Space charge in polymer dielectrics induced by pulsed and DC voltages as a factor influencing the time to breakdown

The behavior of space charges in both all the volume and local zones of the working volume of solid polymer dielectrics is studied during long-term applying a dc and pulsed voltages up to the formation of breakdown channels. The studies show that the larger negative space charge, the smaller the dielectric breakdown time; the appearance of a positive space charge near the anode the cathode and its increase lead to an increase in the lifetime of solid polymeric insulation. The experimental method of measuring space charges during service is proposed to use for monitoring the state of insulation.