Lightweight submarine cable and armor wire used therefor

Abstract

Disclosed are a lightweight submarine cable and an armor wire used therefor. The armor wire may be wound around a power unit to form an armor layer. The armor wire may include a core portion and a cover portion. The core portion may include a bundle of first fibers. The cover portion may include a second fiber which is transversely wound around the core portion.

Description

Lightweight submarine cables and armor wires used therein

[0001] The present invention relates to a cable laid on the seabed and an armor wire used therein.

[0002]

[0003] A submarine cable is a cable laid under the sea to transmit electricity between two points across the sea, such as between continents or between land and islands.

[0004] When submarine cables are laid in waters thousands of meters deep, they are exposed to significant tensile forces. This tensile force is exerted by the cable's own weight as it stretches vertically. To protect the cable from damage or breakage due to this tensile force, the cable's armor can be reinforced. For example, the armor's steel wires can be made thicker (heavier).

[0005] However, as the armor's wires are reinforced, the cable's weight also increases. The increased weight causes the cable to experience greater tensile stress. This, in turn, creates a vicious cycle requiring cable reinforcement. Consequently, it is extremely difficult to create cables suitable for deep-sea installation within the existing concept of wire armor.

[0006] The background technology described above is technical information that the inventor possessed for the purpose of deriving embodiments of the present invention or acquired during the derivation process, and cannot necessarily be said to be publicly known technology disclosed to the general public prior to the present application.

[0007]

[0008] One object of the present invention is to provide a lightweight submarine cable and armor used therein, which has a new concept of armor that breaks away from the concept of conventional steel wire armor.

[0009] Another object of the present invention is to provide a lightweight submarine cable and an armor wire used therein, having an armor layer having an improved tensile strength-to-weight ratio compared to steel wire armor.

[0010]

[0011] According to one aspect of the present invention for achieving the above-described object, a lightweight submarine cable comprises at least one power unit and a protection unit wrapping the at least one power unit, wherein the power unit comprises a conductor, an inner semiconducting layer wrapping the conductor, an insulating layer wrapping the inner semiconducting layer, an outer semiconducting layer wrapping the insulating layer, and a metal shielding layer wrapping the outer semiconducting layer, and the protection unit comprises a bedding layer wrapping the at least one power unit, an armor layer wrapping the bedding layer, and an outermost layer wrapping the armor layer, wherein the armor layer comprises a plurality of armor wires that are transversely wound around the outside of the bedding layer, and the armor wires may include a core portion having a bundle of first fibers and a cover portion having second fibers that are transversely wound around the core portion.

[0012] Here, the armor wire can be wound transversely with the second fiber while the bundle of the first fiber is pulled longitudinally.

[0013] Here, the second fiber can be wound transversely while being pulled in the longitudinal direction.

[0014] Here, the armor wire can have a spot ratio of 80% or more.

[0015] Here, the second fiber can be wound transversely with respect to the first fiber at a pitch angle of 3° or more.

[0016] Here, the bundle of the first fibers may be a plurality of first fibers that are straightly braided.

[0017] Here, the second fiber is provided in a bundle, and the bundle of the second fiber can be made up of a plurality of second fibers.

[0018] Here, the second fiber may include a 2-1 fiber and a 2-2 fiber, and the cover part may include a first cover part in which the 2-1 fiber is transversely wound along a first direction relative to the core part, and a second cover part in which the 2-2 fiber is transversely wound along a second direction relative to the core part.

[0019] Here, the first fiber may be formed of at least one of aramid and UHMWPE.

[0020] Here, the second fiber can be formed of at least one of aramid, UHMWPE, PET, glass fiber, and carbon fiber.

[0021] Here, the diameter of the core portion may be 40 to 80 times the diameter of the cover portion.

[0022] Here, the first fiber and the second fiber may be fibers of the same type.

[0023] Here, the power unit may further include a polymer sheath surrounding the metal shielding layer.

[0024] According to another aspect of the present invention, an armor wire for a submarine cable is an armor wire for wrapping a power unit of a submarine cable to form an armor layer, and may include a core portion having a bundle of first fibers; and a cover portion having a second fiber wound transversely around the core portion.

