Comparative Study of Surface Charge Between Epoxy Impregnated Paper and Epoxy Resin

Epoxy impregnated paper composite material is the main insulating material of ultra-high voltage wall bushing capacitor core. Its surface charge accumulation causes electric field distortion, which has an important influence on the safety and stability of bushing operation. The effect of epoxy impregnated paper composite insulation material and epoxy resin on surface charge accumulation under different polarization time, different voltage levels and different voltage polarity was studied in this paper. It is found that the volume conductivity of epoxy impregnated paper composite insulation material is much higher than that of epoxy resin, which makes the surface charge accumulation of epoxy impregnated paper easier, the maximum surface charge density of epoxy impregnated paper is significantly higher than epoxy resin during the polarization process. Under DC voltage, the surface charge increases with the increase of voltage level and the extension of polarization time, and tends to be stable at 90min, without obvious polarity effect.