Effect of Thermal Aging on Direct Current Integrated Charge Characteristics of XLPE Cable Insulation

The cross-linked polyethylene insulation of power cables under multiple stresses will age and deteriorate, and eventually cause insulation failure, which threatens the reliability of transmission lines. In this contribution, based on Direct Current Integrated Charge method, the performances of XLPE under thermal aging are investigated. The results show that the charge minimally injects into the unaged XLPE insulation, and the charge injected behavior intensifies with the thermal aging time. Thermal aging treatment results in greater relative permittivity, volumetric conductivity, and absorbed charge of XLPE insulation. The permittivity of the aged XLPE insulation gradually increases by 18.24%, whereas the conductivity rises by 14.48 times, and the absorption charge shoots up by 18.03 times. It is conducted that the enhancement in charge injection and the acceleration of charge accumulation reflects the cable insulation thermal aging intensified.