The use of time intervals between consecutive discharges to characterize PD-sources

Pulse sequence analysis is a powerful tool to characterize defects that generate partial discharges. Usually, frequency distributions or scatter plots of sequence correlated parameters such as e.g. the external voltage differences /spl Delta/U between consecutive discharge events are used for diagnosis. In some cases, the analysis of the times of occurrence and especially the sequence of time-intervals /spl Delta/t between consecutive discharge pulses may even be more efficient to characterize a defect or to differentiate between different defects. In the case of only a few discharge events per cycle of the applied voltage, the parameter /spl Delta/U is very efficient and allows to distinguish clearly whether the partial discharge signals are generated by only one or more local defects, information that is very helpful for a reliable diagnosis. Even with only one type of defect, a small change in the height of the measuring voltage may significantly influence the discharge phenomenon, resp. the measured date set. The analysis of the frequency distributions of the time differences /spl Delta/t of consecutive discharge events and the elimination of 'multiple discharge pulses' together with the use of the parameter /spl Delta/U//spl Delta/t reveal very useful additional information.