Deterioration of Insulated Wire by Corona Discharge

Abstract

In relation to the accidents due to bird nests in contact with overhead distribution lines, the authors investigated on deterioration of covered conductor by corona discharge. To simulate the situation where conductive nest material such as wire is in contact with both of an arm and a covered conductor, a copper wire was wound around the covered conductor and was grounded through a resistor which is used to observe corona discharge current waveform. The state of normal operation of 6.6kV distribution line was considered and A.C. 3.8kV was applied between the conductor and the ground. Weak corona discharge was observed. In order to carry out the acceleration test, A.C. 6.6kV was applied. The insulation was punctured after 3760 hours. From the observation of cumulative charge by corona discharge the acceleration factor was estimated about 4. From the acceleration factor estimated, the life of conductor cover will be 627 days.