Charge transport simulation in epoxy used as DC-GIS insulating spacer material

Surface charge accumulation on insulating epoxy spacer in DC-GIS under high DC electric field decreases breakdown voltage on the spacer, but charge accumulation phenomena of insulators are not clear in detail. In this paper, the numerical simulation of electrical conduction in epoxy is conducted to discuss proposed charge transport model. The charge transport model which had developed to explain electrical conduction in polyethylene is modified to simulate the prior profiles of space charge distribution in epoxy. With this model, space charge accumulation is simulated and compared with the experimental results. As a result, the simulated and experimental space charge distributions are consistent under multiple conditions with different electric fields, temperatures and measurement times. In particular, the hetero-charge in the bulk could be reproduced by extraction barrier, and the homo-charge near the electrode could be reproduced by locally increased trap density. It can be explained that changes in space charge density with conditions are determined by the electric field and temperature dependence of charge injection and de-trap rate. From these results, the usefulness of the charge transport model in epoxy is verified. © 2020 The Institute of Electrical Engineers of Japan.