Vibration damper for overhead power lines

1. A Stockbridge vibration damper comprising a pair of damping weights joined by a stranded steel cable, a clamp attached to the cable at a location intermediate the damping weights for attachment to an overhead power transmission line, the cable comprising an outer strand layer comprised of a plurality of wires and at least one inner strand layer comprised of at least one wire, wherein at each localized point of connection between the damping weights and the cable, only one of the outer strand layer or the at least one inner strand layer is fixed to the respective weights, and the other of the outer strand layer or the at least one inner strand layer is free to slide with respect to the fixed strand layer from and including each end of said cable to said clamp.

2. The Stockbridge vibration damper as defined in claim 1 wherein the ends of each layer are allowed to move longitudinally in relation to the other layer(s).

3. The Stockbridge vibration damper as defined in claim 1 wherein a bonding metal or resin is employed to bond the strands between the outer layers and the damping weights and the bonding metal or resin is prevented from penetrating between the layers.

4. The Stockbridge vibration damper as defined in claim 1 wherein either the outer or inner strand layer(s) of the cable are passed through the damping weights and attached thereto by welding.

5. The Stockbridge vibration damper as defined in claim 1 wherein the strands of either the outer or inner layer(s) of the cable are cut or otherwise broken in the region of the connection, such that one layer of strands is connected to the damping wieghts, whilst the remaining layer(s) of strands is/are free to slide with respect to the attached layer of strands.

6. The Stockbridge vibration damper as defined in claim 1 wherein either the outer or inner layer(s) of strands is/are trimmed such that the damping weights are connected only to the inner or outer layer of strands respectively.

7. The Stockbridge vibration damper as defined in claim 1 wherein the damping weights are pressed onto the outer layer of strands of the cable.

8. The Stockbridge vibration damper as defined in claim 1 wherein a collet is employed to connect the outer or inner layer(s) of the cable to the damping weights.

9. A method of producing a Stockbridge vibration damper comprising a pair of damping weights joined by a stranded steel cable, a clamp attached to the cable at a location intermediate the damping weights for attachment to an overhead power transmission line, the cable comprising an outer strand layer comprised of a plurality of wires and at least one inner strand layer comprised of at least one wire, wherein at each localized point of connection between the damping weights and the cable, only one of the outer strand layer or the at least one inner strand layer is fixed to the respective weights and the other of the outer strand layer or the at least one inner strand layer is free to slide with respect to the fixed strand layer from and including each end of said cable to said clamp.

10. The method of producing the Stockbridge vibration damper as defined in claim 9 wherein the ends of each layer are allowed to move longitudinally in relation to the other layer(s).

11. The method of producing the Stockbridge vibration damper as defined in claim 9 wherein a bonding metal or resin is employed to bond the strands of the outer layers and the damping weights and the bonding metal or resin is prevented from penetrating between the layers.

12. The method of producing the Stockbridge vibration damper as defined in claim 9 wherein either the outer or inner strand layer(s) of the cable are passed through the damping weights and attached thereto by welding.

13. The method of producing the Stockbridge vibration damper as defined in claim 9 wherein either the outer or inner layer(s) of strands of the cable are cut or otherwise broken in the region of the connection, such that one layer of strands is connected to the damping weights, whilst the remaining layer(s) of strands is/are free to slide with respect to the attached layer of strands.

14. The method of producing the Stockbridge vibration damper as defined in claim 9 wherein either the outer or inner layers of strands is trimmed such that the damping weights are connected only to the inner or outer layer of strands respectively.

15. The method of producing the Stockbridge vibration damper as defined in claim 9 wherein the damping weights are pressed onto the outer layer of strands of the cable.

16. The method of producing the Stockbridge vibration damper as defined in claim 9 wherein a collet is employed to connect the outer or inner strand layer(s) of the cable to the damping weights.

17. The Stockbridge vibration damper as defined in claim 1 wherein the cable comprises two layers of helically laid up high tensile steel.

18. The Stockbridge vibration damper as defined in claim 1 wherein the cable comprises three layers of helically laid up high tensile steel.

19. The method of producing the Stockbridge vibration damper as defined in claim 9 wherein the cable comprises two layers of helically laid up high tensile steel.

20. The method of producing the Stockbridge vibration damper as defined in claim 9 wherein the cable comprises three layers of helically laid up high tensile steel.

21. The Stockbridge vibration damper as defined in claim 1 wherein only the outer strand layer is fixed to the weights.

22. The Stockbridge vibration damper as defined in claim 1 wherein only the inner strand layer is fixed to the weights.

23. The method of producing the Stockbridge vibration damper as defined in claim 9 wherein only the outer strand layer is fixed to the weights.

24. The method of producing the Stockbridge vibration damper as defined in claim 9 wherein only the inner strand layer is fixed to the weights.