Evaluation of 15-420 kV substation lightning arresters after 25 years of service

Surges caused by lightning and switching overvoltages in power systems continue to be a major loss for electrical utilities and customers. To reduce the losses of power system equipment caused by lightning and switching surges and to improve the reliability of power system operations, it is particularly important to evaluate the lightning arrester performances after some specified years of service. In this paper, some gapped SiC arresters rated from 15 kV to 420 kV have been evaluated after being in service for 25 years. According to ANSI/IEEE Std. C62.1-1984 and IEEE C62.11-1989 standards, power-frequency sparkover voltage, maximum 1.2/50 μs lightning impulse sparkover voltage and front-of-wave impulse sparkover voltage have been studied. It is found that some of the tested arresters were still fitting well with the standard requirements, while some of them failed the evaluation. If these arresters are still to be used in power systems, it is a great economical benefit for utilities and customers. At the end of this paper, some failure reasons regarding gapped SiC arresters are discussed