Analysis of pseudo-breakdown phenomena and phase-field simulation during epoxy resin insulation degradation

Insulation failure in solid dielectrics poses a great challenge to the safe operation of power equipment. In order to analyze the causes and mechanisms of different degradation processes in insulation materials, this paper builds an experimental platform to simulate the degradation of epoxy resin insulation defects. The degradation of conductive and non-conductive electrical trees under alternating current superimposed direct current voltage was studied. Experimental results show that conductive electrical trees have faster insulation failure times. Non-conductive electrical trees do not lead to insulation failure immediately after developing contact with the ground electrode, and still maintain insulation of the order of 102 s. Partial discharges are the cause of the growth of conductive trees, but not the non-conductive ones. A dimensionless phase-field simulation method is proposed to regulate the electrical tree development process through state parameters. The simulation results indicated that the development of two types of electrical trees is influenced by the strength of the electric field. When the electrostatic energy is not sufficient to cross the body free energy barrier, insulation degradation occurs as a non-conductive electrical tree. This paper provides new ideas for simulating insulation material degradation, which helps to understand the mechanisms of different insulation degradation types from an energy standpoint.