Detection of Non-Destructive Pulse Currents in Polyethylene Prior to its Dielectric Breakdown

Prebreakdown, non-destructive current pulses were observed in a solid dielectric under ac voltage stress for the first time. They were detected in polyethylene using a needle-plane configuration. The needle electrode was made of carbon-filled polyethylene, to improve contact with bulk polyethylene. The observed charge pulses were less than 1 pC in magnitude, and appeared well in advance of dielectric failure or tree formation.