Effect of elevated temperatures on mechanical properties of overhead conductors under steady state and short-circuit conditions

The loss of mechanical properties of conductors of transmission overhead lines is, from the point of view of their thermal stressing, the function of temperature and time of duration. Elevated temperatures generally result into the loss of the tensile strength of conductors which indirectly leads to increased sag and decreased safety heights or ground clearances, thus reducing the operational reliability of transmission lines. The paper presents results of a research into mechanical properties of hard-drawn wires and stranded homogeneous and combined conductors made of aluminum and aluminum-alloys at elevated temperatures under conditions of the steady-state operation. Further, results are shown of the changes of mechanical properties of such conductors as a result of short-circuit heating.