Should a varistor have continuity?

A continuity test shouldn’t cause a beep, because a varistor has much greater resistance than, say, a fuse. Try it on the Ohms range of the meter. The varistor is presumably an inrush current limiter whose resistance drops as it heats up.

How is varistor value calculated?

The simplest ways of determining the current duration are simulation or measurement (τ = t*r). The time constant can also be calculated to an approximation with equation 13. Here the varistor resistance of voltage class K20 is calculated for 1 A.

Can a varistor go bad?

The varistor, normally having a very high resistance, responds to the voltage spike by absorbing its energy with a very low resistance. The varistor will likely be wired to a fuse holder. If the varistor is visibly burnt through or broken, it is bad; replace it.

Why would a varistor burn out?

The surge energy is too large and exceeds the absorbed power; 8, the pressure is not enough; 9, current and surge are too large and so on. The safety of the use of varistors has always been a problem that needs attention.

How do I choose a varistor?

For example, selecting a MOV or silicon varistor for that matter, for voltage, its maximum continuous rms voltage rating should be just above the highest expected supply voltage, say 130 volts rms for a 120 volt supply, and 260 volts rms for a 230 volt supply.

Can I replace a varistor with a capacitor?

You can replace it with a new one provided it is for the same voltage levels that it triggers. This AC and DC voltage ratings are the important parts and then the energy capacity. Energy cap. is not a major issue in Computer PSUs since the usually use a small varistor there.

Does a varistor have polarity?

Does a varistor have polarity? In the case of metal oxide varistor, a zinc-oxide layer is basically sandwiched between two metal electrodes. As a result, there is no polarity.

What is a varistor and how does it work?

A varistor is an electronic component that protects expensive devices from harmful power surges, much like a shock absorber. For example if there is a power surge, the varistor, normally having a very high resistance, responds to the voltage spike by absorbing its energy with a very low resistance.

How do you test a varistor for low resistance?

A varistor that’s received a strong electrical jolt may remain at low resistance and should be tested. Disconnect the electronic equipment from the wall outlet. Open the case with the screwdrivers and locate the varistor. It is usually a brightly colored disk the size of a coin.

What does a broken varistor look like?

It is usually a brightly colored disk the size of a coin. The varistor will likely be wired to a fuse holder. If the varistor is visibly burned through or broken, replace it immediately. Desolder and disconnect one of the varistor’s leads.

What should I do if my varistor has received a jolt?