Investigation on heterocharge accumulation in crosslinked polyethylene: Experiment and simulation

Abstract

This paper presents the pulsed electro-acoustic (PEA) measurement results of the space charge behavior in as-received and degassed crosslinked polyethylene (XLPE) plate samples. A modified bipolar charge transport model, taking into account the formation of ionic charges and the extraction barrier for electronic charges, is introduced to explain the origin of the observed heterocharge accumulation. The results show that in degassed sample, the formation of heterocharge at the anode is due to delayed extraction of injected electrons. In as-received sample, the heterocharge near the cathode is positive ionic charges, whereas that observed near the anode is caused by the combined effect of negative ions and injected electrons. It is also found in the simulation that the heterocharge amount increases with the increasing of byproducts content and extraction barrier height. The extraction barrier height at the electrodes only relates to charge amount, but has no effect on the threshold for heterocharge formation.