Effect of temperature rise on leakage current and breakdown of power cables

The present work reports an experimental investigation of the effect of temperature rise on the leakage current and thermal breakdown in power cables under both A. C. and D. C. high voltages. An empirical equation was found to give the relation between the leakage current and the temperature of the insulation. It was observed that the thermal breakdown occurs when the heat generation in the insulation is larger than the heat dissipation in the surrounding soil. The variation of the leakage current with the temperature was well investigated and it was found that the leakage current increases with the increasing of insulation temperature. Leakage current in power cable predicts the critical breakdown voltage of the cable. It was anticipated that a significant of deterioration could be detected by measuring the leakage current at the operating temperature especially if the deterioration had progressed to a point where the cable failure is imminent.