Overhead Transmission Line Vibration and Galloping

Overhead transmission line vibration and galloping have been a design and operating problem since early years of last century. The three forms of wind-induced conductor vibrations are Aeolian vibration, galloping and subspan oscillation. Aeolian vibration is caused by an alternating wind force, which arises from a pressure difference associated with a regular formation of vortices behind a conductor. Galloping is a low frequency, large amplitude, wind-induced vibration of both single and bundle overhead conductors, with a single or a few loops of standing waves per span. It is caused by moderately strong, steady crosswind acting upon an asymmetrically-iced conductor surface. Subspan oscillation is produced by forces from the shielding effect of windward subconductors on their leeward counterparts. It is particular to bundle conductors. This paper highlights the three forms of conductor vibrations, state-of-the-art, and review the major damages and control technologies on galloping. It also captures the challenges of vibration control on high temperature low sag (HTLS) conductors, based on experiences in North America.