WO2019114375A1 - 海底光缆及其制作方法 - Google Patents

海底光缆及其制作方法 Download PDF

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Publication number
WO2019114375A1
WO2019114375A1 PCT/CN2018/108894 CN2018108894W WO2019114375A1 WO 2019114375 A1 WO2019114375 A1 WO 2019114375A1 CN 2018108894 W CN2018108894 W CN 2018108894W WO 2019114375 A1 WO2019114375 A1 WO 2019114375A1
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Prior art keywords
copper conductor
submarine cable
outside
optical fiber
armor layer
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PCT/CN2018/108894
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English (en)
French (fr)
Inventor
顾春飞
栗雪松
李素华
刘伟亮
蔡阳阳
张亚兵
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中天科技海缆有限公司
江苏中天科技股份有限公司
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Publication of WO2019114375A1 publication Critical patent/WO2019114375A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00—Insulated conductors or cables characterised by their form
    • H01B7/14—Submarine cables
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables

Definitions

  • the invention relates to the field of communications, and in particular to a submarine optical cable and a manufacturing method thereof.
  • the backbone submarine cable In order to construct a long-distance, multi-node submarine observation network system, the backbone submarine cable generally adopts unipolar high-voltage DC power supply technology, and needs to realize power and information loop transmission between each branch unit and the main node connected thereto.
  • the prior art is a branch. Two submarine cables need to be used between the unit and the main node to realize the transmission of power and information loops, which greatly increases the manufacturing difficulty of the branch unit, and the difficulty in system construction and maintenance, high construction cost and high risk.
  • a submarine cable comprising a fiber unit and an armor layer, an inner copper conductor, an insulating layer, an outer copper conductor and an outer sheath which are sequentially coated from the inside to the outside of the fiber unit, the fiber unit
  • An optical fiber and a stainless steel tube are included, and the optical fiber is placed in the stainless steel tube. Further, the stainless steel tube is filled with a water blocking material.
  • the maximum number of the optical fiber cores is 96 cores.
  • the armor layer is formed by stranding steel wire or non-metal reinforcing material.
  • the armor layer is provided with at least one layer, and each of the armor layer gaps is provided with a water blocking material.
  • the inner copper conductor is configured to be seamlessly welded by a copper tube.
  • outer copper conductor is arranged to be seamlessly welded by a copper tube or longitudinally wrapped by a copper strip.
  • the insulating layer and the outer sheath are made of polyethylene.
  • the inner copper conductor is soldered outside the armor layer.
  • a manufacturing method of the submarine cable comprising:
  • the outer sheath is extruded outside the outer copper conductor.
  • the submarine optical cable provided by the invention has the design of inner and outer copper conductors and optical fiber units, and a submarine optical cable can realize the loop transmission of electric energy and information, solves the problem that two submarine optical cables need to be laid, and greatly reduces the system of the branch unit. Construction and maintenance are difficult and cost effective.
  • FIG. 1 is a cross-sectional view of a submarine cable in accordance with an embodiment of the present invention.
  • FIG. 2 is a flow chart of a method of fabricating a submarine cable in accordance with an embodiment of the present invention.
  • Submarine cable 100 Fiber unit 10 optical fiber 11 stainless steel pipe 12 Armor layer 20 Inner copper conductor 30 Insulation 40 Outer copper conductor 50 Outer sheath 60
  • FIG. 1 is a cross-sectional view of a submarine cable 100 for transmitting electrical energy and information according to an embodiment of the present invention.
  • the submarine cable 100 includes an optical fiber unit 10 and an armor layer 20, an inner copper conductor 30, an insulating layer 40, an outer copper conductor 50, and an outer sheath 60 which are sequentially coated from the inside to the outside of the optical fiber unit 10.
  • the fiber unit 10 is located at a central position of the submarine cable 100.
  • the fiber unit 10 includes an optical fiber 11 and a stainless steel tube 12, and the optical fiber 11 is placed in the stainless steel tube 12 for transmitting information.
