Recent experiments on space charge and transport in polyethylene under high DC field

Abstract

The development of carefully designed extruded HVDC cables remains a challenge. The field distribution - and therefore the space charge distribution over the insulation thickness determine the behavior and the life expectancy of the cable, since a very high space charge level is obviously undesirable. This article presents the build-up of space charge, as measured by the thermal step method (TSM) in flat samples of polyethylene, under various levels of temperature. The absorption current flowing after application of a voltage step and the decaying surface potential after DC poling, which are indirect manifestations of space charge accumulation, have also been recorded. A blend of LDPE with a conjugated polymer might modify the trapping ability. The results seem interesting from the fundamental as well as the engineering standpoint.