Submarine cable with double metal conductors

Abstract

A bimetallic conductor submarine cable is disclosed. In some embodiments, an optical cable includes a hollow buffer tube having a plurality of optical fibers therein, and a plurality of first layered reinforcement members surrounding the hollow buffer tube. The optical cable may also include a conductor surrounding the plurality of first layered reinforcement members, wherein the conductor includes a first metal layer surrounded by a second metal layer and an outer insulating sheath surrounding the conductor.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application Serial No. 63 / 528,819, filed on July 25, 2023, entitled “Dual Metal Conductor Undersea Cable,” and priority to U.S. Provisional Patent Application Serial No. 18 / 423,771, filed on January 26, 2024, entitled “Dual Metal Conductor Undersea Cable,” which applications are incorporated herein by reference in their entirety. Background Art

[0003] Any underwater cable intended for an optical communication system with repeaters (i.e., a subsea body housing optical amplifiers and network power supplies) has electrical conductors for delivering power from the shore to these underwater repeaters and to other electro-optical subsea bodies. Such cable conductors are insulated from the sea surface by an extruded insulation layer (usually polyethylene). The conductor layer should have a sufficiently low resistance to minimize resistive power dissipation and ensure that sufficient power can be delivered to the network power circuits of the optical amplifiers within the subsea body. Cables with low resistance become increasingly important as capacity requirements grow and the number of optical paths increases, which in turn increases the number of power-consuming optical amplifiers.

[0004] Historically, submarine cables have utilized pure copper as the material for the power conductors to reduce resistive power dissipation. Copper can be easily welded into a gas-tight tube, protecting the underlying fiber and steel strength wires from moisture and hydrogen. However, copper is expensive as a material, and welding thicker layers of copper can result in slower cable manufacturing rates and, thus, increased expense in the cable manufacturing process. Furthermore, the added weight of the copper conductors can limit the depth / handling capabilities of the cable construction.

[0005] It is in response to these and other shortcomings of the prior art that the present disclosure is provided. Summary of the invention

[0006] This Summary is provided to introduce selected concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be an aid in determining the scope of the claimed subject matter.

[0007] In one approach, a fiber optic cable can include a hollow buffer tube having a plurality of optical fibers therein, a plurality of first layered strength members surrounding the hollow buffer tube, a conductor surrounding the plurality of first layered strength members, wherein the conductor includes a first metal layer surrounded by a second metal layer, and an insulating outer jacket surrounding the conductor.

[0008] In another approach, a system may include a set of local feeder stations, and an optical cable extending between the set of local feeder stations. The optical cable may include a hollow buffer tube having a plurality of optical fibers therein, a plurality of first layered strength members surrounding the hollow buffer tube, a conductor surrounding the plurality of first layered strength members, wherein the conductor includes a first metal layer surrounded by a second metal layer, and an insulating outer jacket surrounding the conductor.

[0009] In yet another approach, a method of forming a fiber optic cable may include providing a hollow buffer tube around a plurality of optical fibers, forming a plurality of first layered strength members around the hollow buffer tube, and forming a conductor around the plurality of first layered strength members. The conductor may include a first metal layer wrapped around the plurality of first layered strength members and a second metal layer wrapped around the first metal layer. The method may also include forming an insulating outer jacket around the conductor. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] By way of example, embodiments of the present disclosure will now be described with reference to the accompanying drawings, in which:

[0011] Figure 1 An exemplary optical communication system according to an embodiment of the present disclosure is shown;

[0012] Figure 2 An exemplary submarine cable according to an embodiment of the present disclosure is shown;

[0013] Figure 3 is a graph showing conductor material percentage versus conductor material cost and cable weight according to an embodiment of the present disclosure; and

[0014] Figure 4 is a graph showing the relationship between the DC resistance of a conductor and the material cost of the conductor according to an embodiment of the present disclosure.

[0015] In addition, for the sake of clarity, some elements in some of the drawings may be omitted or not illustrated to scale. The cross-sectional views may be in the form of "sliced" or "close-up" cross-sectional views, and for the sake of clarity, some background lines visible in the "true" cross-sectional views are omitted. In addition, for the sake of clarity, some reference numerals may be omitted in some of the drawings. DETAILED DESCRIPTION

[0016] The present disclosure will now be described more fully below with reference to the accompanying drawings, in which preferred embodiments of the present invention are shown. However, the present disclosure may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. In the accompanying drawings, like numbers always refer to like elements.

