某电力公司变电站用铝合金设备线夹在运行过程发生批次开裂事故，通过宏观观察、断口分析、化学成分分析、力学性能测试、冷冻模拟试验等方法，对设备线夹的开裂原因和开裂机理进行了分析。结果表明：设备线夹焊缝存在焊接缺陷，导致焊缝强度下降；设备线夹接线管底部存在积水空间，寒冷天气下积水结冰，体积膨胀，使焊缝承受设计工况外的负载而过载开裂，造成了线夹开裂。

Aluminum alloy terminal connectors for substation in a power company occurred batch cracking during operation. The cracking causes and mechanisms of terminal connector were analyzed by means of macro observation, fracture analysis, chemical composition analysis, mechanical property test and freezing simulation test. The results show that there were weld defects in weld seam of terminal connector, which decreased the strength of weld. There was cavity at the bottom of connecting tube of terminal connector, the accumulated water in connecting tube frozen and expanded in cold weather, which made the weld seam cracking under the load beyond design condition, and caused the cracking of terminal connector.