[0025] Here, the second fiber can be transversely wound in a longitudinal direction relative to the first fiber bundle while the bundle of the first fiber is pulled in the longitudinal direction.

[0026] Here, the bundle of the first fibers may be a plurality of first fibers that are straightly braided.

[0027] Here, the second fiber is provided in a bundle, and the bundle of the second fiber can be made up of a plurality of second fibers.

[0028] Here, the second fiber is provided as a bundle, and the bundle of the second fiber includes a 2-1 fiber bundle and a 2-2 fiber bundle, and the cover part may include a first cover part in which the 2-1 fiber bundle is transversely wound along a first direction relative to the core part, and a second cover part in which the 2-2 fiber bundle is transversely wound along a second direction relative to the core part.

[0029] According to another aspect of the present invention, a submarine cable comprises at least one power unit and a protection unit wrapping the at least one power unit, wherein the power unit comprises a conductor, an inner semiconductive layer wrapping the conductor, an insulating layer wrapping the inner semiconductive layer, an outer semiconductive layer wrapping the insulating layer, and a metal shielding layer wrapping the outer semiconductive layer, wherein the protection unit comprises a bedding layer wrapping the at least one power unit, an armor layer wrapping the bedding layer, and an outermost layer wrapping the armor layer, wherein the armor layer comprises a plurality of armor wires that are transversely wound around the outside of the bedding layer, and the armor wires comprise a fiber assembly in which a first fiber and a second fiber are composited, and the second fiber can be transversely wound about the first fiber to compress the first fiber.

[0030] Here, the armor wire can be wound transversely while the first fiber is pulled longitudinally and the second fiber is pulled longitudinally relative to the first fiber.

[0031] Here, the second fiber can be wound transversely with respect to the first fiber at a pitch angle of 3° or more.

[0032] Here, the first fiber and the second fiber may be fibers of the same type.

[0033]

[0034] According to the lightweight submarine cable and the armor wire used therein according to the present invention configured as described above, the armor wire of the protection unit surrounding the power unit includes a core portion having a bundle of first fibers and a cover portion having second fibers wound transversely around the core portion, so that the armor layer can be manufactured by a new concept of fiber assembly that goes beyond the concept of conventional steel wire armor.

[0035] Fiber armor layers can have a higher tensile strength-to-weight ratio than steel wire armor. Consequently, lightweight submarine cables can be installed reliably and easily, even in deep waters reaching depths of thousands of meters.

[0036]

[0037] FIG. 1 is a cross-sectional view showing the configuration of a lightweight submarine cable according to one embodiment of the present invention.

[0038] Figure 2 is a front view showing the armor wire of Figure 1.

[0039] Figure 3 is a cross-sectional view of the armor wire of Figure 2.

[0040] Fig. 4 is a cross-sectional view showing an armor wire according to a modified example of the armor wire of Fig. 3.

[0041] FIG. 5 is a front view showing an armor wire according to another modified example of the armor wire of FIG. 2.

[0042] Fig. 6 is a cross-sectional view showing the configuration of a lightweight submarine cable according to a modified example of the lightweight submarine cable of Fig. 1.

[0043] Fig. 7 is a cross-sectional view showing the configuration of a lightweight submarine cable according to another embodiment of the present invention.

[0044]

[0045] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0046] The present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and with various modifications. However, these embodiments are provided to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention. Therefore, the present invention is not limited to the embodiments disclosed below, but should be understood to include all modifications, equivalents, and substitutes included within the technical spirit and scope of the present invention, as well as substitutions or additions of the components of one embodiment with those of another embodiment.

[0047] The attached drawings are merely intended to facilitate understanding of the embodiments disclosed in this specification, and should not be construed as limiting the technical ideas disclosed in this specification, but should be understood to encompass all modifications, equivalents, and substitutes included within the spirit and technical scope of the present invention. In the drawings, the components may be expressed in exaggerated sizes or thicknesses for ease of understanding, but the scope of protection of the present invention should not be construed as being limited thereby.

