A medium-voltage longitudinal water-blocking cable with a large cross-section and a preparation method thereof

Abstract

The present invention discloses a medium-voltage longitudinal water-blocking cable with a large cross-section and a preparation method thereof. The cable includes a conductor, a conductor shield, an insulation layer, a non-metallic insulation shield, a metal shielding layer, an inner sheath, and an outer sheath from the inside to the outside. The conductor is a multi-layer tightly compressed stranded wire conductor, and a water-blocking tape is filled and wrapped between each layer of the stranded wire conductor; the materials of the inner sheath and the outer sheath are both high-density polyethylene. The structure of the present invention is more compact, simple, and lightweight, thus solving the longitudinal water-blocking requirement of the stranded conductor, while having good anti-overload and large short-circuit current withstand capabilities, and being conducive to the vulcanization and sealing connection of matching connectors or joints.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and in particular to a large cross-section medium voltage longitudinally water-blocking cable and a preparation method thereof. Background Art

[0002] With the in-depth development of the ocean by humans, the exploitation of seabed resources and the construction of seabed projects all require the use of large-scale seabed engineering equipment. The current water-tight cables used for conventional exploration have too small current-carrying capacity to meet the power supply requirements of large-scale underwater engineering equipment. Therefore, a cable with a large capacity is needed to supply power to it. At the same time, when this cable meets the power supply requirements, it needs to have a relatively large cross-section metal shielding layer, and even the metal shielding cross-section is equal to the cross-section of the current-carrying conductor, so as to have a relatively large short-circuit current-carrying capacity without damaging the cable when a short circuit occurs. In addition, in some low-elevation countries or regions, the average elevation is below sea level or the local groundwater immerses the cable for a long time, resulting in the cable being prone to water ingress. At present, most longitudinally water-blocking cables can meet the conductor water-blocking requirements under low water pressure conditions, but cannot meet the longitudinal water-blocking requirements under deep water medium voltage conditions. Summary of the Invention

[0003] The purpose of the present invention is to provide a large cross-section medium voltage longitudinally water-blocking cable and a preparation method thereof for the deficiencies of the prior art, which have a relatively large short-circuit current-carrying capacity and excellent longitudinal water-blocking performance at the same time.

[0004] The technical solution to achieve the purpose of the present invention is:

[0005] A large cross-section medium voltage longitudinally water-blocking cable includes a conductor, a conductor shield, an insulation, a non-metallic insulation shield, a metal shielding layer, an inner sheath and an outer sheath from inside to outside. The conductor is a multi-layer tightly compressed stranded wire conductor, and a water-blocking tape is filled and wound between each layer of stranded wire conductors; the materials of the inner sheath and the outer sheath are both high-density polyethylene.

[0006] Further, the conductor is formed by tightly compressing and stranding multiple trapezoidal copper wires around a circular copper single wire or a carbon fiber rod as the center, and the trapezoidal copper wires in adjacent layers are staggered; a water-blocking tape is filled between the trapezoidal copper wires.

[0007] Further, the metal shielding layer is a copper wire loosely wound shielding layer with a sealing paste filled in the gap, and the main component of the sealing paste is a silicon component with a water-blocking and sealing function.

[0008] Further, the single wire of the copper wire loosely wound shielding layer is a flat copper wire.

[0009] Further, a longitudinally wrapped aluminum-plastic composite tape layer is provided between the inner sheath and the outer sheath.

[0010] A method for manufacturing a medium-voltage longitudinally water-blocking cable with a large cross-section as described above, comprising the following steps:

[0011] Step 1: Prepare a multi-layer tightly compacted stranded conductor, and fill water-blocking tapes between each layer and the single wires of adjacent conductors;

[0012] Step 2: Extrude a conductor shield, insulation, and a non-metallic insulation shield in a three-layer co-extrusion manner outside the multi-layer tightly compacted stranded conductor to form a cable core;

[0013] Step 3: Wind a metal shield layer around the cable core using a flat copper wire loose winding device;

[0014] Step 4: Extrude a layer of high-density polyethylene material outside the metal shield layer to form an inner sheath by an extrusion process, and at the same time add a longitudinally wrapped aluminum-plastic composite tape layer outside, and then extrude another layer of high-density polyethylene material to form an outer sheath, thereby forming a comprehensive water-blocking sheath.

