The analysis of water in treed crosslinked polyethylene films

A particularly troublesome problem to the electrical utility industry is the occurrence of tree-like defects in polyolefin insulated transmission cables that have been energized for a period of time in the presence of water. These defects, water trees, are associated with decreased dielectric strength and may be responsible for premature failure of underground cables. Although it is generally agreed that both water and electrical stresses are necessary for the initiation and growth of water trees, neither the mechanism for the formation of these defects nor their morphology is known with certainty.