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Improved Direct-Current Aging Stability and Suppressed Leakage Current of Zinc Oxide Varistors by Co-doping with Boron, Gallium, and Yttrium
Kuan Cheng1, Weiqing Wang1, Dongji Liu1, Qingyun Xie2, Yuanxiang Zhou3, Hongfeng Zhao1
1 School of Electrical Engineering, Xinjiang University, Urumqi 830047, China
2 Xidian Surge Arrester Co., Ltd, Xi'an, Shanxi, 710200, China
3 State Key Lab of Power Systems, Department of Electrical Engineering, Tsinghua University, Beijing 100084, China
received March 24, 2020, received in revised form June 7, 2020, accepted June 17, 2020
Vol. 11, No. 2, Pages 111-116 DOI: 10.4416/JCST2020-00008
Abstract
The effect of B3+, Ga3+ and Y3+ co-doping on the microscopic and electrical properties of ZnO varistors is studied. Co-doping with multiple ions greatly improves the comprehensive performance of the ZnO varistors. The doped Ga3+ increases the acceptor concentration, raises the barrier height, and inhibits the increase of leakage current. Y3+ increases the voltage gradient by limiting the growth of grains. B3+ improves the resistance of ZnO varistors to direct-current aging. The varistor with a B3+ content of 0.2 mol% achieves a voltage gradient of 450 V/mm, leakage current of 0.54 A/cm2, and a nonlinear coefficient of 79. Accelerated aging experiments carried out for 1 000 h at 0.9 U1mA and 115 °C give an aging coefficient of 0.027. This research illustrates the ability of cation co-doping to improve the protection effect of metal oxide arrestors and the stability of power systems that operate at ± 1100 kV.
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Keywords
Ceramic, varistor, electrical properties, DC aging, aging coefficient
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