[0048] The terminology used in this specification is only used to describe specific implementations or examples and is not intended to limit the present invention. In addition, the singular expression includes the plural expression unless the context clearly indicates otherwise. In the specification, terms such as "comprises" and "consists of" are intended to indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification. In other words, it should be understood that terms such as "comprises" and "consists of" do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0049] Terms that include ordinal numbers, such as first, second, etc., may be used to describe various components, but the components are not limited by these terms. These terms are used solely to distinguish one component from another.

[0050] When a component is referred to as being "connected / connected" or "connected" to another component, it should be understood that it may be directly connected / connected to that other component, or that there may be other components in between. Conversely, when a component is referred to as being "directly connected / connected" or "directly connected" to another component, it should be understood that there are no other components in between.

[0051] When a component is referred to as being "above" or "below" another component, it should be understood that it is not only positioned directly above that other component, but that there may also be other components present in between.

[0052] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0053] FIG. 1 is a cross-sectional view showing the configuration of a lightweight submarine cable according to one embodiment of the present invention.

[0054] Referring to this drawing, a submarine cable (1000) has a power unit (100) that forms a conductive path through which current flows. In this embodiment, a single-phase cable having one power unit (100) is exemplified.

[0055] The power unit (100) may include a conductor (110), an inner semiconducting layer (120), an insulating layer (130), an outer semiconducting layer (140), a metal shielding layer (150), and a polymer sheath (160). These (110 to 160) are sequentially arranged in a radial direction from the center of the power unit (100). In this embodiment, the power unit (100) is described as having six components (layers), but the present invention is not limited thereto. Some of the above components may be removed or other layers may be added as needed.

[0056] The conductor (110) is a component that serves as a path through which current flows. It can be said that the conductive path is formed along the extension direction of the conductor (110). The conductor (110) can be manufactured from a material with excellent conductivity and strength and flexibility suitable for cable manufacturing and use. The conductor (110) can be manufactured from, for example, copper (Cu) or aluminum (Al).

[0057] The conductor (110), as illustrated in this drawing, has a flat wire layer composed of a circular central wire and flat wires stranded to surround the circular central wire. The conductor (110) may be a flat conductor having an overall circular cross-section. The flat conductor has a higher space factor than a circular compressed conductor, thereby providing an advantage of reducing the outer diameter of the cable. The circular compressed conductor is obtained by stranding a plurality of circular wires and compressing them into a circular shape, and may be used as the conductor (110) in place of the flat conductor (see FIG. 7).

[0058] The conductor (110) has an uneven surface, so the electric field formed thereon may be uneven, and corona discharge may easily occur partially. If a gap is created between the surface of the conductor (110) and the insulating layer (130) described below, the insulating performance may deteriorate.

[0059] To address this issue, the conductor (110) may be surrounded by an internal semiconducting layer (120). The internal semiconducting layer (120) has a semiconducting property by adding conductive particles to an insulating material. As the conductive particles, for example, carbon black, carbon nanotubes, carbon nanoplates, graphite, etc. may be used.

[0060] The inner semiconducting layer (120) prevents a sudden change in electric field between the conductor (110) and the insulating layer (130) by suppressing the formation of a gap between the conductor (110) and the insulating layer (130), thereby stabilizing the insulating performance of the insulating layer (130). The inner semiconducting layer (120) also suppresses the uneven charge distribution of the conductor (110), thereby uniformizing the electric field, and prevents the formation of a gap between the conductor (110) and the insulating layer (130), thereby suppressing corona discharge, insulation breakdown, etc.

[0061] The insulating layer (130) is provided on the outside of the inner semiconducting layer (120) and is configured to electrically insulate the conductor (110) from the outside. In general, the insulating layer (130) must have a high breakdown voltage and must be able to maintain its insulating performance stably for a long period of time. The insulating layer (130) must also have a low dielectric loss and have heat resistance performance such as heat resistance. In consideration of these, a polyolefin resin such as polyethylene and polypropylene may be used as the insulating layer (130). The polyethylene resin may be formed of a crosslinked paper.

[0062] An external semiconducting layer (140) may be provided on the outside of the insulating layer (130). The external semiconducting layer (140) is formed of a semiconducting material, like the internal semiconducting layer (120). The external semiconducting layer (140) stabilizes the insulating performance of the insulating layer (130) by suppressing uneven charge distribution between the insulating layer (130) and the metal shielding layer (150) described below. In addition, the external semiconducting layer (140) may smooth the surface of the insulating layer (130) in the cable to alleviate electric field concentration, thereby preventing corona discharge, and may also perform the function of physically protecting the insulating layer (130).

