On the aging mechanism of solid insulating materials exposed to repetitive high voltage pulses

This paper proposes an explanation for the aging of solid insulating materials exposed to high frequency voltage impulses based on thermal stimulating processes triggered by losses generated in insulating materials due to damped oscillations of molecular dipoles in high frequency electrical fields. For this purpose, total dissipation of insulating materials is calculated based on frequency domain description of applied voltage and frequency dependent dielectric properties of insulating materials. To validate the proposed theory, different experimental investigations are carried out on thin oil impregnated paper exposed to high voltage square wave shape pulses with different pulse durations, rise times and repetition rates. The trends obtained in experimental studies can be satisfactorily explained using the proposed theory.