Impact Index Method for Railway Catenary Short-Wave Irregularity Evaluation

A new Catenary Impact Index (CII) for evaluating catenary short-wave diseases, such as the bad hanger ear, the wire with hard bend, the curved hanger and so on, is proposed by use of the pantograph vertical acceleration. In comparison to amplitude evaluation method, the catenary impact index method can reduce the influence of various random factors. Firstly, the filter frequency range for calculating the root mean square (RMS) of the pantograph vertical acceleration is obtained by deeply analyzing its frequency distribution characteristics. Then the RMS and CII of the pantograph vertical acceleration, instead of the original signal, is calculated and used for diagnose catenary short-wave diseases. This method demodulates the catenary short-wave impact from the high-frequency signal to a low-frequency signal, and has the advantage of being more stable. Furthermore, the appropriate window length is selected to calculate the energy index RMS according to impact response characteristics of the catenary short-wave disease. Finally, the pantograph acceleration data is normalized according to the average value of massive data to solve the problem that the absolute threshold is difficult to determine. This new method is applied to analyze the measured data from Catenary Inspection Vehicle, and the field verification results show that it is efficient and dependent in detecting catenary short-wave diseases.