Termination device for overhead cables comprising a tensile strain jacket

Abstract

A termination device for securing an overhead power cable and a method for securing an overhead power cable. The termination device includes a longitudinally extending sheath having a high tensile modulus, the sheath being configured to receive a strength member of the overhead power cable therein. Upon crimping of a connector body over the strength member, the sheath significantly reduces tensile strain experienced by the strength member and reduces the risk of the strength member breaking.

Description

[0001] Citation of relevant applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 704,516, filed May 14, 2020, by Webb et al., which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to the field of termination devices, including terminals and joints, for overhead cables with composite strength components. Summary of the Invention

[0004] In one embodiment, a termination device is disclosed. The termination device is configured to secure an overhead cable including a strength member and an electrical conductor arranged around the strength member. The termination device includes: a connector comprising a fastener disposed at a first end of the connector and a connector body extending from the fastener toward an end of the connector opposite the fastener; a longitudinally extending sheath having a central hole configured to receive the strength member therein; and a conductive sleeve configured to be disposed on (i) the end of the cable, (ii) the sheath, and (iii) at least a portion of the connector body when the termination device is operably assembled.

[0005] In another embodiment, a termination device is disclosed for attaching to an overhead cable including a strength member and an electrical conductor arranged around the strength member. The termination device includes: a connector including a fastener disposed at a first end of the connector and a connector body extending from the fastener toward an end of the connector opposite the fastener; a longitudinally extending sheath having a central hole therethrough, the sheath being operably disposed on a portion of the strength member and compressed onto that portion to operably clamp the strength member; and a conductive sleeve disposed on (i) the end of the cable, (ii) the sheath, and (iii) at least a portion of the connector body. The sheath is operably attached to the connector body by one of the following methods: (i) disposed within a cavity of the connector body and with the connector body pressed against the sheath, or (ii) disposed within the conductive sleeve and with the conductive sleeve pressed against the sheath.

[0006] In another embodiment, a method for terminating an overhead cable is disclosed, the overhead cable including a strength member and an electrical conductor arranged around the strength member. The method includes the steps of: removing the electrical conductor from a termination end of the cable to expose an end of the strength member; passing the exposed end of the strength member through a central hole arranged within a longitudinally extending sheath; and operably attaching the sheath to a connector including a fastener arranged at a first end of the connector and a connector body extending from the fastener toward an end of the connector opposite to the fastener, the attachment including one of the following operations: (i) arranging the sheath within a cavity of the connector body and pressing the connector body against the steel sheath, or arranging the sheath within a conduit of a conductive sleeve and pressing the conductive sleeve against the sheath. Attached Figure Description

[0007] Figure 1A and 1B Two examples of prior art overhead cables with composite strength members are shown.

[0008] Figure 2 A partial cross-section of a prior art overhead cable termination device with composite strength members is shown.

[0009] Figure 3 A perspective view of a prior art termination device for an overhead cable with composite strength members is shown.

[0010] Figure 4A and 4B A partial cross-section of a prior art overhead cable termination device with composite strength members is shown.

[0011] Figure 5A and 5B An embodiment of the termination device of this disclosure is shown.

[0012] Figure 6A and 6B An embodiment of the termination device of this disclosure is shown.

[0013] Figures 7A to 7E An embodiment of the steel sheath of this disclosure is shown.

[0014] Figures 8A to 8D An embodiment of the termination device of this disclosure is shown.

[0015] Figures 9A to 9D An embodiment of the termination device of this disclosure is shown.

[0016] Figure 10 A method for measuring strain on a composite strength member during crimping is illustrated schematically. Detailed Implementation

[0017] Overhead power transmission and distribution lines are constructed by raising cables (such as bare, uninsulated cables) above the ground using support towers (such as pylons). Transmission and distribution lines can span miles, requiring very long cables and numerous support towers. Some of these support towers, called terminal towers or anchor towers, are placed at termination points, such as substations or locations where power lines run underground. Terminal towers may also be needed where power lines change direction (such as at bends) or are laid out at regular intervals along long straight paths. Another type of termination device is a joint, which is used to make a mechanical and electrical connection between the ends of two adjacent cables in a power line.

[0018] Traditionally, overhead cables are constructed using an internal steel reinforcing member surrounded by multiple strands of conductive aluminum strands spirally wound around it; this configuration is known as "aluminum steel-cored wire" (ACSR). More recently, overhead cables with fiber-reinforced composite reinforcing members have been manufactured and are used in many power lines. Compared to steel, fiber-reinforced composites used for the reinforcing members are lighter, have a lower coefficient of thermal expansion, and higher stiffness per unit area. However, when subjected to stress, the fiber-reinforced material does not reach its yield point, which allows for plastic deformation.

