Surface functional graded spacer for compact HVDC gaseous insulated system

Electrical field distortion induced flashover is a bottleneck for the stable operation of HVDC gas insulated system (GIS). Functional graded materials (FGM) have attempted to homogenize the electrical field distribution along the gas-solid interface; however, the complicated fabrication process and huge dielectric loss makes it difficult into industrial application. This paper proposed a novel concept as that a spacer with functional surface was fabricated by magnetron sputtering ZnO onto the epoxy resin forming a surface conductivity gradient, namely surface functional graded materials (SFGM). The feasibility was first demonstrated by simulating the electrical field distribution. Two kinds of disc-type spacers with SFGM were designed as linear and inverse proportional annular gradients. Results show that the more uniform electrical field distribution contributes to the improved surface flashover voltage of the SFGM spacer. Therefore, the SFGM epoxy spacer has great potential in HVDC GIS insulation.