Analysis of Dynamic Voltage Current Characteristics of ZnO Varistors Under 8/20 μs Impulse Current

Dynamic voltage-current(U-I) characteristic of ZnO varistors under 8/20 μs impulse current was measured and analyzed.The dynamic U-I characteristics curve shows that its rising process does not repeat its falling process accurately.At the same current,the voltage in respect of the rising process is always higher than that related to the falling process.This phenomenon could be inferred to involve with the transition process of varistor under impulse voltage.Using hole-induced tunnel breakdown theory,the mechanism of this phenomenon was explained qualitatively.