[0019] like Figure 1A As shown, such a fiber-reinforced composite strength member may comprise a single fiber-reinforced composite strength element (e.g., a single rod). An example of this configuration is disclosed in U.S. Patent No. 7,368,162 to Hiel et al., which is incorporated herein by reference in its entirety. Alternatively, the composite strength member may consist of multiple individual fiber-reinforced composite strength elements (e.g., individual rods) that are operably combined (e.g., twisted or knotted together) to form a strength member, such as... Figure 1B As shown. Examples of such multi-element composite strength members include, but are not limited to: multi-element aluminum-based composite strength members described in U.S. Patent No. 6,245,425 to McCulough et al.; multi-element carbon fiber strength members shown in U.S. Patent No. 6,015,953 to Tosaka et al.; and multi-element strength members shown in U.S. Patent No. 9,685,257 to Daniel et al., each of which is incorporated herein by reference. Other configurations of fiber-reinforced composite strength members can be realized, as will be known to those skilled in the art.

[0020] Please refer to Figure 1AThe overhead cable shown, cable 160A, includes an electrical conductor 162A, which comprises a first conductive layer 164a and a second conductive layer 164b. Each conductive layer includes multiple individual conductive strands spirally wound around a fiber-reinforced composite strength member 166A. It should be understood that, depending on the intended use of the overhead cable, such an overhead cable may include a single conductive layer or more than two conductive layers. The conductive strands may be made of a conductive metal (e.g., copper or aluminum), and are typically made of aluminum, such as hardened aluminum, annealed aluminum, and / or aluminum alloys, when used in bare overhead cables. Figure 1A As shown, the conductive stranded wire has a substantially trapezoidal cross-section; however, other configurations, such as a circular cross-section, can also be used. For example, compared to stranded wires with a circular cross-section, using a polygonal cross-section (e.g., a trapezoidal cross-section) advantageously increases the cross-sectional area of ​​the conductive metal for the same effective cable diameter.

[0021] Conductive materials (e.g., aluminum) do not possess sufficient mechanical properties (e.g., sufficient tensile strength) to self-support and form overhead power lines for transmission and / or distribution when stretched between support towers. Therefore, the overhead cable 160A includes a strength member 166A to support the conductive layers 164a / 164b when the overhead cable 160A is stretched between support towers under high mechanical tension. Figure 1A In the illustrated embodiment, the strength member 166A includes a single (e.g., only one) strength element 168A. The strength element 168A includes a high-strength carbon-reinforced fiber core 170A and an electrochemical corrosion protection layer 172A (e.g., made of glass fiber) located in the bonding matrix to prevent contact between the carbon fibers and the first conductive layer 164A, which could lead to corrosion of the aluminum.

[0022] Figure 1B It shows the relationship with Figure 1A The cable shown is similar to one embodiment of an overhead cable 160B, wherein the strength member 166B comprises a plurality of individual strength elements (e.g., strength element 168B) that are twisted or twisted together to form the strength member 166B. Although in Figure 1B The component is shown as comprising seven separate strength elements; however, it should be understood that a multi-element strength member may include any number of strength elements suitable for a particular application.

[0023] As described above, fiber-reinforced composites constituting strength elements may include reinforcing fibers operably arranged in a bonding matrix. The reinforcing fibers may be substantially continuous reinforcing fibers extending along the length of the fiber-reinforced composite, and / or may be short reinforcing fibers (e.g., fiber whiskers or chopped fibers) dispersed in the bonding matrix. The reinforcing fibers may be selected from a variety of materials, including but not limited to carbon, glass, boron, metal oxides, metal carbides, high-strength polymers (e.g., polyamide fibers or fluoropolymer fibers), basalt fibers, etc. Carbon fibers are particularly advantageous in many applications due to their extremely high tensile strength and / or their low coefficient of thermal expansion (CTE).

[0024] The adhesive matrix may include, for example, plastics (e.g., polymers), such as thermoplastic or thermosetting polymers. For instance, the adhesive matrix may include thermoplastic polymers, including semi-crystalline thermoplastics. Specific examples of useful thermoplastics include, but are not limited to, polyetheretherketone (PEEK), polypropylene (PP), polyphenylene sulfide (PPS), polyetherimide (PEI), liquid crystal polymers (LCP), polyoxymethylene (POM, or acetal), polyamide (PA, or nylon), polyethylene (PE), fluoropolymers, and thermoplastic polyesters.

[0025] The adhesive matrix may also comprise thermosetting polymers. Examples of useful thermosetting polymers include, but are not limited to, benzoxazine, thermosetting polyimide (PI), polyetheramide resin (PEAR), phenolic resin, epoxy vinyl ester resin, polycyanate resin, and cyanate ester resin. In one exemplary embodiment, a vinyl ester resin is used in the adhesive matrix. Another embodiment includes the use of an epoxy resin, for example, bisphenol A diglycidyl ether (DGEBA), a reaction product of epichlorohydrin and bisphenol A. The curing agent (e.g., hardener) used for the epoxy resin can be selected based on the desired properties and processing methods of the fiber-reinforced composite strength member. For example, the curing agent may be selected from aliphatic polyamines, polyamides, and modified forms of these compounds. Anhydrides and isocyanates can also be used as curing agents. Other examples of polymeric materials that can be used in the adhesive matrix may include addition-cured phenolic resins (e.g., bismaleimide (BIM)), polyetheramides, various anhydrides, or imides.

