## What is varistor voltage in MOV?

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. This varistor voltage level is essentially the point on the I-V characteristic curve when the device starts to conduct.

How does a MOV varistor 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.

### 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 I select a MOV varistor?

The first step of choosing a MOV is determining the continuous working voltage that will be provided across the varistor, you have to choose the varistor with maximum AC or DC voltage that matches or slightly higher than the applied voltage.

#### How do I read a MOV file?

The current rating of the MOV could be twice that of the SMPS rating, meaning if the SMPS wattage is rated at 24 watts at the secondary, then the primary could be calculated as 24/285 = 0.084 amps, therefore the MOV current could be anywhere above 0.084 x 2 = 0.168 amps or 200mA.

How do I know what MOV I have?

Estimate the MOV’s energy rating in units of joules. This is the electrical energy that the MOV can safely absorb at least once before failing. You can calculate the energy by multiplying peak surge volts by amps, and then by seconds of time. For example, 1,000 volts x .

## What is the purpose of a MOV?

MOV Performance The main function of MOV is to work as a surge suppressor. When the voltage across the varistor is below the clamping voltage then varistor will not conduct. The performance of the varistor gets slow down based on time even if tiny surges flow throughout it.

What happens when a MOV fails?

When subjected to stresses above its ratings, an MOV can fail as a short circuit. If applied conditions significantly exceed the energy rating of the device, and current is not limited, the MOV may be completely destroyed. For this reason, the use of current-limiting fuses is suggested.

### How do I check my MOV varistor?

Work the lead loose with a long-nose pliers. Turn the multimeter on and set its function knob to read resistance. Touch the meter probe tips to the MOV’s leads and measure its resistance. If it has a resistance much under 100 ohms, it has blown.