SE1200619A1

SE1200619A1 - Kabel innefattande åtminstone en omgivande armering och förfarande för tillverkning av en sådan kabel

Info

Publication number: SE1200619A1
Application number: SE1200619A
Authority: SE
Inventors: Joern Antonischki; Kristian Gustafsson
Original assignee: Abb Technology Ltd
Priority date: 2012-10-10
Filing date: 2012-10-10
Publication date: 2012-10-12

Abstract

KABEL INNEFATTANDE ÅTMINSTONE EN OMGIVANDE ARMERING OCH FÖRFARANDE FÖR TILLVERKNING AV EN SÅDAN KABEL. Kabel (202; 302) innefattande åtminstone en längsgående kabelkärna (203, 205, 207; 303) och åtminstone en omgivande armering (214; 314) belägen utanför den åtminstone ena kabelkärnan. Armeringen har en längsgående utsträckning och innefattar åtminstone ett omgivande skikt av ett flertal trådar (234; 334), varvid varje tråd åtminstone har en längsående utsträckning. Trådarna är anordande långsides med varandra i riktningen för kabelkärnans längsgående utsträckning. Det åtminstone ena omgivande skiktet av ett flertal trådar (234; 334) innefattar en första grupp (402) trådar (404). Längs åtminstone en del (406) av kabelkärnans längsgående utsträckning är respektive tråd hos den första gruppen trådar lateralt fäst eller låst, på en eller ett flertal platser (408), vid åtminstone en angränsande annan tråd hos den första gruppen trådar. Förfarande för tillverkning av nämnda kabel.(Fig. 4)

Description

15 20 25 30 Å CABLE COMPRISING AT LEÅST ONE CIRCUMFERENTIAL ARMOURING AND A METHOD FOR MANUFACTURING SUCH A CABLE Technical Field The present invention relates to a cable comprising at least one Iongitudi- nal cable core and at least one circumferential armouring located outside of the at least one cable core, the armouring having a Iongitudinal extension and compris- ing at least one circumferential layer of a plurality of wires. Further, the present invention relates to a method for manufacturing a cable of the above-mentioned sort Background of the lnvention ln general, a submarine cable for use in offshore applications comprises at least one circumferential armouring, which comprises at least one circumferential layer of armouring wires, in order to protect the interior of the cable. The wires may be made of metal or a metal composition, or any other suitable material, e.g. a pol- ymer. ln general, the wires are arranged alongside one another and are slightly wound around the interior of the cable to form a coil in the Iongitudinal direction of the cable. The cable may comprise at least one cable core for transferring or transmitting electric power, a medium, such as ﬂuid, e.g. gas, liquid or oil etc., sig- nals and/or light for fibre optical communication. ln general, an electric power cable for electrical power transmission or distribution, e.g. an electric power cable for carrying alternating current, AC, com- prises for each phase an electrical conductor, e.g. made of copper or aluminium, a circumferential electrically insulating layer located outside of the electrical con- ductor, and a circumferential conductive or semi-conductive screen, also called outer semicon, located outside of the insulating layer and the electrical conductor.

Additional layers may be provided, e.g. a so called inner semicon, which is a semi- conductive layer circu mferentially surrounding the electrical conductor and located inside of the insulating layer. ln general, a submarine electric power cable for use in offshore applications comprises the above-mentioned at least one armouring, which comprises at least one circumferential layer of armouring wires, in order to protect the interior of the power cable.

For submarine or offshore applications, some electric power cables are subjected to a lot of stress, e.g. because of movement caused by the movement of 10 15 20 25 30 2 the sea water. An example of a submarine or offshore application is disclosed in more detail in the detailed description.

Summary of the Invention For storing the cable before placing the cable at site, e.g. at the bottom of sea with regard to submarine or offshore applications, two different prior-art storing methods may be used. One storing method is to place and store the submarine cable on a turntable on which the cable is wound to form a spiral shape. Another storing method, which in some cases is preferred to the turntable storing method, is the method of coiling. For storing by coiling, the cable is successively or gradu- ally dropped on the ﬂoor, e.g. on the ﬂoor of the vessel which transports and stores the cable while placing the cable in the sea, allowing the cable to coil itself to form some kind of coil shape. During the storing method by coiling, the armour- ing layer is released and thus "opens" and produces a so called “moving bird cage" along the longitudinal extension of the cable. As long as the armouring has homogeneous properties the “bird cage" travels along the longitudinal extension of the cable during coiling without causing any problems or damages. However, in some cases the mechanical properties of the armouring are not homogeneous.

