Lightweight submarine cable, armor wire used therefor, and method for manufacturing armor wire

Abstract

A lightweight submarine cable, an armor wire used therefor, and a method for manufacturing the armor wire are disclosed. The armor wire may wrap a power unit to form an armor layer. The armor wire may include a core portion and a cover portion. The core portion may have a bundle of first fibers. The cover portion may have second fibers wrapping the core portion by one of weaving or braiding methods.

Description

Lightweight submarine cable, armor wire used therein, and method of manufacturing armor wire

[0001] The present disclosure relates to a cable laid on the seabed, an armor wire used therein, and a method for manufacturing the armor wire.

[0002]

[0003] A submarine cable is a cable laid underwater to transmit power between two points separated by the sea, for example, between continents or between land and an island.

[0004] When submarine cables are laid in oceans reaching depths of thousands of meters, they are exposed to significant tensile forces. This tensile force is exerted on the cable by its own weight as it hangs vertically.

[0005] Generally, submarine cables utilize steel wire armor to prevent damage or breakage from various underwater environments. However, since steel wire armor contributes significantly to the overall weight increase of the submarine cable, it presented a challenge in applying this to the recent technological trend of manufacturing larger and longer cables for deployment in deep water.

[0006] Accordingly, there is a need for a submarine cable equipped with a new armor that can sufficiently protect the cable from various external forces occurring in the underwater environment and tensile forces caused by the weight of the cable itself, while simultaneously being lightweight to reduce the tensile force applied to the cable.

[0007] The aforementioned background technology is technical information that the inventor possessed or acquired during the process of deriving the embodiments of the present disclosure, and it cannot be considered as prior art disclosed to the general public prior to the filing of this application.

[0008]

[0009] One objective of the present disclosure is to provide a lightweight submarine cable having a new concept of lightweight armor that departs from the concept of conventional steel wire armor, an armor wire used therein, and a method for manufacturing the armor wire.

[0010] Another objective of the present disclosure is to provide a lightweight submarine cable having an armor layer with an improved ratio of tensile strength to weight compared to steel wire armor, an armor wire used therein, and a method for manufacturing the armor wire.

[0011]

[0012] A lightweight submarine cable according to one aspect of the present disclosure for realizing the above-mentioned problem comprises at least one power unit and a protection unit surrounding the at least one power unit, wherein the 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, wherein the 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, wherein the armor layer comprises a plurality of armor wires wound transversely outside the bedding layer, and the armor wire may comprise a core portion having a bundle of a first fiber and a cover portion having a second fiber that wraps the core portion in one of weaving and braiding.

[0013] Here, let L be the length of the armor wire and Lo be the average length of the first fiber constituting the first fiber bundle of the armor wire, and the following relationship can be satisfied: 1 ≤ Lo / L ≤ 1.01

[0014] Here, the bundle of the first fiber may be a plurality of first fibers straightly plied together.

[0015] The above armor wire may be such that the second fiber wraps around the bundle of the first fiber while the bundle of the first fiber is pulled in the longitudinal direction.

[0016] Here, the second fiber comprises a plurality of braided yarns, and the plurality of braided yarns can be braided with respect to the core portion while being pulled in the longitudinal direction to form the cover portion.

[0017] Here, the armor wire may have a packing rate of 80% or more.

[0018] Here, the core portion may have a cross-sectional shape of either a circle or a square, and the cover portion may form a tube having a cross-section of either a circle or a square corresponding to the cross-sectional shape of the core portion.

[0019] Here, the bundle of the first fiber may be twisted.

[0020] Here, the core portion includes a central group and a peripheral group, each of the central group and the peripheral group is composed of a plurality of first fibers, the peripheral group is provided in a plurality, and the plurality of peripheral groups may be arranged to surround the outer surface of the central group.

[0021] Here, the first fiber may be formed of at least one of aramid and UHMWPE.

[0022] Here, the second fiber may be formed from at least one of aramid, UHMWPE, PET, glass fiber, and carbon fiber.

[0023] Here, the first fiber and the second fiber may be fibers of the same type.

[0024] Here, the power unit may additionally include a polymer sheath surrounding the metal shielding layer.

[0025] A lightweight submarine cable according to another aspect of the present disclosure comprises at least one power unit and a protection unit surrounding the at least one power unit, wherein the 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, wherein the 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, wherein the armor layer comprises a plurality of armor wires transversely wound outside the bedding layer, and the specific strength of the armor wires may be 120 N·m / g or more.

