Effect of microvoids on V-t characteristics and tree growth in crosslinked polyethylene

Crosslinked polyethylene is being used as an insulation of electric power cables because of its excellent quality. But in spite of the fact that polyethylene and corsslinked polyethylene cables have established an excellent service record, it was reported that some polyethylene and crosslinked polyethylene cables had failed in service over several years.1,2This might be because the quality of polyethylene or crosslinked polyethylene is deteriorated by trees initiated and grown at an asymmetrical conductor or a void under a high electric field. In fact, careful microscopic analysis of polyethylene or crosslinked polyethylene cable which had been in service for several years had found various types of trees.1, 2