TSC characteristics of AC aged ZnO varistors

The AC aging characteristics and mechanism of ZnO varistors have been widely concerned for a long time. In this paper, accelerated aging test of ZnO varistors was carried out based on the "ten degrees and a half" rule, power loss and thermally stimulated current (TSC) of samples were tested during each aging stage. The test results show that with the increasing of aging time, the power loss increases, the trapped charges increase and the trap level becomes deeper. In addition, the increase of power loss and the increase of trapped charge with the aging time have the same trend. A preliminary analysis shows that the migration of interstitial zinc ions will change the space charge distribution and decrease the Schottky barrier height to cause the change of the trap level.