[0063] The power unit (100) may additionally include a moisture absorbing portion (not shown) to prevent moisture from penetrating into the cable. The moisture absorbing portion may be positioned between the wires constituting the conductor (110) and / or on the outside of the conductor (110). The moisture absorbing portion may be made of a material that rapidly absorbs moisture penetrating into the cable and has an excellent ability to maintain the absorbed state. For example, a powder, tape, coating layer, or film containing a super absorbent polymer (SAP) may be used as the material. The moisture absorbing portion may serve to prevent moisture from penetrating in the longitudinal direction of the cable. The moisture absorbing portion may also have semiconductivity to prevent a sudden change in the electric field.

[0064] A metal shielding layer (150) may be provided on the outside of the outer semiconducting layer (140). The metal shielding layer (150) can protect the conductor (110), the inner semiconducting layer (120), the insulating layer (130), and the outer semiconducting layer (140) (hereinafter referred to as “center layers”) from various environmental factors such as moisture intrusion, mechanical trauma, corrosion, and fault currents that may affect the power transmission performance of the cable. The metal shielding layer (150) is grounded at the end of the cable and serves as a path for the fault current to flow in the event of an accident such as a ground fault or short circuit, and can protect the cable from external impact and shield the electric field from being discharged to the outside of the cable.

[0065] In the case of submarine cables, a metal shielding layer (150) may be formed to seal the core layers, thereby preventing foreign substances such as moisture from penetrating and deteriorating the insulation performance. For example, if a molten metal is extruded into the core layers to form a seamless, continuous outer surface, the water-proofing performance of the core layers may be improved. Lead or aluminum may be used as the metal. In the case of submarine cables, lead, which has excellent corrosion resistance against seawater, may be used. Additionally, a lead alloy with added metal elements may be used to improve mechanical properties.

[0066] A copper wire direct-insertion tape (not shown) or a moisture-absorbing layer (not shown) may be additionally provided between the metal shielding layer (150) and the outer semiconducting layer (140). The copper wire direct-insertion tape may be composed of copper wire and a non-woven tape, etc., and may facilitate electrical contact between the outer semiconducting layer (140) and the metal shielding layer (150). The moisture-absorbing layer (not shown) may be formed in the form of a powder, tape, coating layer, film, etc., including a super absorbent polymer (SAP) that rapidly absorbs moisture that has penetrated into the cable and has an excellent ability to maintain an absorbed state. The moisture-absorbing layer may prevent moisture from penetrating in the longitudinal direction of the cable. In order to prevent a rapid electric field change in the moisture-absorbing layer, the moisture-absorbing layer may include copper wire.

[0067] A polymer sheath (160) may be formed to surround the metal shielding layer (150). The polymer sheath (160) may be composed of a resin such as, for example, polyvinyl chloride (PVC), polyethylene, etc. The polymer sheath (160) may improve the corrosion resistance and water resistance of the submarine cable, and may perform the function of protecting the cable from mechanical trauma and other external environmental factors such as heat and ultraviolet rays.

[0068] A protection unit (500) is additionally provided to protect the power unit (100). The protection unit (500) protects the power unit (100) against harsh environments such as seawater, salt, and external forces (such as pressure or tensile force applied during installation) for cables installed across the seabed.

[0069] The protection unit (500) is formed to surround the power unit (100). The protection unit (500) is formed to extend along the length of the cable. The protection unit (500) may include a bedding layer (510), an armor layer (530), and an outermost layer (520). These layers (510 to 530) may be sequentially arranged in a radial direction from the center of the protection unit (500). In this embodiment, the protection unit (500) is described as having three components (layers), but the present invention is not limited thereto. Some of the above components may be removed or other layers may be added as needed.

