Spiral Vibration vs. Stockbridge Dampers

AFL’s Stockbridge dampers (1700 and 1700AA series) and Spiral Vibration Dampers (SVD) are different forms of vibration dampers  that are both used to mitigate fatigue damage caused by aeolian vibration. SVD s can be used interchangeably with AFL’s Stockbridge dampers for the same application when the conductor, Optical Ground Wire (OPGW) or Overhead Ground Wire (OHSW), is within the SVD’s diameter range (0.25”-0.77”).

Although Stockbridge dampers and SVDs accomplish the same goal, these devices function differently. A Stockbridge is a form of tuned mass damper and will dissipate energy through the heat created by inter-strand friction of the messenger cable. A SVD is a form of impact damper which will physically contact the shaking cable within the “damping section” so the vibrational amplitude does not reach damaging levels. AFL SVDs  are made of a proprietary PVC material that will not damage the cable during these impacts.

Installation and placement should also be taken into consideration for these dampers. Stockbridge dampers must be placed at specific locations to ensure they dissipate the maximum amount of vibrational energy. AFL uses its Vibrec® software to recommend Stockbridge damper placements for customers. SVDs are placement-independent  and the “gripping section” only needs to be placed approximately 5” or a hand’s width away from any other line hardware (suspension clamp, dead-end, armor rods, etc.).