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What are the components, circled in red in the figure, on this transmission line ?

  • 7
    \$\begingroup\$ It's there to fuel conspiracy theories ;) \$\endgroup\$
    – Atsby
    Commented May 2, 2015 at 9:27

1 Answer 1


The are called aeolean vibration dampers, or Stockbridge dampers. They aren't rigid weights: the weights vibrate on the ends of the centre-clamped bars.

You can see the wavelength that they are trying to damp: it's approximately twice the distance from insulator to the damper. If the whole wire length is swinging, that's something different, and not what these dampers are designed to combat. You can also get higher frequency vibration, caused by some other vibrating thing: these dampers don't help with that either. They are just the right size and right position to damp the kind of singing you get from a wire in the wind: aeloean vibration.

Aeolean vibration causes metal fatigue in the wire. Using dampers to reduce the vibration allows you to use lighter and cheaper wire and towers. Vibration is particularly a problem with long high wires in windy locations, which is why you don't see these on the wires going into your house.

  • 7
    \$\begingroup\$ My wires are buried in the ground, if there are any, thats the reason why I can not see them ;) \$\endgroup\$
    – PlasmaHH
    Commented Apr 30, 2015 at 8:27
  • \$\begingroup\$ Just a random thought. How much mechanical vibration does the current in the transmission long lines create? \$\endgroup\$
    – Password
    Commented Apr 30, 2015 at 8:30
  • \$\begingroup\$ @Password Orders of magnitude too low, probably. \$\endgroup\$
    – yo'
    Commented Apr 30, 2015 at 9:32
  • 3
    \$\begingroup\$ @Password: Not enough to worry about. You only get significant movement under fault conditions, when 10-100× the normal current flows for a short time. You can bend solid copper busbar that way, or tear cable ties off cables, if the mechanical restraints aren't adequate. \$\endgroup\$ Commented Apr 30, 2015 at 13:53
  • \$\begingroup\$ @PlasmaHH if the underground wires vibrate, you have a bigger problem :) \$\endgroup\$
    – user56384
    Commented Jun 5, 2017 at 16:15

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