Studies on TSC characteristic of ZnO varistor under the applied impulse current

ZnO varistors have high nonlinearly which are widely utilized in protecting power systems and electronic devices against the dangerous over-voltages or surges. In this paper, the thermally stimulated current (TSC) characteristic and U-I characteristic performance of aging ZnO varistors had been investigated in different aging conditions(impulse current amplitude, impulse time). Based on the experimental results, with the increase of impulse time, U-I characteristic drifts. It was found that the trapped charges would be increasing with the increase of impulse time, and this might bring the decrease of the Schottky barrier height aggravating, which would lead to the impulse aging of ZnO varistors. In addition, the trend of U-I characteristic is consistent with the trend of TSC characteristic. Consequently, the thermally stimulated current experiment is an effective method to present the impulse aging degree of ZnO varistors.