[0026] Here, let L be the length of the armor wire and Lo be the average length of the first fiber constituting the first fiber bundle, and the following relationship can be satisfied: 1 ≤ Lo / L ≤ 1.01

[0027] An armor wire according to another aspect of the present disclosure may comprise a core portion having a bundle of first fibers, and a cover portion having second fibers that wrap the core portion in one of weaving and braiding, as an armor wire for wrapping a power unit of a submarine cable to form an armor layer.

[0028] Here, the specific strength of the armor wire may be 120 N·m / g or more.

[0029] Here, the bundle of the first fiber may be a plurality of first fibers straightly plied together.

[0030] Here, the second fiber comprises a plurality of braided yarns, and the plurality of braided yarns may be braided with respect to the core portion while being pulled in the longitudinal direction to form the cover portion.

[0031] Here, the core portion includes a central group and a plurality of peripheral groups, each of the central group and the peripheral group is composed of a plurality of first fibers, and the plurality of peripheral groups may be arranged to surround the central group.

[0032] A method for manufacturing an armor wire for a submarine cable according to yet another aspect of the present disclosure may include the step of pulling a bundle of first fibers in a longitudinal direction; and the step of braiding a second fiber to wrap around the bundle of first fibers pulled in a longitudinal direction.

[0033] Here, the method may further include the step of compressing the braided second fiber so that the armor wire has a square cross-section.

[0034]

[0035] According to the lightweight submarine cable configured as described above, the armor wire used therein, and the method for manufacturing the armor wire according to the present disclosure, the fiber armor layer can have a higher ratio of tensile strength to weight than the steel wire armor, so the lightweight submarine cable can be laid stably and easily even in deep seas 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 disclosure.

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

[0039] FIG. 3 is a perspective view showing an armor wire according to one variation of the armor wire of FIG. 2.

[0040] FIG. 4 is a perspective view showing an armor wire according to another variation of the armor wire of FIG. 2.

[0041] FIG. 5 is a cross-sectional view showing the configuration of a lightweight submarine cable according to one modified example of the lightweight submarine cable of FIG. 1.

[0042] FIG. 6 is a cross-sectional view showing the configuration of a lightweight submarine cable according to another embodiment of the present disclosure.

[0043]

[0044] Hereinafter, the present disclosure is described in detail with reference to the accompanying drawings for preferred embodiments.

[0045] The present disclosure is not limited to the embodiments disclosed below, but may be modified and implemented in various different forms. The embodiments provided are merely intended to make the present disclosure complete and to fully inform those skilled in the art of the scope of the disclosure. Accordingly, the present disclosure should be understood not to be limited to the embodiments presented below, but to include all modifications, equivalents, and substitutions that fall within the technical spirit and scope of the present disclosure, as well as substituting or adding the configuration of any one embodiment with the configuration of another embodiment.

[0046] The attached drawings are intended only to facilitate understanding of the embodiments disclosed in this specification. The technical concept of this disclosure is not limited by the attached drawings and should be understood to include all modifications, equivalents, and substitutions that fall within the concept and technical scope of this disclosure. In the drawings, the size or thickness of components may be exaggerated for the sake of ease of understanding, but this should not be interpreted as limiting the scope of protection of this disclosure.

[0047] The terms used in this specification are used merely to describe specific embodiments or examples and are not intended to limit the disclosure. Furthermore, singular expressions include plural expressions unless the context clearly indicates otherwise. Terms such as “comprise,” “include,” “have,” “contain,” and other variations thereof in this specification are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in this specification. That is, terms such as “comprise,” “include,” “have,” “contain,” and other variations thereof in this specification should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0048] Terms including ordinal numbers, such as first, second, etc., may be used to describe various elements, but said elements are not limited by said terms. These terms are used solely for the purpose of distinguishing one element from another.

[0049] When it is stated that one component is "connected / communicated" or "connected" to another component, it should be understood that while it may be directly connected / communicated or connected to that other component, there may also be other components in between. On the other hand, when it is stated that one component is "directly connected / communicated" or "directly connected" to another component, it should be understood that there are no other components in between.

[0050] 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 the other component, but that another component may also exist in between.

[0051] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which this disclosure pertains.

