MOV is the abbreviation for Metal Oxide Varistor, sometimes referred to as a Varistor or VDR. An MOV is a type of device in which the resistance changes depending upon the applied voltage. The electrical operation of the device is similar to that of two zener diodes placed in an anode-to-anode configuration. Because of this electrical behavior, they can be used to absorb excess energy initiated by an overvoltage event and thereby protect downstream circuit components from damage.