  • the number of cores in which the optical fiber 11 is placed in the stainless steel tube 12 ranges from 1 to 96 cores (including 1 and 96), and the specific number of cores can be set according to specific information transmission requirements.
  • the stainless steel tube 12 is formed by laser seamless welding of stainless steel tubes, and the stainless steel tube 12 is filled with a high-performance water-blocking grease to improve the water-blocking performance of the submarine cable 100 under water.
  • the armor layer 20 is stranded outside the fiber unit, and the armor layer 20 is used to protect the fiber 11 from external force.
  • the armor layer 20 is made of steel wire or non-metal.
  • the reinforcing material or other equivalent reinforcing material is stranded, the armor layer 20 is provided with different layers, and the highest number of layers is three layers, and the number of layers of the armor layer 20 is set according to different water depths,
  • the gap of the armor layer 20 is filled with a high performance water blocking material to improve the water blocking performance of the submarine cable 100 under water.
  • the armor layer 20 is adapted for use in different water depths by adding steel strips, steel wires, non-metallic reinforcing materials, or other equivalent reinforcing materials.
  • the inner copper conductor 30 is used for transmitting electrical energy, and the inner copper conductor 30 is wrapped around the armor layer 20.
  • the inner copper conductor 30 is coated on the raft by welding. Outside the cladding layer 20, the inner copper conductor 30 is formed by seamless soldering of copper tubes.
  • the insulating layer 40 is coated on the outside of the inner copper conductor 30.
  • the insulating layer 40 is used to protect the inner copper conductor 30 from external damage and the power transmission is not affected.
  • the insulating layer 40 is made of polyethylene material. In the present embodiment, the insulating layer is coated on the outside of the inner copper conductor 30 by extrusion.
  • the outer copper conductor 50 is wrapped outside the insulating layer 40 by a copper strip or the copper tube is seamlessly welded to the outside of the insulating layer 40.
  • the outer copper conductor 50 is spaced apart from the inner copper conductor 30 by the insulating layer 40 for transmitting electrical energy.
  • the outer sheath 60 is coated on the outer copper conductor 50, and the outer sheath 60 is made of a polyethylene material. In the embodiment, the outer sheath 60 is coated by extrusion. The outer copper conductor 50 is outside. The outer sheath is used to insulate the submarine cable 100 from the external environment, protect the submarine cable 100 from external force damage, and the power transmission is not affected.
  • the DC resistance of the inner copper conductor 30 and the outer copper conductor 50 is controlled by the design of the inner copper conductor 30 and the outer copper conductor 50.
  • the submarine cable 100 is used for connecting a branching unit and a main node, and the branching unit transmits electrical energy to the main node through the inner copper conductor 30, and the outer copper conductor 50 transmits power to the branch node by the main node, or through the outer
  • the copper conductor 50 transmits electrical energy from the branching unit to the primary node
  • the inner copper conductor 30 transmits electrical energy from the primary node to the branch node
  • the optical fiber unit 10 implements loop transmission of electrical energy and information between the branching unit and the primary node.
  • FIG. 2 is a flowchart of a method for manufacturing a submarine cable according to an embodiment of the present invention, where the manufacturing method includes:
  • the optical fiber is placed in a stainless steel tube, and the stainless steel tube is filled with a high-performance water blocking material.
  • a copper tube is used to form an inner copper conductor outside the armor layer.
  • the submarine optical cable provided by the invention has the design of inner and outer copper conductors and optical fiber units, and a submarine optical cable can realize the loop transmission of electric energy and information, solves the problem that two submarine optical cables need to be laid, and greatly reduces the system of the branch unit. Construction and maintenance are difficult and cost effective.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Insulated Conductors (AREA)

Abstract

一种海底光缆(100)，所述海底光缆(100)包括光纤单元(10)以及由内而外依次包覆在所述光纤单元(10)外的铠装层(20)、内铜导体(30)、绝缘层(40)、外铜导体(50)及外护层(60)，所述光纤单元(10)包括光纤(11)和不锈钢管(12)，所述光纤(11)置于所述不锈钢管(12)中。该海底光缆通过内外铜导体(30,50)和光纤单元(10)的设计，一根海底光缆(100)即可实现电能和信息的回路传输，解决了需要敷设两根海底光缆的问题，极大的降低了分支单元的系统施工和维修的难度，节约成本。

