Resumo:
Surge arresters are protective devices installed throughout power systems to limit overvoltages caused by lightning impulses, switching operations, and network faults. However, these devices are subject to degradation processes that may compromise their performance, lead to failure, and affect system reliability. In this context, it is essential to investigate the mechanisms associated with surge arrester aging and to identify the most sensitive parameters for monitoring their operational condition. For this purpose, an aging procedure based on current impulse stresses was applied to three groups of surge arresters from different manufacturers, each group consisting of three 15 kV samples. Throughout the aging process, the devices were evaluated through leakage current and partial discharge measurements. At the end of the aging procedure, microstructural analyses were performed on both new and aged samples to investigate the effects of degradation. The results indicated that leakage current-derived parameters exhibited the highest sensitivity for monitoring surge arrester aging, with dissipated power and third-order harmonics standing out as the most representative indicators. Partial discharge activity was detected only in a subset of the samples and during the final stages of the degradation process. Furthermore, samples exhibiting partial discharge activity also showed changes in the final leakage current measurements. Microstructural analyses confirmed the degradation evidence observed in the electrical tests. Therefore, it was concluded that the combined application of the employed techniques was effective for assessing the aging of distribution surge arresters, with leakage current-derived parameters emerging as the most promising indicators for monitoring the degradation of these devices.
