## What do the numbers mean on a varistor?

k = a constant for the component. V = applied voltage. n = value for the device style. Typically for silicon carbide the value of n is between about 3 – 7, but for zinc oxide device the value can be in the region of 20 – 50 making the characteristic much sharper. Varistor characteristic.

What are metal oxide varistors?

The Metal Oxide Varistor or MOV for short, is a voltage dependant resistor in which the resistance material is a metallic oxide, primarily zinc oxide (ZnO) pressed into a ceramic like material.

What is varistor and for what it is used for?

Varistors are used to protect a circuit from high voltage surges. When a high voltage surge is applied to a circuit, the outcome is usually catastrophic to the circuit. A capacitor may be installed across the signal lines. However, this capacitor cannot suppress voltage surges.

### How do metal oxide varistors work?

An MOV is a voltage dependent device which has an electrical behavior similar to back to back zener diodes. changes from a near open circuit to a very low value, thus clamping the transient voltage to a safe level. pulse is absorbed by the Varistor, thereby protecting vulnerable circuit components.

How do I read varistor codes?

Touch one meter probe to the free varistor lead and the other probe to the connected lead. Read the resistance on the meter. If it reads nearly infinite resistance, the varistor is still good. If it reads very low resistance, the varistor is blown.

How do I select varistor value?

Select a model to provide the required voltage-clamping characteristic A final consideration is to choose the appropriate package style to suit the application. Consider the maximum continuous voltage that will be applied to the varistor including any high line conditions (i.e., 110% or more of nominal voltage).

## What is the working principle of varistor?

A varistor does not obey Ohm’s law and hence it is not like an ohmic resistor. It is basically a non-ohmic resistor that does not follow Ohm’s law and hence it is also called a non-linear resistor or a voltage-dependent resistor.

Can I remove varistor?

Just leave it open. Simply remove it untill you find a replacement. The circuit will work without it.

How does a varistor fail?

Under different current conditions, failure modes include electrical puncture (see Figure 4), physical cracking (see Figure 5), and thermal runaway. Cracking happens because varistors are basically a ceramic material, and hitting them with a sharp high-amplitude surge is like hitting a dinner plate with a hammer.