[0052] FIG. 1 is a cross-sectional view showing the configuration of a lightweight submarine cable according to one embodiment of the present disclosure.

[0053] Referring to the drawing, the submarine cable (1000) has a power unit (100) that forms a conductive path through which current flows. In this embodiment, a single-phase cable is exemplified in which the power unit (100) is provided as one.

[0054] The power unit (100) may comprise 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 arranged sequentially along the 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 disclosure is not limited thereto. Some of the above components may be removed or other layers may be added as needed.

[0055] The conductor (110) is a component that serves as a passage for current flow. It can be said that the conductive path is formed along the extension direction of the conductor (110). The conductor (110) can be made of a material that has excellent conductivity and possesses strength and flexibility suitable for cable manufacturing and use. The conductor (110) can be made of, for example, copper (Cu) or aluminum (Al).

[0056] The conductor (110) may have a flat wire layer composed of a circular central wire (110a) and a flat wire (110b) that is wired to wrap around the circular central wire, as illustrated in the drawing. The conductor (110) may be a flat conductor in which the central wire (110a) and the flat wire (110b) are arranged to have a circular cross-section overall.

[0057] The above-mentioned flat conductor has a higher space factor compared to the circular compressed conductor, which provides the advantage of being able to reduce the outer diameter of the cable. The above-mentioned circular compressed conductor is formed by twisting multiple circular wires together and compressing them into a circle, and may be used as a conductor (110) in place of the above-mentioned flat conductor.

[0058] The surface of the conductor (110) is not smooth, so the electric field formed when current is applied may be uneven, and corona discharge is likely to occur in some areas. In addition, if a gap is formed between the surface of the conductor (110) and the insulating layer (130) described later, the insulation performance may be degraded.

[0059] To solve this problem, the conductor (110) may be wrapped by an inner semiconducting layer (120). The inner semiconducting layer (120) has semiconducting properties by adding conductive particles to an insulating material. Examples of the conductive particles may be carbon black, carbon nanotubes, carbon nanoplates, graphite, etc.

[0060] The inner semiconducting layer (120) stabilizes the insulation performance of the insulation layer (130) by suppressing corona discharge, insulation breakdown, etc., by suppressing the uneven charge distribution of the conductor (110) and preventing the formation of a gap between the conductor (110) and the insulation layer (130), thereby preventing sudden changes in the electric field between the conductor (110) and the insulation layer (130).

[0061] The insulating layer (130) is provided on the outside of the inner semiconducting layer (120) to electrically insulate the conductor (110) from external components. Generally, the insulating layer (130) must have a high breakdown voltage and be able to maintain its insulating performance stably for a long period. The insulating layer (130) must also have low dielectric loss and possess thermal resistance performance such as heat resistance. In this regard, polyolefin resins such as polyethylene and polypropylene may be used as the insulating layer (130), and preferably, the polyethylene resin may be made of a crosslinked resin.

[0062] An outer semiconducting layer (140) may be provided on the outside of the insulating layer (130). The outer semiconducting layer (140) may be formed of a semiconducting material, similar to the inner semiconducting layer (120). The outer semiconducting layer (140) stabilizes the insulation performance of the insulating layer (130) by suppressing the non-uniform charge distribution between the insulating layer (130) and the metal shielding layer (150) described later. Additionally, the outer semiconducting layer (140) can smooth the surface of the insulating layer (130) in the cable to mitigate electric field concentration and prevent corona discharge, and can also perform the function of physically protecting the insulating layer (130).

[0063] The power unit (100) may additionally be provided with a moisture absorbent part (not shown) to prevent moisture from penetrating into the cable. The moisture absorbent part may be placed between the wires constituting the conductor (110) and / or outside the conductor (110). The moisture absorbent part may be made of a material that has a fast rate of absorbing moisture penetrating into the cable and excellent ability to maintain the absorbed state. For example, the material may be a powder, tape, coating layer, or film containing a super absorbent polymer (SAP). The moisture absorbent part may serve to prevent moisture from penetrating along the length of the cable. The moisture absorbent part may also have semiconductivity to prevent sudden changes 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 "core layers") from various environmental factors such as moisture penetration, mechanical trauma, and corrosion, as well as fault currents, which 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 passage for the fault current to flow in the event of an accident such as a ground fault or short circuit, protects the cable from external impacts, and shields the electric field so that it is not discharged outside the cable.

