An Initial Study on How PD Influences Dissipation Factor Values of a Stator Bar

The purpose of this investigation is to evaluate how Partial Discharges (PD) can affect measured Dissipation Factor (DF) values of a stator bar. The investigation found that the harmonics of positive and negative PD pulses can interfere measured DF values. Influence of the different PD parameters (e.g. the pulse amplitudes, pulse numbers and pulse time interval) on the magnitude of the harmonic components was analyzed with simulated PD pulses. PD and DF tests were performed on a stator bar with artificial defects at different voltage levels. The correlation between the measured DF values and various PD parameters was studied. It was found a good correlation between the measured DF values and the 50-Hz harmonic component of PD signals.