what is varistor

A varistor is an electrical component commonly used in electronic circuits to protect sensitive devices from excessive voltage spikes or surges. It acts as a voltage-dependent resistor, providing a low impedance path when there is a surge in voltage above a predetermined level. The varistor is designed to divert the excessive voltage away from the protected component by rapidly changing resistance with the increase in voltage. It offers a high resistance at normal operating voltages, allowing the current to flow through the protected device. However, when the voltage exceeds the threshold, the varistor quickly decreases its resistance to limit the voltage and protect the device. This essential component can be found in various applications, including power supplies, telecommunications equipment, home appliances, industrial machinery, and automotive systems. Its compact size, high reliability, and fast response time make it a crucial element in preventing damage caused by voltage transients. Overall, a varistor provides an effective and affordable solution for surge protection in electronic circuits, ensuring the safety and longevity of electronic devices.