[0065] In the case of a submarine cable, a metal shielding layer (150) is formed to seal the core layers to prevent foreign substances, such as moisture, from entering and degrading the insulation performance. For example, molten metal can be extruded onto the core layers to form a seamless, continuous outer surface, thereby improving the water-blocking performance of the core layers. Lead or aluminum, among others, may be used as the metal. In the case of a submarine cable, lead, which has excellent corrosion resistance to seawater, may be used. Additionally, a lead alloy with added metal elements may be used to supplement mechanical properties.

[0066] A copper wire insertion tape (not shown) or a moisture absorption layer (not shown) may be additionally provided between the metal shielding layer (150) and the outer semiconducting layer (140). The copper wire insertion tape may be composed of copper wire and non-woven tape, etc., to facilitate electrical contact between the outer semiconducting layer (140) and the metal shielding layer (150). The moisture absorption layer (not shown) may be formed in the form of a powder, tape, coating layer, or film containing a super absorbent polymer (SAP) that has a fast rate of absorbing moisture penetrating the cable and excellent ability to maintain the absorbed state. The moisture absorption layer may prevent moisture from penetrating along the length of the cable. To prevent a sudden change in the electric field in the moisture absorption layer, the moisture absorption layer may include copper wire.

[0067] A polymer sheath (160) can be formed to surround a metal shielding layer (150). The polymer sheath (160) can be composed of a resin such as polyvinyl chloride (PVC), polyethylene, etc. The polymer sheath (160) can improve the corrosion resistance and water resistance of the submarine cable and 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 for the protection of the power unit (100). The protection unit (500) protects the power unit (100) against harsh environments such as seawater, salt, and external forces (external impact, pressure, or tensile force acting during installation) for cables installed on the seabed.

[0069] A protection unit (500) is formed to surround a power unit (100). The protection unit (500) is formed to extend along the longitudinal direction of the cable. The protection unit (500) may include a bedding layer (510), an armor layer (530), and an outermost layer (520). These (510 to 530) may be arranged sequentially along the 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 disclosure 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 winding a non-woven tape transversely over 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 a composition generally identical to that of the bedding layer (510).

[0071] An armor layer (530) may be placed between the bedding layer (510) and the outermost layer (520), specifically outside the bedding layer (510). The armor layer (530) is a component that protects the submarine cable (1000) and improves tensile strength, so that the submarine cable (1000) is not damaged or broken by external impact or its own weight when laid in deep sea.

[0072] 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).

[0073] The armor layer (530) may be formed by an armor wire (550) being wound transversely on the outside of the bedding layer (510), and multiple armor wires (550) may be employed.

[0074] The specific configuration of the armor wire (550) will be explained with reference to FIGS. 2 to 5.

[0075] Figure 2 is a perspective view showing the armor wire of Figure 1.

[0076] Referring to the drawing, the armor wire (550) is formed of a fiber material rather than a metal material and may be a fiber assembly composed of multiple fibers. Here, the fiber may be formed by combining multiple filaments to have a constant denier.

[0077] As an example of an armor wire (550), a second fiber (555) may be positioned on the outside of a first fiber (551). Due to this positioning relationship, 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).

[0078] If the first fiber (551) extends in the longitudinal direction in the core portion (553), the second fiber (555) forming the cover portion (557) may be a braided material that wraps around the core portion (553). The braided material is formed by braiding a plurality of braiding fibers. The braiding fiber may be the second fiber (555).

[0079] The first fiber (551) may be provided as one or multiple fibers. When the first fiber (551) is provided as multiple fibers, the tensile strength of the core portion (553) may be improved. Multiple first fibers (551) may be straight-plyed. The straight-plying refers to the case where multiple fibers are plied so that they are nearly parallel to each other.

[0080] The above straight braided yarn may, for example, be a case where the pitch angle between multiple fibers is less than 3°. If the pitch angle is 3° or more, the twist of multiple first fibers (551) may be untwisted by the tensile force applied in the longitudinal direction of the cable. At this time, until the twist of multiple first fibers (551) is untwisted, no force is applied to the core part (553) and further to the armor wire (550), and thus little force is applied, so a problem may occur in which the tensile force is concentrated on the conductor (110). The above multiple first fibers (551) may also be referred to as a first fiber bundle.

