Aging Characteristics of XLPE under Electrical Stress

To study the aging characteristics and insulation failure process of XLPE under electrical stress, this paper takes XLPE sheet samples as the object and studies the effects of insulation thickness, temperature, electric field strength, and voltage application duration on the breakdown field strength, breakdown time, and partial discharge parameters of XLPE through electrical aging tests, breakdown experiments, partial discharge measurements, and physical and chemical properties analyses. The results show that the breakdown field strength of XLPE is negatively correlated with its thickness. The breakdown time increases first and then decreases with the increase of temperature, and is negatively correlated with the electric field strength. With the increase in electrical aging time, both the number of partial discharges and the average discharge magnitude increase, and the quantity and size of defects in the insulation increase. Electrical aging has a minimal impact on the crystalline regions of XLPE, whereas the electrical orientation of molecular chains and the thermal motion of carriers are the primary factors for destroying the molecular chains in the amorphous regions of XLPE. This study provides a theoretical foundation for the insulation design of high-voltage cables.