Capacitance Changes in Degraded Metal Oxide Varistors
Jaroszewski, M (Wrocław University of Technology) ; Wieczorek, K (Wrocław University of Technology) ; Bretuj, W (Wrocław University of Technology) ; Kostyla, P (Wrocław University of Technology)
Abstract: ZnO based ceramics show a highly nonlinear current-voltage (I-V) characteristic due to intergranular layers at the boundaries of ZnO grains. This research indicates that the junctions formed on the border between ZnO grains and the intergranular phase are responsible for the creation of potential barriers which control the flow of current through the bulk of such a ceramic. Having polycrystalline nature and a large number of intergranular barriers, and so a high energy absorption capability, ZnO ceramics are used as active components in overvoltage protection devices. But as a result of charge transport the height of the barriers decreases and varistor degradation occurs. The degradation seems to affect mainly the prebreakdown region of the I-V curve and it results in increased leakage current. This paper presents a part of research aimed at assessing the effect of ageing on the capacitance characteristic of ZnO varistors.
Keyword(s): varistor ; ZnO ; degradation
Note: 2004 International Conference on Solid Dielectrics, Toulouse, France, July 5-9, 2004
Fulltext : http://zet10.ipee.pwr.wroc.pl/record/228/files/
Cited by: try citation search for ENY-ARTICLE-2008-178
Record created 2008-09-30, last modified 2008-09-30
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