Impulse degradation behavior of Co–Cr–Al–Y-doped ZnO–Pr 6O 11-based varistors with sintering temperature

Abstract

The degradation behavior against impulse-current stress of the Co–Cr–Al–Y-doped ZnO–Pr 6O 11-based varistors was investigated in accordance with sintering temperature. The clamp voltage ratio ( K) for impulse current increased in accordance with increasing sintering temperature. The varistors sintered at 1300 °C exhibited the best voltage clamp characteristics, which the clamping voltage ratio was in the range of 1.49–1.57 at a low impulse-current region (5–10 A) and was in the range of 1.70–2.44 at a high impulse-current region (400–1200 A). The best electrical stability against multi-impulse stress for continuously 3 times 1200 A was obtained at 1350 °C in sintering temperature, where % Δ E 1 mA/cm 2 = − 5.0 % , %Δ α = −13.9%, and %Δ J L = −21.9%.