Wide band measurements of partial discharge in epoxy

Continuous observation of partial discharge may enable warning of incipient failure of gas-insulated switchgear (GIS). This paper reports measurements of partial discharges from electric treeing in epoxy, as well as from artificial defects in a GIS test piece. The measurements were performed with an ultrawide detection bandwidth (up to 1 GHz). Some partial discharge pulses have durations of at most a few nanoseconds; a multichannel analyzer capable of responding to such fast pulses was developed for these experiments.