Abstract
Distribution surge arresters with an internal series gap have been installed on Japanese distribution lines in high density for reducing lightning-related overvoltages. In contrast, surge arresters are sometimes damaged by direct lightning strokes, particularly in winter. Measurement of insulation resistance between terminals of the surge arrester and measurement of DC discharge voltage of the surge arrester are generally adopted to detect damaged arresters. However, if metal-oxide (MO) varistors are damaged and the internal series gap is not damaged, it is difficult to detect damaged arresters by two conventional methods. Therefore, this paper presents the proposed detection method which can accurately detect damaged arresters. In the proposed method, first, the voltage between terminals of the surge arrester is measured when the output of an impulse generator is applied to the surge arrester. Secondly, the damaged arrester is detected by the comparison between its voltage waveform and the voltage waveform of the non-damaged arrester. The detection rate of damaged arresters by the proposed method is remarkably higher than those by two conventional methods.
