Research of the Influence of Degradation of ZnO Varistor on Its Dynamic Characteristic
Leijun Xu · Insulators and Surge Arresters · 2014
In order to judge the deterioration degree of the Metal Oxide Varistor(MOV), it is often to use the static parameters of MOV such as the varistor voltage U1 mAand the leakage current IL. But these static parameters can only reflect the overall performance of the piezoresistor, and can't effectively characterize the aging deterioration trends of varistor. According to the volt-ampere features of MOV,combing with the double schottky barrier model as well as the ion migration theory, it is found that the dynamic resistance of MOV(Rd)increases with increasing degradation degree by the experiment of degradation MOV-model under different impulse current. Results are as follows: the dynamic resistance presents the distribution of U shape under 8/20 impulse current and a slow upward trend increasing rapidly under 10/350 impulse current before deterioration. After degradation, the dynamic resistance did not change significantly, only partially decreasing trend for 8/20 impulse current, but the while the dynamic resistance under 10/350 impulse current appears irregular osillation. The experiments