Application of the Extended Phase-Resolved PD Patterns for Analysis of PD Activity in Epoxy Resin Insulation

For many years, one of the tools allowing the observation and analysis of activity of partial discharges (PD) occurring in the insulating systems of electrical equipment is the phase-resolved PD pattern acquisition method. Usually, raw PD measurement data collected during test of the insulating system regarding the number (intensity) of discharges during the defined test time are collected in a matrix representing 2-dimensional PD phase-charge space. Because of their digital form, it is possible to perform their complex numerical processing/transforming to obtain extended in-depth information on 2-dimensional distributions of other quantities describing large sets of registered PD pulses. The paper presents the application of this type of extended analysis for the description of selected properties of partial discharges arising in the thermosetting epoxy-mica insulation of rotating machines. Results of measurements made in laboratory conditions on insulating system of a motor stator bar were used for PD data analysis.