Abstract
It has been reported in polymer insulation that the ac loss current in phase to applied voltage is distorted with developing of water trees. We have also obtained the distorted ac loss current from the water treed polyethylene sheets. In order to analyze this distorted ac loss current, we have discussed with the modified Maxwell-Wagner two layer model, in which the capacitance C1 for the non-degraded region is connected in series to the parallel combination of the capacitance C2 and the non-linear conductance G2 for the water treed region. This model takes account of a non-linear dependence of conduction current through G2 on voltage across the capacitance C2. By numerically solving a non-linear differential equation for the electric charge on the capacitance C2, the ac loss current was calculated. The observed wave forms were compared with the calculated ones by changing parameters of non-linear conduction.
