Polarization and Depolarization Current measurements of oil impregnated paper insulation system under thermal runaway

In the current research work, systematic investigations on the influence of thermal transients on the Polarization and Depolarization Current (PDC) measurements are presented. The test object consisted in a laboratory made oil paper condenser. A series of experiments have been performed under controlled temperature conditions on an oil impregnated bushing model. The PDC currents along with the temperature transition are simultaneously recorded. The obtained results indicate that better interpretation is obtained when using the temperature values registered at the beginning of the measurements for the polarization current and the final temperature for the depolarization current.