Affiliation:
1. The Wind Solar Storage Division of State Key Laboratory of Control and Simulation of Power System and Generation Equipment School of Electrical Engineering Xinjiang University Urumqi 830046 P. R. China
2. Xidian Surge Arrester Co., Ltd. Xi'an 710200 Shaanxi P. R. China
Abstract
As a new core component of surge arresters, it is crucial for manganese dioxide varistors to solve the challenges of reducing the leakage current and lowering the residual voltage ratio. In this study, the electrical characteristics of tin dioxide varistors using B2O3 as the acceptor dopant and Ta2O5 as the donor dopant are investigated. Several tin dioxide based varistors doped with different amounts of B2O3 are prepared and characterized by the researchers. X ray diffraction (XRD) is used to analyze the structural features of the samples and to observe the phases involved. It is found that the B2O3 dopant provides oxygen vacancies, reduces the grain size, increases the barrier height, and decreases the residual pressure ratio. The Ta2O5 dopant provides donor defects and free electrons needed to form the barrier. When balancing the concentrations of B2O3 and Ta2O5, the optimum dopant concentrations is found to be 0.1 mol% of B and 0.05 mol% of Ta; these concentrations result in a leakage current of 0.25 μA cm−2, a residual pressure ratio of 1.95, a nonlinear coefficient of 25, and a voltage gradient of 394 V mm−1 for the varistor.