Crosslinked polyethylene (XLPE)-insulated power cables exposed to a combination of high electric stress in the presence of water are susceptible to a form of degradation known as water treeing, which is largely responsible for the premature failures encountered in extruded HV cables. The present paper reports results obtained with both two-dimensional mu -PIXE (proton induced X-ray emission) scans and NAA (neutron activation analysis) measurements on a number of samples aged under different conditions. The impurity distribution in polyethylene insulation adjacent to the interface with the inner and the outer semiconductors was investigated. No convincing evidence was found of migration of impurities (atomic numberNa) from the semiconductor into the polyethylene insulation under electric aging conditions.
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