The inhomogeneous mechanical properties of the armouring may be caused by events during the production of the cable and the armouring, by repaired or re- stored regions of the armouring, e.g. by welding, by so called ﬂexible joints (with- out a stiff metal pipe), where the wires of the armouring have been joined end to end by welding, or by other weakening events. A ﬂexible joint is a joint that allows the cable to be handled as if there was no joint. The inventors of the present invention have found that the inhomogeneous mechanical properties of the armouring may cause the wires of the armouring to twist and form twists, or folds, or form a zigzag shape, during coiling. These twists of the armouring wires make the armouring non-functional at the region where they occur, which in turn may subject the interior of the cable, including the cable core and its electrical conductor, to a lot of stress and may thus damage the interior of the cable. The tvvists create an overlength of the armouring, and during tension load, the twists must first be stretched out before the armouring can start protecting the interior of the cable, but at the time when the twists have been stretched out, the interior of the cable already have been subjected to stress from the tension load and may have been damaged. 10 15 20 25 30 3 The object of the present invention is to provide an improved cable having at least one cable core.

The above-mentioned object of the present invention is attained by provid- ing a cable comprising at least one longitudinal cable core and at least one cir- cumferential armouring located outside of the at least one cable core. The ar- mouring has a longitudinal extension and comprises at least one circumferential layer of a plurality of wires. Each wire has at least a longitudinal extension, and the wires are arranged alongside one another in the direction of the longitudinal ex- tension of the cable core. The at least one circumferential layer of a plurality of wires comprises a first group of wires, and along at least a part of the longitudinal extension of the cable core, each wire of the ﬁrst group of wires is laterally at- tached or locked, at one or a plurality of locations, to at least one neighbouring other wire of the first group of wires.

By means of the cable according to the present invention, the wire armour- ing is stiffened in the circumferential direction, preventing the formation of the wire twists during storing by coiling, while at the same time the armouring is ﬂexible in the radial and the longitudinal directions, allowing the armouring to open and close to let the “bird cage” travel along the longitudinal extension of the cable during storing by coiling. Thus, by means of the present invention, the cable with ar- mouring may be stored without the above-mentioned turntable, even when the armouring includes ﬂexible joints, is impaired or has been restored for other rea- sons. Further, by means of the present invention, ﬂexible joints may be manufac- tured on completed armoured cables. Further, by means of the present invention, the fatigue life of the cable core is increased in relation to cable with prior-art ar- mouring. Consequently, the durability of the cable, especially a moving cable, e.g. a dynamic electric power cable, is increased. By means of the present invention, an improved cable, e.g. an electric power cable, is provided, especially for subma- rine or offshore applications, e.g. where the cable is subjected to a lot of move- ment.

The above-mentioned object of the present invention is also attained by providing a method for manufacturing a cable comprising at least one longitudinal cable core, as disclosed in the detailed description of embodiments.

The features and embodiments of the cable and the method respectively, may be combined in various possible ways providing further embodiments. 10 15 20 25 30 4 Embodiments of the cable and the method, respectively, according to the present invention and further advantages with the present invention emerge from the dependent claims and the detailed description of embodiments.

Brief Description of the Drawings The present invention will now be described, for exemplary purposes, in more detail by way of embodiments and with reference to the enclosed drawings, in which: Fig. 1 Fig. 2 is a schematic diagram illustrating a submarine power link; is a schematic cross-section view of a first embodiment of the ca- ble according to the present invention; Fig. 3 is a schematic cross-section view of a second embodiment of the cable according to the present invention; and Fig. 4 is a schematic longitudinal view of the first or the second embodi- ment of Fig. 2 and 3.

Detailed Description of Embodiments Fig. 1 schematically illustrates a submarine power link 102 for electrical power transmission or distribution, e.g. between shore and an offshore ﬂoating platform 104 at the surface 103 of the sea 108. The power link 102 may comprise a static submarine electric power cable 105 placed at the bottom 106 of the sea 108. Since, inter alia, the platform is movable in relation to the bottom 106 of the sea 108, the static electric power cable 104 may be connected to the ﬂoating platform 104 by a dynamic electric power cable 110. ln a conventional manner, the dynamic electric power cable 110 may be connected to the platform 104 via a bending stiffener 112. The dynamic electric power cable 110 may be connected to the static electric power cable 104 by means of a joint element. Buoyancy mem- bers 114 may be connected to the dynamic electric power cable 110. The general structure of a submarine power link 102 as shown in Fig. 1 is well known to the skilled person and is thus not disclosed in further detail. The arrows in Fig. 1 illus- trate different forces applied to the dynamic electric power cable 110, such as sea currents, gravity, hydrodynamic drag, forces of the buoyancy members 114 etc.

