The Discharge-Repetition Rate in Cavities in Epoxy Resin, Polyethylene, and Mica under Alternating Voltage Conditions

An investigation into the repetition rate and magnitude of internal discharges in artificial cavities in epoxy resin, polyethylene, and mica, using a multichannel pulse height analyzer is described. The effect of time of voltage application, cavity dimensions, and location, and opening the cavity or ventilating it in air and nitrogen has been studied. The results indicate that it is the discharge quantity rather than the discharge energy measured externally in the largest pulse that is important. It is suggested that in order to correlate discharge damage with discharge activity, it is essential to measure continuously both discharge magnitudes and repetition rates.