The resistance material of radial leaded metal oxide varistor is semiconductor, and the widely used "zinc oxide" (ZnO) varistors are composed of divalent element (Zn) and hexavalent element oxygen (O) as their main materials.

WEET will give you an example of a metal oxide varistor China dipped radial MOV, a lightning resistant varistor.

As the name suggests, the main function of lightning protection round zinc oxide varistor is to protect electrical appliances during thunderstorm weather.

The working principle of this type of WEET radial leaded zinc oxide varistor 6KV3KA is to be connected in parallel with the electrical appliance in the circuit. During normal operation of the electrical appliance, due to its high resistance, it basically does not work.

When a large current flows through the circuit, the lightning protection 10mm DIP Radial Varistors instantly conducts and causes all the current in the circuit to flow through the lightning protection varistor, thereby protecting the electrical appliances.

One issue that engineers need to pay attention to here is that although lightning protection radial leaded varistors can absorb a large amount of surge energy, they cannot withstand continuous currents above milliampere level. 

Therefore, this must be taken into account when used for over voltage protection. In the usual selection process, the selection of lightning protection dipped varistors is usually based on two parameters: nominal radial metal oxide varistor voltage V1mA and current carrying capacity.

Here are pictures of 07D Epoxy Resin Metal Oxide Varistor and UL VDE Metal Oxide Mov 10D511K Varistor Epoxy Resin.