Temperature Aging Characteristics of Zinc Oxide Varistors at DC Overvoltage

Operating temperature was one of the factors affecting the performance of zinc oxide varistors. A kind of test method of DC aging under constant temperature heating was presented and the experimental study was carried. The volt-ampere characteristics of zinc oxide varistors before and after aging at different temperatures were obtained through comparison experiments. It was found that, after DC aging, the threshold voltage of ZnO varistors increased. The effect of temperature on the band gap of ZnO varistor ceramics was not significant, but the relative dielectric constant of grain boundary decreased with the temperature increasing and the goodness of linear fitting decreased significantly.