通过宏观检查、化学成分分析、力学性能试验、X射线数字成像（DR）检测、金相分析、断口分析等方法对某500 kV输电线路四分裂导线间隔棒断裂失效原因进行了分析。结果表明：间隔棒材料ZL102铸造铝合金变质处理不充分、组织状态异常，铸造质量差、存在严重的铸造缺陷，使得间隔棒支架的承载能力严重不足，在导线运行中的风摆、舞动等载荷作用下于支架严重缺陷处形成极大的应力集中并超过其承载极限，是间隔棒断裂失效的根本原因。

Through macroscopic examination, chemical composition analysis, mechanical property test, X-ray digital radioscopy (DR) detection, metallographic analysis, fracture analysis and other methods, the fracture failure causes of the four split interphase spacer of 500 kV transmission lines were analyzed. The results show that because of the insufficient modification treatment and the poor casting quality, the microstructure of material of the interphase spacer, ZL102 casting aluminum alloy, was abnormal and there were a lot of defects in it, so the bearing capacity of the interphase spacer bracket was seriously insufficient. Under the action of wind pendulum, dancing and other loads during the running of the lines, a great stress concentration formed at the severe defect site of the bracket. When the stress exceeded the bearing limit of the interphase spacer braket, fracture would occur, and that was the primary cause for the failure.