Description

海底光缆及其制作方法 技术领域
本发明涉及通信领域尤其涉及一种海底光缆及其制作方法。
背景技术
为了构建远距离、多节点海底观测网系统，主干海底光缆一般采用单极高压直流供电技术，在每个分支单元及与其连接的主节点之间需要实现电能和信息回路传输，现有技术是分支单元与主节点之间需要使用两根海底光缆才能实现电能和信息回路传输，极大的增加了分支单元的制造难度，以及系统施工、维修难度，建设成本高、风险大。
发明内容
有鉴于此，有必要提供一种海底光缆，通过一根海底光缆就可以实现分支单元与主节点之间的回路传输。
一种海底光缆，所述海底光缆包括光纤单元以及由内而外依次包覆在所述光纤单元外的铠装层、内铜导体、绝缘层、外铜导体及外护层，所述光纤单元包括光纤和不锈钢管，所述光纤置于所述不锈钢管中。进一步的，所述不锈钢管内填充有阻水材料。
进一步的，所述光纤芯数最大值为96芯。
进一步的，所述铠装层采用钢丝或非金属增强材料绞合而成。
进一步的，所述铠装层设置有至少一个层数，每一所述铠装层间隙中设置有阻水材料。
进一步的，所述内铜导体被设置为由铜管无缝焊接形成。
进一步的，所述外铜导体被设置为由铜管无缝焊接或者铜带纵包形成。
进一步的，所述绝缘层和外护层采用聚乙烯材料。
进一步的，所述内铜导体焊接在所述铠装层外。
一种所述海底电缆的制作方法，所述制作方法包括：
制作光纤单元；
在光纤单元外绞合铠装层；
在铠装层外包覆内铜导体；
在内铜导体外挤塑绝缘层；
将外铜导体包覆在绝缘层外；
在外铜导体外挤塑外护层。
本发明提供的海底光缆通过内外铜导体和光纤单元的设计，一根海底光缆即可实现电能和信息的回路传输，解决了需要敷设两根海底光缆的问题，极大的降低了分支单元的系统施工和维修的难度，节约成本。
附图说明
图1为本发明一实施例中海底光缆的剖视图。
图2为本发明一实施例中海底光缆的制作方法的流程图。
主要元件符号说明
海底光缆 100
光纤单元 10
光纤 11
不锈钢管 12
铠装层 20
内铜导体 30
绝缘层 40
外铜导体 50
外护层 60
如下具体实施方式将结合上述附图进一步说明本发明。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
除非另有定义，本文所使用的所有的技术和科学术语与属于本发明的技术领域的技术人员通常理解的含义相同。本文中在本发明的说明书中所使用的术语只是为了描述具体的实施例的目的，不是旨在于限制本发明。本文所使用的术语“或/及”包括一个或多个相关的所列项目的任意的和所有的组合。
请参阅图1，图1为本发明实施方式的海底光缆100的剖视图，所述海底光缆100用于传输电能和信息。所述海底光缆100包括光纤单元10以及由内而外依次包覆在所述光纤单元10外的铠装层20、内铜导体30、绝缘层40、外铜导体50及外护层60。
所述光纤单元10位于所述海底光缆100的中心位置，所述光纤单元10包括光纤11和不锈钢管12，所述光纤11置于所述不锈钢管12中，所述光纤11用于传输信息。
在本实施方式中，所述光纤11置于所述不锈钢管12中的芯数的范围为1至96芯(包含1和96)，具体的芯数可根据具体信息传输要求设定。所述不锈钢管12由不锈钢带激光无缝焊接形成，所述不锈钢管12内填充有高性能阻水油膏，可以提升所述海底光缆100在水下的阻水性能。
