ZnO varistors are highly non-ohmic resistor and they are widely utilized in protecting electric power transmission line and electronic device against the dangerous overvoltage or voltage surge, and the ac voltage aging characteristic of ZnO varistors is one of the most concerning performance parameters. In this paper, the thermally stimulated current (TSC) performance of ZnO samples has been investigated before and after an accelerated aging test, which was prepared with a common formula. The experimental results show that with the increasing of aging time, the temperature corresponding to TSC peak increases slowly and the trap level becomes deeper, in addition to, the TSC current peak volume and the trapped charges increase markedly.
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