[0015] Further, in the above Step 3, the wire feeding device of the flat copper wire loose winding device adopts a wire feeding device with adjustable angle.

[0016] Further, in the above Step 4, the extrusion unit of the extrusion process includes an extrusion machine main body and an extrusion head fixedly installed at the output end of the extrusion machine main body. A first-stage cooling water tank is provided at the output end of the extrusion head along the extrusion direction. A sealed pressurized outer shell filled with compressed air at 0.8 Mpa is provided outside the first-stage cooling water tank. A vacuum pumping die hole and a vacuum pumping device with a pipeline are sequentially connected at the wire inlet of the extrusion head (10).

[0017] Adopting the above technical solutions, the present invention has the following beneficial effects:

[0018] (1) The conductor of the present invention adopts a multi-layer tightly compacted stranded conductor, and water-blocking tapes are filled and wound between each layer of the stranded conductor, so the structure is more compact, thus solving the longitudinal water-blocking requirement of the stranded conductor; by providing a conductor shield, insulation, a non-metallic insulation shield outside the conductor and winding a metal shield layer, the cable has good anti-overload and large short-circuit current bearing capacity; by providing inner and outer sheaths of high-density polyethylene materials, it effectively prevents water from penetrating along the radial direction of the cable. At the same time, the outer surface of the conventional submarine cable is wound with PP ropes and is not smooth. The outer surface of the sheath of the cable of the present invention is smooth and flat, and when connected to underwater equipment, it is easy to ensure the sealing performance of the joint, which is beneficial to the vulcanized sealing connection of supporting connectors or joints; the entire cable structure is more concise and lightweight than general submarine cables.

[0019] (2) The conductor of the present invention is formed by taking a round copper single wire or a carbon fiber rod as the center and multiple trapezoidal copper single wires are spirally wound around the round copper single wire in a staggered and layered manner and tightly pressed and stranded, thereby reducing the stranding gap of the conductor and further ensuring a tight structure; by filling a water-blocking tape between the trapezoidal copper single wires, the filling coefficient of the conductor is larger than that of the traditional tightly pressed conductor and reaches more than 95%, which can prevent water from diffusing longitudinally along the conductor under a pressure of 1 Mpa; when the cable is used for power supply of underwater operation equipment and the power source is on the shore, offshore platform or ship, according to the actual use occasion, if it is used horizontally with a small drop, a round copper single wire is used as the center, and if it is used vertically with a large drop, a carbon fiber rod is used as the center to enhance the vertical tensile strength of the cable.

[0020] (3) The metal shielding layer of the present invention is a copper wire loosely wound shielding layer with a sealing paste filled in the gap. The sealing paste is used to fill the gap of the copper wire winding, so that the cable meets the longitudinal watertightness under medium and high water pressure.

[0021] (4) The single wire of the copper wire loosely wound shielding layer of the present invention is a flat copper wire, which increases the adhesion between the non-metallic insulation shielding and the metal shielding layer, maximizes the stability of the contact surface between the copper wire and the non-metallic insulation shielding, effectively solves the problem that the round copper wire is easy to slip on the smooth outer screen surface, and improves the stability and tightness of the overall structure.

[0022] (5) A longitudinally wrapped aluminum-plastic composite tape layer is provided between the inner sheath and the outer sheath of the present invention, which effectively protects the inner sheath. At the same time, the combination of the longitudinally wrapped aluminum-plastic composite tape and the high-density polyethylene sheath can also effectively prevent water from penetrating radially along the cable and improve the watertight performance of the cable.

