Stability of Metal-Oxide Varistor Characteristics in Exploitation Conditions

B. Lončara, M. Vujisićb, K. Stankovićc and P. Osmokrovićb a Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11120 Belgrade, Serbia b Faculty of Electrical Engineering, University of Belgrade, Bulevar Kralja Aleksandra 73, 11120 Belgrade, Serbia c Institute of Nuclear Sciences ``Vinča'', P.O. Box 522, 11001 Belgrade, Serbia

Received: May 14, 2009

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Wide-spread use of metal-oxide varistors for non-linearity over-voltage protection results in a variety of possible working conditions. It is therefore essential to have a thorough insight into their reliability in various exploitation environments. The influences of temperature variation, aging and radiation exposure on metal-oxide varistors characteristics were investigated in this paper. Stable and effective over-voltage protection over a wide temperature range is always a desirable property, one which significantly contributes to overall system reliability. Behaviour of metal-oxide varistors in the temperature range from -50°C to 150°C was investigated. Aging caused by exploitation was investigated by applying 1000 consecutive double exponential over-voltage pulses to the varistors. Resistance of metal-oxide varistors to the radiation is of special interest in nuclear, military, and space technology. Radiation effects of californium-252 combined neutron/gamma radiation were examined. Voltage-current characteristics, voltage-resistance characteristics and the value of breakdown voltage were used to characterize metal-oxide varistors operation. Non-linearity coefficient, defined from the voltage-current curve, was also used as a parameter. Results are presented with the accompanying theoretical interpretations of the observed changes in metal-oxide varistors behaviour.

DOI: 10.12693/APhysPolA.116.1081 PACS numbers: 85.85.+j