Investigation the Impact of Partial Discharges Polarity on Reliability Assessment of Insulation Condition in High Voltage Equipment

Abstract

The partial discharge (PD) method is widely used to assess the condition of insulation in high voltage equipment. Moreover, the magnitude and the number of pulses are the most important characteristics of partial discharge. However, there are many factors that affect the reliability of these parameters, which in turn leads to wrong estimations of insulation conditions during the PD measurements through the electrical method. Therefore, there are many kinds of research to minimize the effect of various parameters on measured PD magnitudes. However, until now there are not any explanations of the appearance of PD pulses with opposite polarities, which do not correspond to the theory of PD. As result, some devices filter these numbers of unusual PDs and consider them as noise. For this reason, this work will explain the detection of different PD pulse polarities by carrying out computer simulation and experimental analysis using different applied voltages. It will also illustrate how ignoring the PDs pulses with opposite polarities affects the reliability of the assessment method of the insulation condition in HV equipment.