DOWN CONDUCTOR CONNECTION SYSTEM, WIND TURBINE LIGHTNING PROTECTION SYSTEM, AND METHOD FOR ARRANGING A DOWN CONDUCTOR CONNECTION SYSTEM

Abstract

The present invention relates to conductor connection system for a wind turbine lightning protection system adapted to protect a wind turbine blade from lightning strikes. The lightning protection system comprises a down conductor cable adapted to extend in a longitudinal direction of the wind turbine blade and arranged for connection to the root end of the wind turbine blade, and comprises a number of lightning receptors electrically connected to and distributed along the length of the down conductor cable. The down conductor connection system comprises a modular down conductor cable having a first and second down conductor cable part, and at least one down conductor connector arranged between and connected to the ends of the down conductor cable parts. The down conductor connector comprises first and second terminals, connected to an end of each down conductor part, respectively, where the first and second terminals are adapted for mutual connection.

Claims

1. A down conductor connection system for a lightning protection system adapted to protect a wind turbine blade from lightning strikes, said lightning protection system having a down conductor cable adapted to extend in a longitudinal direction of said wind turbine blade and being connected to the root end of said wind turbine blade, and a number of lightning receptors electrically connected to and distributed along the length of said down conductor cable, said down conductor connection system having a modular down conductor cable having a first and second down conductor cable part, and at least one down conductor connector arranged between and connected to ends of said first and second down conductor cable parts, said down conductor connector having a first terminal connected to an end of a first down connector cable part, and a second terminal connected to an end of a second down conductor cable part, said first and second terminals being adapted for mutual connection, such that when being connected, said first and second down conductor cable parts at least partly define said modular down conductor cable.

2. A down conductor connection system according to claim 1, wherein said first and second terminals have a first end connected to said end of said first and second down conductor cable parts, respectively, and a second end having a connection surface extending in a substantially longitudinal direction of said modular down conductor cable for mutual interconnection of said terminals.

3. A down conductor connection system according to claim 2, wherein said first and said second terminals have releasable locking means for securing said connection surfaces in a mutual locked connection.

4. A down conductor connection system according to claim 1, wherein said down conductor connector comprises semi-conductive layers, each being arranged around said first end of said terminals and said ends of said first and second down conductor cable parts, respectively, hereby partly enclosing said first and second terminals and any uninsulated end part of said down conductor cable parts.

5. A down conductor connection system according to claim 4, wherein said down conductor connector comprises insulation layers, each being arranged around and enclosing each of said semi-conductive layers, such that said connection between said terminals and said down conductor cable parts is insulated.

6. A down conductor connection system according to claim 4, wherein said down conductor connector comprises a pre-manufactured semi-conductive insert, which is arranged around said interconnected terminals, between said semi-conductive layers.

7. A down conductor connection system according to claim 4, wherein said down conductor connector comprises: a first outer protective insulation cover, connected to and surrounding said first down conductor cable part, said first outer protective insulation cover being arranged for at least partly enclosing said premanufactured semi-conductive insert; a second outer protective insulation cover, connected to and surrounding said second down conductor cable part, said second outer protection cover being arranged for at least partly enclosing said premanufactured semi-conductive insert and mating said first outer protective insulation cover.

8. A down conductor connection system according to claim 7, wherein said second outer protective insulation cover partly overlaps said first outer protection insulation cover, said first and second outer protection insulation covers having mutual locking means, arranged for interlocking said outer protection covers, hereby fully enclosing said terminals and said premanufactured semi-conductive insert.

9. A down conductor connection system according to claim 7, wherein an outer surface of said insulating layers comprises a stepped contour corresponding to an internal stepped contour of said outer protective covers, such that a movement of said outer protective covers on each down conductor cable part is limited in a direction of said connector parts.

10. A down conductor connection system according to claim 7, wherein said connection system has a slideable end seal, such as a sealing ring, for arranging said outer protective covers in water tight connection with said cable parts, said end seal being arranged on each of said ends of said down conductor cable parts and disposed between said cables and said first and second outer protection covers, respectively.

11. A down conductor connection system according to claim 7, wherein said connection system comprises a clamp for securing said connection system against said wind turbine blade, said clamping element having a bonding surface for bonding against a part of a said wind turbine blade, and a number of clamping elements for at least partly enclosing said outer protective covers and clamping said connection system against said wind turbine blade.

12. A lightning protection system adapted to protect a wind turbine blade from lightning strikes, said protection system including a down conductor cable adapted to extend in the longitudinal direction of said wind turbine blade and being connected to the root end of said wind turbine blade, said lightning protection system having a number of lightning receptors electrically connected to and distributed along the length of said down conductor cable, wherein said down conductor cable is a modular down conductor cable having a down conductor connection system according to claim 11.