所述铠装层20绞合在所述光纤单元外，所述铠装层20用于保护所述光纤11不受外力损坏，在本实施方式中，所述铠装层20采用钢丝、非金属增强材料或者其他等效增强材料绞合而成，所述铠装层20设有不同的层数，最高层数为三层，根据不同的水深设置所述铠装层20的层数，所述铠装层20的间隙中填充有高性能阻水材料，提升所述海底光缆100在水下的阻水性能。在其他实施方式中，通过增加钢带、钢丝、非金属增强材料或其他等效增强材料使所述铠装层20适用于不同水深海域。
所述内铜导体30用于传输电能，所述内铜导体30包覆在所述铠装层20外，在本实施方式中，所述内铜导体30通过焊接的方式包覆在所述铠装层20外，所述内铜导体30由铜管无缝焊接形成。
所述绝缘层40包覆在所述内铜导体30外，所述绝缘层40用于保护所述内铜导体30不受外力损坏以及电能传输不受影响，所述绝缘层40采用聚乙烯材料制成，在本实施方式中，所述绝缘层通过挤塑的方式包覆在所述内铜导体30外。
所述外铜导体50通过铜带纵包在所述绝缘层40外或者铜管无缝焊接后包 覆在所述绝缘层40外。所述外铜导体50通过所述绝缘层40与所述内铜导体30间隔，所述外铜导体50用于传输电能。
所述外护层60包覆在所述外铜导体50外，所述外护层60采用聚乙烯材料制成，在本实施方式中，所述外护层60通过挤塑的方式包覆在所述外铜导体50外。所述外护层用于隔绝所述海底光缆100与外部环境，保护所述海底光缆100免受外力损伤以及电能传输不受影响。
通过对所述内铜导体30和外铜导体50的设计，控制所述内铜导体30和外铜导体50的直流电阻。所述海底光缆100用于连接分支单元和主节点，通过所述内铜导体30由分支单元传输电能到主节点，所述外铜导体50由主节点传输电能至分支节点，或者通过所述外铜导体50由分支单元传输电能到主节点，所述内铜导体30由主节点传输电能至分支节点，以及所述光纤单元10实现分支单元与主节点之间的电能和信息的回路传输。
请参阅图2，图2为本发明一实施例中海底光缆的制作方法的流程图，所述制作方法包括：
S21，制作光纤单元。具体的，将光纤置于不锈钢管中，并在不锈钢管中填充高性能阻水材料。
S22，在光纤单元外绞合铠装层。具体的，将铠装层包覆在光纤单元外，并在铠装层间隙中填充高性能阻水材料。
S23，在铠装层外包覆内铜导体。具体的，使用铜管焊接在铠装层外形成内铜导体。
S24，在内铜导体外挤塑绝缘层。具体的，使用聚乙烯材料包覆在内铜导体外形成绝缘层。
S25，将外铜导体包覆在绝缘层外。具体的，使用铜带或者铜管纵包在绝缘层外形成外铜导体。
S26，在外铜导体外挤塑外护层。具体的，使用聚乙烯材料包覆在外铜导体外形成外护层。
本发明提供的海底光缆通过内外铜导体和光纤单元的设计，一根海底光缆即可实现电能和信息的回路传输，解决了需要敷设两根海底光缆的问题，极大的降低了分支单元的系统施工和维修的难度，节约成本。
本技术领域的普通技术人员应当认识到，以上的实施方式仅是用来说明本 发明，而并非用作为对本发明的限定，只要在本发明的实质精神范围的内，对以上实施方式所作的适当改变和变化都落在本发明要求保护的范围的内。

