Metal oxide varistors as surge suppressors

Abstract

High voltage transients and surges are produced due to lightning, inductive load switching, and spikes or electrical noise on power lines. These voltage surges can be as high as 6 kV and the transient period can vary from a few microseconds to milliseconds. The frequencies of these surges vary randomly depending upon the source voltage. These surges, irrespective of their short duration, can cause severe damage to the electronic equipment which may adversely affect semiconductor devices, corrode electromechanical contacts, breakdown insulators, and generate noise. To cope up with the problem associated with transients, commonly, surge suppressor devices are used. Among the surge suppressor devices the most reliable, economic and the latest are metal oxide varistors (MOVs). The surge suppressor To cope up with the problem associated with transients, commonly, surge suppressor devices are used. Among the surge suppressor devices the most reliable, economic and the latest are metal oxide varistors (MOVs). The surge suppressor can be simply connected between the two leads of the circuit which is to be protected. For a normal supply voltage, the surge suppressor will work almost like an open-circuit. When a high voltage appears, it will draw a large current and will not allow the voltage across itself to increase beyond a safe limit.