Modified Pulse Sequence Analysis for PD measurement at DC

The Partial Discharge Behavior at DC conditions is currently investigated worldwide to find out an appropriate method and/ or principle for quality testing of HVDC components. Due to the lack of knowledge concerns a lot of basic investigations is performed. These kind of investigations should be continued also for other arrangements like surface discharge and cavity discharge test sets. The paper deals with results of PD measurement at a simple corona test set - needle-to-plane - under DC conditions using the Pulse Sequence Analysis of the PD behavior. For better understanding of the measured data some comparison measurement at AC conditions were performed. Despite of some differences in the PD behavior it could be shown, that the parameters cumulative charge Qsum and dQ/dt are the most important parameters for characterizing the PD behavior at DC conditions. Additionally, the measuring time in depending on the insulation type is of great importance too, which was confirmed by a special arrangement - corona with insulating sheet. The method of cumulative charge and the PSA analysis were used to determine the partial discharge activity at AC and DC conditions. There was shown the differences between the cases of measurement without and with an insulating sheet between the electrodes. It seems to be that the parameter Delta Q/Delta t could be useful for better understanding of the PD behavior and should be measured at further investigations