Electric Field Regulation of Post Insulators Based on Local SiC Doping

Electric field in the leg area of gas-insulated transmission line (GIL) tri-post insulators is relatively high, which results in epoxy (EP) being susceptible to aging. The operation life of insulators is shortened. This article aims to optimize the scheme of local SiC doping to improve the insulation reliability of post insulators. The dc electric field calculation model for SiC doping in the local area of insulators is constructed. The regulation of the concentration, thickness, and center height of the transition zone between different materials on the electric field is studied. The findings suggest that there is a polarity reversal phenomenon in the surface charge of the transition zone after SiC doping. Besides, the negative peak of the surface charge density increases with doping concentration. As the thickness rises to 9 mm, the tangential electric field distribution of the transition zone becomes more homogeneous. Furthermore, the surface charge density displays a conspicuous negative peak precisely at the center of the transition zone, which varies depending on the height of the transition zone. When the center height of the transition zone is 45 mm, the maximum of the normal electric field on the grounded electrode is only −1.3 kV/mm. This can effectively avoid material aging. Thus, the transition zone formed by local doping SiC can efficiently regulate the electric field distribution, which provides a novel approach for the structural optimization of tri-post insulators.