A "varistor" is a resistive device with nonlinear volt-ampere characteristics, which is mainly used for voltage clamping when the circuit is subjected to overvoltage, absorbing excess current to protect sensitive devices. The main parameters of varistor are: varistor voltage, current capacity, junction capacitance, response time, etc.

Varistor Generally, it is a component connected between the two stages of the circuit power supply. Its function is to maintain the power supply voltage of the entire circuit within a reasonable design range to prevent sudden changes in voltage from burning the circuit, so it is also called a surge protector. It is a semiconductor material, which is equivalent to a variable resistor. When the power supply is normal and there is no surge, the varistor is equivalent to an open circuit, and the resistance is infinite; when the voltage increases to a certain extent, the varistor starts to conduct, and there is a current flowing through itself. Divide the voltage to ensure that the rated voltage output by the subsequent circuit remains unchanged.

Component design has parameters and indicators. When the voltage is too large, it will cause the varistor to flow too much current, generate heat, and then break down. Some breakdowns can be self-recovery, and some will burn the components. If the voltage is not a varistor breakdown, the resistor will generate heat, so the recovery time is more than 60 seconds. If the varistor is broken down, it will not recover. Different waveforms will cause different damages. For example, the 8/20 waveform will cause the varistor to burst. A 2ms waveform will perforate the varistor.