13. A lightning protection system according to claim 12, wherein said lightning protection system comprises a plurality of said conductor connection systems.

14. A method for arranging a down conductor connection system according to claim 5, in a lightning protection system comprising the following steps: providing a number of terminals, providing a number of down conductor cable parts, connecting a first end of said terminals to an end of said down conductor cable parts, respectively, arranging a semi-conductive layer around said first end of said terminals and said end of said cable parts, respectively, arranging said number of down conductor cable parts, each having a terminal, inside said wind turbine blade in a longitudinal direction thereof, and interconnecting at least two adjacent cable parts by connecting second ends of said terminals.

15. A method according to claim 14, further comprising: arranging an insulation layer around said semi-conductive layers, such that said connection between said terminals and said down conductor cable parts is insulated.

16. A method according to claim 14, further comprising: arranging a premanufactured semi-conductive insert around said connected terminals, between said semi-conductive layers or said insulation layers.

17. A method according to claim 14, further comprising: arranging said first and second outer protective insulation covers on adjacent cable parts, interlocking said first and second outer protection insulation covers by mutual locking, hereby enclosing said terminals.

18. A method according to claim 17, further providing a clamp according to claim 11 for bonding to a part of said wind turbine blade and clamping said connection system to said clamp.

Description

[0066] The invention will now be explained in more detail below by means of examples of embodiments with reference to the very schematic drawing, in which:

[0067] FIG. 1 shows a perspective view of the down conductor connection system.

[0068] FIG. 2A—2D show perspective views of the down conductor connection system in partly assembled states.

[0069] FIG. 3A-3B show perspective views of the down conductor connection system being assembled.

[0070] FIG. 4 shows a perspective view of the assembling of the outer protective insulation covers.

[0071] FIG. 5 shows a perspective view of the down conductor connection system.

[0072] FIG. 6 shows a cross-section of the down conductor connection system.

[0073] FIG. 7 shows a perspective of a wind turbine blade having a lightning protection system comprising a down conductor connection system.

[0074] The present invention wilt now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals refer to like elements throughout. Like elements will, thus, not be described in detail with respect to the description of each figure.

[0075] FIG. 1 shows a perspective view of the down conductor connection system 10. The down conductor connection system 10 is illustrated fully assembled, though without illustrating the clamp. The illustrated down conductor connection system 10 comprises two down conductor cable parts 12 being mutual interconnected at one end, and being illustrated with an opposite free end, which in the illustrated embodiment is uninsulated. The uninsulated end parts 30 (not shown) of the down conductor cable parts 12 are arranged for being connected to another opposed down conductor cable part via another down conductor connection system 10 or suitable for being connected to a lightning receptor.

[0076] The down conductor cables 12 are shown interconnected via the first and second outer protective insulation covers 26, 28, fully enclosing the internal interconnected terminals 14 (not shown). Further, insulation layers 22 are shown extending from an inside of the connection system to and outside, and partly overlapping an outer surface of the down conductor cable parts. In a preferred alternative embodiment, the first and second outer protective insulation covers 26, 28 also enclose the ends of the insulation layers. The connection between the first and second outer protective insulation covers 26, 28 is in the figure established by an integrated locking mechanism 38 illustrated as a bayonet lock. The outer protective insulation covers 26,28 may alternatively be fabricated without the integrated locking mechanism 38, and thus, the mutual interconnection between the two protective insulation covers 26, 28 may be accomplished by other suitable locking means, such as a screw mechanism, an external mechanical locking element, or a semi-conductive tape wrapped around the abutting outer protective insulation covers 26, 28.

[0077] FIGS. 2A-2D show perspective views of the down conductor connection system 10 in partly assembled states. The figures illustrate parts of the down conductor connection system 10 before the down conductor parts 12 are interconnected.

[0078] FIG. 2A illustrates the connection of the terminals 14 on uninsulated end parts 30 of the down conductor cable parts 12. Each terminal 14 comprises a first end for connection to the opposed terminal 14, and a second end comprising a opening for receiving the uninsulated end part 30 of the down conductor cable part 12. The ends of the down conductor parts are preferable connected to the open ends of the terminals 14 by crimping process or e.g. by welding.

[0079] FIG. 2B illustrates the terminals 14 being arranged on ends of the down conductor cable parts 12, and illustrates a remaining part of the uninsulated end part 30 still exposed between the terminals 14 and the insulated cable part 12. This exposed uninsulated end part 30 may vary according to production tolerances, however, as little as possible of the remaining exposed uninsulated end part 30 is requested.

[0080] FIG. 2C illustrates the semi-conductive layers 20 being arranged over the transition regions of the insulated down conductor cable parts 12 and the terminals 14. The semi-conductive layers 20 partly overlap the terminals 14, fully cover any exposed uninsulated end part 30, and preferable overlaps a part of the insulated down conductor cable parts 12 as well. In a basis embodiment, the semi-conductive layers 20 do not overlap the insulated cable parts 12, but only span the uninsulated cable parts 30, and partly the terminals 14.

