Zinc oxide-praseodymia semiconducting varistors having a powerful surge suppression capability

Abstract

We introduced the varistor having more powerful surge suppression capability. This research focuses on the effect of sintering time on electrical properties and pulse current degradation of Pr/Co/Cr/Y/Mg co-doped zinc oxide varistors for surge suppression. With increasing sintering time, the breakdown field decreased from 2768 to 1680V/cm, and the nonlinear coefficient decreased from 57.7 to 29.3. Considering pulse current, a higher nonlinear coefficient led to the lower clamp voltage ratio. Therefore, the sample sintered for 1h exhibited the best clamp characteristics, in which the clamp voltage ratio was in the range of K=1.52–1.77 for pulse currents of 1–10A and K=2.04–3.43 for pulse currents of 400–2500A. Considering pulse absorption capability, the sample sintered for 3h exhibited the strongest electrical stability; −3.9% in ∆E1mA/cm2/E1mA/cm2 and −6.9% ∆α1/α1 after application of a pulse current of 2500A.