Experimental investigation on the arc damage and fatigue crack initiation risk of copper-silver contact wires

Contact wires are subjected to both mechanical and electrical interactions while electrical energy is transmitted to the trains by overhead lines and train pantographs. Particularly, an increase in the speed of trains can result in greater contact force fluctuations and more intense pantograph arcs, therefore, these mechanical and electrical interactions have potential to drive failure of Overhead Line Equipment (OLE) conductors. In this paper, the effect on fatigue crack initiation risk of material ablation from the contact wire surface due to arc discharge is experimentally investigated under laboratory conditions. Fatigue life, crack propagation directions and crack initiation locations in arc-exposed copper silver contact wire samples are compared with those in comparable arc-free samples. The results show that under the conditions of having arc damage on the contact wire surface could result in 50% shorter fatigue life compared to arc-free contact wires. It is often considered that wear rather than fatigue cracking defines the life of the contact wires, but under some conditions with the combination of arcing, the fatigue life in the contact wire can become the controlling failure risk. Therefore, in determining system life and maintenance requirements the fatigue life of the contact wire should be taken into consideration at locations where the arc discharge is likely.