Possibilities and limits of partial discharge analysis in insulation diagnostics

It is pointed out that more information about partial discharges (PDs) in insulation of high-voltage equipment can be obtained by using a sophisticated computer-aided analyzing system. The characteristics derived from the measurable apparent charge and their statistical distribution can be used as a pattern for identification and evaluation of the PD sources. For this purpose investigations are carried out by means of models representing practical insulating arrangements. Methods are described for the improvement of PD recognition and elimination of interferences as well as basic requirements of automatic PD analysis. It is pointed out that detection, localization, and identification of PD are limited in the case of complicated and complex insulating systems, particularly during service of the equipment. The computer-aided analyzing methods, however, are a step forward in this direction. Nevertheless, additional nonelectric methods should be introduced in order to gain a combined effect. Application fields of acoustical devices are discussed