Research on Long-Term Withstand Voltage Characteristics and Lifetime Prediction of Grafted Modified Polypropylene Cable Insulation

In actual cable operation, insulation is subjected simultaneously to both electrical and thermal stresses. In this study, polypropylene (PP) insulation modified by grafting IRGANOX 3052 was prepared, and a long-term withstand voltage test platform combining electrical and thermal aging was established. The results show that graft modification increases the short-term alternating current (AC) breakdown strength of PP insulation and reduces the extent of insulation performance degradation at high temperatures. Furthermore, fitting with the inverse power model under single electrical stress reveals that the breakdown coefficient of grafted PP increases, indicating a reduced degree of electrical damage to the insulation. Additionally, fitting with the SIMONI model under coupled electro-thermal stresses demonstrates that graft-modified PP insulation maintains a longer insulation lifetime under long-term multi-stress conditions, making it suitable as an insulation material for cable applications.