Condition assessment of mixed oil-paper and XLPE insulated cable lines by voltage response method

The voltage response method is an effective tool to diagnose the condition of the oil-paper insulation. The initial slopes of decay and return voltages are in direct correlation with dielectric processes. Testing of oil-paper insulation with this method the two main deteriorating processes thermal aging and moistening can be investigated separately. The thermal aging of PVC insulation can also be followed by this method. By the newest result of the authors, this method seems a promising tool to solve the diagnostic problem of joint polymeric and oil-paper insulated cable lines. By the newly developed correction method, the aging state of joint (oil-paper and extruded) cable lines can be determined at certain circumstances. Practically, after only one measurement on a mixed cable line the feasible values of voltage response of the both parts can be estimated by the knowledge of the parameters of the sections.