Figs. 2-3 schematically illustrate in cross-section two embodiments of the cable 202; 302 according to the present invention. Each cable 202; 302 may be an electric power cable for alternating current or direct current. Each cable 202; 302 10 15 20 25 30 5 may be a submarine cable, which may be applied to the submarine power link 102 of Fig. 1, or may be a land cable. A submarine cable may have a Iongitudinal, or axial, extension of up to approximately 100 km. A land cable may have a longitu- dinal extension of up to approximately 800 metres. However, other longitudinal lengths are possible. When being an electric power cable, each cable 202; 302 may be adapted for alternating current, AC, and low voltage, medium voltage and/or high voltage. ln general, for AC, low voltage may be below 1000 V, medium voltage may be below 36 kV or below 56 kV, and high voltage may be about 56 kV and above. For example, the electric power cable and the submarine power link may be adapted for AC and for voltages of about 7 kV to about 245 kV. Other volt- age levels are possible. Each cable 202; 302 may comprise at least one Iongitudi- nal cable core 203, 205, 207; 303 which may have a Iongitudinal, or axial, exten- sion in the direction of the longitudinal extension of the cable 202; 302. Each cable core 203, 205, 207; 303 may be arranged to transfer, transmit or distribute electric power. Each cable core 203, 205, 207; 303 may comprise an electrical conductor 208, 210, 212; 308, which may have a longitudinal extension in the direction of the longitudinal extension of the cable 202; 302 and may be made of a suitable elec- trically conductive material, e.g. copper, or any other material. Alternatively, each cable core may instead be arranged to transfer or transmit a medium, such as ﬂuid, e.g. gas, liquid or oil etc., transmit signals and/or transmit light for fibre optical communication. The cable 302 shown in Fig. 3 comprises one electrical conductor 308, whereas the cable 202 shown in Fig. 2 comprises a plurality of electrical con- ductors 208, 210, 212, e.g. three electrical conductors 208, 210, 212. The cable 202 of Fig. 2 may be a three-phase electric power cable. However, the amount of the conductors may be different from what is illustrated in Figs. 2-3. Each cable 202; 302 may comprise at least one circumferential armouring armouring 214; 314 located outside of the at least one cable core 203, 205, 207; 303, the armouring 214; 314 having a longitudinal extension. The circumferential armouring 214; 314 may be tubular and may surround the cable cores 203, 205, 207; 303.

Each cable 202; 302 may comprise a circumferential outer jacket 216; 316 located outside of the armouring 214; 314 and outside of the cable cores 203, 205, 207; 303. The outer jacket 216; 316, or sheath, may be tubular and may be made of a polymer material, e.g. PVC or any other suitable material, and is provided to protect the elements of the cable 202; 302 located inside of the outer jacket 216; 10 15 20 25 30 6 316. The outer jacket 216; 316 may have a longitudinal extension in the direction of the longitudinal extension of the cable 202; 302. Each cable 202; 302 may com- prise a circumferential, or tubular, electrically insulating layer 218; 318 located out- side of each cable core 203, 205, 207; 303. The electrically insulating layer 218; 318 may be made of a dielectric material. The outer jacket 216; 316 may be lo- cated outside of the electrically insulating layer 218; 318. The electrically insulating layer 218; 318 may be located inside of the armouring 214; 314. With reference to Fig. 2, each of the plurality of electrical conductors 208, 210, 212 may be sur- rounded by a tubular electrically insulating layer 220, 222, 224, made of a suitable polymer material, e.g. XLPE, or any other material, to isolate the electrical con- ductors 208, 210, 212 from one another.

With reference to Figs. 2-3, each armouring 214; 314 may comprise at least one circumferential layer of a plurality of wires 234; 334, each wire 234; 334 having at least a longitudinal extension. The wires 234; 334 are arranged along- side one another in the direction of the longitudinal extension of the cable core 203, 205, 207; 303. The wires 234, 334 may be made of a metal material, or a polymer material, or mixture thereof. The metal material may be stainless steel, copper, or alloys thereof, e.g. brass. Other materials are possible. Each wire may have a diameter of about 1 to 12 mm, e.g. 3 to 8 mm. Each wire may have a cir- cular cross-section, an oval cross-section, or a rectangular cross-section, or any other suitable cross-section. However, other dimensions are possible. The ar- mouring 214; 314 is provided to protect the elements of the cable 202; 302 located inside of the armouring 214; 314. The armouring 214; 314 may comprise about 80 to 100 wires. However, other numbers are possible. ln Figs. 2 and 3, only one layer of wires is shown. However, it is to be understood that each armouring 214; 314 may comprise one or a plurality of additional layers of wires which may adjoin one another. ln some cases, a plurality of circumferential armouring layers radially spaced apart from one another may be provided.