[0026] The bonding matrix can also be a metallic matrix, such as an aluminum matrix. An example of an aluminum-based fiber-reinforced composite material is described in U.S. Patent No. 6,245,425 to McCulough et al., mentioned above.

[0027] A particularly advantageous configuration for composite strength members used in overhead cables is A composite configuration, such a composite strength member, is available from CTC Global Corporation of Irvine, California, and is shown in U.S. Patent No. 7,368,162 to Hiel et al., mentioned above. In a commercially available embodiment of the ACCC cable, the strength member is a single-piece strength member having a substantially circular cross-section, comprising a substantially continuous reinforcing carbon fiber core disposed within a polymer matrix. This carbon fiber core is surrounded by a robust glass fiber insulation layer, also disposed within the polymer matrix, which insulates the carbon fibers from the surrounding conductive aluminum strands. See also Figure 1A Glass fiber also has a higher compressive strain capacity than carbon fiber and provides flexibility, so that the strength member and the cable can be wound on a reel for storage and transportation.

[0028] During power line installation, overhead cables must be terminated and secured to terminal towers under high tension. Overhead cables utilizing steel or other tough metal strength members can be attached to termination devices by crimping the components surrounding the strength member with high compressive force, because the underlying strength member is tough and will not break under compressive stress. Fiber-reinforced composite strength members, which have lower ductility and elongation at break than steel, are prone to breakage under high compressive forces, and termination devices for such strength members are typically designed to reduce the compressive force on the strength member. Figure 2 Figures 4 to 4 show two different termination devices that are particularly useful for overhead cables with fiber-reinforced composite strength members. Figure 2 A cross-section of a termination device (e.g., a terminal) used in conjunction with a bare overhead cable is shown, i.e., the termination device is used to terminate the cable while keeping the cable under high tension. Figure 2 The termination device 200 shown herein is similar to the termination device shown and described in Bryant’s PCT Publication No. WO 2005 / 041358 and U.S. Patent No. 8,022,301 to Bryant et al., the entire contents of which are incorporated herein by reference.

[0029] In summary, Figure 2 The termination device 200 shown includes a clamping element 210 fixed to a connector 220, which anchors the termination device 200 to a termination structure (e.g., a tower) not shown, for example, using a fastener 226 (e.g., a bolt with an eye). At the end of the termination device 200, opposite to the fastener 226, the termination device 200 is operatively connected to a bare overhead cable 260, which includes an electrical conductor 262 (e.g., a conductive stranded wire) surrounding and supported by a strength member 266 (e.g., a fiber-reinforced composite strength member).

[0030] The clamping element 210 tightly clamps the strength member 266 to secure the overhead cable 260 to the termination device 200. For example... Figure 2 As shown, the clamping element 210 includes a compression fitting, particularly a collet 212 having an inner cavity 216 (e.g., a hole) surrounding and clamping the strength member 266. The collet 212 is arranged within a collet housing 214, and as the cable 260 is tensioned (e.g., pulled onto a support tower), the collet 212 is further pulled into the collet housing 214, thereby generating friction between the strength member 266 and the collet 212. The tapered (external) shape of the collet 212 and the mating funnel shape of the collet housing 214 increase the compressive force on the strength member 266, ensuring that the strength member 264 does not slip out of the collet 212, and thus ensuring that the overhead cable 260 is secured to the termination device 200.

[0031] like Figure 2 As shown, a conductive outer sleeve 240 is disposed on a clamping element 210, which includes a conductor 244 to facilitate electrical conduction between the electrical conductor 262 and the jumper plate 246. An inner sleeve 248 (e.g., a conductive inner sleeve) may be disposed between the electrical conductor 262 and the conductor 244 to facilitate electrical connection between the electrical conductor 262 and the conductor 244. For example, the inner sleeve 248 and the conductor 244 may be made of aluminum. The jumper plate 246 is attached (e.g., soldered) to the conductor 244 and configured to be attached to a connecting plate 276 to facilitate electrical conduction between the electrical conductor 262 and another conductor, such as another cable (not shown) electrically connected to the connecting plate 276.

[0032] Connector 220 includes a fastener 226 and a clamping element mating thread 228 disposed at a clamping element end of connector 220, with connector body 222 disposed between the fastener 226 and the clamping element mating thread 228. The clamping element mating thread 228 is configured to operably engage with a connector mating thread 218 on collet housing 214, so that when threads 218 and 228 are engaged and connector 220 rotates relative to collet housing 214, connector 220 moves toward collet 212, thereby pushing collet 212 into collet housing 214. This strengthens the clamping of collet 212 on strength member 266, thereby securing overhead cable 260 to termination device 200. Fastener 226 is configured to attach to a terminal structure, such as a terminal tower, to secure termination device 200 and cable 260 to the terminal structure.

