Some Effects of Conductor Twisting on Galloping

This paper considers some simplified and approximate approaches to the effects of torsional rotation or twist on the dynamic instability of conductors. The conductor is considered in the classical sense as a beam rod having uniform torsion stiffness all along its length, and a uniform aerodynamic profile shape initially resulting from an accumulation of glaze ice in a horizontal wind. Considering that conductor twisting is the result of aero-dynamic moment distribution along the span and further, that the moment distribution is modified by the twist, a solution is obtained once certain simplifications are employed. The ressult relies on experimental data from model investigations in wind tunnels, from full scale twisting tests of single, twin, and quad bundled conductors, and on wind tunnel tests of an aerodynamic damper known as WINDAMPER. Various considerations indicate the desirability of an augmented twisting for improved stability.