Cause Analysis And Risk Assessment Of Overhead Contact Lines Defects Based On Cox Model

The high-speed railway overhead contact lines(OCLs)are crutial eqipments for providing electrical energy for high-speed trains,whose reliability is directly related to the safety performance of high-speed railways.Owing to complex structure,the OCLs are more vulnerable to the influences of external extreme weather and environmental pollution,in addition to the impacts of the pantograph and the vibration caused by high-speed trains.These factors lead to the frequent occurrences of OCL defects,and the types of defects are complex and diverse.Therefore,it is urgent to carry out an investigation on the causes of OCL defects,explore the failure modeling method of OCL components,quantitatively evaluate the failure risk,and improve the reliability of OCLs.Considering the complexity and variety of failure modes of OCL components,this paper proposes a method for analyze the significant factors for the causes of OCL component defects based on failure mode and effect analysis method.Two typical OCL components,dropper,and steady arm,are selected as the research objects,the failure mode and effect analysis method is used to analyze the failure modes and defect causes of two components.The significant factors for the causes of OCL defects are analyzed from design,manufacture,and construction,combined with the critical index and expert judgment in the failure mode and impact analysis method,which can help extract the significant factors of the failures of two components.In order to explore the influence of the above significant factors on the failure rate of two typical OCL components,this paper uses the Cox model to analyze the failure rate of typical OCL components,and find out the influence mechanism of different significant factors on the occurrence of OCL defects.Based on the life cycle data of the OCLs of a railway bureau in southern China,the research results show that the most significant factors that cause dropper failures include pre-configuration error,tightening torque and manufacturing process.The most significant factors that cause steady arm failures include the pull-out value,material grade,and connection manner of main body.Aiming at the risk of OCL pantograph-collision failure,this paper proposes a quantitative assessment method for evaluating pantograph-collision failure risk based on risk matrix.In view of the probability of different failure modes and the severity of failure consequences,the corresponding risk indicators are established to realize the quantitative assessment from two perspectives,including different failure modes of OCLs,and the overall pantograph-collision failure of OCLs,based on the failure rate model of OCL components.Then,the maintenance personnel take corresponding measures in a timely manner based on evaluation results,which is of great significance to reduce or avoid failure risks.Based on the above modeling analysis and research results,this paper is of great significance for improving the reliability of OCLs,guiding the preventive maintenance for OCLs,and strengthening the health management of OCLs throughout their life cycle.