Electric welding effect: detection via phototube sensor and maintenance activities

A crucial problem for railway companies is to prevent damage to the overhead line equipment and to pantographs. Unfortunately high speeds worsen the problem and a monitoring system has to be set up and tested to plan maintenance activities. Test runs were performed on board of an ETR500, a high-speed train of Italian Railways, with a double pantograph and an acquisition system on board of a measurement coach, based on a twin phototube sensor. Besides critical points of the overhead line, due to break arcs, it was revealed that the current collection between pantograph and overhead line is of a poor quality in the presence of a continuous flashing (the electric welding effect). Aim of the paper is to investigate the impact of such phenomenon on the overhead con-tact lines. Photographs from a visual inspection of the line are included to demonstrate both the line deterioration due to the electric welding effect, and the reliability of the twin phototube sensor for planning maintenance activities