Transient Suppression for Surge and Lightning Pulses

Abstract

The types of pulses used in surge and lightning testing include double exponential style pulses and damped sine wave pulses. Of the two, the double exponential pulse is the most difficult to deal with. The pulse durations are much longer than damped sine. Also, since they are not oscillatory, the components exposed to the pulse are experiencing a flow of charge in one direction and not able to discharge until after the threat signal is passed. Types of transient suppression devices include gas discharge tubes, transient voltage suppressors (TVS), metal-oxide varistors (MOV), diodes, thyristor, and other basic filter components. High-energy impulses are different from those of electrical fast transient (EFT) or ESD style pulses. The latter two can be treated as RF signals or highfrequency noise and typically do not require components that can handle significant energy. High-energy pulses, known as surge in the commercial electronics world and lightning or EMP in the military and aerospace electronics, are significantly slower in rise time and decay. They also have much lower source impedance than the other pulses. Lower source impedance results in greater current levels at the same voltage.