[0081] FIG. 2D illustrates the additional insulation layers 22 arranged on top of, and enclosing the semi-conductive layers 20. Alternatively, the insulation layers 22 only partly enclose the semi-conductive layers 20. The insulation layers 22 preferably overlap part of the insulated down conductor cable part 12, hereby arranging the transition between the down conductor cable parts 12 end the terminals 14 in enhanced electrical insulation.

[0082] FIGS. 3A-3B show perspective views of the down conductor connection system being assembled.

[0083] FIG. 3A illustrates a possible connection between the two opposed terminals 14. Each of the terminals 14 may comprise a number of apertures (shown as two apertures), where each aperture aligns with a corresponding aperture of the opposed terminal 14, such that when the two terminals 14 are correctly arranged in relation to each other, locking means 18, 19, such as bolts 18, may arranged through the apertures and secured in place by a cooperating nut 19. The illustrated embodiment of the locking elements 18, 19 being bolts 18 and nuts 19 just illustrates only one of several possible embodiments of interconnecting the two terminals. Other suitable embodiments include screws, locking pawls, glue, or a further alternative embodiment where the connecting surfaces of each terminal 14 comprise projecting elements that interlock with the projecting element of the opposed terminal 14.

[0084] FIG. 3B illustrates the two terminals 14 being connected, and illustrates the pre-manufactured semi-conductive insert 24 being ready for insertion around the connected terminals 14. The pre-manufactured semi-conductive insert 24 is illustrated as a tubular element having a through-going longitudinal slit, such that the pre-manufactured semi-conductive insert 24 may be wrapped around the interconnected terminals 14.

[0085] FIG. 4 shows a perspective view of the assembling of the outer protective insulation covers 26, 28.

[0086] The figure illustrates a possible final step in interconnecting the opposed down conductor cable parts 12. The pre-manufactured semi-conductive insert 24 is shown arranged over the interconnected terminals 14 (not shown). An end seal 32 and a first or second outer protection insulation cover are arranged on each side of the pre-manufactured semi-conductive insert 24. In the illustrated embodiment, each end seal 32 is moved into abutment with the stepped contour of the insulation layer 22, and the first and second outer protective insulation covers 26, 28 are moved into mutual interlocked connection, whereby the pre-manufactured semi-conductive insert 24 is fully enclosed.

[0087] FIG. 5 shows a perspective view of the down conductor connection system 10 being arranged in a clamp 34. The down conductor connection system 10 is illustrated in a position where the connection system 10 is being arranged in the clamp 34. The clamp 34 is in this embodiment arranged with a flat base portion for connecting to an inner part of the wind turbine blade via suitable connection means. The base portion comprises a number of projecting elements 36 for clamping around portions of the first and second outer protection insulation covers 26, 28. The clamp 34 may comprise a suitable number of clamping elements 36 for clamping the protective insulation covers 26, 28 and/or the down conductor cable parts 12. Alternatively, the clamp 34 may be integrated with one of the protective insulation covers.

[0088] FIG. 6 shows a cross section of the down conductor connection system and clearly illustrates the mutual relationship between the individual elements. The illustration is just a basic, possible embodiment, and thus the arrangement of the individual parts may vary.

[0089] FIG. 7 shows a perspective view of a wind turbine with a wind turbine blade having a lightning protection system comprising a down conductor connection system. The figure is a schematic illustration of a possible embodiment of a wind turbine blade having a down conductor 40 extending in the longitudinal direction of the wind turbine blade from the tip end to the root end 46. The lightning protection system comprises a tip receptor 42 arranged at an end of the down conductor 40, and a number of side receptors 44 electrically connected to and distributed along the length of the down conductor 40. The embodiment shown in the figure illustrates the lightning protection system having two down conductor connection systems 10; however, any further number, or just one connection system 10 may be employed into the lightning protection system.

[0090] In the following is given a list of reference signs that are used in the detailed description of the invention and the drawings referred to in the detailed description of the invention. [0091] 10. Down conductor connection system [0092] 12. Down conductor cable parts [0093] 14. Terminals [0094] 16. Connection surface [0095] 18. Locking means [0096] 19. Locking means [0097] 20. Semi-conductive layer [0098] 22. Insulation layer [0099] 24. Pre-manufactured semi-conductive insert [0100] 26. First outer protective insulation cover [0101] 28. Second outer protective insulation cover [0102] 30. Uninsulated cable part end [0103] 32. End seal [0104] 34. Clamp [0105] 36. Clamping elements [0106] 38. Outer protection insulation cover lock [0107] 40. Down conductor [0108] 42. Tip receptor [0109] 44. Side receptor [0110] 46. Blade root