A metal oxide varistor, or MOV, is a passive component with an electrical resistance that varies with supplied voltage. They are used in circuits to provide optimal operating conditions and to protect against excessive transient voltages.
MOVs are the most common type of varistor, and they provide excellent transient voltage suppression. When the voltage across the varistor is low during normal operation, the MOV remains non-conductive. When voltage exceeds the varistor's clamping voltage, the MOV provides shunt-like behavior by diverting the excess voltage away from the circuit where it dissipates as heat.
Metal oxide varistors are available in a wide variety of sizes and offer high surge protection capabilities. They are often the first line of defense in industrial applications for transient surge protection.