SUN Guanyue 1, ZHAO Hongfeng 1, ZHOU Yuanxiang 1, 2, XIE Qingyun 3, MENG Xiaoji 3
(1. The Wind Solar Storage Division of State Key Laboratory of Control and Simulation of Power System and Generation Equipment, School of Electrical Engineering, Xinjiang University, Urumqi 830046, Xinjiang, China; 2. State Key Laboratory of Power System and Power Generation Equipment Control and Simulation, Department of Electrical Engineering and Applied Electronics Technology, Tsinghua University, Beijing 100084, China;3. Xi’an XD Arrester Co. Ltd., Xi'an 710200, Shaanxi, China)
Abstract: The effect of CaO on the stability of SnO2 varistors was studied. Samples were subjected to accelerated AC (50 Hz) aging test at the conditions of 0.9 E1mA/135 ℃/160 h, while the electrical properties and microstructure before and after aging were evaluated, by scanning electron microscopy (SEM), X-ray diffraction (XRD), current-voltage (E-J) and capacitance - voltage (C-V) characteristics. As the CaO concentration is 0.04 mol%, the voltage gradient of the sample is up to 744.65 V•mm−1, the leakage current is 6.88 μA•cm−2 and the aging coefficient is 0.058. The main reason for this change is the production of oxygen vacancy and deep defect due to the doping with CaO, where the solid solution reaction promoted the formation of barrier and hence improved stability of the varistors.
Key words: ceramics; SnO2 varistor; leakage current; voltage gradient; microstructure