Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
  • H02G9/00—Installations of electric cables or lines in or on the ground or water
  • H02G9/02—Installations of electric cables or lines in or on the ground or water laid directly in or on the ground, river-bed or sea-bottom; Coverings therefor, e.g. tile
  • H02G9/025—Coverings therefor, e.g. tile
• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
  • E02D29/00—Independent underground or underwater structures; Retaining walls
  • E02D29/12—Manhole shafts; Other inspection or access chambers; Accessories therefor
  • E02D29/14—Covers for manholes or the like; Frames for covers

Definitions

• the present invention relates to a cover frame for an electrode for a device for transmitting heavy current over a sea, said device comprising a first conductor in the form of a cable, which is adapted to be placed on the bottom of the sea and to be connected to/integrated with a land-based connection cable, and a second conductor, which consists of the sea water and which by means of said electrode immersed in the sea is connected to a land-based connection cable, the cover frame being adapted to be placed on the bottom of the sea over the electrode.
• the protective structure is made of concrete, consists of a plurality of parts and is adapted to protect a pipeline.
• the concrete structure closest to the pipeline is tight relative to the surrounding sea water and therefore cannot act as cover for a sea electrode since the sea water would not have access thereto.
• Swedish patent application 9502263-8 discloses an anchor device for anchoring of underwater electrodes in HVDC transmission over water.
• the anchor device is a concrete structure resembling a cable drum.
• the electrode in the form of a mat is wound onto the drum and thus is not protected against violence caused by e.g. on- hooking boat anchors, stones rolling down and the like.
• the fluke of an anchor can easily get stuck in the actual drum.
• the drum construction also results in the amount of surrounding water flowing through the electrode mat being limited.
• An object of the present invention is to provide a cover frame for an electrode for a device for transmitting heavy current over a sea, which effectively protects the electrode against damage that could be caused by on- hooking boat anchors, attacking stone blocks and the like.
• One more object of the invention is to provide an electrode cover frame, which allows good throughflow of surrounding sea ' water through the electrode.
• a further object is to provide an electrode cover frame which to some extent can follow the contour of the bottom of the sea.
• an electrode cover frame according to the introductory portion, which is characterised in that the cover frame comprises at least two opposite side walls, which are essentially parallel with the longitudinal axis of the cover frame, and a roof, that the cover frame is formed with a plurality of through openings in the side walls and in the roof, and that the electrode is sup- ported by the cover frame at a distance from the bottom of the sea.
• Fig. 1 is a top plan view of an electrode cover frame according to the invention.
• Fig. 2 is a longitudinal side view of a pair of electrode cover frames according to Fig. 1 assembled to a coherent protective structure for the electrode and with an end wall mounted;
• Fig. 3 is a short side view of the construction according to Fig. 2 in the direction of arrows A-A;
• Fig. 4 is a cross-sectional view of an electrode cover frame along line B-B in Fig. 2;
• Fig. 5 illustrates on a larger scale the upper portion of two adjoining cover frames in a coherent structure with a plurality of electrode cover frames
• Fig. 6 is a top plan view and two side views perpendicular to each other, illustrating an embodiment of an electrode which is intended for use together with the cover frame according to the invention.
• a cover frame 2 for an electrode 1 comprises a shell structure, preferably of concrete with non-conductive or poorly electrically conductive reinforcement, such as resin, glass fibre etc., or of concrete with glass fibre added.
• the cover frame 2 can be made in one piece, but it is preferred from the viewpoint of manufacture, transport and handling that the total cover frame for the electrode 1 be formed of a number of interconnected cover frames 2, as shown in the drawings. This also results in greater flexibility of the cover frame for adaptation to the contour of the bottom of the sea, as will be described in more detail below.
