Pressure-sensitive resistor is a kind of resistive device with non-linear voltammetry characteristics, mainly used in the protection of the circuit when it is subjected to overvoltage, absorbing excess current to protect sensitive devices, pressure-sensitive resistor is also called "surge absorber", the English name is "Varistor", and now a large number of "Copper Oxide" (ZnO) pressure-sensitive resistors.

Pressure-sensitive resistor is a pressure-limiting protection device that takes advantage of the non-linear characteristics of pressure-sensitive resistor to protect subsequent circuits when the voltage occurs between the two poles of pressure-sensitive resistance. Pressure-sensitive resistors are characterized by large inrush currents and low manufacturing costs, which are widely used in surge protection of industrial frequency AC currents.