Method of selecting step stress test parameters for XLPE insulation DC voltage endurance coefficient

Cross-linked polyethylene (XLPE) insulation DC voltage endurance coefficient (VEC) is an important basis in the selection of DC cable insulation design and factory test parameters. Studies on the degradation of XLPE insulation performance under DC electric field can also provide technical support for the reliability evaluation of cable operation. The step stress method as an efficient electrical life test method is widely used to obtain VEC. The parameters of step stress method present considerable influences on VEC. An analytical method based on the trajectory of the damage curve and equivalence between step stress test and constant stress test within zone division is proposed in this paper. According to the proposed method, several sets of step stress tests with different test parameters have been carried out. The accuracy of the test results has been confirmed via analyzing test data. The experimental results show that the VEC (n=12.0) obtained by the step stress test whose parameters are selected by proposed method has good equivalence with the result (n=12.2) under constant-stress method.