摘要
介绍了某变电站配用液压碟簧机构的断路器运行中误动分闸事故,确定了事故原因为副分电磁阀堵头螺栓断裂.通过对断裂螺栓进行宏观检验、化学成分分析、力学性能测试、金相组织检验、微观分析等,发现螺栓断裂的原因是硬度偏低,现场装配预紧力过大造成螺栓根部螺纹应力集中,长期服役后螺栓性能发生蠕变,抗冲击能力下降,最终发生脆性断裂.根据分析结果提出了针对性的控制措施,以期为此类缺陷的预防提供指导.
Abstract
In this paper,misoperation accident of brake separating of the circuit breaker equipped with hydraulic disc spring mechanism in a substation is introduced,and it is determined that the cause of the accident is the fracture of the plug bolt of the auxilia-ry solenoid valve.The fracture bolt was analyzed by macroscopic inspection,chemical composition analysis,mechanical property test,metallographic structure test,microscopic analysis and so on,and it was found that the cause of bolt fracture was low hardness,and then the stress of bolt root thread is concentrated by excessive preloading force in field assembly,the bolt properties creep after long-term service,and the impact resistance is reduced.Eventually,brittle fracture occurs.According to the analysis results,the corre-sponding control measures are put forward,to provide guidance for the prevention of such defects.
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