Electro-thermal-mechanical coupling analysis of ZnO arresters under synergistic effect of alternating moisture absorption and impulse aging

During the service life of a metal oxide surge arrester, the synergistic effect of alternating moisture absorption and impulse aging significantly accelerates the failure process of varistors, thereby compromising power system reliability. To quantitatively evaluate the impact of this synergy, accelerated experiments on alternating moisture absorption and impulse aging are first conducted. Subsequently, the experimental results are used as inputs for finite element simulations to investigate the electro-thermal-mechanical coupling mechanisms under the alternating moisture absorption and impulse aging. Finally, the degradation of varistor performance is comparatively assessed by integrating simulation and experimental results. The results demonstrate that under 100 kA impulse, the fracture probability for varistors under alternating moisture absorption and impulse aging conditions is three times higher than that under impulse aging alone. Furthermore, the synergistic effect leads to more severe electrical parameter degradation and structural damage. This study reveals the mechanism underlying the significant discrepancy between the actual service life and theoretical lifespan of arresters.