Loss current studies of partial discharge activity

Partial discharge measurements have important applications in evaluating insulation systems as well as for dielectric materials studies. This work investigates a measurement technique to study partial discharge activity by measuring the PD loss current. The method is similar to dielectric response measurement and measures the current through a test object with and without PD. By comparing the dielectric current and the discharge current, all conduction processes, both fast and slow, can be explored. This is in contrast to traditional pulse PD detections, where only the fast PD transients have been measured. The method is demonstrated through measurements of PDs appearing in twisted pair and needle-plate test objects under sinusoidal and square wave voltage excitations. Comparisons are made to results of simultaneously employed traditional pulse PD detection technique.