Each cable 202; 302 may comprise one or a plurality of additional layers or jackets of different materials, e.g. an additional circumferential electrically in- sulating layer, an additional circumferential conductive layer, an additional semi- conducting layer etc. The layers may be tubular. Each cable 202; 302 may comprise additional cable features known to the skilled person. The operation and 10 15 20 25 30 7 function of conventional electric power cables are well known to the person skilled in the art and thus not discussed in more detail.

With reference to Fig. 4, showing a schematic longitudinal view of the first or the second embodiment of Fig. 2 and 3. The at least one circumferential layer of a plurality of wires 234; 334 (illustrated as lines) comprises a first group 402 of wires 404. Along at least a part 406 of the longitudinal extension of the cable core 203, 205, 207; 303, or the cable 202; 302, e.g. a part 406 including a ﬂexible joint or a region restored for other reasons, each wire 404 of the first group 402 of wires 404 is laterally attached or locked, at one or a plurality of locations 408, to at least one neighbouring other wire 404 of the first group 402 of wires 404. The plurality of locations 408 may be spaced apart in the direction of the longitudinal extension of respective wire 404, e.g., two locations 408 may be spaced apart by a distance of a few decimetres. For example, five to ten wires 404 of the first group 402 may laterally attached or locked to one another to form the first group 402. The cable 202; 302 may have a first and a second end between which the cable 202; 302 extends. Said at least one part 406 of the longitudinal extension of the cable core 203, 205, 207; 303 may at least be located at a distance from each of the first and second ends. Alternatively, each wire 404 of the first group 402 of wires 404 may be laterally attached or locked, at one or a plurality of locations 408, to at least one neighbouring other wire 404 of the first group 402 of wires 404 along the entire longitudinal extension of the cable core 203, 205, 207; 303 or cable 202; 302. The at least one circumferential layer of a plurality of wires 234; 334 may comprise at least one second group of wires, and along said at least one part 406 of the longi- tudinal extension of the cable core 203, 205, 207; 303 each wire of the second group of wires may be laterally attached or locked, at one or a plurality of loca- tions, to at least one neighbouring other wire of the second group of wires. Each group 402 may comprise at least three wires 404, and each wire 404 that extends alongside and laterally adjoins a neighbouring wire 404 of the same group 402 on each long side is attached or locked, at one or a plurality of locations 406, to both of these two neighbouring wires 404. Each wire 404 that is laterally attached or locked, at one or a plurality of locations 406, to at least one neighbouring other wire 404 may be attached or locked thereto by welding, e.g. spot welding. How- ever, as an alternative, said lateral attachment or locking may be executed by other means of attachment, e.g. at least one clip, at least one tape, e.g. at least 10 15 20 25 30 8 one tape provided with an adhesive, at least one loop and/or at least one string.

Each wire 234; 334 of the at least one circumferential layer of a plurality of wires 234; 334 may be included in the first group 402 or in the at least one second group. The at least one second group may be one or a plurality of second groups, e.g. three or more.

The Iateral attachment or locking of the armouring wires 404 is preferably performed at places where there is a risk or an increased likelihood for “twists” to occur during coiling, e.g. where there is a ﬂexible cable joint or a restored region etc. and where the wires consequently are impaired. The Iateral attachment or locking of the armouring wires 404 may be performed a bit before and a bit after the “risk region”. Preferably, not all wires of the armouring should be locked to form one single group, as this would prevent the movement of the wires in the ra- dial direction and thus block the travelling “bird cage”, resulting in a negative effect during storing by coiling.

With reference to Fig. 4, a method for manufacturing a cable comprising at least one longitudinal cable core is provided. The method comprises the steps of: o surrounding the at least one cable core with at least one circumferential ar- mouring comprising at least one circumferential layer of a plurality of wires, each wire having at least a longitudinal extension, such that the armouring has a longitudinal extension; v arranging the wires alongside one another in the direction of the longitudinal extension of the cable core, wherein the at least one circumferential layer of a plurality of wires comprises a first group of wires; and - along at least a part of the longitudinal extension of the cable core laterally attaching or locking each wire of the ﬁrst group of wires, at one or a plurality of locations, to at least one neighbouring other wire of the first group of wires.

