Vibration Protection Systems

The laminar wind flow causes vibrations and oscillations on transmission lines and can damage conductors, conductor equipment or towers. In order to reduce such vibrations and oscillations to an acceptable level, we install vibration damping systems on transmission lines.
STOCKBRIDGE 4-R Vibration Dampers
The purpose of these vibration dampers is to supress vibrations caused by the wind, the so-called Karman or Aeolian vibrations. Depending on the type of conductor and protective earthing ropes, various types of dampers are available. If the client so requests, the dampers can be made with hot-dip galvanised or stainless ropes, hot-dip galvanised or stainless bolts, with or without removable heads. Although many other types of dampers have been invented over the years, Stockbridge dampers are still the best technical and economical solution for controlling conductor and earthing rope vibrations.
Spacer Dampers
Spacers maintain the distances between conductors in a bundle. If vibrations caused by the wind (Aeolian) and oscillations of the conductor within the bundle are expected on the line, it is necessary to use spacer dampers that reduce the conductor vibration amplitudes. Various models of spacer dampers are available (screw clamp, Nutcracker), and they are installed at various distances between conductors in a bundle.
These Aeolian vibration dampers consist of conductors of particular lengths (similar to the main conductor) mounted below load-bearing strings and connected by the so-called Bretelle clamps to each neighbouring span. The so-called FESTOONs are made for large spans, such as river and fiord crossings. They consist of several Brettele dampers connected together and are used for spans of more than 50 m. We manufacture forged Bretelle clamps for active conductors and earthing ropes, of both the open and closed type.

In cooperation with the Faculty of Mechanical Engineering and Naval Architecture, we have developed a computer program based on the data obtained from laboratory and field tests as well as internal knowledge bases. The program enables the analysis of transmission lines by entering various parameters that impact vibrations. We use the program as the basis for damping studies used to determine the necessary number of vibration dampers or spacer dampers for each span, as well as their mounting positions.
We use a vibration recorder to gather data from the field and then we process and compare such data against the data from the damping study in order to verify the results.

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