A novel technique for the identification of defects in stator bar insulation systems by partial discharge measurements

Results of investigations performed in order to improve the current diagnostic techniques used for the evaluation of insulation systems of AC rotating machine stator windings are presented. Improvements come from the development of a new measuring system and the stochastic analysis of partial discharge (PD) pulse signals. The measuring system allows the digital acquisition of PD-pulse signals, operates at a sampling rate high enough to avoid frequency aliasing and provides an amount of PD-pulses which enables PD stochastic analysis. In addition to the traditional PD-pulse height and phase analysis, PD-pulse shape processing is also available. The first results of PD measurements performed on different types of complete stator bars, with and without defects, are reported to show the system performance