Partial discharge detection in medium voltage stators using an antenna

Partial Discharges, if initiated give rise to progressive deterioration of insulation material and lowers its life expectancy. If allowed to persist further, PD can even lead to the electric breakdown of insulation. However, in spite of its damaging effects on machine insulation, its application during the production phase of machines, to avoid their permanent failure has gained importance in this research field. This paper discusses a Partial Discharge detection technique developed for medium voltage stator insulation utilizing an antenna to sense the discharge currents and record PD events produced inside a stator insulation. To reduce the effect of noise on detections process, some grounding techniques incorporated and later Undecimated Discrete Wavelet Transform was used to extract the discharge events from antenna output. To extract the best out of the technique, outputs were analyzed on a repetitive basis to make a confident decision on the presence of PD. This technique of detecting PD shows high sensitivity, as the detections are independent of the impedance of test setup used for experiments.