Effect of Conductor Notches Size Inside of 150kV Gas Insulated Switchgear Spacer on Electric Field Distribution

This paper discusses novel method to significantly reduce electric field stress on gas insulated switchgear (GIS) spacer mainly at its triple junction area. Spacer is secondary insulation used in GIS, with it primary insulation being gas. Spacer is used to hold conductor inside GIS so that it doesn’t move and remain stationary during its operational. Spacer has been well known as most vulnerable part of GIS Installation, and its vulnerability could be traced back at triple junction area. This area is where SF6 gas, Spacer, and Conductor meet, and due to its high electric field nature, is one of the causes of Spacer failure. To further increase its mechanical strength property, notches is added inside spacer to hold conductor bulge to fill said notches). This paper tests the effect of said notches on electric field distribution both inside and on the surface (mainly at its triple junction area). Size of notches is varied from 6mm to 24mm with 3mm increment. The result suggests that that the smaller the conductor notches, the intensity of electric field will increase. It is also observed that, the change of conductor notches size inside spacer will have effect on spacer surface. Increasing the size of conductor notches inside spacer could potentially reduced electric field intensity on triple junction area by more than 80% compared to original design with 3mm notches.