[0070] The bedding layer (510) may be formed by transversely winding a non-woven tape on the outer surface of the power unit (100). The outer surface of the cable is occupied by the outermost layer (520). The outermost layer (520) may be composed of a polymer material or may have substantially the same composition as the bedding layer (510). An armor layer (530) may be arranged between the bedding layer (510) and the outermost layer (520), specifically, on the outside of the bedding layer (510). The armor layer (530) improves the tensile strength relative to the weight of the submarine cable (1000). By virtue of this armor layer (530), the submarine cable (1000) may not be damaged or broken by its own weight during installation in the deep sea. Another layer may be added between the bedding layer (510) and the armor layer (530). Even in that case, the armor layer (530) is located outside the bedding layer (510).

[0071] The armor layer (530) may be formed by armor wires being wound transversely on the outside of the bedding layer (510). A plurality of armor wires may be employed.

[0072] The specific configuration of the above armor wire is described with reference to FIGS. 2 to 5.

[0073] Figure 2 is a front view showing the armor wire of Figure 1.

[0074] Referring to this drawing, the armor wire (550) is formed of a fiber material, not a metal material. Specifically, the armor wire (550) may be a fiber assembly in which two types of fibers (551 and 545) are combined. Here, the fibers may be a plurality of filaments combined to have a constant denier. The second fiber (555) may be arranged on the outside of the first fiber (551), and accordingly, the first fiber (551) may be arranged on the inside of the second fiber (555). Due to this arrangement, the first fiber (551) may form a core portion (553), and the second fiber (555) may form a cover portion (557) that surrounds the core portion (553).

[0075] If the first fiber (551) extends in the longitudinal direction in the core portion (553), the second fiber (555) forming the cover portion (557) can be transversely wound with respect to the core portion (553). The second fiber (555) can be transversely wound at a pitch angle of 3° or more. If the pitch angle is less than 3°, the cover portion (557) may not have enough force to hold the core portion (553).

[0076] The first fiber (551) may be provided as one or more. When the first fiber (551) is provided as multiple, the tensile strength of the core portion (553) can be improved. The plurality of first fibers (551) can be linearly spun. The linear spun refers to a case where the plurality of fibers are spun so that they are substantially parallel to each other. The linear spun may be, for example, a case where the pitch angle between the plurality of fibers is less than 3°. When the pitch angle is 3° or more, the plurality of first fibers (551) are in a twisted form and can be unwound by a tensile force applied in the longitudinal direction. Spinning refers to combining and twisting two fiber strands to form a new single strand. When the first fiber (551) is unwound, the core portion (553) and further the armor wire (550) may be stretched, which may cause a problem in which a greater tensile force is applied to the conductor (110). The plurality of first fibers (551) may be referred to as a first fiber bundle.

[0077] As the plurality of first fibers (551) are straightly braided, when the length of the armor wire is L and the length of the first fiber constituting the first fiber bundle is Lo, the following relationship can be satisfied.

[0078] 1 ≤ Lo / L ≤ 1.01

[0079] Meanwhile, in terms of material, the first fiber (551) can be made of a synthetic resin that is lightweight but has high tensile strength. For example, the first fiber (551) can be a synthetic fiber made of aramid and / or ultra-high-molecular-weight polyethylene (UHMWPE). Aramid is a general term for aromatic polyamide fibers, as opposed to aliphatic polyamide (nylon), and is heat-resistant and strong. Aramid is a fiber that is heat-resistant and chemical-resistant, not combustible even at 500℃, and is called a "super fiber" because it is the strongest fiber. A piece of aramid cut to a size of 1㎟ (approximately 1.6mm in diameter) can lift a weight of 350kg. Currently, it is being produced by DuPont (Kevlar) in the US, Teijin (Twaron) in Japan, and Kolon (Heracron) in Korea. UHMWPE is a special PE product with a molecular weight of over one million. It has excellent mechanical properties due to its ultra-high molecular weight.

[0080] The second fiber (555) may be a synthetic fiber made of, for example, one of PET (polyethylene terephthalate), glass fiber, and carbon fiber in addition to aramid and UHMWPE. The second fiber (555) may be made of the same material as the first fiber (551), or may be made of a different material. Since the tensile force applied to the fiber assembly is mainly borne by the core portion (553), the cover portion (557) may have a tensile strength equal to or lower than that of the core portion (553).