[0081] As a plurality of first fibers (551) are straight-copied, the following relationship can be satisfied when the length of the armor wire (550) is L and the average length of the first fibers (551) constituting the first fiber bundle is Lo.

[0082] 1 ≤ Lo / L ≤ 1.01

[0083] According to the relationship Lo / L ≤ 1.01, the problem of the tensile force being applied directly to the conductor (110) without being applied to the armor wire (550) can be minimized.

[0084] Specifically, a sample of armor wire (550) with a length of 10 m can be prepared, and after measuring the lengths of all the multiple first fibers (551) included in the sample and averaging them to calculate Lo, it can be applied to the above relationship.

[0085] In terms of material, the first fiber (551) can be made of a synthetic resin that is lightweight yet has high tensile strength. For example, the first fiber (551) may be a synthetic fiber made of aramid and / or UHMWPE (ultra-high-molecular-weight polyethylene). Aramid is a general term for aromatic polyamide fibers that are distinct from aliphatic polyamides (nylon), and it is strong and resistant to heat. Aramid is a fiber that possesses heat resistance that does not burn even at 500°C and strong chemical resistance to chemicals, and it is called a super fiber because it is the strongest among fibers. A piece of aramid cut to a size of 1 mm² (about 1.6 mm in diameter) can lift a weight of 350 kg. Currently, it is produced by DuPont (Kevlar) in the United States, Teijin (Twaron) in Japan, and Kolon (Heraclon) 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.

[0086] The second fiber (555) may be a synthetic fiber made of, for example, 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 differently. Since the tensile force applied to the fiber assembly is mainly borne by the core part (553), the cover part (557) may have a tensile strength equal to or lower than that of the core part (553). In order to increase the tensile strength of the armor wire (550) while keeping it compact, the first fiber (551) may be in a state where it is pulled in the longitudinal direction. Specifically, the second fiber (555) may be braided against the first fiber (551) while the first fiber (551) is pulled in the longitudinal direction. The second fiber (555) can also be braided while being pulled in the longitudinal direction to compress the first fiber (551). In this case, the degree of elongation along its longitudinal direction when subjected to external force can also be reduced. With this configuration of the armor wire (550), the armor wire (550) can have a space factor of 80% or more. Here, the space factor refers to the ratio of the area of ​​the effective portion to the area of ​​the defined space.

[0087] Additionally, the armor wire (550) may be made of a material with excellent tensile strength relative to weight, that is, a material with high specific strength, in order to increase tensile strength while being compact and lightweight. The specific strength of the armor wire (550) may be composed of a material having a value of 120 N·m / g or more, preferably 1000 N·m / g or more. If the armor wire (550) is composed of a material having a specific strength of less than 120 N·m / g, problems may arise in which the weight of the armor wire (550) increases excessively to satisfy the tensile strength required by the cable (1000), or a large number of armor wires (550) must be included or a thick armor layer (530) must be provided, thereby increasing the outer diameter and weight of the submarine cable (1000).

[0088] In an alternative embodiment, a plurality of first fibers (551) may be spun. The spinning process involves combining and twisting two or more fiber strands to form a new single strand. Through the spinning process, the bundle of first fibers (551) can withstand greater tensile force.

[0089] In an alternative embodiment, a plurality of second fibers (555) may be woven to wrap around the first fiber (551). While the first fiber (551) is pulled in the longitudinal direction, the second fiber (555) may also be woven while pulled along the longitudinal direction or wrap around the first fiber (551) while pulled in the woven state.

[0090] FIG. 3 is a perspective view showing an armor wire according to one variation of the armor wire of FIG. 2.

[0091] Referring to the drawing, the armor wire (550a) has a configuration generally identical to the armor wire (550, see FIG. 2) according to the preceding embodiment, but differs in that the core part (553a) and the cover part (557a) generally have a square cross-sectional shape.

[0092] The core portion (553a) may be formed by gathering a plurality of first fibers (551) to form a square cross-section, for example, a rectangular or trapezoidal cross-section. The bundles of the first fibers (551) may be straight-copied or twisted.

[0093] Corresponding to the core portion (553a), the cover portion (557a) may have a rectangular tubular shape. The cover portion (557a) may be woven or braided with respect to the core portion (553a) by the second fiber (555).

