Metal Oxide Varistor Circuit

A metal oxide varistor is frequently used in different circuits along with a fuse.

Metal oxide varistor circuit.

A metal oxide varistor or mov is the blue or orange colored circular component that you can commonly spot on the ac input side of any power supply circuit the metal oxide varistor can be considered as another type of variable resistor that can vary its resistance based on the applied voltage across it. Metal oxide varistors or mov s are typically made from a small disk shaped metal zinc oxide material. The metal oxide varistor or mov is a voltage dependent nonlinear device that provides excellent transient voltage suppression. The components needed to build this circuit are shown below.

This mov circuit will clamp up to 300vac if a power surge allowing transients into the circuit were to be that high. Metal oxide varistors movs are available in a variety of form factors and sizes for a broad range of applications. An mov s voltage rating called the varistor voltage is the voltage across a varistor when a current of 1ma is passed through the device. Working of metal oxide varistor mov working of metal oxide varistor mov the working of a mov is shown in the figure above.

The energy of the incoming surge is partially conducted and partially absorbed protecting the circuit. 300vac metal oxide varistor. When a high current passes through a mov its resistance value decreases and acts as a short. Metal oxide varistor circuit.

The circuit we will build is shown below. The metal oxide varistor is designed to protect various types of electronic devices and semiconductor elements from switching and induced lightning surges. Varistors are voltage dependent nonlinear devices which have electrical characteristics similar to back to back zener diodes. The most common type is the mov or metal oxide varistor.

They are composed primarily of z n o with small additions of other metal oxides such as bismuth cobalt magnese and others. These two are connected in parallel to the protected circuit. The radial leaded disc type is the most common version. This type contains a ceramic mass of zinc oxide grains in a matrix of other metal oxides such as small amounts of bismuth cobalt manganese oxides sandwiched between two metal plates which constitute the electrodes of the device.

The circuit of the mov is shown below. When the circuit is exposed to a high voltage transient the varistor starts to conduct and clamps the transient voltage to a safe level. Metal oxide varistors and multi layered varistors. The most common modern type of varistor is the metal oxide varistor mov.

The component starts conducting as soon as the voltage across it reaches the threshold voltage. The main components used to protect the circuit are fuse and varistor. The boundary between each grain and a neighbor forms a diode junction which allows. They are available in many values for specific voltage ranges.