NZ239020A

NZ239020A - Submarine fibre-optic cable: lay-up structure

Info

Publication number: NZ239020A
Application number: NZ23902091A
Authority: NZ
Inventors: Gery Marlier; Jean-Francois Libert
Original assignee: Alcatel Australia
Priority date: 1991-07-18
Filing date: 1991-07-18
Publication date: 1993-11-25

Description

<div class="application article clearfix" id="description"> 23 9 0^0 i°\ "v?to j y.u* i j V\0 \ft V\\*2-2. . P-7 7/ 25 N0V 1993 P.O. J. .." ->: . •l^"lLr NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION "SUBMARINE OPTICAL CABLE' WE, ALCATEL AUSTRALIA LIMITED. A Company of the State of New South Wales, of 280 Botany Road, Alexandria. New South Wales, 2015. Australia, hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: I 239 02 This invention relates to a submarine fibre optic telecommunication cablc including a tube containing optical fibres embedded in a filling material, inside a strand of high strength wires. Document AU-A-81304,87 already proposed a submarine telecommunication 5 cablc including a tube of conducting metal surrounding the optical fibres embedded in a filling material inside the tube, an clectrical insulator surrounding the tube of conducting metal, and at least one layer of high-tensile wires surrounding the insulator, forming a protective shield. Nevertheless, such a cablc is not sufficiently strong to prevent possible water ingress and lengthwise spreading of the water, cspc-10 cially when the immersed cablc is damaged. Moreover, once in contact with salt water, the wires forming the protccthc shield can become corroded by bactcrial action for instance. This corrosion phenomenon could then generate molecular hydrogen which, under certain conditions, may migrate to come in contact with the optical fibres and thus downgrade the tranmission characteristics. Furthermore, the 15 tube of conducting metal containing the fibres implies an expensive structure when a link is not remotely powered, or imposes a different optical module dictated by the tube containing the fibres depending whether or not the link is remotely powered. The purpose of the present invention is to provide a submarine telecommunication cablc which prevents the water entering its damaged shield from spreading. 20 which has a light and compact structure and a low production cost, and which can be fitted, if need be. with repeater power supply conductors without modifying its ccntrc part. The cable in accordancc with the invention is characterised in that a strand of high strength wircss directly encases the tube containing the fibres. It is further 25 characterised in that, the spaccs between the high strength wircss of the strands, and between the strand and the said tube arc filled with a scaling material preventing the 2 239020 water from spreading into the cable, and in that, the said strand of high strength wiress is itself surrounded by an abrasion-resistant extruded sheath made of electrically insulating material. Furthermore, it preferably incorporates at least one of the following features: 5 - dcviccs dedicated to remote power supply of equipment inserted along the cablc, arranged on the outskirts of the strand of high strength wircss, and made up of a conducting strip on the strand, or of conducting wires which, together with the said high strength wircss. belong to the strand: - a semiconducting interface layer, between the dcviccs dedicated to remote power 10 supply and the extruded sheath, made of insulating material laden with conducting particles; - the insulating material is also laden with conducting particles. In order that the invention may be readily carried into effect, embodiments thereof will now be described in relation to the drawings, in which: 15 Figure I is a cross-section of a cablc in accordance with the invention. Figure 2 is a cross-section of another version of the cablc in accordancc with the invention. In both figures, the same item numbers have been used when the same components arc illustrated. 20 The cable shown in Figure I includes a tube (I) filled with a scaling compound, silica gel (2) for instance, in which the optical fibres (3) arc embedded. The optical fibres may or may not be wired and may or may not have cxccss length in the tube. The tube (I) is made of metal, steel for instance, and is resistant to water pressure. It is welded lengthwise either by means of laser, arc welding, or any other 25 suitable method. This tube (1) may also be made of extruded plastic, in this ease it 3 239020 will be associated with some means mentioned below providing the cablc with sufficient pressure resistance. The tube (1) is surrounded by a strand of high tensile wires (4 and 5), in one or preferably several layers arranged either in the same or the opposite direction. 5 Moreover, when dealing with a plastic tube (I), the arch shape of this strand provides resistance to pressure. These wires (4 and 5) arc preferably made of steel. The spaces (6) between the wires (4 and 5) and between the strand and the tube (1) arc filled with scaling material (no! illustrated) to prevent overloads, preventing the water from spreading lengthwise in the cablc, especially when the immersed cablc 10 is accidcntiallv damaged. This scaling material may for instance be a polyurcthanc resin or any other suitable scaling material. In addition. Figure I cablc includes a conducting strip (7) made of copper, aluminium or other metal or alloy being a good conductor of electricity, and surrounding the strand of high strength wircss. This conducting strip (7) is dedicated to 15 remote power supply of amplifier repeaters or regenerators inserted between the cablc sections making up the submarine link. It reduces to a suitable value the clcctrical rcsistancc of the steel wire strand and steel tube which is generally too high. The conducting strip (7) is welded lengthwise to form a tube and is contracted over the strand, or it may consist of one or several tapes wound in coils, or it may also consist 20 of one or several foils placcd lengthwise on the strand and assembled. A sheath (8), made of polyethylene or other electrically insulating and abrasion rcsistancc material, is extruded in one or several layers over the strand covered by the conducting strip (7), especially when the latter is taped or otherwise and is not perfectly smooth. It is a very poor conductor. It acts as a potential barrier providing 25 uniform distribution of the electric loads through the strip (7), and for the same degree of insulation the sheath (8) can be thinner, since this layer prevents high con- 4 239020 ccntration of clectric fields where roughness exists, which may damage the sheath (8). This semiconducting layer is made of polyethylene laden with conducting particlcs, carbon particles for instance. A bonding agent, a copolymer for instance, may be used to ensure that this layer adheres to the conducting strip (7). 5 Furthermore, the scaling material may also be laden with conducting particles, and/or another semiconducting layer, similar to layer (9), may be used to cover the outer spaces (10) between the wires of the strand, with a bonding agent which, if required. will ensure its adhcrencc to the peripheral wires (5) of the strand and the conducting strip (7), in order to avoid any electrical problem at conducting 10 strip/strand interface level. The cablc shown in Figure 2 is a different version of the above cablc. Only its differences with regard to Figure I cablc arc mentioned here. Figure 2 cable docs not have the conducting strip (7) of Figure 1 cablc. Its conducting strip (9) is placed directly against the wire strand and adheres to the pels ripheral wires. Moreover, its strand consists of wires (4), (5a) and (5b), preferably in several layers, some of these wires no longer being high strength wircss but conducting wires instead. The strand is preferably made of steel wires (4) in one or several layers against the tube (1) and having the characteristics of an arch when the tube (I) is made of plastic, and outer layer wires (5a) and (5b), respectively made of steel, and 20 aluminium or copper. Wires (5a) and (5b) arc shown with different sections and alternate. Conducting wires (5a) or (5b) have a diameter providing suitable clcctrical rcsistancc to power the repeaters or regenerators. The cablcs, with or without remote power supply, have the same ccntral module defined by tube (1) containing the fibres upon which the suitable external components 25 are added. Without remote power supply, the cablc has an all steel wire strand filled with sealing material, and has no conducting strip and/or semiconducting layer. With 5 23 9 020 remote power supply, the cablc has an all steel wire strand filled with a scaling material rccciving the conducting strip upon which is preferably formed the semiconducting layer being the interface with the sheath, and eventually the layer being the interface with the strand; or the cablc has a strand made of steel wires and con-5 ducting wires which is filled with a scaling material and preferably receives the seminconducting layer being the interface with the sheath. Whether or not the link is remotely power supplied, production cost of both types of cables is lower. Their structure is compact and lighter and offers good resistance to pressure. From the different cables described above, it becomes clcar that the existence. 10 nature and sections of the conducting devices can be modified in accordancc with the system's requirements with regard to remote power supply, without having to handle other cablc components. The section of these conducting dcviccs may either be nil for systems without repeater, small for systems with optical amplifiers, or normal for systems with regenerators. This docs not affect the rcsistancc to hydrogen and to 15 pressure of the cablc. 20 25 6 </div>

