Metal-oxide varistor (MOV) also known as a voltage-dependent resistor (VDR).Metal oxide varistors consist of approximately 90% zinc oxide as a ceramic base material plus other filler materials for the formation of junctions between the zinc oxide grains. Metal oxide varistors are now the most common type of voltage clamping device and are available for use at a wide range of voltages and currents. The use of a metallic oxide within their construction means that MOV’s are extremely effective in absorbing short term voltage transients and have higher energy handling capabilities.