Partial-discharge phenomenology in compressed SF6 under stochastic conditions

Erratic discharges of low intensity in compressed SF₆ were produced in a plane-point-plane electrode configuration. Both DC (negative-corona conditions) and AC voltages were used, the applied voltage-values being chosen close to corona threshold. The test cell was filled at 500 kPa and the gap length, fixed at 5 mm. The present paper focuses on the pulse characteristics, as observed by recording real-time sequences via a fast digitizer. The high-resolution sampling has given a detailed access to the time relation between consecutive pulses. Emphasis of measurements was put on the DC conditions, while comparison of some AC results is offered. The large data set obtained under DC conditions allowed to establish the existence of a discharge regime and to characterize it quantitatively. In the AC-situation, the discharge events showed similar traits, but pulse parameters differed in magnitude, and stochasticity was different