Acoustic emission method as a tool of partial discharges indication

The present paper deals with a method of tracking the partial discharges using the acoustic emission method. The quantity under study was the overshoot counting rate in acoustic emission signals. The subject of the experiment was a high-voltage generator rod, which had been provided with Relanex insulation. Acoustic signals, which were generated in the Relanex insulation layer, were picked up by wide-band sensors. Measurement results proved that electric discharges in a cavity are accompanied by the generation of mechanical oscillations, which in turn act as a source of standing waves in the cavity and standing waves in the rod and the insulator. The frequency spectrum therefore extends from the rod fundamental oscillation mode (i.e., 3 kHz) up to the cavity natural frequencies (in the order of several MHz).