Dynamic Behavior of Surface Potential on Insulator Under SiC/Epoxy Coatings

Due to the serious charge accumulation at gas-solid interface, the surface flashover voltage of insulator in gas insulated equipment may be significantly reduced. In order to pursue a method inhibiting surface charge accumulation, the epoxy composites modified by nano-SiC particles were coated on the insulator surface in this paper. The thickness of coating was 300 μm, and the SiC content was 5, 7 and 10 wt%. With the help of a couple of finger-shaped electrodes, the insulators with different coatings were charged at −10 kV voltage, and then the dynamic surface potential distributions were investigated. The results showed that only positive potential appeared on the surface and it mainly distributed near the high voltage electrode. With the passage of charging time, the shrinking phenomenon of high-potential region and the expansion of low-potential region can be observed. In addition, with the increase of SiC content, the average value of surface potential decreased monotonously and the shrinking speed of high-potential region seemed to be increased. Especially when the SiC content rose to 7 and 10 wt%, the magnitude and distribution area of surface potential declined sharply from 40 to 60 min. After 60 min, the surface potential distribution of the insulator with 5 wt% SiC/Epoxy coatings nearly unchanged, whereas it remained a slight fluctuation with 7 and 10 wt% fillers. Our study indicates that the coating with nano-SiC fillers has an inhibition effect on surface charge accumulation.