[0033] After the termination device is assembled, the outer sleeve can be press-fitted (e.g., compressed, forged) onto a portion of the underlying structure to prevent movement of the outer sleeve and / or enhance the connection between the conductor and the electrical conductor. Figure 3 It shows the relationship with Figure 2The diagram shows a perspective view of a termination device similar to the one shown, which has been crimped onto the overhead cable. Termination device 300 includes a connector with a fastener 326 extending outward from the proximal end of the outer sheath 340. A jumper plate 346 is integrally formed with a conductor 342 for electrical connection to a connection plate (see, for example, [link to other document]). Figure 2 ).like Figure 3 As shown, the outer sleeve 340 is crimped above (e.g., crimped onto) two regions of the lower structure (i.e., crimp sleeve region 340b and crimp sleeve region 340a). The crimp sleeve region 340b is generally located above the connector body (see, for example, see...). Figure 2 (222) and the crimp sleeve region 340a is generally located above a portion of the overhead cable 360, for example, to enhance the electrical connection with the cable. The compressive force applied to the outer sleeve 340 during the crimping operation is transmitted to the underlying components, namely, to the connector body below the crimp region 340b and the overhead cable 360 ​​below the crimp region 340a.

[0034] The aforementioned termination device uses a smooth-surfaced clamp 214 to clamp onto the composite strength member over a sufficient length, thereby generally avoiding high stress points and making it unlikely that the composite strength member will break under the clamp.

[0035] Figure 4A and 4B An alternative to existing termination device 400 for use in conjunction with a composite strength member is shown. For clarity, Figure 4A and 4B The relevant components of the termination device are shown, but details in... Figure 2 and 3 The image shows the outer sheath, jumper plate, etc. Figure 4A and 4B The termination device shown does not use a tapered chuck to hold the strength member, but instead secures it to the strength member by radially compressing (e.g., crimping, forging) the connector body onto the strength member using a crimping tool (e.g., a hydraulic press). The device 400 includes a steel connector 420 having a connector body 422 and a fastener 426 (e.g., an eye bolt). An aluminum inner sleeve 432, softer than the surrounding steel connector body 422, is arranged between the composite strength member 466 and the connector body 422. The crimping operation typically involves sequentially crimping the connector body from the proximal end (i.e., near the fastener 426) to the distal end using a crimping tool. The crimping tool can apply a compressive force of up to approximately 100 tons to the connector body 422 to secure the connector body to the strength member 466. The inner aluminum sleeve 432 is designed to redistribute a portion of this radial crimping force, thereby reducing the force on the strength member 466.

[0036] like Figure 4BAs shown, when the connector body 422 is pressed against the lower inner aluminum sleeve 432 and the strength member 466, the sleeve 432 and the body 422 elongate due to the pressing force, for example from the initial length l1. Figure 4A ) elongated to extended length l2 ( Figure 4B During this elongation, the aluminum sleeve 432 is expected to slide on the strength member 466 as the sleeve 432 elongates, applying almost no elongation strain to the strength member. For example, the crimp connector body 422 may cause the aluminum sleeve 432 to elongate by up to about 5%, which is significantly higher than the strain failure limit of the underlying composite strength member 466, which is typically less than 2%. However, it has been found that the aluminum sleeve 432 can “pull” the underlying strength member 466 (e.g., due to friction) so that the strength member 466 elongates as the sleeve 432 elongates, subjecting the strength member to high elongation (e.g., tensile) strain. If the elongation strain is too high, the strength member 466 may break due to the lower elongation characteristics of the composite strength member 466 (e.g., fracture 466f).

[0037] One object of this disclosure is to provide an termination device that reduces elongation strain on a strength member caused by the crimping of surrounding components. In embodiments of this disclosure, elongation strain on the strength member is reduced or substantially eliminated by arranging a high tensile modulus sheath (e.g., a hardened steel sheath) on the strength member. The steel sheath is then compressed onto the strength member by crimping the connector body and / or conductive sleeve onto the steel sheath. The properties of the sheath (e.g., the material in which the sheath is made and / or the wall thickness of the sheath) protect the strength member from tensile strain that could damage the strength member, and the sheath may be referred to as a tensile strain sheath. While tensile strain sheaths are generally described herein as steel sheaths, tensile strain sheaths may be made of other high tensile modulus materials, such as materials having a higher tensile modulus than aluminum. In addition to steel (e.g., hardened steel), the sheath may also be made of other materials, such as high tensile modulus composite materials, such as carbon fibers, boron fibers, or ceramic fibers in a matrix such as a thermosetting polymer matrix, a thermoplastic polymer matrix, or a metal matrix. In one feature, the tensile strain sheath is made of a material with a tensile modulus of at least about 125 GPa, for example at least about 150 GPa, or even at least about 175 GPa.

[0038] Figure 5A and 5B An embodiment of the termination device of this disclosure is shown. The termination device 500 is configured to secure an overhead cable including a strength member and an electrical conductor (e.g., conductive stranded wire) arranged around the strength member. In general, the termination device includes a sheath (e.g., a steel sheath) operably surrounding the strength member of the overhead cable to reduce elongation strain on the strength member.

