electric field distribution of a ±550kV GIS spacer was investigated. The mechanical verification was also conducted. The results show that the through-holes significantly increase charge density and distribution of the spacer. While appropriately reducing the area of through-holes effectively suppresses the surface charge density and weakens the electric field. Compared with the commonly used hole shapes in GIS through-hole insulators, the rugby-shaped through-hole reduces the maximum total electric field by 47.9%. When the center of through-hole is located at a radius of approximately 5/9 from the axis, the electric field shows the lowest value under different polarity lightning impulses. The results of this work can provide references for the design of a light-weight DC GIS.