The knowledge of the varistor can be better protected

When the voltage at both ends is within the nominal rating of 1, its resistance value is almost infinite, and it is in a high resistance state. The leakage current varistor exceeds its action voltage to produce the current to clamp the overvoltage and eventually converts the electric energy into thermal energy. The varistor D has protective measures in the use of the circuit, such as adding fuse before the varistor, and so on. When the voltage is higher than the voltage sensitive resistor, the current in the varistor will be very large, and the fuse will fuse and protect. Generally, the overpressure will not burn the varistor in a short period of time, but if a lot of overpressure is overpressed in a short time, the varistor will burn out (such as lightning) when the fuse has not been fused.

When the voltage at the two ends of the varistor is lower than the nominal rated voltage, the resistance value of the varistor is close to infinity, and there is hardly any internal current flowing through it. When the voltage at both ends of the varistor is slightly higher than the nominal voltage, the varistor will quickly pass through and change from high resistance to low resistance state, and the working current will increase sharply. When the voltage at both ends is below the nominal rated voltage, the varistor can be restored to a high impedance state. When the voltage at the two ends of the varistor exceeds its limiting voltage, the varistor will completely burn out and no longer be able to recover itself.