Measurement and statistical analysis of Partial Discharges at DC voltage

Partial Discharge (PD) detection and diagnostics is an established tool to test the condition of the insulation in HV-facilities. One basic question while performing PD measurements is the one concerning the type and location of the defect. Under AC stress there are several instruments to interpret the measured PD, most important the phase angle histogram. At DC voltages this approach is inapplicable and therefore new parameters to analyze PD under DC stress have to be identified. In this paper it is shown, that a statistical analysis of pulse shape parameters can give information about the type of defect and thus could be used for DC-PD diagnostics.