Temperature-dependent Surface Charge and Flashover Characteristics of Double-layer Oil-paper Insulation under DC Voltage

Ambient temperature has significant influence on electrical property of oil-paper insulation, which makes the surface flashover process complex. This paper aims at revealing the influence mechanism of ambient temperature on surface flashover behavior under DC voltage. In the experiments, double layer oil-papers with thickness of 0.08 mm were used, the ambient temperature was varied from 20 to $80^{\circ}\mathrm {C}$ and the amplitude of DC voltage was 3.5 kV. The results of surface potential decay (SPD) measurement show that with the increase of temperature, the initial surface potential declines and the process of SPD accelerates. The results of surface flashover indicate that it is prone to occurring surface flashover at higher ambient temperature. It is concluded that more carriers escape from deep traps to participate the procedure of surface discharge at higher temperature, which declines the surface flashover voltage.