[0023] (6) In the preparation method of the present invention, a water-blocking tape is filled between each layer and the single wires of the adjacent conductor, thereby solving the longitudinal water-blocking requirement of the stranded conductor. The conductor shielding, insulation and non-metallic insulation shielding are extruded by a three-layer co-extrusion method, making the overall structure more compact. At the same time, a flat copper wire loose winding device is used to improve the production efficiency, and an extrusion extrusion process is adopted to form a sealed space between the metal shielding layer and the inner sheath, effectively preventing water from penetrating longitudinally along the cable, thereby ensuring the longitudinal water-blocking requirement of the loose winding structure of the cable metal shielding layer, enabling the cable to meet the longitudinal watertight sealing requirement of 100 meters underwater, and meeting the requirement when the longitudinal water tightness of the cable reaches below 1 Mpa of water pressure. At the same time, the whole cable assembly is more tightly bonded, more reliable and has a longer service life.

[0024] (7) In the preparation method of the present invention, the wire feeding device of the flat copper wire loose winding device adopts a wire feeding device with adjustable angle, which effectively prevents the flat copper wire from turning over, is convenient for loose winding the metal shielding layer at the same time, and improves the loose winding efficiency.

[0025] (8) The extrusion process in the preparation method of the present invention, by installing a sealed pressurized outer shell outside the first-stage cooling water tank in front of the extrusion head, makes the high-density polyethylene sheath in a sealed state after leaving the extrusion die and the first-stage cooling water tank, and fills the sealed pressurized outer shell with compressed air at 0.8 Mpa, so that the high-density polyethylene inner sheath is closely attached to the loosely wound copper wire metal shield and the non-metallic insulation shield at the place where the inner sheath is not covered by the loosely wound copper wire, discharges the gaps therebetween, forms a sealed space, thereby effectively preventing water from penetrating longitudinally along the cable and meeting the longitudinal water-blocking requirements of the cable with a loosely wound copper wire structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to make the content of the present invention easier to be clearly understood, the following further details the present invention according to specific embodiments in conjunction with the drawings, where:

[0027] Figure 1 is a schematic structural diagram of the cable of the present invention;

[0028] Figure 2 is a schematic structural diagram of the extrusion unit of the present invention.

[0029] The reference numerals in the drawings are:

[0030] Conductor 1, Conductor Shield 2, Insulation 3, Non-Metallic Insulation Shield 4, Metal Shield Layer 5, Inner Sheath 6, Outer Sheath 7, Longitudinally Wrapped Aluminum-Plastic Composite Tape Layer 8, Extrusion Machine Main Body 9, Extrusion Head 10, First-Stage Cooling Water Tank 11, Sealed Pressurized Outer Shell 12, Sealed Shell 12-1, Sealed Shell Outlet Box 12-2, Air Compressor 12-3, Vacuum Pump 13, Vacuum Exhaust Die Hole 14. SPECIFIC EMBODIMENTS

[0031] In order to better understand the above technical solutions, the following will detail the above technical solutions in conjunction with the drawings of the specification and specific embodiments.

[0032] (Example 1)

[0033] As Figure 1The shown medium-voltage longitudinal water-blocking cable with a large cross-section includes a conductor 1, a conductor shield 2, an insulation 3, a non-metallic insulation shield 4, a metal shielding layer 5, an inner sheath 6, and an outer sheath 7 from the inside to the outside. By arranging the conductor shield 2, the insulation 3, and the non-metallic insulation shield 4 outside the conductor and winding the metal shielding layer 5, the cable has good anti-overload and large short-circuit current-carrying capabilities. The conductor 1 is a multi-layer tightly compressed stranded wire conductor, and a water-blocking tape is filled and wound between each layer of the stranded wire conductor, thereby solving the longitudinal water-blocking requirement of the stranded conductor; the materials of the inner sheath 6 and the outer sheath 7 are both high-density polyethylene, effectively preventing water from penetrating along the radial direction of the cable. At the same time, the outside of a conventional submarine cable is wound with PP ropes and the surface is not smooth. The outer surface of the sheath of the cable of the present invention is smooth and flat. When connected to underwater equipment, it is easy to ensure the sealing performance of the joint, which is beneficial to the vulcanized sealing connection of the supporting connector or joint. The entire cable structure of this embodiment is more concise and lightweight than a general submarine cable.