[0081] In order to increase the tensile strength of the armor wire (550) while making it compact, the first fiber (551) may be pulled in the longitudinal direction. Specifically, the second fiber (555) may be transversely wound about the first fiber (551) while the first fiber (551) is pulled in the longitudinal direction. The second fiber (555) may also be transversely wound while being pulled in the longitudinal direction to compress the first fiber (551). By this configuration of the armor wire (550), the armor wire (550) may have a space factor of 80% or more. The armor wire (550) has a tensile strength relative to its weight better than that of metal, and also has a low degree of elongation along its longitudinal direction when subjected to an external force.

[0082] Figure 3 is a cross-sectional view of the armor wire of Figure 2.

[0083] Referring to this drawing, for a core portion (553) formed by a first fiber (551), a cover portion (557) formed by a second fiber (555) can be arranged along the circumferential direction of the core portion (553).

[0084] The diameter (D2) of the cover portion (557) may be significantly smaller than the diameter (D1) of the core portion (553). D2 is the diameter of the second fiber (555) or the thickness of the cover portion (557). For example, D1 may be 40 to 80 times larger than D2.

[0085] If D2 is less than 1 / 80 of D1, the cover part (557) may not have enough power to protect or pressurize the core part (553). If D2 exceeds 1 / 40 of D1, the cover part (557) may become unnecessarily large, which may hinder the weight reduction and compactness of the armor wire (550).

[0086] Fig. 4 is a cross-sectional view showing an armor wire according to a modified example of the armor wire of Fig. 3.

[0087] Referring to this drawing, the armor wire (550a) is generally the same as the armor wire (550, see FIG. 3) of the previous embodiment, but there is a difference in the second fiber (555a).

[0088] The second fiber (555a) may be provided in multiple pieces. The plurality of second fibers (555a) may be spun. The spun plurality of second fibers (555a) allow the cover portion (557a) to maintain a more stable shape. Such a cover portion (557a) may protect or compress the core portion (553a) with strong force. The plurality of second fibers (555a) may be referred to as a second fiber bundle.

[0089] The relationship in which D1 is 40 to 80 times that of D2 in the previous embodiment can also be satisfied in this embodiment. As the second fiber bundle is employed, D1 can have a value close to 40 times that of D2. Conversely, if the second fiber (555a) is made thinner (having a lower denier) than the second fiber (555, see FIG. 3) in the previous embodiment, D1 can have a value close to 80 times that of D2.

[0090] FIG. 5 is a front view showing an armor wire according to another modified example of the armor wire of FIG. 2.

[0091] Referring to this drawing, the second fiber (555b) of the armor wire (550b) may have a second-first fiber (556) and a second-second fiber (557) that are wound in different directions, unlike the previous embodiment.

[0092] If the 2-1 fiber (556) is wound transversely along the first direction with respect to the core portion (first cover portion), the 2-2 fiber (557) may be wound transversely along the second direction (second cover portion). Here, the first direction and the second direction may be opposite to each other.

[0093] As the second-first fiber (556) and the second-second fiber (557) are wound in opposite directions, the cover portion can more firmly maintain its shape. If necessary, each of the second-first fiber (556) and the second-second fiber (557) may be wound in multiple layers.

[0094] In an alternative embodiment, the first direction and the second direction may be the same, but the pitch angles of the 2-1 fiber (556) and the 2-2 fiber (557) may be different.

[0095] Fig. 6 is a cross-sectional view showing the configuration of a lightweight submarine cable according to a modified example of the lightweight submarine cable of Fig. 1.

[0096] Referring to this drawing, the lightweight submarine cable (1000') is generally the same as the lightweight submarine cable (1000) of the previous embodiment, but differs in the armor layer (530').

[0097] The armor layer (530') may have a first armor layer (531') and a second armor layer (535'). If the first armor layer (531') is disposed close to the bedding layer (510), the second armor layer (535') may be disposed close to the outermost layer (520). An intermediate layer (539') may be additionally disposed between the first armor layer (531') and the second armor layer (535'). The intermediate layer (539') may be, for example, a non-woven tape wound horizontally with respect to the first armor layer (531'). The intermediate layer (539') fixes the first armor layer (531') and allows the second armor layer (535') to be firmly bonded to the first armor layer (531').

