Numerical simulation of surface charge inhibition performance on epoxy insulator under DC voltage by flexible coating strategy

Abstract

Epoxy insulator is affected by surface charge accumulation under a strong electric field, which causes a decrease in the surface flashover voltage, threatening the safe operation of power equipment. This study reports on a flexible coating strategy for the insulator to inhibit the charge accumulation through numerical simulation. The experiment was conducted initially to reveal the charge accumulation feature. Then, the flexible coating method was proposed, in which the insulator surface was divided into three parts, and surface coatings with various conductivities were painted on the designated areas to adjust the charge distribution. Finally, the efficiency of such a coating strategy was estimated considering the temperature gradient. The results presented that the homo-charge was mostly deposited on the non-planar area of the spacer. The maximum charge density first decreased and then increased with increasing surface conductivity. The charge accumulation could be restrained by increasing the surface conductivity of insulator effectively. A significant suppression was achieved by properly coating with high conductivity at the non-planar region and with low conductivity at the planar region. The suppression performance of such a strategy became reduced as the temperature gradient increased. The results indicate that the flexible coating can balance charge deposition in the non-planar region and restrain charge injection near the electrode, thereby inhibiting the charge accumulation.