[0034] Specifically, the conductor 1 is formed by tightly compressing and stranding with a circular copper single wire as the center and multiple trapezoidal copper single wires layered around the circular copper single wire. In this embodiment, there are two layers of trapezoidal copper single wires outside the central circular copper single wire, thereby reducing the stranding gap of the conductor and further ensuring a tight structure. The first layer has five trapezoidal copper single wires, and the second layer has eight trapezoidal copper single wires, so as to ensure that each trapezoidal copper single wire in the second layer is misaligned with the trapezoidal copper single wires in the first layer. At the same time, a water-blocking tape is filled between each trapezoidal copper single wire, so that the filling coefficient of the conductor is larger than that of a traditional tightly compressed conductor and reaches more than 95%, and it can prevent moisture from diffusing longitudinally along the conductor under a pressure of 1 Mpa.

[0035] The metal shielding layer 5 is a copper wire loosely wound shielding layer with a sealing paste filled in the gaps. The main component of the sealing paste is a silicon component with a water-blocking and sealing effect, so that the cable meets the longitudinal watertightness under medium and high water pressures. It should be noted that the sealing paste should not be excessive. It is fluid and can fill the gaps between the single wires to prevent it from being extruded in subsequent processes. The single wires of the copper wire loosely wound shielding layer are flat copper wires, which increases the conformability between the non-metallic insulation shield 4 and the metal shielding layer 5, maximizes the stability of the contact surface between the copper wires and the non-metallic insulation shield 4, effectively solves the problem that round copper wires are prone to slipping on the smooth outer screen surface, and improves the stability and tightness of the overall structure.

[0036] In order to further improve the watertight performance of the cable, a longitudinally wrapped aluminum-plastic composite tape layer 8 is provided between the inner sheath 6 and the outer sheath 7 of this embodiment, which effectively protects the inner sheath 6. At the same time, the combination of the longitudinally wrapped aluminum-plastic composite tape layer 8 and the high-density polyethylene sheath can also effectively prevent moisture from penetrating along the radial direction of the cable and improve the radial watertightness.

[0037] The preparation method of the medium-voltage longitudinal water-blocking cable with a large cross-section of this embodiment includes the following steps:

[0038] Step 1: Prepare a multi-layer tightly compressed stranded conductor, and fill water-blocking tapes between each layer and the single wires of adjacent conductors.

[0039] Step 2: Extrude a conductor shield 2, an insulation 3, and a non-metallic insulation shield 4 in a three-layer co-extrusion manner outside the multi-layer tightly compressed stranded conductor to form a cable core.

[0040] Step 3: Wind a metal shield layer 5 around the cable core using a flat copper wire loose winding device. The wire pay-off device of the flat copper wire loose winding device uses an angle-adjustable wire pay-off device to prevent the flat copper wire from flipping, which facilitates the loose winding of the metal shield layer 5 and improves the loose winding efficiency at the same time.

[0041] Step 4: Extrude a layer of high-density polyethylene material outside the metal shield layer 5 to form an inner sheath 6. At the same time, add a longitudinally wrapped aluminum-plastic composite tape layer 8 on the outside, and then extrude a layer of high-density polyethylene material to form an outer sheath 7, thereby forming a comprehensive water-blocking sheath.

