The Impact of Current and Thermal Loads on the Properties of Copper Contact Wires Used in Railway Transport Systems

The paper presents the results of investigations of the effect of current heating on the microstructure and properties of copper profile contact wires used in railway traction networks. The aim of the study was to determine the effect of the contact wire temperature rising as a result of current heating on the occurrence of permanent changes in material characteristics. The tests were conducted in laboratory conditions through controlled heating of samples with a current of approx. 1500–1600 A, reaching temperatures of up to approx. 280 °C. It was found that in the temperature range of 120–200 °C, changes in the mechanical properties of the material were insignificant, while above 200 °C, a marked decrease in microhardness and a reduction in the indentation modulus were observed. The results obtained indicate that long-term current load leading to an increase in the temperature of the contact wire may cause deterioration of the mechanical properties of the material, its increased susceptibility to permanent deformation and an increased risk of damage to the traction network, which has a direct impact on the durability of contact wires and the maintenance costs of the rail transport infrastructure.