Polarization technique to assess the operating state of polymeric insulation

Polarization current measurements obtained from two different brands of cross-linked polyethylene subjected to water tree aging are discussed. It is shown that the RC time constant and the area under the polarization current curve consistently change with the aging time, i.e., with the extent of water treeing. In comparison, depolarization current measurements used in some diagnostic cable insulation assessment tests, did not produce consistent results.