Effects of Dispersant on Electrical Properties of Zinc-Oxide Varistors and Methods to Improve Protection Performance

The effect of the polyacrylate dispersant (AN-103P) on the electrical properties of ZnO varistors was investigated. With the increase of the dispersant content, the voltage gradient of the ZnO varistors increased, the leakage current decreased, the non-ohmic property first improved and then decreased, and the ratio of residual voltage under surge current to breakdown voltage (residual voltage ratio) gradually increased. To reduce the residual voltage ratio of the ZnO varistors, three different experiments were carried out to adjust the content of Sb 2 O 3 , the sintering temperature, and the content of Al 3+ , respectively. The results showed that increasing the content of Al 3+ decreased the residual voltage ratio of the ZnO varistors most effectively. When the Al 3+ content increased to 0.013 mol%, the ZnO varistors have the optimal comprehensive electrical performance with a voltage gradient of 321 V mm −1 , and a residual voltage ratio of 1.76. This current capacity is higher than that of other reported varistors with similar gradients.