The effect of multiple lightning impulse on the electrical characteristics of opto-isolators

A natural lightning generates simple unidirectional double-exponential impulses which are complex and oscillatory with multiple strokes in one flash. The behavior and performance of low surge protective devices under the application of multiple lightning impulse voltage are different from the standard testing procedure. Since opto-isolator now days becomes the most common, economical and reliable device for low voltage and telecommunication systems surge protection, a precise method of testing has to be adopted based on natural characteristics of lightning to accurately determine its performance and capability. It is therefore vital to simulate this natural lightning characteristic in order to study the response of the lightning protective devices. In this paper, results of laboratory studies carried out on opto isolator which are subjected to a 1/1000 mus, 1 kV multiple voltage impulses by using the newly constructed multiple impulse generator, MIGe are presented. The electrical characteristics responses of the opto-isolator such as the forward current I_f, forward voltage V_f and reverse voltage V_R parameters are being discussed. From the experimental work, it has been shown that the multiple voltage impulse has significant effects on the forward current I_F and forward voltage V_f characteristics of the opto-isolator.