[0017] The present disclosure relates to at least one improved submarine fiber optic communication cable having a bimetallic conductor. The above-mentioned prior art methods result in low-cost solutions and result in heavier cables that are more difficult to handle at deep sea depths. Cables with copper conductors and low resistance are expensive. Cables with pure aluminum conductors can be difficult to manufacture. In order to address the deficiencies of the prior art, embodiments of the present disclosure relate to a cable structure with a bimetallic conductor, wherein the inner conductor layer is aluminum and the outer conductor layer is copper. More specifically, the aluminum is an aluminum layer tape formed around the steel strength wire of the cable, and the aluminum layer is thick enough to provide reduced resistance. The aluminum layer is surrounded by a relatively thin copper tape, which is longitudinally wrapped and welded to form an airtight sealed conductive cable vault. The copper layer and the aluminum layer together lock the steel wire in place.

[0018] The cable of the present disclosure provides at least the following advantages. First, for the same resistance, the proposed cable provides a lower material cost. Although the raw material cost ratio between copper and aluminum fluctuates depending on market prices, the cost of copper per unit weight may be 2-5 times that of aluminum. By using a combination of copper and aluminum in the conductor, the same reduction in cable resistance can be achieved with a lower total conductor material cost.

[0019] Secondly, for the same resistance, the proposed cable provides better handling characteristics. Aluminum is about 70% lighter than copper. By using a combination of copper and aluminum in the conductor, a cable with the same resistance in water and lower cable weight can be achieved. The relationship between weight in water and tensile strength is an important characteristic for cable handling operations in deep sea depths.

[0020] Third, the proposed cable has improved bending stiffness compared to the all-aluminum conductor design.

[0021] Fourth, the proposed cable improves manufacturability for the same resistance. Soldering only copper enables the copper thickness to be selected to obtain a higher manufacturing process capability.

[0022] Fifth, in the proposed cable, aluminum tape is provided on the strength member, but not welded, and copper is subsequently provided, which can be welded. As a result, the production volume is increased because thick conductor metal does not need to be welded.

[0023] Sixth, due to the hermetically welded copper layer, the proposed cable provides adequate fiber protection against hydrogen aging.

[0024] Go to the attached picture, Figure 1 An exemplary optical communication system (hereinafter referred to as "system") 100 according to an embodiment of the present disclosure is shown. For ease of description, the system 100 is shown in a highly simplified form. As shown, the system 100 includes a double-ended submarine optical fiber cable (hereinafter referred to as "cable") 102 powered by a first local feeding equipment (PFE) 104 and a second PFE 106. The PFEs 104 and 106 can be located at opposite cable landing stations (e.g., station A and station B). Each of the PFEs 104, 106 can be configured to provide up to 23kW of power, for example. However, the embodiments herein are not limited to any particular power limit.

[0025] Figure 2 A cross-sectional view of an example cable is shown, such as Figure 1 1. An underwater fiber optic cable 102 is shown in FIG. 1. As shown, a tube 110 may enclose or include a plurality of optical fibers 112 therein. The tube 110 may be a single, centrally located, gel-filled buffer tube made of a plastic material or a welded metal. As further shown, a first layer 114 and a second layer 116 of strength members may be wrapped around the tube 110. For example, the strength members may have a circular cross-section, and each layer of the strength members may be arranged in a closely packed configuration, for example, the inner first layer 114 may include eight (8) strength members, wherein adjacent strength members are in contact with each other. Similarly, the outer second layer 116 may include sixteen (16) strength members, wherein adjacent members are in contact with each other. In alternative embodiments, other numbers of strength members, such as 10 and 20 for the first and second layers, respectively, are also possible.

