Spontaneous partial discharge oscillations studied by excess current

This work discusses appearance of spontaneous partial discharge (PD) oscillations in specimen containing dielectrically isolated gas cavity as well as a measurement technique that allows to study such PD activity by quantifying the resulting excess current, which includes both fast PD current pulses and relatively slower charge movements. This is achieved through a comparison of currents measured with and without PDs by simultaneously performed conventional pulse PD detection and dielectric response (DR) measurement from which the excess current wave shape is deduced. The obtained results reveal appearance of an additional “slwo” current contribution and this paper discusses how this current is generated and why it may influence the PD activity.