Degradation and destruction of ZnO varistors caused by current pulses
Chrzan, K L (Wroclaw University of Technology) ; Wroblewski, Z. (Wroclaw University of Technology)
Abstract: Although the modern metal oxide elements are resistant to degradation caused by continuous operating voltage the degradation or destruction caused by current impulses, especially lightning currents, is still a serious problem. This phenomenon was the subject of the current study where single zinc oxide elements and 6 kV arresters manufactured in Poland were tested with 8/20 ms impulse currents. During our investigation the temperature and changes in current-voltage characteristics were recorded. These results indicate that even varistors that were stressed with high currents could reach saturation state in which following impulses did not cause any further degradation. Both single varistor elements and 6 kV arresters showed only little ageing if stressed with 0,5 kA impulses. The 6 kV arresters composed of 10 elements were able to withstand smaller currents than single varistors. Our findings suggest that a combination of sparking effects and less than optimal contacts are the cause varistor degradation.
Keyword(s): puncture ; surface flashover
Note: International Conference on Advances in Processing,Testing and Application of Dielectric Materials APTADM, Wroclaw 2001, paper 55
Fulltext : http://zet10.ipee.pwr.wroc.pl/record/432/files/
Cited by: try citation search for ENY-ARTICLE-2013-345
Rekord stworzony 2013-01-08, ostatnia modyfikacja 2013-01-21
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