Modelling of Partial Discharges in A Cavity Within an Insulation Material Under Various Applied Frequencies

Partial discharge is both a cause and symptom of electrical insulation degradation in high voltage power equipment. Its measurement is an important diagnostic tool for insulation assessment. This investigation compares partial discharge characteristics in a cavity under different applied voltage stresses at very low frequency of 0.1 Hz and at power frequency. A model is proposed to describe physical phenomena of discharges in the cavity at both applied frequencies. Measurement and numerical simulation results show that discharge magnitude and repetition rate are generally smaller at lower applied frequency. From simulation, it can be concluded that surface charge decay plays a significant contribution to discharge behaviors at very low frequency