Claims

<div class="application article clearfix printTableText" id="claims"> 23 0 0 2 0 What we claim is:

1. A submarine fibre optic telecommunication cable including a tube containing optical fibres embedded in a filling material and a layer of high strength wires around the tube, wherein said layer of high strength wires directly 5 encases the tube containing the fibres, and wherein the spaces between the high strength wires of the layer, and between the layer and the said tube are filled with a sealing material preventing water from spreading into the cable, the high strength wires layer being surrounded by an abrasion-resistant and electrically insulating extruded sheath. 10

2. A cable as claimed in claim 1, including conducting devices dedicated to remote power supply of equipment inserted along the cable, wherein the said conducting devices are arranged on or around the outer periphery of the layer and are surrounded by the said extruded sheath, and have a section suited to the said equipment. 15

3. A cable as claimed in claim 2, wherein said conducting devices dedicated to remote power supply include a conducting strip welded lengthwise and shrunk over the layer or taped in coils or placed lengthwise along the said layer.

4. A cable as claimed in claim 2, wherein said conducting devices dedicated to remote power supply are made up of conducting wires which, together with 20 the said high strength wires, belong to the layer.

5. A cable as claimed in claim 4, wherein said layer has at least one layer of high strength wires against the said tube and one peripheral layer of wires being respectively high strength wires and conducting wires. N.Z. PATENT OFF ICE 150CT 1993 R5*CCIV!:D 23 S 0 2 a

6. A cable as claimed in any one of claims 2 to 5, including a semiconducting layer interfacing the said conducting devices dedicated to remote power supply and the said extruded sheath.

7. A cable as claimed in claim 3, including a semiconducting layer filling the 5 outer spaces between the peripheral wires of the layer of high strength wires and adhering to these peripheral wires, forming an interface with the said conducting strip to which it adheres.

8. A cable as claimed in any one of claims 6 and 7, wherein said semiconducting layer is a polyethylene resin laden with conducting particles. 10

9. A cable as claimed in any one of claims 2 to 8, wherein said sealing material is laden with conducting particles.

10. A cable as claimed in claim 9, wherein said sealing material is a polyurethane resin.

11. A cable as claimed in any one of claims 1 to 10, wherein said tube is 15 either made of metal and is pressure resistant, or of plastics whereby the said high strength wires strand forms an arch around the plastics tube.

12. A submarine fibre optic telecommunication cable, substantially as herein described with reference to Figures 1 - 2 of the accompanying drawings. 20 ALCATEL AUSTRALIA LIMITED //?/ c. P.M. Conrick Authorized Agent P5/1/1703 ■r«-Z. l-'ATEftiT OFF ICS 15 OCT 1993 8 </div>