[0098] Each of the first armor layer (531') and the second armor layer (535') can be formed by the fiber assembly. In the first armor layer (531') and the second armor layer (535'), the fiber assembly can be transversely wound along opposite directions.

[0099] According to this configuration, the tensile strength of the armor layer (530') can be significantly improved compared to the previous embodiment. This release cable (1000') can be more suitable for installation in deep water.

[0100] Fig. 7 is a cross-sectional view showing the configuration of a lightweight submarine cable according to another embodiment of the present invention.

[0101] Referring to this drawing, the lightweight submarine cable (1000”) is generally the same as the preceding lightweight submarine cable (1000), but differs mainly in that it is a three-phase (AC) cable equipped with three power units (100).

[0102] The power unit (100) is generally the same as in the previous embodiment. The submarine cable (1000") may further include an optical unit (200) as needed. In that case, the submarine cable (1000") may be a composite cable in which power and information transmission occur simultaneously.

[0103] The optical unit (200) may include at least one optical fiber (211) and a tube (215) that accommodates the optical fiber (211). The optical unit (200) may include a predetermined number of optical fibers (211) mounted together with a filler inside the tube (215). The tube (215) may be made of a rigid material such as stainless steel. The optical unit (200) may further include a sheath (230) that surrounds the tube (215).

[0104] Meanwhile, while this drawing illustrates an example of a single protective tube within a single sheath, the present invention is not limited thereto. For example, a single sheath may include multiple tubes, with at least one optical fiber positioned within each protective tube. In this case, the optical fibers and tubes may be connected and then wrapped in an outer sheath.

[0105] In addition to the power unit (100) and the optical unit (200), a shaped filler (300) may be additionally provided. The shaped filler (300) is positioned in relation to the power unit (100) and the optical unit (200) to maintain the circularity of the submarine cable (1000). The shaped filler (300) may also distribute the force acting on the cable, thereby preventing damage or breakage of the power unit (100) and the optical unit (200) of the cable.

[0106] The interposition (300) can be specifically placed between the power unit (100) and the protection unit (400) described later. The interposition (300) can accommodate the optical unit (200) and protect the optical unit (200) from external forces applied during installation, etc.

[0107] The protection unit (400) may have a bedding layer (410) that surrounds the power unit (100) and the intervening material (300) {and the optical unit (200)}. The bedding layer (410) may be composed of polypropylene (PP) fibers, etc. In order to protect the power unit (100) and the optical unit (200), a filler (not shown) may be additionally provided between the power unit (100) and the optical unit (200) and the bedding layer (410). The outer surface of the cable is occupied by the outermost layer (420). The outermost layer (420) may be composed of a polymer material or may have substantially the same configuration as the bedding layer (410).

[0108] An armor layer (430) is provided between the bedding layer (410) and the outermost layer (420). The armor layer (430) may have the same configuration as the armor layer (530, 530') in the previous embodiment.

[0109]

[0110] The present invention has industrial applicability in the field of manufacturing lightweight submarine cables.

Claims

1. Comprising at least one power unit and a protection unit surrounding the at least one power unit, The above power unit comprises a conductor, an inner semiconducting layer surrounding the conductor, an insulating layer surrounding the inner semiconducting layer, an outer semiconducting layer surrounding the insulating layer, and a metal shielding layer surrounding the outer semiconducting layer. The above protection unit comprises a bedding layer surrounding the at least one power unit, an armor layer surrounding the bedding layer, and an outermost layer surrounding the armor layer, The above armor layer comprises a plurality of armor wires that are wound transversely outside the bedding layer, A lightweight submarine cable, wherein the armor wire comprises a core portion having a bundle of first fibers and a cover portion having second fibers wound transversely around the core portion.

2. In paragraph 1, A lightweight submarine cable that satisfies the following relationship, where the length of the armor wire is L and the length of the first fiber constituting the first fiber bundle is Lo. 1 ≤ Lo / L ≤ 1.01 3. In paragraph 1, A lightweight submarine cable, wherein the bundle of the first fiber is a straight braiding of a plurality of first fibers.