[0039] Please refer to Figure 5A and 5B The termination device 500 includes a connector 520 having a connector body 522 and fasteners 526. The connector body 522 defines an internal cylindrical chamber 524 for receiving a strength member 566 therein. Optionally, a steel sheath 510 having one or more slits 514 is placed on the strength member 566 such that the sheath 510 is arranged between the strength member 566 and the connector body 522. Figure 5A and 5B In the embodiment shown, the inner sleeve 532 (e.g., an aluminum sleeve that is softer than the connector body 522 and the sheath 510) is placed between the steel sheath 510 and the connector body 522.

[0040] Figure 5A The termination device 500 is shown in an uncrimped state, for example, before the connector body 522 is crimped onto the underlying aluminum inner sleeve 532, the steel sheath 510 with one or more slits 514, and the strength member 566. Before crimping, the connector body has an initial length l3. Figure 5B The termination device 500 is shown after the connector body 522 has been crimped onto the underlying component. The crimping process involves compressing a portion of the connector body 522 using a crimping tool, starting from the distal end of the connector body 522 (i.e., adjacent to the fastener 526) toward the opposite end, until the connector body 522 is crimped along its length onto the sleeve 532 and the sheath 510, for example as... Figure 5B As shown above. Figure 4B As in the illustrated embodiment, the connector body elongates to the extended length l4 due to crimping strain, as does the aluminum sleeve 532. However, the underlying steel sheath 510 substantially resists elongation and thus limits the elongation of the strength member 566, for example, to a point substantially below the point required for the strength member 566 to break. In one feature, the steel sheath 510 is formed of a harder steel than the steel used to form the connector body 522. In this configuration, the harder steel sheath is less likely to elongate during crimping. In another feature, additional elongation resistance can be achieved by increasing the cross-sectional area (e.g., wall thickness) of the steel sheath.

[0041] Figure 6A and 6B Another configuration of the termination device 600 of this disclosure is shown. This termination device includes a connector 620 having a connector body 622 and a fastener 626. The connector body 622 defines a cylindrical space 624 for receiving a strength member 666 therein. A steel sheath 610 having one or more slits 614 is arranged on the strength member 666 such that the steel sheath 610 is positioned between the strength member 666 and the connector body 622.

[0042] Figure 6A The termination device 600 is shown in an uncrimped state, for example, before the connector body 622 is crimped onto the underlying steel sheath 610 and the strength member 666. Before crimping, the connector body has an initial length l5. Figure 6B The termination device 600 is shown after the connector body 622 has been crimped onto the underlying component as described above. The connector body 622 elongates to the extended length l6 due to crimp strain. However, the underlying steel sheath 610 does not elongate to a considerable extent, thus preventing the strength member 666 from elongating to a point where it would break. Figure 6A and 6B The illustrated embodiments show that the inner aluminum sleeve (e.g.) Figure 5A The sleeve 532 in the middle is not necessary to adequately protect the strength member 666 from compression and elongation forces.

[0043] Please refer to Figures 7A to 7E An embodiment of a steel sheath 710 is shown, for example, a sheath that can be used in the termination devices shown in Figures 5 and 6. The sheath 710 has an outer diameter (d...). o ) and length (l7), and includes having an inner diameter (d) i The hole 712 is configured (e.g., its shape and size) to allow a strength member to be inserted into the hole 712, for example, through a first end 716a of a sleeve and out through a second end 716b of the sleeve. This inner diameter should be large enough to allow the strength member to be inserted through the hole 712 (e.g., with only moderate friction against the sidewalls of the hole). However, the diameter of the hole 712 should not be so large that the strength member can move axially within the hole when the one or more slits are nearly in contact (e.g., when closed). In one feature, the hole 712 has a diameter of at least about 2.5 mm. In another feature, the diameter of the hole is no greater than about 15 mm.

[0044] The outer diameter d of the sheath 710 o It should be large enough that the sheath can fit within the cylindrical space defined by the connector body, and between the sheath and the inner wall of the connector body or within the aluminum sleeve ( Figure 5A There are no obvious gaps. Figure 6A In one feature, the outer diameter d o It is at least approximately 5 millimeters. In another characteristic, the outer diameter d... o No larger than approximately 46 millimeters.

[0045] The length l7 of the sheath 710 should be sufficiently long to ensure that a sufficiently long strength member is arranged within the sheath to form adequate clamping on the strength member after crimping without any high stress concentration points. For example, the sheath 710 may have a length l7 of at least approximately 100 mm. Typically, the length l7 will not exceed approximately 300 mm. In another feature, the sheath 710 has an outer diameter d. o The length l7 is at least 10 times larger than the outer diameter, for example, at least about 15 times larger than the outer diameter, or at least about 20 times larger than the outer diameter. In another feature, the length is not greater than about 50 times the outer diameter, for example, not greater than about 40 times the outer diameter. However, smaller diameter strength members (e.g., strength members with a diameter of about 3 mm or less) may benefit from the use of a sheath 710 with a length close to or slightly greater than 50 times the outer diameter.

[0046] Sheath 710 also has a wall thickness, such as the outer diameter d of the sheath. o With inner diameter d i The difference between the two. The wall thickness of the sheath 710 should be sufficient to limit axial tension. In one feature, the wall thickness of the sheath 710 is at least about 3 mm. In another feature, the wall thickness of the sheath is no greater than about 20 mm. As mentioned above, increasing the wall thickness of the sheath can increase elongation resistance.