• the cover frame 2 or each identical unit 2', 2", etc. included in the total electrode cover frame, comprises two opposite side walls 6, which are essentially parallel with the longitudinal axis of the cover frame, said longitudinal axis being schematically indicated by reference numeral 15.
• a roof 5 connects the side walls 6 to each other, which are inclined outwards away from the roof, i.e. the width of the roof is smaller than the total width of the cover frame.
• the cover frame has no bottom wall or short side walls, but can suitably be fitted with end walls as will be discussed in more detail below. Owing to the inclination, it will be more difficult for, for instance, boat anchors to catch the cover frame, the cover frame will be steadier on the bottom of the sea which is designated 3 in Fig. 4, and the cover frames are stackable.
• the cover frame 2 is formed with a plurality of through openings 7 in the side walls 6 and in the roof 5 to give the surrounding sea water access to the interior of the cover frame 2 and the possibility of flowing through the same.
• the total area of the openings 7 suitably is maximised such that the flow of water round the electrode 1 becomes as great as possible.
• the cover frame must withstand the strain to which it may be subjected, such as its dead weight, the weight of the electrode and external stress against which the electrode is to be protected.
• the total area of the openings 7 relative to the total external area of the cover frame is preferably in the range of 25- 70%.
• the openings 7 are elongate and, for instance, rectangular, as shown in the Figures.
• the openings 7 are oriented transversely of the longitudinal axis 15 of the cover frame, see Fig. 1, but they can also be oriented in parallel with the longitudinal axis at an optional angle thereto, if desired.
• the sides of the openings taper inwards to the interior of the cover frame or, in other words, the boundary surfaces 16 and 17 of the openings 7 converge from the outside of the cover frame to the inside thereof.
• Fig. 4 illustrates that the electrode 1 is supported by the cover frame 2 at a distance from the bottom of the sea 3.
• the electrode can be supported by a shelf construction (not shown) under the roof 5 but is preferably suspended by means of cables, ropes, clamps or similar fixing elements 8, which are laid through suitable openings 7 in the roof 5 and/or in the side walls 6.
• the electrode 1 can be directly suspended from the fixing elements 8.
• a suitable electrode 1, which is known per se, is shown in Fig. 6.
• the electrode 1 is a flexible metal netting 21, preferably of titanium, which on both sides is enclosed by a plurality of parallel, interconnected and elongate plastic tubes 22.
• the plastic tubes 22 are oriented transversely of the longitudinal direction of the netting 21 (and of the cover frame 2), the lower layer of tubes 22, during mounting of the electrode 1, resting on the beams 20 and the upper layer of tubes 22 engaging in a fixed manner projections 23 on the lower portion of the roof 5, see Fig. 4.
• Figs 2 and 3 show that one or both short sides 4 or ends of the cover frame 2, or the ends of the outermost cover frames 2 ' when a plurality of cover frames have been joined together in the longitudinal direction, are suitably sealed by means of end walls 9.
• the end walls 9 serve to prevent boat anchors and the like from being inserted or penetrating into the cover frame 2 and hooking onto the sides 6 or roof 5 thereof or onto the electrode 1.
• These end walls can be integrated with the cover frame 2, but are preferably formed as a separate, plate-like element of reinforced concrete or the like and have a shape which essentially conforms with the profile which, transversely of the longitudinal axis 15 of the cover frame 2, is defined by the outside of the side walls 6 and the roof 5 and the bottom of the sea 3.
• the shape of the end wall 9 is such as to completely seal the short side 4 of the cover frame 2, see especially Fig. 3.
• the end wall 9 is formed with a number of through holes 10 at its periphery and is fixed to the cover frame by means of cables, ropes, clamps or similar fixing elements 11, which are laid through the holes 10 and neighbouring openings 7 in the side walls 6 and/or roof 5 of the cover frame.
