Simulation of Space Charge Characteristics of Epoxy Materials at High Temperature

The main insulating material of converter transformer bushing is epoxy composite material, epoxy composite material has prominent interface effect and obvious space charge accumulation under high temperature, which is easy to cause electric field distortion and aging of insulation material, leading to bushing insulation failure. There is little research on numerical simulation of space charge of epoxy composites at high temperature, and the influence mechanism of space charge effect on casing electric field is not clear. In this paper, the space charge characteristics of epoxy composites are studied from the perspective of space charge. The simulation shows that the charge in the medium has different dynamic characteristics at different temperatures. High temperature conditions promote the injection and mobility of charges, making the extraction rate of holes less than the transport rate, and the migrated holes accumulate due to limited extraction, resulting in the accumulation of heterogeneous charges. The contribution of trapped carriers to space charge is most prominent during the later stage of pressurization. Due to the amass of different polarity charges, the electric field at the two electrodes is seriously distorted.