Modeling partial discharges in a cavity at different applied frequencies

A model of partial discharges (PD) in an insulated disc-shaped cavity is presented. The flat cavity walls are covered with copper foil and each PD is assumed to affect the whole cavity. The discharge process in the cavity is simulated dynamically and the model is charge consistent. The model is used to simulate the sequence of PDs in the cavity at two different applied frequencies: 0.02 Hz and 100 Hz. The simulation results are compared with measurements and good agreement is found. As the applied frequency is increased from 0.02 Hz to 100 Hz, the mean apparent charge increases and the number of PDs per cycle of the applied voltage reduces. This is interpreted as an effect of the statistical time lag of PD.