Transforming life and reliability of railway overhead power lines

This thesis investigates the dynamic behaviour of an overhead line system interacting with a pantograph under conditions affecting both the mechanical aspects of the system, as well as the geometry of the overhead line. To determine the effects of environmental conditions such as crosswinds, an experiment making use of the Sheffield Large Scale Wind Tunnel was developed to assess the effects of wear and the wind angle of attack on the aerodynamic forces acting on the contact wire. Using the predicted aerodynamic forces, the effect of crosswinds on the catenary pantograph interaction has been investigated. By considering the wear state of the contact wire, the dynamic performance of the system worsens due to larger amplitude oscillations caused by aerodynamic lift forces, and that wear was a bigger driver of contact force variation than lateral deflections due to aerodynamic drag. This thesis also investigates the effects of contact wire irregularity beyond the wear state of the contact wire. By matching the contact and messenger wire tensions, the contact force variation was found to improve, indicating that better performance of the system can be achieved with only increases in the line tension and avoiding the need for redesigns of existing equipment. As the overhead line passes under bridges and tunnels it is often necessary to raise or lower the contact wire height and thus impose gradients in the contact wire. In this thesis, the effects of a range of wire gradients on the contact force have been studied using a validated finite element model and the results presented here indicate that maximum permitted gradients are conservative. The minimal effect on the contact wire due to increasing steepness of gradient suggests that there may be opportunities for electrification available without the need for expensive bridge reconstruction, representing significant cost savings.