[0047] like Figures 7A to 7E As shown, the sheath 710 includes two longitudinally extending slits (e.g., slits 714a) arranged through a first end 716a of the sheath and extending toward a second end 716b of the sheath, but not through the second end 716b. These two slits are arranged, for example, at a radial angle of approximately 180° on opposite sides of the sheath 710. The sheath 710 also includes two slits (e.g., slits 714b) arranged through the second end 716b and extending toward the first end 716a of the sheath, but not through the first end 716a. These longitudinally extending slits advantageously allow the sheath 710 to accommodate variations in the diameter of the strength member and to resist axial tension, while providing minimal restriction on the closure of the sheath on the strength member during crimping. Although the sheath is shown as including four longitudinally extending slits, the sheath may include a single slit, two slits, three slits, or more slits. The inner surface of the sheath 710 (e.g., the surface of the hole 712) may be smooth, or it may have a surface texture to enhance the clamping of the sheath 710 onto the strength member. For example, the inner surface may have a frosted finish applied to the surface, or it may be machined to provide a surface texture, such as small ridges on the surface. Furthermore, although not shown, the sheath may taper slightly from one end to the other; for example, the outer diameter of the sheath may vary along the length of the sheath.

[0048] Figure 8A and8B A schematic cross-sectional view of the termination device 800 of this disclosure is shown before the outer sleeve 840 is arranged and crimped. Figure 8C and 8D The arrangement of the outer sleeve 840 is shown. Figure 8C ) and crimped outer sleeve 840 ( Figure 8D The following is a schematic cross-sectional view of the termination device 800. The termination device 800 includes a longitudinally extending steel sleeve 810 having a central sleeve hole therethrough, for example, passing through one end of the sleeve 816a to the opposite end 816b of the sleeve. In this way, the end of the strength member 864 is arranged within the sleeve 810.

[0049] Connector 820 (e.g., a steel connector) includes a fastener 826 disposed at a first end of connector 820 and a connector body 822 extending from the fastener 826 to a second end of connector 820. The second end of the connector includes an axial hole 824 configured (e.g., in its size and shape) to receive the end of a strength member 864. Thus, as Figure 8A As shown, a portion of the electrical conductor 862 of the cable 860 is stripped to expose the underlying strength member 864. The exposed strength member is then inserted into a sheath 810 positioned within the axial bore 824 of the connector 820. Figure 8B As shown, a portion 828 of the connector body 822 (e.g., the portion including the axial hole 824) is press-fitted (e.g., compressed, forged) onto the sheath 810, which is then compressed onto the strength member 864 to secure the connector 820 to the strength member 864.

[0050] like Figure 8C As shown, the outer tube 840 can then be placed... Figure 8B The termination device 800 is shown. After the outer sleeve 840 is in place on the termination device 800, the sleeve 840 can be crimped onto the sub-assembly and cable 860, as shown. Figure 8D As shown. The outer sleeve 840 is crimped in two locations, namely, the first portion 840a on the cable and the second portion 840b on the connector body 822.

[0051] As described above, the overhead cable 860 can be configured for power transmission and / or distribution when placed on a support tower (e.g., a tower). In one arrangement, the conductor 862 comprises one or more layers of aluminum stranded wire wound (e.g., spirally wound) around a strength member 864. In another arrangement, the strength member 864 comprises longitudinally extending reinforcing fibers (e.g., high-strength carbon fibers) located in an adhesive matrix (e.g., an epoxy resin or thermoplastic matrix).

[0052] Figures 9A to 9DAn alternative embodiment of the termination device of this disclosure is shown. Specifically, Figure 9A and 9B The perspective view and cross-sectional view of the termination device 900 before crimping are shown respectively. Figure 9C and 9D Cross-sectional and perspective views of the crimped termination device 900 are shown. The termination device 900 includes a longitudinally extending steel sleeve 910 having a central sleeve hole 912 extending therethrough (e.g., from one end 916a (e.g., the distal end) through the opposite end 916b (e.g., the proximal end) of the sleeve) and at least one or more slits. In this way, a portion 964b of the strength member 964 is arranged within the sleeve 910.

[0053] Connector 920 (e.g., a steel connector) includes a fastener 926 disposed at a first end of connector 920 and a connector body 922 extending from the fastener 926 to a second end of connector 920. The second end of the connector includes a notch 924 configured to receive one end of a strength member 964. A conductive outer sleeve 940 is disposed on a sheath 910, for example at a location where the outer sleeve 940 can be pressed against the sheath 910, for example for compressing the sheath 910 against the strength member 964. Figure 9C and 9D As shown, the outer sleeve 940 is crimped substantially along its entire length (e.g., at least about 80% or 90% of its length) such that the outer sleeve 940 is crimped onto the connector body 922 and, in addition to being crimped onto the sheath 910, also onto a portion of the overhead cable 960.

