A Surface Discharge Model for Partial Discharges Under DC Stress

With the trend in industrial electronics towards higher voltage levels and power densities stimulated by the clean-energy transition and electrified transportation, the design of surface insulation systems must face the challenge of coping with the increasing risk of faster insulation degradation rate caused, in particular, by inception of extrinsic aging mechanisms as partial discharges. This demands for models that can help insulation designers to evaluate the likelihood of inception of such extrinsic aging acceleration phenomena. This article deals with a new model for the estimation of surface partial discharge inception in dc insulation systems. The model is validated experimentally by tests on insulating materials used in electrified transportation electrical assets. Peculiar characteristics of the model, namely the electric field transient duration under dc voltage supply and the impact of temperature and surface conductivity on partial discharge inception voltage are also discussed.