Vibration Dampers are used to absorb Aolian Vibrations of conductor of Transmission Lines, as well as ground wire, OPGW, and ADSS. It is mostly composed of the following; Weights – made up of cast iron, Clamp – made up of Aluminum Alloy, Nuts and Bolts made up of galvanized or stainless steel and Messenger cable made up of Galvanized Steel.
Vibration Dampers are used in areas of severe vibration. Dampers act to decrease aolian vibration amplitudes thereby reduce the dynamic bending stress at hardware location and extend conductor life.
These fatigues stresses have maxima at suspension and dead end attachments. They can also occur at mass discontinuities and may lead to failures of individual strands. In composite conductors (ACSR, ACCR, etc. ) it may eventually lead to failure of all aluminum layers.
How Vibration Damper Works
When a vibration wave passes the damper location, the clamp of a suspension type damper
oscillates up and down, causing flexure of the damper cable and creating relative motion
between the damper clamp and damper weights.
Stored energy from the vibration wave is dissipated to the damper in the form of heat. For a damper to be effective, its response characteristics should be consistent with the frequencies of the conductor on which it is installed.
Vibration Damper Typical Types
Most utilities use Stockbridge Type Vibration Damper as standard for controlling vibration in case of single conductors.
Dampers of various designs are available from a number of manufactures. The number of
dampers required, as well as their location in the span should be determined by consultation with
the damper manufacturer.
It is a suspension type dampers that make use of the connecting cables between weights to dissipate the energy supplied to the damper. It function according to the principle of a damped spring/ mass oscillator and dissipate a main portion of the wind energy into the conductor.
For smaller size conductors, spiral dampers may be used. While for bundled conductors, you may use spacer dampers.
Note On The Use of Vibration Dampers
The use of such vibration dampers should be on a case-by-case basis. A certain item should not be used merely because it has given satisfactory performance in another location.
Vibration Dampers should be selected on the basis of the frequencies one expects to encounter in the terrain that must be traversed. The engineer should not specify a certain type of damper or armor rod simply because everyone else is using them.
An improperly located damper can affect the amount of protection and ability ofthe damper to suppress the damaging effects of aeolian vibration.