[0054] Example

[0055] To evaluate the effectiveness of the termination device of this disclosure, two overhead cables comprising fiber-reinforced composite strength members with a diameter of 7.11 mm were tested during the compression forging (e.g., crimping) of the terminal assembly onto the strength member. One of the termination devices is a prior art termination device (e.g., ...). Figures 4A-4B As shown), the second termination device includes a steel sheath (e.g., as shown). Figures 6A-6B (As shown).

[0056] To measure the strain on the strength members during crimping, a single optical fiber is arranged along the outer surface of each of the two strength members. For example... Figure 10 As shown, the optical fiber comprises six fiber Bragg gratings (FBGs), each approximately 7 mm long, evenly spaced at approximately 18 mm intervals, resulting in a center-to-center spacing of approximately 25 mm. The eyed bolts of the termination are press-fitted (crimped) onto the composite strength member, including the FBGs, using the same procedures and equipment as field attachment.

[0057] During the crimping process, strain measured by FBGs was continuously monitored. The FBGs were numbered sequentially as follows: FBG #6, closest to the eye bolt, was subjected to crimping force first, followed by FBG #5, and so on down to FBG #1. Typically, FBG #6 did not experience significant axial strain, while subsequent FBGs accumulated higher levels of axial strain. Modeling results for this arrangement indicate that significant plastic deformation also occurs with radial compression. If this axial deformation is not mitigated by slippage of the crimp metal on the composite strength member, the strain could be large enough to exceed the maximum elongation of the composite strength member, which is 1.9%.

[0058] The foregoing tests and analyses revealed that the end-joint device with a steel sheath disclosed in this invention significantly reduces axial strain while allowing full radial compression to clamp the composite strength member. Specifically, the peak strain in the standard assembly of the prior art reaches 1.2% in FBG#5, while the peak strain in the composite strength member protected by the steel sheath is reduced to 0.52%, which is also present in FBG#5.

[0059] While various embodiments of termination devices and methods for terminating overhead cables have been described in detail above, it will be apparent to those skilled in the art that various modifications and adjustments to these embodiments will occur. However, it should be clearly understood that such modifications and adjustments are within the spirit and scope of this disclosure.

Claims

1. A termination device for securing an overhead cable including a strength member and an electrical conductor arranged around the strength member, the termination device comprising: A steel connector includes a fastener disposed at a first end of the connector and a connector body extending from the fastener toward an end of the connector opposite the fastener, wherein the connector body includes a longitudinally extending internal chamber that can be accessed through a chamber inlet. The longitudinally extending sheath has a tensile modulus of at least about 125 GPa and includes a central hole extending through the entire length of the sheath, the central hole being configured to receive a strength member therein, wherein the internal cavity of the connector body is configured to operably receive the sheath therein when the termination device is assembled. as well as A conductive sleeve is configured to be disposed on (i) the end of the cable, (ii) the sheath, and (iii) at least a portion of the connector body when the termination device is operably assembled.

2. The termination device as claimed in claim 1, wherein the sheath is made of steel.

3. The termination device according to any one of claims 1 to 2, wherein the central hole has a substantially circular cross-section.

4. The termination device according to any one of claims 1 to 3, wherein the central hole has a substantially smooth hole surface.

5. The termination device according to any one of claims 1 to 3, wherein the central hole has a hole surface including a surface configuration configured to improve the clamping of the sheath on the strength member when the sheath is operably placed on the strength member.

6. The termination device of claim 5, wherein the surface texture is selected from surface sanding and surface scoring.

7. The termination device according to any one of claims 1 to 6, wherein the sheath has an outer diameter and a length, and wherein the length is at least 20 times larger than the outer diameter.

8. The termination device according to any one of claims 1 to 7, wherein the sheath has an outer diameter and a length, and wherein the length is not greater than approximately 30 times the outer diameter.

9. The termination device according to any one of claims 1 to 8, wherein the sheath includes at least one first longitudinal slit extending through a first end of the sheath and toward a second end of the sheath.

10. The termination device of claim 9, wherein the sheath includes at least one second longitudinal slit extending through a second end of the sheath and toward a first end of the sheath.

11. The termination device of claim 10, wherein the sheath includes at least one third longitudinal slit extending through a first end of the sheath and toward a second end of the sheath.

12. The termination device of claim 11, wherein the sheath includes at least one fourth longitudinal slit extending through a second end of the sheath and toward a first end of the sheath.

13. The termination device according to any one of claims 10 to 12, wherein the slits are arranged around the sheath in a substantially equidistant manner.

14. The termination device of claim 12, wherein the slits are arranged around the sheath at approximately 90 degrees between adjacent slits.

15. The termination device according to any one of claims 1 to 14, further comprising an aluminum sleeve configured to be disposed in an internal chamber and between the chamber wall and the sheath when the termination device is operably assembled.

16. The termination device according to any one of claims 1 to 15, wherein the conductive sleeve is configured to operably receive a sheath therein when the termination device is operably assembled.

