DC polarization characteristics of XLPE and EPR insulation subjected to water treeing

Polarization currents obtained at a low dc field for two different brands of XLPE and EPR insulation subjected to water treeing were correlated with the corresponding time to breakdown characteristics of these materials. It is shown that although the RC time constant and the area under the polarization current curve changed consistently with the aging time for all three materials tested, the consistency and the diagnostic value of the information they provide about imminent insulation failure depends on the type of material.