A DC cable failure model by using two parameters Weibull distribution

LDPE is one of the main power cable insulation materials, the temperature and voltage duration are the key factors to impact the lifetime of LDPE. Today study on the DC cable failure model is the key point. This paper adopts step-stress test to the LDPE samples in different temperatures. The voltage durations applied to the samples are 20s, 45s, 120s, 300s. The test results show the withstand voltage time of the LDPE samples during different temperatures and voltage durations. According to the test results, the parameters are calculated by using least square method. The Weibull distribution affected by temperatures, and the Weibull distribution affected by voltage durations are established respectively. On this basis, combining with the competing risk model, this paper establishes a DC cable failure model affected by temperatures and voltage durations. The failure model can effectively assess the insulation conditions of a DC cable.