Investigation on electrical aging of thin polypropylene films for power capacitors by means of thermally stimulated depolarisation currents (TSC)

Electrical aging of polymer materials in different geometries have been the subject of many investigations. Aging of polypropylene films for power capacitors is of interest mainly with respect to the lifetime. Dielectric films in capacitors are stressed by high electrical fields, high temperatures and chemicals. For reducing the electrical field stress in gaseous voids, inevitable during manufacturing, capacitors are impregnated with fluids. Interactions with the fluids cannot be excluded. It can be supposed that the temperature and the level of the electric field influence the build-up of space charges. The method of thermally stimulated currents of depolarisation (TSC) allows indication of changes in space charges build-up by electrical stress. By this method, influences of temperature, electrical field stress and the surface treatment of the films can be elaborated