Space Charge and Dc Dielectric Breakdown in Polymeric Insulation

Dielectric breakdown of solid insulation has been studied for many years but the mechanisms that cause breakdown have not been fully understood. Charge injection always occurs at high electric fields and especially under dc conditions. The presence of space charge in solid dielectrics will result in distortion of electric field distribution. Dielectric breakdown can be initiated in the region where electric field enhancement takes place if the electric field exceeds the “threshold strength” of the material. Evidence of the presence of “threshold strength” has emerged from recent experimental work [1].