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Open AccessArticle

An Experimental Study of the Failure Mode of ZnO Varistors Under Multiple Lightning Strokes

by Chunlong Zhang 1,2,3,4, Hongyan Xing 1,2,3,*, Pengfei Li 3,4, Chunying Li 3,4, Dongbo Lv 3,4 and Shaojie Yang 4
1
Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science & Technology, Nanjing 210044, China
2
Jiangsu Key Laboratory of Meteorological Observation and Information Processing, Nanjing University of Information Science & Technology, Nanjing 210044, China
3
School of Atmospheric Physics, Nanjing University of Information Science & Technology, Nanjing 210044, China
4
Meteorological Disaster Prevention Technology Center of Heilongjiang Province, Harbin, 150030, China
*
Author to whom correspondence should be addressed.
Electronics 2019, 8(2), 172; https://doi.org/10.3390/electronics8020172
Received: 15 January 2019 / Revised: 26 January 2019 / Accepted: 31 January 2019 / Published: 2 February 2019
(This article belongs to the Special Issue Industrial Applications of Power Electronics)
In this study, in order to explore the failure mode of ZnO varistors under multiple lightning strokes, a five-pulse 8/20 μs nominal lightning current with pulse intervals of 50 ms was applied to ZnO varistors. Scanning electron microscopy (SEM) and X-ray diffractometry (XRD) were used to analyze the microstructure of the material. The failure processes of ZnO varistors caused by multiple lightning impulse currents were described. The performance changes of ZnO varistors after multiple lightning impulses were analyzed from both macro and micro perspectives. According to the results of this study’s experiments, the macroscopic failure mode of ZnO varistors after multiple lightning impulses involved the rapid deterioration of the electrical parameters with the increase of the number of impulse groups, until destruction occurred by side-corner cracking. The microstructural examination indicated that, after the multiple lightning strokes, the proportion of Bi in the crystal phases was altered, the grain size of the ZnO varistors became smaller, and the white intergranular phase (Bi-rich grain boundary layer) increased significantly. The failure mechanism was thermal damage and grain boundary structure damage caused by temperature gradient thermal stress, generated by multiple lightning currents. View Full-Text
Keywords: failure mode; impulse current; microstructure; multiple lightning; ZnO varistors failure mode; impulse current; microstructure; multiple lightning; ZnO varistors
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MDPI and ACS Style

Zhang, C.; Xing, H.; Li, P.; Li, C.; Lv, D.; Yang, S. An Experimental Study of the Failure Mode of ZnO Varistors Under Multiple Lightning Strokes. Electronics 2019, 8, 172.

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