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. ... Therefore, when circuit protection from voltage surges is required, a varistor is used as a voltage protection device.

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 do I choose a varistor?

Choose a varistor with an energy absorption rating that equals or slightly exceeds the energy values associated with the event the circuit may experience. If, however, the transient voltage is due to an external event, the magnitude of the source energy is unknown.