Investigation on insulation reliability of 380 kV XLPE cable systems

This paper investigates the insulation reliability of 380 kV XLPE cable systems. In order to obtain sufficient service experience of 380 kV XLPE cable systems and detailed failure information, both literature survey and internal interview with several TSO's (Transmission System Operators) in Europe have been carried out. Based on the collected in-service and failure populations regarding insulation, failure rates of 380 kV XLPE cable systems are statistically investigated with a confidence interval, regarding to some uncertainties. The calculated failure rates are compared with those from literatures. It shows that the results that the failure rates from the existing literatures are not suitable for 380 kV XLPE cable systems, because they are dominated by the failures from 220 kV cable systems. The most important consequence for TSO's is forced outage time, therefore these outage time caused by failures is also discussed.