As train speed increases, contact wire irregularity affects the quality of current collection more and more. The possibility of achieving the maximum operating speed depends also on the maintenance level of the overhead line (OHL). In the present paper, the influence of contact wire irregularity (in terms of vertical deviation of its position) is investigated both experimentally and by means of numerical simulation of the dynamic interaction of pantograph and catenary. In a first step, the capability of the simulation to reproduce the effect of a singularity in the contact wire height along the line has been tested by comparison with available experimental results. The same model has been subsequently used to perform numerical experiments concerning the effects of several types of distributed defects on the catenary. Afterwards, considering the data generated with the simulation as experimental data, a procedure to find the signature in terms of the contact force of the considered distributed defects on the OHL has been proposed. In this procedure, the contact force is not measured, but estimated from the motion of the pantograph, by means of an application of the extended Kalman filter. The adoption of an estimation procedure for the contact force, instead of a direct measurement, would allow the installation of a measurement system that is much simpler than the one required for the direct measurement of contact force. For this feature, it could be installed, at least in principle, on ordinary trains, allowing to perform an extensive monitoring and diagnostic activity with a large database. © IMechE 2007.
