Surface Conductivity Graded Insulator for DC-GIS—Part I: Design and Fabrication

Surface conductivity graded insulators (SCGI) present promising application for compact DC-GIS, where the lifting behavior of particles and the occurrence of abnormal surface discharge are highly dependent on the electric field distribution. In this part, an iterative method for optimizing the surface conductivity distribution of the SCGI is proposed. Surface electric field inhomogeneity coefficients were used to assess the optimization of electric field. After optimization, the inhomogeneity coefficient of tangential electric field on the insulator surface is decreased from 3.79 to 2.07. The electric field strength around the insulator’s grounded shell is significantly reduced. The optimized surface conductivity distribution presented obvious zoning characteristics. To simplify the manufacturing process of surface conductivity graded insulator, the optimal surface conductivity distribution was discretized. Surface fluorination technology is utilized to manufacture surface conductivity graded insulators. A graded distribution of surface conductivity along the SCGI is achieved, by adjusting the fluorination time in various areas. enhancing the surface insulating properties of insulators and inhibiting the activity of metal particles around insulators in DC-GIS.