Development and Application of the High-Gradient Zinc Oxide Varistor

In order to further reduce the volume of the GIS arrester and improve its performance, this article carried out the experimental analysis on the doping formula and process of high-gradient high-performance zinc oxide varistors. The influence of crucial additives on the overall performance of the varistor is obtained. Crucial processes such as debinding of the unburnt body and heat treatment of the side insulation layer are optimized. Based on the analysis, this paper completed samples of ZnO varistors with four specifications of D62, D71, D115, and D128. The D115 varistor has been applied to the 500 kV GIS arrester prototype with the miniaturized structure design and potential distribution optimization. The test results show that the potential gradient of the varistors studied in this paper is close to 400 V/mm. Varistors possess a series of excellent properties such as voltage ratio as low as 1.55 at a nominal discharge current and a current capacity up to 300 J/mm3. The 500 kV GIS arrester developed based on this varistor has a 10% reduction in residual voltage than the GB/T 11032 standard, a 15% reduction in volume compared to the traditional ones, and superior overall performance.