Study on Electrical Treeing Characteristics of ERIP under High Temperature with Combined AC-Positive DC Voltage

Dry Bushing core adopts epoxy resin impregnated paper (ERIP) material as the main insulation, which can bear the stress of high temperature with combined AC-DC voltage under actual operating conditions. In order to avoid bushing insulation failure under high temperature, it is urgent to study the electrical treeing characteristics of ERIP material under high temperature with combined AC-DC voltage. In this paper, a 16kV AC combined 0kV, 8kV, 12kV and 16kV positive DC voltage was applied to ERIP samples at 80°C. Under the same AC voltage, the higher the amplitude of the positive DC voltage, the shorter the breakdown time of the sample. The breakdown time of samples corresponding to different morphologies of electrical trees is obviously different, and the breakdown time decreases with the increase of the density of electrical trees. The research results of this paper are helpful to understand the insulation failure process of ERIP materials under the combined effect of electricity and heat.