Claims (10)

  1. 一种海底光缆，其特征在于：所述海底光缆包括光纤单元以及由内而外依次包覆在所述光纤单元外的铠装层、内铜导体、绝缘层、外铜导体及外护层，所述光纤单元包括光纤和不锈钢管，所述光纤置于所述不锈钢管中。
  2. 如权利要求1所述的海底光缆，其特征在于：所述不锈钢管内填充有阻水材料。
  3. 如权利要求1所述的海底光缆，其特征在于：所述光纤芯数最大值为96芯。
  4. 如权利要求1所述的海底光缆，其特征在于：所述铠装层采用钢丝或非金属增强材料绞合而成。
  5. 如权利要求1所述的海底光缆，其特征在于：所述铠装层设置有至少一个层数，每一所述铠装层间隙中设置有阻水材料。
  6. 如权利要求1所述的海底光缆，其特征在于：所述内铜导体被设置为由铜管无缝焊接形成。
  7. 如权利要求1所述的海底光缆，其特征在于：所述外铜导体被设置为由铜管无缝焊接或者铜带纵包形成。
  8. 如权利要求1所述的海底光缆，其特征在于：所述绝缘层和外护层采用聚乙烯材料。
  9. 如权利要求1所述的海底光缆，其特征在于：所述内铜导体焊接在所述铠装层外。
  10. 一种海底电缆的制作方法，所述制作方法包括：
    制作光纤单元；
    在光纤单元外绞合铠装层；
    在铠装层外包覆内铜导体；
    在内铜导体外挤塑绝缘层；
    将外铜导体包覆在绝缘层外；
    在外铜导体外挤塑外护层。
PCT/CN2018/108894 2017-12-15 2018-09-29 海底光缆及其制作方法 WO2019114375A1 (zh)

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CN110426798A (zh) * 2019-07-08 2019-11-08 江苏亨通海洋光网系统有限公司 一种大容量低电阻跨洋有中继海底光缆
CN111427124A (zh) * 2020-03-18 2020-07-17 江苏亨通海洋光网系统有限公司 海底光缆奇数不等径钢丝复合铜管一体化拱形内铠结构
CN111679383A (zh) * 2020-05-20 2020-09-18 中航宝胜海洋工程电缆有限公司 一种高强度耐侧压、耐冲击的海底光缆缆芯及其制备方法
CN111897070B (zh) * 2020-08-26 2022-09-06 江苏亨通海洋光网系统有限公司 一种降低直流电阻的有中继海底光缆结构

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4278835A (en) * 1977-12-16 1981-07-14 The Post Office Submarine communication cable including optical fibres within an electrically conductive tube
CN101241213A (zh) * 2008-02-13 2008-08-13 中天科技海缆有限公司 深海光缆及其制作方法
CN102623089A (zh) * 2011-01-27 2012-08-01 江苏晨光电缆有限公司 一种钢丝铠装充油深海探测电缆
CN205609281U (zh) * 2015-12-19 2016-09-28 天津安讯达科技有限公司 一种皱纹铜管内导体防水型钢丝铠装射频电缆
CN108109742A (zh) * 2017-12-15 2018-06-01 中天科技海缆有限公司 海底光缆及其制作方法

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN201229792Y (zh) * 2008-12-24 2009-04-29 汕头市金桥电缆有限公司 一种有线电视电缆
CN202142350U (zh) * 2011-08-16 2012-02-08 徐云 同心式全干漏泄光电综合缆
CN106098241A (zh) * 2016-08-29 2016-11-09 中天科技海缆有限公司 一种轻型保护型海底光缆
CN107154292B (zh) * 2016-10-25 2018-11-13 陕西一通通信设备有限公司 一种用于航空的高强度低重量光电复合缆的制造方法
CN206558274U (zh) * 2017-02-14 2017-10-13 珠海汉胜科技股份有限公司 一种光电混合缆

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4278835A (en) * 1977-12-16 1981-07-14 The Post Office Submarine communication cable including optical fibres within an electrically conductive tube
CN101241213A (zh) * 2008-02-13 2008-08-13 中天科技海缆有限公司 深海光缆及其制作方法
CN102623089A (zh) * 2011-01-27 2012-08-01 江苏晨光电缆有限公司 一种钢丝铠装充油深海探测电缆
CN205609281U (zh) * 2015-12-19 2016-09-28 天津安讯达科技有限公司 一种皱纹铜管内导体防水型钢丝铠装射频电缆
CN108109742A (zh) * 2017-12-15 2018-06-01 中天科技海缆有限公司 海底光缆及其制作方法

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