Ring Varistor refers to a resistor whose resistance varies with voltage within a certain range of current voltage. English name is called "Voltage DependentResistor" abbreviated as "system" VDR, may be called the Varistor." The resistor data of ring Varistor is a semiconductor, so it is a type of semiconductor resistor. Much of today's use of "zinc oxide" ring Varistor, whose principal data are composed of bivalent elements (Zn) and hexavalent elements (O). So from the perspective of information, zinc oxide annular pressure sensitive resistor is a kind of "Ⅱ - oxide semiconductor Ⅵ family".
Effect of ring Varistor:
The main characteristic of ring Varistor is that when the voltage applied to it is below its threshold, the current flowing through it is very small, equivalent to a closed valve. When the voltage exceeds UN, the current flowing through it surges, equivalent to opening the valve. Using this function, the abnormal overvoltage often appears in the circuit can be controlled, so as to protect the circuit from overvoltage. Generally, the ring Varistor is highly resistive at low voltage, but it turns into a low-resistivity state when the voltage is exceeded. It is primarily used for overvoltage maintenance and absorbing surge current. In the case of over-pressure leakage maintenance switch, ring piezoresistive is used as the sensitive element.
One parameter on ring Varistor is the voltage parameter. If the voltage exceeds its value, the ring Varistor will be switched on and the voltage will be lowered to maintain the normal operation of the device.
When the voltage at both ends of the ring Varistor is greater than the resistance value of the ring piezoresistor, the ring piezoresistor is switched on, the circuit current increases, the fuse is burned, and the maintenance appliance is not damaged by high pressure.