Along at least a part of the longitudinal extension of the cable core each wire of the first group of wires may be laterally attached or locked, at one or a plu- rality of locations, to at least one neighbouring other wire of the first group of wires by welding, e.g. spot welding, or by means of at least one clip, at least one tape, e.g. at least one tape provided with an adhesive, at least one loop and/or at least one string. 10 9 The features of the different embodiments disclosed above may be com- bined in various possible ways providing further advantageous embodiments. The electric power cable may also be arranged for High Voltage Direct Current, HVDC, for two-phase or one-phase alternating current. For HVDC applications and sys- tems, High Voltage may be about 100 kV and above, e.g. 150 kV, 320 kV, 500 kV, 800 kV or 1000 kV, and above. The cable of the present invention may also be applied to cables other than electric power cables and submarine cables.

The invention shall not be considered limited to the embodiments illus- trated, but can be modified and altered in many ways by one skilled in the art.

Claims

10 15 20 25 30 10 CLAIMS

1. A cable (202; 302) comprising at least one longitudinal cable core (203, 205, 207; 303) and at least one circumferential armouring (214; 314) located out- side of the at least one cable core, the armouring having a longitudinal extension and comprising at least one circumferential layer of a plurality of wires (234; 334), each wire having at least a longitudinal extension, and the wires are arranged alongside one another in the direction of the longitudinal extension of the cable core, wherein the at least one circumferential layer of a plurality of wires (234; 334) comprises a first group (402) of wires (404), and wherein along at least a part (406) of the longitudinal extension of the cable core each wire of the ﬁrst group of wires is laterally attached or locked, at one or a plurality of locations (408), to at least one neighbouring other wire of the first group of wires.

2. A cable according to claim 1, characterized in that the at least one cir- cumferential layer of a plurality of wires comprises at least one second group of wires, and in that along said at least one part of the longitudinal extension of the cable core each wire of the second group of wires is laterally attached or locked, at one or a plurality of locations, to at least one neighbouring other wire of the second group of wires.

3. A cable according to claim 1 or 2, characterized in that each group comprises at least three wires, and wherein each wire that extends alongside and laterally adjoins a neighbouring wire of the same group on each long side is at- tached or locked, at one or a plurality of locations, to both of these two neighbour- ing wires.

4. A cable according to any of the claims 1 to 3, characterized in that each wire that is laterally attached or locked, at one or a plurality of locations, to at least one neighbouring other wire is attached or Iocked thereto by welding, e.g. spot welding, or by other means of attachment, e.g. at least one clip, at least one tape, e.g. at least one tape provided with an adhesive, at least one loop and/or at least one string. 10 15 20 25 30 11

5. A cable according to any of the claims 1 to 4, characterized in that the at least one cable core is arranged to transfer or transmit electric power, a me- dium, such as ﬂuid, e.g. gas, liquid or oil etc., signals and/or light for fibre optical communication.

6. A cable according to any of the claims 1 to 5, characterized in that the cable is a submarine cable.

7. A cable according to any of the claims 1 to 6, characterized in that the cable is an electric power cable, e.g. a three-phase electric power cable.

8. A cable according to any of the claims 1 to 7, characterized in that each wire of the at least one circumferential layer of a plurality of wires is included in the first group or in the at least one second group.

9. A method for manufacturing a cable comprising at least one longitudinal cable core, the method comprising the steps of: o surrounding the at least one cable core with at least one circumferential ar- mouring comprising at least one circumferential layer of a plurality of wires, each wire having at least a longitudinal extension, such that the armouring has a longitudinal extension; o arranging the wires alongside one another in the direction of the longitudinal extension of the cable core, wherein the at least one circumferential layer of a plurality of wires comprises a first group of wires; and o along at least a part of the longitudinal extension of the cable core laterally attaching or locking each wire of the first group of wires, at one or a plurality of locations, to at least one neighbouring other wire of the ﬁrst group of wires.

10. part of the longitudinal extension of the cable core each wire of the first group of A method according to claim 9, characterized in that along at least a wires is laterally attached or locked, at one or a plurality of locations, to at least one neighbouring other wire of the first group of wires by welding, e.g. spot weld- 12 ing, or by means of at least one clip, at least one tape, e.g. at least one tape pro- vided with an adhesive, at least one loop and/or at least one string.