Response of a Surge Arrester With a Series Gap for 6.6-kV Distribution Lines to Steep-Front Transients

Surge arresters with a series gap are commonly installed in distribution lines to effectively protect insulators, transformers, and other equipment from lightning threats in Japan. On the other hand, it has been well known that the high-altitude electromagnetic pulse (HEMP) at an early stage, called E1 HEMP, may extensively cause overvoltage on distribution lines, and the rise time of the E1 HEMP is as short as a few nanoseconds, which is much shorter than that of lightning electromagnetic pulses. To evaluate the effectiveness of surge arresters with a series gap against overvoltage induced by the E1 HEMP, it is necessary to evaluate the effect of a discharge delay due to the series gap on the protection level of surge arresters for steep-front transients. In this work, using a pulse current injection system, we apply a high voltage to a surge arrester with a series gap widely used for 6.6-kV distribution lines in Japan and measure the response of the surge arrester to steep-front transients. From the measured results, we obtain the voltage–time characteristics of the surge arrester with a series gap and residual voltages, which are compared with the results for lightning impulse voltage.