• the end wall 9 is formed with a continuous or discontinuous projection 24 which projects perpendicular from the end wall 9 and whose extent con- forms with the outer profile of the cover frame 2 in the transverse direction, such that the projection 24, after mounting of the end wall, rests on the end portion or short side 4 of the cover frame, as illustrated in Fig. 2.
• the electrode cover frame can consist of a single unit 2 or a plurality of interconnected cover frames 2', 2" etc.
• the electrode cover frame is preferably made of a plurality of units, cf. Figs 2 and 5, i.e. a plurality of cover frames 2', 2" etc. are joined to a complete, enclosing cover frame for the electrode (together with the bottom of the sea 3) .
• both short sides 4 of each cover frame have two preferably cylindrical holes each, which are directed in parallel with the longitudinal axis 15, e.g. the holes 12 in Fig. 3 and the holes 12' and 12" in Fig. 5.
• guide plugs or the like 13 of an electrically non-conductive mate- rial which are inserted into the opposite alignment holes 12', 12" of two adjoining cover frames 2', 2", the cover frames 2', 2" are aligned with each other, see Fig.
• cover frames 2', 2" are fixed to each other by means of cables, ropes, clamps or similar fixing elements 26, which are laid through neighbouring openings 7 in the side walls 6 and the roof 7 of adjoining cover frames 2', 2", see Fig. 2.
• said openings are formed with recesses 25 extending toward the short side 4 and being aligned with the alignment holes 12', 12" to hold the fixing elements 26 and the guide plugs 13 in place.
• a spacer or insert of plastic (not shown) is advantageously arranged round, or integrated with, each guide plug 13, thereby making it possible to angle adjoining cover frames somewhat in the vertical direction relative to each other so as to be able to better follow the contour of the bottom of the sea 3.
• the short sides 4 can bevelled one or two degrees from the alignment holes 12', 12", as illustrated in Fig. 5.
• the cover frame and the electrode can suitably be mounted in the following fashion.
• Two longitudinal beams 20 of an electrically non-conductive material are placed on an assembly table which is designed in an appropriate manner.
• beams use can be made of e.g. VP tubes having a diameter of 50 mm.
• An electrode netting 21 supplied in rolls where the actual netting is positioned between two tight layers of transverse plastic tubes 22 is unrolled on an assembly table. The electrode netting is thus placed along and on top of the two previously laid-out longitudinal beams.
• the cover frames are lifted onto the electrode netting and joined together. After joining all the cover frames, the longitudinal supporting beams are raised by pulling bands 8 round the beams 20 and through openings 7 in the roof 5 of the cover frames.
• the bands and their locking device are not allowed to contain any electrically conductive material.
• the complete cover frame 2', 2", 9 and the enclosed electrode 1 are suitably launched by means of a lifting yoke with a number of lifting straps, from which the cover frame is suspended.
• the bottom of the sea 3 has suitably been cleaned and levelled out to some extent, and preferably the lower edges of the side walls 6 are designed so as to sink a distance into the bottom of the sea, thereby reducing the risk that, for instance, the fluke of an anchor hooks onto said lower edges.

Landscapes

• Catching Or Destruction (AREA)
• Revetment (AREA)
• Laying Of Electric Cables Or Lines Outside (AREA)

Applications Claiming Priority (5)

Publications (1)

Family

ID=26662980

Family Applications (1)

Country Status (7)

Families Citing this family (1)

Family Cites Families (4)

• 1997
  • 1997-11-06 SE SE9704065A patent/SE511874C2/sv not_active IP Right Cessation
• 1998
  • 1998-05-07 AU AU74627/98A patent/AU7462798A/en not_active Abandoned
  • 1998-05-07 WO PCT/SE1998/000841 patent/WO1998050991A1/sv not_active Application Discontinuation
  • 1998-05-07 EE EEP199900472A patent/EE9900472A/xx unknown
  • 1998-05-07 EP EP98921987A patent/EP0980596A1/en not_active Withdrawn
  • 1998-05-07 PL PL33684998A patent/PL336849A1/xx unknown
• 1999
  • 1999-11-03 NO NO995361A patent/NO995361L/no not_active Application Discontinuation

Non-Patent Citations (1)

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