How do you use varistor in a circuit?

How do you use varistor in a circuit?

As such varistors are used in sensitive electronic circuits to ensure that if the voltage does suddenly exceeds a predetermined value, the varistor will effectively become a short circuit to protect the circuit that it shunts from excessive voltage as they are able to withstand peak currents of hundreds of amperes.

How does a varistor work?

When a voltage surge exceeding a specified voltage (varistor voltage) is applied, the varistor suppresses the voltage to protect the circuit. When the voltage surge does not exceed the varistor voltage, the varistor works as a capacitor. If the peak pulse current rating is insufficient,then the varistor may be damaged.

How do you read a varistor?

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.

What happens when varistor fails?

Varistors need to absorb the energy deposited by temporary overvoltage, switching surges, or lightning impulses. The energy absorption capability can be divided into thermal energy absorption capability and impulse energy absorption capability. …

Do varistors degrade over time?

To address these transients, Metal Oxide Varistors (MOVs) are widely used in electronic circuits and power supplies. They absorb surges in the circuit input and maintain the voltage within acceptable limits. However, these surges and overvoltage transients can degrade MOVs over time.

How do you test a varistor in a circuit?

How do you test for varistor? 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.

What happens if a fuse blows on a varistor?

The varistor is simply connected between line and neutral but after the fuse. If the varistors gets a short circuit the fuse will blow and disconnect the main from the following application. Simple solution for effective protection. The original high current fuse should be replaced with one matching with the equipment.

What do you need to know about a varistor?

Judging the varistor usually requires a power supply with a wide regulating voltage range, and it has a good current limiting effect. A voltmeter with good precision is connected in parallel across the varistor when measuring. Connect the adjustable power lead to both ends of the varistor. The voltmeter indicates the power supply voltage.

Why does a varistor collapse at high voltage?

When high voltage is encountered, the diode reverse collapse occurs due to hot electrons and tunneling effect, and a large current flows. Therefore, the current-voltage characteristic curve of a varistor is highly non-linear: high resistance at low voltage and low resistance at high voltage.

Which is better a varistors or a gas arrestor?

Compare to varistors gas tubes have higher breakdown voltages. They can handle significantly higher fault currents and withstand multiple high-voltage hits without self destruction. On the other hand the response times is longer. Gas arrestors are commonly used in telecommunication equipment to protect against lightning strikes.