Measuring the energy handling capability of metal oxide varistors

M. M.R. Ahmed*, G. A. Putrus, L. Ran, R. Penlington

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

4 Citations (Scopus)
16 Downloads (Pure)


Metal oxide varistors are widely used in many power electronics circuits to protect against transient over voltages. Certain applications are very demanding on the energy handling capability of the varistors. This paper gives an overview of the failure modes of ZnO varistors and investigates their characteristics when subjected to repetitive current pulses. It describes the puncture failure mode caused by melting of a region in the varistor of local current concentration. Experimental tests are performed to evaluate the puncture energy using an infrared imaging camera. A relationship between the energy absorption and the varistor maximum surface temperature is obtained. It is shown that the destructive energy depends strongly on the uniformity of the varistor; the more uniform, the higher the energy handling capability. The paper also presents the results of nondestructive tests using a scanning acoustic microscope to evaluate the uniformity of the varistor.

Original languageEnglish
Article number7081091
Number of pages5
JournalIEE Conference Publication
Issue number482
Publication statusPublished - 27 Sept 2001
Event16th International Conference and Exhibition on Electricity Distribution - Amsterdam, Netherlands
Duration: 18 Jun 200121 Jun 2001


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