Measurement of switching voltage of zinc oxide varistors between pre-breakdown and breakdown regions

Direct measurement of the switching voltage between pre-breakdown and breakdown regions in the current-voltage (I-V) characteristics of zinc oxide varistors is difficult, and the varistor voltage is normally measured at 10(-3) A as a reference current. In this study, using a simple I-V measurement system, the change in leak current associated with device degradation was measured to determine the switching voltage of commercial zinc oxide varistors. The switching voltage was found to be 45.3 V while the varistor voltage as determined from the I-V characteristics at a reference current of 10(-3) A was 47.9 V. This new method can be effectively used for measuring the switching voltage of varistors. (C) 2010 The Ceramic Society of Japan. All rights reserved.