An Accelerated Life Test for Evaluating Power Cable Insulation

For many years, the power cable industry has sought an accelerated test that would quantitatively evaluate the life of polyethylene insulation for high voltage cables. This paper describes preliminary results leading to development of such a test. This test employs full size cables with accelerating factors such as temperature, water, electrical stress, frequency and mechanical stress. Times-to-failure for thernnplastic and crosslinked polyethylene insulation materials are canpared at different temperatures and the effect of water in the strand is illustrated. Data are presented showing the performance differences of two peroxide comipounds in crosslinked polyethylene. The influence of a tree-retardant additive to thermo-plastic polyethylene is described. General observations are made of the failure mode and nature of tree formation in test specimens.