The effect of multiple lightning impulse on the electrical characteristics of opto-isolators as low voltage lightning protector

Abstract

Theoretical studies and experimental surveys related to overvoltage induced on power lines by lightning strikes have shown that the waveshapes are different from that of the standard impulse in the presently adopted standards [1]. A considerable amount of analysis has been made on the frequency of the multiple stroke of lightning. It has been shown that between 60% to 70% of ground flashes have more than one stroke [2] with an average of 3 or 4 strokes/flash and the possibility of more than 10 strokes/flash is about 5%. A multiple stroke ground flash is a sequence of multiple pulses separated by time intervals of tens of milliseconds. These multi-stroke flashes can impose surges of exceptional severity on service equipment and protective devices such as distribution surge arresters, insulators, opto isolator and surge varistor.