The influence of partial discharge exposure time on the thermally estimated depolarization and on the natural relaxation in polymer dielectrics is described. The polypropylene and polyethylene terephtalate foils were the object of investigations. Study of partial discharge plays an important role in the aging and the rupturing process of solid and mixed insulation systems. The PD analysis is a predictive test which indicates insulation degradation in advance, which may lead to the failure of the system, and it is performed under normal operating conditions.
Keywords: Discharge Action, Foils, Influence, Insulation, Partial discharge, Relaxation., Transformer, depolarization, exposure
