PD-Source identification and characterization on the basis of pulse shape analysis

The analysis of partial discharge data has been improved by the introduction of the Pulse-Sequence-Analysis which takes into account that each discharge influences the ignition of the consecutive discharge. This leads in most cases to a systematic individual shift of the phase angles of occurrence of the discharges that is often interpreted as a ´statistical´ scatter. In commercial power equipment in many cases discharges occur simultaneously at different spots in the apparatus. In this case the Pulse-Sequence-Analysis (PSA) correlates partial discharges from different sources and hence may lead to an erroneous interpretation. The more detailed analysis of the pulse shapes of the pd-signals revealed that there are differences in accordance to the type of the pd-active defect. These differences can be used to separate discharge signals from different sources and to split up the measured data sets into different sets that are characteristic for a specific defect and that can be analysed separately. With this procedure different sources or even different stages of the degradation process can be identified. The paper will show some examples.