高速铁路接触网吊弦断裂电气因素研究

Study on Electrical Factors of Dropper Breakage in High-Speed Railway Catenary

基于Carson理论建立简单链型悬挂接触网电流分布模型;结合铁路现场的实际供流数据,分别对受流点位于跨中和跨端2种情况下的接触网各导线实际受流情况进行仿真计算;基于电致塑性效应理论,采用对断裂吊弦进行SEM形貌分析、成分分析及对新旧吊弦的金相组织进行对比观察等试验手段,研究吊弦断裂过程中电气因素的作用机理。结果表明:在满足机车正常运行的条件下,吊弦在受电弓滑过其正下方瞬间处于电流过载状态,随后迅速衰减;断裂吊弦的表面和断口处均存在过载引起的氧化腐蚀现象;吊弦在电致塑性效应影响下会发生金相组织再结晶、材料变形抗力降低现象;电流过载引起的表面缺陷及电致塑性效应引起的材料变形抗力降低是加速吊弦疲劳断裂的重要原因。

A current distribution model of simple overhead contact system with catenary was established based on Carson theory.Combined with the actual current supply data of the railway site,the actual current receiving situation of each conductor of the catenary was simulated and calculated under the conditions of the current receiving point located in the middle and at the end of the span.Based on the theory of electroplastic effect,the mechanism of electrical factors in the fracture process of droppers was studied by means of SEM morphology analysis,composition analysis and the comparative observation of the metallographic structure of the old and new droppers,etc.Results show that under the conditions of satisfying the normal operation of the locomotive,the dropper is in a current overload state at the moment when the pantograph slides directly below it,and then decays rapidly.The oxidation and corrosion caused by overload exist on both the surface of the broken dropper and the fracture surface.Under the influence of electroplastic effect,the recrystallization of metallographic structure and the reduction of the material deformation resistance will occur in the dropper.The surface defects caused by current overload and the reduction of material deformation resistance caused by electroplastic effect are important reasons for accelerating the fatigue fracture of the dropper.