[0094] As the armor wire (550a) has a square cross-section, the armor wires (550a) that are transversely wound on the bedding layer (510, see FIG. 1) can be more closely attached to each other. Additionally, the thickness of the armor layer (530) can be reduced, so that the overall outer diameter of the submarine cable can also be reduced.

[0095] In the case of the armor wire (550a) having the above-mentioned square cross section, it can be manufactured by weaving or braiding a cover portion (557a) onto the core portion (553a) and then compressing it to have a square cross section. Alternatively, the core portion (553a) may be compressed first to have a square cross section, and then the cover portion (557a) may be braided in close contact with the outer surface of the core portion (553a).

[0096] FIG. 4 is a perspective view showing an armor wire according to another variation of the armor wire of FIG. 2.

[0097] Referring to the drawing, the core portion (553b) of the armor wire (550b) may differ from that of the preceding embodiments. Since the cover portion of the armor wire (550b) may be the same as that of the preceding embodiments, it is omitted from illustration and description.

[0098] The core portion (553b) may also have a plurality of first fibers (551). The plurality of first fibers (551) may be divided into a central group (554a) and a peripheral group (554b). The peripheral group (554b) is provided in multiple numbers; in this embodiment, six numbers are provided, but this is not limited thereto. Each of the central group (554a) and the peripheral group (554b) may be formed by twisting or straight-plying the plurality of first fibers (551).

[0099] With the central group (554a) positioned at the center, multiple peripheral groups (554b) may be arranged to surround the outer surface of the central group (554a). The multiple peripheral groups (554b) may be arranged in a straight line relative to the central group (554a), or may be wound horizontally or spun.

[0100] According to this configuration, the strength of the core part (553b) may be slightly lower than that of the straight braided yarn, but workability may be improved.

[0101] FIG. 5 is a cross-sectional view showing the configuration of a lightweight submarine cable according to one modified example of the lightweight submarine cable of FIG. 1.

[0102] Referring to the 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').

[0103] The armor layer (530') may have a first armor layer (531') and a second armor layer (535'). If the first armor layer (531') is positioned close to the bedding layer (510), the second armor layer (535') may be positioned close to the outermost layer (520). An intermediate layer (539') may be additionally positioned 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 transversely over the first armor layer (531'). The intermediate layer (539') secures the first armor layer (531') and allows the second armor layer (535') to be firmly bonded to the first armor layer (531').

[0104] 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 wound transversely along opposite directions.

[0105] 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') may be more suitable for laying in deep water.

[0106] FIG. 6 is a cross-sectional view showing the configuration of a lightweight submarine cable according to another embodiment of the present disclosure.

[0107] Referring to the drawing, the lightweight submarine cable (1000) is generally the same as the previous lightweight submarine cable (1000), but differs mainly in that it is a three-phase (AC) cable equipped with three power units (100).

[0108] The power unit (100) is largely the same as in the preceding embodiment. The submarine cable (1000) may further be equipped with 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.

[0109] The optical unit (200) may have at least one optical fiber (211) and a tube (215) that accommodates the optical fiber (211). The optical unit (200) may have a predetermined number of optical fibers (211) mounted together with a filler material within the tube (215). The tube (215) may be made of a rigid material such as stainless steel. The optical unit (200) may further have a sheath (230) that surrounds the tube (215).

[0110] Meanwhile, the present drawing illustrates an example in which a single protective tube is provided inside a single sheath, but the present disclosure is not limited thereto. For example, a plurality of tubes may be provided inside a single sheath, and at least one optical fiber may be disposed inside each protective tube. In this case, the optical fiber and the tube may be wrapped with an outer sheath after they are all connected.

[0111] 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 roundness of the submarine cable (1000). The shaped filler (300) can also disperse the force acting on the cable to prevent damage or breakage of the power unit (100) and the optical unit (200) of the cable.

[0112] Specifically, the interposition (300) can be placed between the power unit (100) and the protection unit (400) described later. The interposition (300) can accommodate the light unit (200) and protect the light unit (200) from external forces acting in the case of installation, etc.

[0113] The protection unit (400) may have a bedding layer (410) that encloses the power unit (100) and the interlayer (300) {and the optical unit (200)}. The bedding layer (410) may be composed of polypropylene (PP) fibers, etc. To protect the power unit (100) and the optical unit (200), a filler material (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 an outermost layer (420). The outermost layer (420) may be composed of a polymer material or have a composition generally identical to that of the bedding layer (410).

