Improving the protective effect of surge arresters by optimizing the electrical property of ZnO varistors

• Published in: Electric power systems research 2020-01, Vol.178, p.106041, Article 106041
• Main Authors: Meng, Pengfei, Yuan, Chao, Xu, Heng, Wan, Shuai, Xie, Qingyun, He, Jimou, Zhao, Hongfeng, Hu, Jun, He, Jinliang
• Format: Article
• Language: English
• Subjects: Electric currents; Electric power systems; Electric properties; Electrical properties; Electronic devices; Insulation; Metal oxides; Multiple dopants; Overvoltage; Rare earth elements; Sintering; Sintering process; Substations; Surge arrester; Surge arresters; Transmission lines; Varistors; Waveforms; Yttrium; Zinc oxide; Zinc oxides; ZnO varistors
• ISSN: 0378-7796; 1873-2046
• DOI: 10.1016/j.epsr.2019.106041

•Tailoring sintering process of multiple dopants based ZnO varistors.•Varistors exhibiting a voltage gradient of 520V/mm and a residual voltage ratio of 1.55.•Using the high-performance varistors to suppress overvoltage in UHV grid.•The overvoltage level along the transmission line decrease by up to 31.14%.•The overvoltage level in the substation can be reduced by 33.53% in maximum. In the present research, we studied ZnO varistors having multiple dopants and optimized their microstructure and electrical properties by tailoring the sintering process. At certain concentrations of the rare-earth elements yttrium and indium, the voltage gradient decreased from 683.7 to 293.0V/mm as the sintering temperature was increased from 1160 to 1320°C. In addition, the nonlinear coefficient first increased and then decreased as sintering temperature was increased. When sintered at 1240°C, the multiple doped ZnO varistors samples showed excellent performance, exhibiting a voltage gradient of 520V/mm, a residual voltage ratio of 1.55, and a density of 63.7A/cm2 under a current waveform of 8/20μs, and a nonlinear coefficient of 74.5. These optimized properties will be of great utility in the manufacture of metal oxide arresters. When the high-performance varistors were used in surge arresters of ultra-high voltage grids, the overvoltage level along the transmission line and in the substation were reduced by 31.14% and 33.53%, respectively. This combination of characteristics will dramatically improve the protective effect of surge arresters for deeply suppressing over-voltages in power systems, significantly reduce the insulation requirement and cost of power apparatus as well as greatly increase the safety of power systems.