Vol. 62 | no. 2 | April - June 2014 Article 9

ZnO Varistors I-V Characteristics Change against Current-Pulse Load and Thermal Aging Stress
(full text in English)

Surge arresters based on ZnO have excellent non-linear voltage dependent characteristics. Therefore, they are suitable for use as a surge protection device of electric and electronic equipment. The operating life of installed varistor is affected by several factors, such as overvoltages having different duration and amplitude and increased ambient temperature. The article deals with the changes in electric properties of low-voltage varistor caused by injection of current pulses with a defined shape and energy. Comparison of changes in electric properties is based on the observation of shift dependening of the DC voltage and the corresponding current. Moreover, changes of nonlinearity coefficient and the absorbed energy have been observed. It was found that repeated injection of current can lead to significant change in electric characteristics of the ZnO varistor.
Keywords: ZnO varistor, current pulse, thermal aging, nonlinearity coefficient