Temperature influence on the anomalous breakdown phenomena in XLPE insulated cables

The author reports results of investigations of the anomalous breakdown in XLPE (cross-linked polyethylene) insulated cables immersed in transformer oil under alternating (50 Hz) voltage when the temperature of the oil is increased. The study confirms that anomalous breakdown occurs in XLPE insulated power cables subjected to alternating voltages and that the breakdown voltage decreases as the insulation temperature increases. The distance of breakdown site from the high-voltage electrode decreases with increasing temperature up to 80°C. Above that value, the entire breakdown is of direct type; no anomalous breakdown occurs