[0114] 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 layers (530, 530') in the preceding embodiment.

[0115]

[0116] The present disclosure has industrial applicability in the field of submarine cable manufacturing.

Claims

1. Includes at least one power unit and a protection unit surrounding the at least one power unit, and 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 includes 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 includes a plurality of armor wires that are transversely wound outside the above bedding layer, and The above armor wire is a lightweight submarine cable comprising a core portion having a bundle of first fibers and a cover portion having second fibers that wrap the core portion in one of weaving and braiding.

2. In Paragraph 1, A lightweight submarine cable satisfying the following relationship, where L is the length of the armor wire and Lo is the average length of the first fiber constituting the first fiber bundle of the armor wire. 1 ≤ Lo / L ≤ 1.01 3. In Paragraph 1, A lightweight submarine cable in which the bundle of the first fibers is a plurality of first fibers straightly twisted together.

4. In Paragraph 1, The above armor wire is a lightweight submarine cable in which the second fiber wraps around the bundle of the first fiber while the bundle of the first fiber is pulled in the longitudinal direction.

5. In Paragraph 1, The second fiber above comprises a plurality of knitted yarns, and A lightweight submarine cable in which the plurality of braided strands are braided with respect to the core portion while being pulled in the longitudinal direction to form the cover portion.

6. In Paragraph 1, The above armor wire is a lightweight submarine cable having a packing ratio of 80% or more.

7. In Paragraph 1, The above core part forms a cross-sectional shape of either circular or square, and A lightweight submarine cable in which the cover portion forms a tubular body having a cross-section of either circular or square corresponding to the cross-sectional shape of the core portion.

8. In Paragraph 1, A lightweight submarine cable in which the bundle of the first fibers above is twisted.

9. In Paragraph 1, The above core part includes a central group and a peripheral group, and Each of the above central group and the above peripheral group is composed of a plurality of first fibers, and The above surrounding group is provided in multiple quantities, and A lightweight submarine cable in which the plurality of surrounding groups are arranged to surround the outer surface of the central group.

10. In Paragraph 1, A lightweight submarine cable in which the first fiber is formed from at least one of aramid and UHMWPE.

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

12. In Paragraph 1, A lightweight submarine cable in which the first fiber and the second fiber are fibers of the same type.

13. In Paragraph 1, The above power unit is a lightweight submarine cable further comprising a polymer sheath surrounding the metal shielding layer.

14. Includes at least one power unit and a protection unit surrounding the at least one power unit, and 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 includes 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 includes a plurality of armor wires that are transversely wound outside the above bedding layer, and A lightweight submarine cable having a specific strength of 120 N·m / g or more of the above armor wire.

15. In Paragraph 14, A lightweight submarine cable satisfying the following relationship, where L is the length of the armor wire and Lo is the average length of the first fiber constituting the first fiber bundle. 1 ≤ Lo / L ≤ 1.01 16. As an armor wire for wrapping a power unit of a submarine cable to form an armor layer, A core portion having a bundle of first fibers; and Armor wire for submarine cables, comprising a cover portion having a second fiber that wraps the core portion in one of weaving and braiding.

17. In Paragraph 16, Armor wire for submarine cables having a specific strength of 120 N·m / g or more.

18. In Paragraph 16, The above-mentioned bundle of first fibers is an armor wire for submarine cables in which a plurality of first fibers are straightly twisted.

19. In Paragraph 16, The second fiber above comprises a plurality of knitted yarns, and Armor wire for a submarine cable, wherein the plurality of braided wires are braided with respect to the core portion while being pulled in the longitudinal direction to form the cover portion.

20. In Paragraph 16, The above core part includes a central group and a plurality of peripheral groups, and Each of the above central group and the above peripheral group is composed of a plurality of first fibers, and The above plurality of peripheral groups are arranged to surround the central group, an armor wire for a submarine cable.

21. A step of pulling the bundle of the first fiber in the longitudinal direction; and A method for manufacturing an armor wire for a submarine cable, comprising the step of braiding a second fiber to wrap around a bundle of a first fiber pulled in the longitudinal direction.

22. In Paragraph 21, A method for manufacturing an armor wire for a submarine cable, further comprising the step of compressing the braided second fiber so that the armor wire has a square cross-section.

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