17. The termination device according to any one of claims 1 to 16, wherein the conductive sleeve is made of aluminum.

18. A termination device fixed to an overhead cable, the overhead cable including a fiber-reinforced composite strength member and an electrical conductor arranged around the composite strength member, the termination device comprising: A steel connector includes a fastener disposed at a first end of the connector and a connector body extending from the fastener toward an end of the connector opposite to the fastener, wherein the connector body includes a longitudinally extending internal chamber that can be accessed through a chamber inlet at the end opposite to the fastener. A longitudinally extending sheath having a tensile modulus of at least about 125 GPa and including a central hole extending through the entire length of the sheath, the sheath being operably disposed on a portion of the strength member and compressed onto that portion to operably clamp the strength member. as well as A conductive sleeve is disposed on (i) the end of the cable, (ii) the sheath, and (iii) at least a portion of the connector body; The sheath is operably attached to the connector body in one of the following ways: (i) Arranged within the cavity of the connector body, thereby pressing the connector body against the sheath; or (ii) Arranged inside the conductive sleeve and pressed onto the sheath.

19. The termination device of claim 18, wherein the composite strength member comprises longitudinally extending reinforcing fibers in the adhesive matrix.

20. The termination device of claim 19, wherein the reinforcing fiber comprises fibers selected from the group consisting of carbon fiber, glass fiber, ceramic fiber, and combinations thereof.

21. The termination device of any one of claims 19 or 20, wherein the adhesive matrix comprises a material selected from epoxy resin, thermoplastic resin and metal.

22. The termination device according to any one of claims 18 to 21, wherein the sheath is formed of a material selected from the group consisting of steel and fiber-reinforced composite materials.

23. The termination device of any one of claims 18 to 22, wherein the sheath includes at least one first longitudinally extending slit that passes through a first end of the sheath and extends toward a second end of the sheath.

24. The termination device of claim 23, wherein the sheath includes at least one second longitudinally extending slit that passes through a second end of the sheath and extends toward a first end of the sheath.

25. The termination device of any one of claims 18 to 24, wherein the sheath is operatively attached to the connector body by being disposed within a cavity of the connector body and by pressing the connector body against the sheath.

26. The termination device of claim 25, wherein an aluminum sleeve is arranged between the connector body and the sheath.

27. The termination device of claim 25 or 26, wherein the connector body is pressed onto the sheath along the entire length of the sheath.

28. The termination device according to any one of claims 18 to 24, wherein the sheath is operatively attached to the connector body by being disposed within a conductive sleeve and by pressing the conductive sleeve against the steel sheath.

29. The termination device of claim 28, wherein the conductive sleeve is made of aluminum.

30. The termination device of claim 28 or 29, wherein the conductive sleeve is pressed onto the sheath substantially along the entire length of the sheath.

31. The termination device according to any one of claims 28 to 30, wherein the conductive sleeve is attached to the connector body by pressing the conductive sleeve onto the connector body.

32. The termination device according to any one of claims 18 to 31, wherein the termination device is fixed to an overhead cable.

33. The termination device according to any one of claims 18 to 32, wherein the composite strength member comprises a single strength member, the single strength member comprising reinforcing fibers in a plastic matrix.

34. A method for terminating an overhead cable comprising a fiber-reinforced composite strength member and an electrical conductor arranged around said composite strength member, employing the termination device as claimed in claim 1, the method comprising the following steps: Remove the electrical conductor from the termination end of the overhead cable to expose the end of the composite strength member; The exposed end of the composite strength member passes through the central hole arranged in the longitudinally extending steel sheath; The sheath is operably attached to a steel connector, the steel connector including a fastener disposed at a first end of the steel connector and a connector body extending from the fastener toward an end of the steel connector opposite to the fastener, the attachment comprising: The sheath is placed inside the cavity of the connector body, and the connector body is pressed onto the steel sheath.

35. The method of claim 34, wherein the composite strength member comprises longitudinally extending reinforcing fibers in a bonding matrix.

36. The method of claim 35, wherein the reinforcing fiber comprises fibers selected from the group consisting of carbon fibers, glass fibers, ceramic fibers, and combinations thereof.

37. The method of any one of claims 35 or 36, wherein the adhesive matrix comprises a material selected from the group consisting of epoxy resins, thermoplastic resins, and metals.

38. The method of any one of claims 34 to 37, wherein the steel sheath includes at least one first longitudinally extending slit that passes through a first end of the steel sheath and extends toward a second end of the steel sheath.

39. The method of claim 38, wherein the steel sheath includes at least one second longitudinally extending slit that passes through a second end of the steel sheath and extends toward a first end of the steel sheath.

40. The method according to any one of claims 34 to 39, wherein, An aluminum sleeve is placed between the connector body and the steel sheath before the connector body is pressed onto the steel sheath.

41. The method of any one of claims 34 or 40, wherein the connector body is pressed onto the steel sheath substantially along the entire length of the steel sheath.

42. The method of any one of claims 34 to 41, further comprising the steps of placing the conductive sleeve on the connector body and the steel sheath and pressing the conductive sleeve onto the connector body.

43. The method of claim 42, wherein the conductive sleeve is made of aluminum.

44. The method of any one of claims 34 to 43, wherein the composite strength member comprises a single strength member, the single strength member comprising reinforcing fibers in a plastic matrix.

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