[0026] As further shown, the conductor 120 can surround the first layer 114 and the second layer 116 of the reinforcement member, and can be used as both an electrical conductor and an airtight barrier. In some embodiments, the conductor 120 may include a first layer 122 surrounded by a second layer 124. More specifically, the first layer 122 may be an aluminum strip wrapped spirally or longitudinally along the second layer 116 of the reinforcement member, and the second layer 124 may be a copper strip wrapped longitudinally around the first layer 122. Other metal materials are also possible. As shown, the first layer 122 and the second layer 124 may be in direct physical and electrical contact with each other. This bimetallic conductor structure provides low resistance and dimensions similar to existing cable structures for the cable 102. In addition, once the second layer 124 is welded, this bimetallic conductor cable structure provides airtight protection against fiber hydrogen aging.

[0027] In the illustrated embodiment, the volumes of the first layer 122 and the second layer 124 are approximately the same, and the radial thickness of the first layer 122 is slightly greater than the radial thickness of the second layer 124. However, in other embodiments, the relative thickness between the first layer 122 and the second layer 124 may vary. In other embodiments, the radial thickness of the first layer 122 and the second layer 124 may be approximately the same or may be completely different. During assembly, the first layer 122 of aluminum is wrapped around the first layer 114 and the second layer 116 of the reinforcement member, but is not welded. However, the second layer 124 of copper may be wrapped around the first layer 122 and then welded. As a result, production volume is increased because aluminum welding is not required.

[0028] Further shown is an outer jacket 130 formed of polyethylene and can encapsulate the conductor 120. For example, the outer jacket 130 can serve as an electrical insulation layer. The outer jacket 130 can be extruded over the conductor 120.

[0029] Figure 3 is a graph 150 showing the relationship between the conductor material volume percentage of the cable 102 according to an embodiment of the present disclosure and the conductor material cost and the weight of the cable in water, and Figure 4 1 is a graph 160 showing cable direct current resistance (DCR) versus conductor material cost of cable 102 according to an embodiment of the present disclosure. It should be understood that the specific monetary values ​​are variable and, therefore, not shown. Figure 3 to Figure 4 Example cost benefits of the bimetallic conductor 120 are generally demonstrated.

[0030] As used herein, an element or step recited in the singular and beginning with "a" or "an" should be understood as not excluding plural elements or steps, unless such exclusion is explicitly stated. In addition, reference to "one embodiment" of the present disclosure is not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the described features.

[0031] The use of "including," "comprising," or "having" and variations thereof herein is meant to include the items listed thereafter and equivalents thereof as well as additional items. Therefore, the terms "including," "comprising," or "having" and variations thereof are open-ended expressions and may be used interchangeably herein.

[0032] As used herein, the phrases "at least one", "one or more", and "and / or" are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions "at least one of A, B, and C", "at least one of A, B, or C", "one or more of A, B, and C", "one or more of A, B, or C", and "A, B, and / or C" means A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B, and C together.

[0033] All directional references (e.g., proximal, distal, upper, lower, upward, downward, left, right, lateral, longitudinal, front, rear, top, bottom, above, below, vertical, horizontal, radial, axial, clockwise, and counterclockwise) are used for identification purposes only to assist the reader in understanding the present disclosure and are not intended to be limiting, particularly with respect to the position, orientation, or use of the present disclosure. Unless otherwise indicated, connection references (e.g., attach, couple, connect, and join) are to be interpreted broadly and may include intermediate members between a collection of elements and relative movement between elements. Thus, connection references do not necessarily infer that two elements are directly connected and fixed to each other.

[0034] Furthermore, identifying references (e.g., primary, secondary, first, second, third, fourth, etc.) do not imply importance or priority, but are used to distinguish one feature from another. The drawings are for illustration purposes only, and the size, position, order, and relative sizes reflected in the drawings may vary.

[0035] The terms "substantially" or "substantially" and the terms "approximately" or "approximately" may be used interchangeably in some embodiments and may be described using any relevant metric acceptable to one of ordinary skill in the art. For example, these terms may be used as a comparison to a reference parameter to indicate a deviation from being able to provide the intended function. Although not limiting, the deviation from a reference parameter may be, for example, an amount less than 1%, less than 3%, less than 5%, less than 10%, less than 15%, less than 20%, and the like.

