A Review of Zinc Oxide Varistors for Surge Arrester

Zinc Oxide (ZnO) surge arresters are used as a protective device for transient overvoltages. This is mainly due to the high nonlinearity of voltage-current characteristics of ZnO varistor. The electrical characteristics of ZnO varistor is determined by its microstructure. This paper reviews about the ZnO varistor for surge arrester applications. The paper starts with the concept of nonlinear characteristics and microstructure of the ZnO varistor. The fabrication method and characterization of varistors are discussed. The effects of various additives and sintering process are explained.