Influence of epoxy insulating materials parameters on surface charge characteristics and surface flashover under DC

As an insulating material, epoxy resin is widely used in the power system. However, its surface charge accumulation and decay behaviors have been the key problem restricting the development of high voltage direct current power equipment. In this paper, pure epoxy and several kinds of epoxy composites were used. And the relative permittivity, volume resistivity and surface resistivity of the insulating materials were measured. We studied the influence of material parameters on surface charge characteristics and the surface flashover voltages under dc. The results show that the dissipate rate of surface charge becomes faster under small relative permittivity and volume resistivity. And the larger the relative permittivity is, the slower the flashover voltage, the larger the volume resistivity is, the larger the flashover voltage, the larger the surface resistivity is, the larger the flashover voltage and tend to saturation.