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Micro-Degradation Characteristics and Mechanism of ZnO Varistors under Multi-Pulse Lightning Strike

by Chunlong Zhang 1,2,3, Hongyan Xing 2,3, Chunying Li 1,3, Ran Cai 4 and Dongbo Lv 1,3,*
1
Heilongjiang Meteorological Disaster Prevention Technology Center, Haerbin 150030, 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 21004, China
4
Shenzhen Meteorological Service Center, Shenzhen 518000, China
*
Author to whom correspondence should be addressed.
Energies 2020, 13(10), 2620; https://doi.org/10.3390/en13102620
Received: 26 April 2020 / Revised: 18 May 2020 / Accepted: 19 May 2020 / Published: 21 May 2020
(This article belongs to the Section Electrical Power and Energy System)
In view of the problem that ZnO varistors are often subjected to thermal breakdown and deterioration due to lightning strikes in low-voltage power distribution systems, this article used a 8/20 µs multi-pulse surge current with a pulse time interval of 50 ms to perform shock experiments on ZnO varistors. SEM scanning electron microscope and an XRD diffractometer were used to analyze the structure of the grain boundary layer and the change of the crystalline phase material of ZnO varistor under the action of a multi-pulse current. The damage mechanism of ZnO varistor under the multi-pulse current was studied at the micro level. The results show that the average impact life of different types of ZnO varistor is significantly different. It was found that the types of trace elements and grain size in the grain boundary layer will affect the ability of ZnO varistor to withstand multi-pulse current. As the number of impulses increases, the grain structure of the ZnO varistor continues to degenerate. The unevenness of internal ion migration and the nonuniformity of the micro-grain boundary layer cause the local energy density to be too large and cause the local temperature rise to be too high, which eventually causes the internal grain boundary to melt through, and the local high temperature may cause the Bi element in the ZnO varistor to change in different crystal phases. View Full-Text
Keywords: microscopic; degradation characteristics; impulse current; multiple lightning; ZnO varistors microscopic; degradation characteristics; impulse current; multiple lightning; ZnO varistors
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Zhang, C.; Xing, H.; Li, C.; Cai, R.; Lv, D. Micro-Degradation Characteristics and Mechanism of ZnO Varistors under Multi-Pulse Lightning Strike. Energies 2020, 13, 2620.

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