Development and application of partial discharge analyzing system for swarming pulsive microdischarges

The authors developed a personal-computer-aided partial discharge analyzing system for SPMD (swarming pulsed microdischarge) measurement. The system has two detection methods for partial discharge measurement: a conventional pulse charge method and a balanced Lissajous figure method. The former failed to detect SPMD due to the sensitivity limit of the detector, while the latter integrated all charges including SPMD per half cycle. Therefore, the difference between the charge integrals of partial discharges per half cycle measured by these two methods must be a good measure of SPMD. Based on this idea, a new parameter, the SPMD ratio, was introduced. Using the developed system, partial discharge characteristics were studied for the CIGRE method II specimen with internal void in order to examine the factor in the presence of SPMD. The results show that the magnitude of applied voltage, its frequency, and roughness of the void surface affect the appearance of SPMD