电极留边距离对电流冲击下ZnO电阻片通流性能和故障模式的影响

Effect of Electrode Edge Margins on the Current Carrying Performance and Failure Modes of ZnO Varistors Under Current Impulse

在2 ms方波冲击和4/10μs大电流冲击下测试了具有不同电极留边距离的ZnO电阻片。结果表明,电极边缘和ZnO电阻片边缘留有一定余量可使冲击下的通流性能表现更稳定、减少分散性,但过多的留边距离则会使承受冲击电流的有限面积减少,留有0.5 mm左右的电极留边距离比较合适。在电流冲击测试过程中,一些ZnO电阻片样品出现故障,包括穿孔、破裂和侧闪。观察发现冲击试验后ZnO电阻片局部微观结构的形态和组成出现变化,被认为是ZnO电阻片劣化或故障的根本原因。

ZnO varistors with different electrode edge margins were tested under 2 ms square impulses and 4/10 μs high current impulses.The results show that leaving a certain margin between the electrode edge and the edge of the ZnO varistor can make the current carrying performance under impulses more stable and reduce the dispersion,but too much edge margin will reduce the limited area to withstand current impulses,and an electrode margin of about 0.5 mm is more suitable.During the current impulse test,some ZnO varistor samples failed,including puncture,cracking and flashover.It was observed that changes in the morphology and composition of the local microstructure of the ZnO varistor after the impulse test were considered to be the origin of the degradation or failure of the ZnO varistor.