4. In paragraph 1, The above armor wire is a lightweight submarine cable in which the second fiber is wound transversely while the bundle of the first fiber is pulled longitudinally.

5. In paragraph 1, A lightweight submarine cable in which the second fiber is wound transversely while being pulled in the longitudinal direction.

6. In paragraph 1, A lightweight submarine cable, wherein the above armor wire has a fill factor of 80% or more.

7. In paragraph 1, A lightweight submarine cable, wherein the second fiber is wound transversely relative to the first fiber at a pitch angle of 3° or greater.

8. In paragraph 1, The above second fibers are provided in a bundle, A lightweight submarine cable, wherein the bundle of the second fibers is made up of a plurality of second fibers.

9. In paragraph 1, The above second fiber includes a second-1 fiber and a second-2 fiber, A lightweight submarine cable, wherein the cover part comprises a first cover part in which the 2-1 fiber is wound transversely along a first direction relative to the core part, and a second cover part in which the 2-2 fiber is wound transversely along a second direction relative to the core part.

10. In paragraph 1, A lightweight submarine cable, wherein the first fiber is formed of at least one of aramid and UHMWPE.

11. In paragraph 1, A lightweight submarine cable, wherein the second fiber is formed of at least one of aramid, UHMWPE, PET, glass fiber, and carbon fiber.

12. In paragraph 1, A lightweight submarine cable, wherein the diameter of the core portion is 40 to 80 times the diameter of the cover portion.

13. In paragraph 1, A lightweight submarine cable, wherein the first fiber and the second fiber are fibers of the same type.

14. In paragraph 1, A lightweight submarine cable, wherein the power unit further comprises a polymer sheath surrounding the metal shielding layer.

15. As an armor wire for wrapping the power unit of a submarine cable to form an armor layer, A core portion having a bundle of first fibers; and An armor wire for a submarine cable, comprising a cover portion having a second fiber wound transversely around the core portion.

16. In paragraph 15, An armor wire for a submarine cable, wherein the second fiber is wound transversely with respect to the first fiber bundle while the bundle of the first fibers is pulled longitudinally.

17. In paragraph 15, An armor wire for a submarine cable, wherein the bundle of the first fibers is a straight braiding of a plurality of first fibers.

18. In paragraph 15, The above second fibers are provided in a bundle, An armor wire for a submarine cable, wherein the bundle of the second fibers is made up of a plurality of second fibers.

19. In paragraph 15, The above second fibers are provided in a bundle, The above second fiber bundle includes a second-1 fiber bundle and a second-2 fiber bundle, An armor wire for a submarine cable, wherein the cover portion includes a first cover portion in which the 2-1 fiber bundle is transversely wound along a first direction relative to the core portion, and a second cover portion in which the 2-2 fiber bundle is transversely wound along a second direction relative to the core portion.

20. Comprising at least one power unit and a protection unit surrounding the at least one power unit, The above power unit comprises a conductor, an inner semiconducting layer surrounding the conductor, an insulating layer surrounding the inner semiconducting layer, an outer semiconducting layer surrounding the insulating layer, and a metal shielding layer surrounding the outer semiconducting layer. The above protection unit comprises a bedding layer surrounding the at least one power unit, an armor layer surrounding the bedding layer, and an outermost layer surrounding the armor layer, The above armor layer comprises a plurality of armor wires that are wound transversely outside the bedding layer, The above armor wire comprises a fiber assembly comprising a first fiber and a second fiber, A lightweight submarine cable, wherein the second fiber is wound transversely about the first fiber so as to compress the first fiber.

21. In paragraph 20, A lightweight submarine cable that satisfies the following relationship, where the length of the armor wire is L and the length of the first fiber constituting the first fiber bundle is Lo. 1 ≤ Lo / L ≤ 1.01 22. In paragraph 20, A lightweight submarine cable, wherein the armor wire is wound transversely while the first fiber is pulled longitudinally and the second fiber is pulled longitudinally relative to the first fiber.

23. In paragraph 20, A lightweight submarine cable, wherein the second fiber is wound transversely relative to the first fiber at a pitch angle of 3° or greater.

24. In paragraph 20, A lightweight submarine cable, wherein the first fiber and the second fiber are fibers of the same type.

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