[0036] Therefore, such other embodiments and modifications are intended to fall within the scope of the present disclosure. In addition, although the present disclosure has been described in the context of a specific implementation for a specific purpose in a specific environment, one of ordinary skill in the art will recognize that its usefulness is not limited thereto, and that the present disclosure may be advantageously implemented in any number of environments for any number of purposes. Therefore, the claims set forth below should be interpreted in light of the full breadth and spirit of the present disclosure as described herein.

Claims

1. An optical cable, comprising: a hollow buffer tube having a plurality of optical fibers therein; a plurality of first layered reinforcement members surrounding the hollow buffer tube; a conductor surrounding the plurality of first layered reinforcement members, wherein the conductor comprises a first metal layer surrounded by a second metal layer; and An outer insulating jacket surrounds the conductor.

2. The optical cable of claim 1 , further comprising a plurality of second layered strength members surrounding the hollow buffer tube, wherein each of the plurality of first layered strength members has a first diameter, and wherein each of the plurality of second layered strength members has a second diameter and a third diameter different from the first diameter.

3. The optical cable according to claim 1, wherein The conductor is directly adjacent to the outer sheath.

4. The fiber optic cable of claim 1, wherein the first metal layer is aluminum, and wherein the second metal layer is copper.

5. The optical cable according to claim 4, wherein: The aluminum is an aluminum tape that is helically wrapped or longitudinally wrapped around the plurality of second layered reinforcement members.

6. The optical cable according to claim 4, wherein: The copper is wrapped longitudinally along the exterior of the aluminum strip.

7. The optical cable according to claim 4, wherein: The copper is soldered to the aluminum strip.

8. The optical cable according to claim 1, wherein A first radial thickness of the first metal layer is greater than a second radial thickness of the second metal layer.

9. An optical communication system, comprising: a group of local feeder equipment stations; and an optical fiber cable extending between the set of local feeder stations, wherein the optical fiber cable comprises: a hollow buffer tube having a plurality of optical fibers therein; a plurality of first layered reinforcement members surrounding the hollow buffer tube; a conductor surrounding the plurality of first layered reinforcement members, wherein the conductor comprises a first metal layer surrounded by a second metal layer; and An insulating outer jacket surrounds the conductor.

10. The optical communication system according to claim 9, wherein: The fiber optic cable also includes a plurality of second layered strength members surrounding the hollow buffer tube, wherein each of the plurality of first layered strength members has a first diameter, and wherein each of the plurality of second layered strength members has a second diameter different than the first diameter and a third diameter.

11. The optical communication system according to claim 10, wherein: The conductor is directly adjacent to the outer jacket and directly adjacent to the second plurality of layered strength members.

12. The optical communication system according to claim 10, wherein: The first metal layer is aluminum, and wherein the second metal layer is copper.

13. The optical communication system according to claim 12, wherein: The aluminum is an aluminum tape that is helically wrapped or longitudinally wrapped around the exterior of the plurality of second layered reinforcement members.

14. The optical communication system according to claim 12, wherein: The copper is wrapped longitudinally along the exterior of the aluminum strip.

15. The optical communication system according to claim 12, wherein: The copper is soldered to the aluminum strip.

16. The optical communication system according to claim 9, wherein: A first radial thickness of the first metal layer is greater than a second radial thickness of the second metal layer.

17. A method of forming an optical cable, the method comprising: providing a hollow buffer tube around the plurality of optical fibers; forming a plurality of first layered reinforcement members around the hollow buffer tube; forming a conductor around the plurality of first layered reinforcement members, wherein the conductor comprises a first metal layer wrapped around the plurality of first layered reinforcement members and a second metal layer wrapped around the first metal layer; and An insulating outer sheath is formed around the conductor.

18. The method according to claim 17, wherein: Forming the conductor includes soldering the second metal layer onto the first metal layer, wherein the first metal layer is not soldered, wherein the first metal layer is aluminum, and wherein the second metal layer is copper.

19. The method of claim 17, further comprising forming a plurality of second layered reinforcement members around the plurality of first layered reinforcement members.

20. The method according to claim 19, wherein: Forming the conductor includes helically or longitudinally wrapping the first metal layer and the second metal layer around the plurality of second layered strength members.

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