高压断路器操作机构拉杆销轴孔断裂原因分析

Cause Analysis on Pivot Pin Bore Fracture of Pull Rod of High Voltage Circuit Breaker Operating Mechanism

为查明某220 kV变电站断路器操作机构铝合金水平拉杆销轴孔断裂导致断路器合闸未成功的原因,利用宏观形貌分析、化学成分分析、力学性能检测、显微组织检测等试验方法进行了分析,结果表明:铝合金拉杆显微组织无异常、低倍组织无缺陷特征,拉杆化学成分与设计材料要求不符,但代用材料的强度和塑性能够满足使用要求,水平拉杆在连接销轴孔处微动磨损痕迹明显,在拉杆操作过程中,销轴孔处承受冲击载荷而断裂。

In order to find out the reason why the fracture of the pivot pin bore of aluminum alloy horizontal pull rod of the circuit breaker operating mechanism occurred and the circuit breaker failed to close in a 220 kV substation,an analysis is carried out by test methods of macro-morphology analysis,chemical composition analysis,mechanical property test,micro structural test and so on.The results show that there is no abnormal micro-structure in the aluminium alloy pull rod and the low-power structure has no defect.The chemical composition of the pull rod is not in conformity with the requirements of design material,but the strength and plasticity of the substitute material can meet the requirements of use.The fretting wear marks of the horizontal pull rod are obvious at the connecting pivot pin bore.During the operation of the pull rod,the pivot pin bore is subjected to impact load and breaks.