[0042] As Figure 2 shown, the extrusion unit of the extrusion process includes an extrusion machine main body 9 and an extrusion head 10 fixedly installed at the output end of the extrusion machine main body 9. A first-stage cooling water tank 11 is provided at the output end of the extrusion head 10 along the extrusion direction. A sealed pressurized outer shell 12 is provided outside the first-stage cooling water tank 11. The sealed pressurized outer shell includes a sealing shell 12-1 covering the outside of the first-stage cooling water tank 11 and a sealing shell outlet box 12-2 located at the right end of the sealing shell 12-1. The right end of the first-stage cooling water tank 11 extends into the sealing shell outlet box 12-2. An air compressor 12-3 connected to the sealing shell 12-1 is also provided on one side of the left end of the sealing shell 12-1 for filling 0.8 Mpa of compressed air into the sealing shell 12-1. A vacuum extraction die hole 14 and a vacuum extraction pump 13 with a pipeline are sequentially connected at the wire inlet of the extrusion head 10. The vacuum extraction pump 13 generates a negative pressure of 0.5 Mpa, and the vacuum extraction die hole 14 helps to discharge the air between the wire core and the sheath. Using the extrusion process of this embodiment, the high-density polyethylene sheath is in a sealed state after leaving the extrusion die of the extrusion machine and the first-stage cooling water tank 11, and 0.8 Mpa of compressed air is filled in the sealed pressurized outer shell, so that the high-density polyethylene inner sheath is closely attached to the loose-wound copper wire metal shield and between the inner sheath and the non-metallic insulation shield where the loose-wound copper wire is not covered, discharging the voids therebetween to form a sealed space, thereby effectively preventing water from penetrating longitudinally along the cable and meeting the longitudinal water-blocking requirements of the cable with a loose-wound copper wire structure.

[0043] The preparation method of this embodiment solves the longitudinal water-blocking requirement of the stranded conductor by filling a water-blocking tape between each layer and the single wires of the adjacent conductor. The conductor shield, insulation, and non-metallic insulation shield are extruded in a three-layer co-extrusion manner, making the overall structure more compact. At the same time, a flat copper wire loose winding device is used to improve production efficiency, and an extrusion extrusion process is adopted to form a sealed space between the metal shield layer and the inner sheath, effectively preventing water from penetrating longitudinally along the cable, thereby ensuring the longitudinal water-blocking requirement of the loose winding structure of the cable metal shield layer, enabling the cable to meet the longitudinal watertight sealing requirement of 100 meters underwater, and can meet the requirement when the longitudinal water pressure of the cable is below 1 MPa. At the same time, the entire cable assembly is more tightly bonded, has higher reliability, and a longer service life. For the traditional large-section copper wire loose winding shield with longitudinal water-blocking, due to the large cross-section of the copper wire loose winding, the gap between the loose winding copper wires is too large, that is, the gap between the metal shield layer 5 and the inner sheath 6 is too large, and conventional means cannot solve the problem of longitudinal water-blocking at the copper wire loose winding, and it is difficult to meet the longitudinal water-blocking requirement. The design of the cable in this embodiment can effectively solve the longitudinal water-blocking between the copper wire shields on the premise of meeting the longitudinal water-blocking of the conductor.

[0044] (Embodiment 2)

[0045] The structure of this embodiment is similar to that of Embodiment 1, except that the conductor 1 is tightly pressed and stranded with a carbon fiber rod as the center and multiple trapezoidal copper single wires misaligned and layered around the outside of the circular copper single wire. The cable of this embodiment is mainly used for power supply of underwater operation equipment, and the power supply is on the shore, offshore platform or ship. When used vertically with a large drop, using a carbon fiber rod as the center can enhance the vertical tensile strength of the cable to meet the use requirements.

[0046] The specific embodiments described above have further elaborated on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A medium-voltage longitudinal water-blocking cable with a large cross-section, characterized in that: It includes a conductor (1) from the inside to the outside, a conductor shield (2), insulation (3), a non-metallic insulation shield (4), a metal shielding layer (5), an inner sheath (6) and an outer sheath (7). The conductor (1) is a multi-layer tightly compressed stranded wire conductor, and a water-blocking tape is filled and wrapped between each layer of the stranded wire conductors; the materials of the inner sheath (6) and the outer sheath (7) are both high-density polyethylene; the metal shielding layer (5) is a copper wire loosely wound shielding layer with a sealing paste filled in the gaps, and the single wire of the copper wire loosely wound shielding layer is a flat copper wire. The inner sheath (6) is produced by an extrusion process to form a sealed space between the metal shielding layer and the inner sheath; the conductor (1) is tightly compressed and stranded with a circular copper single wire or a carbon fiber rod as the center and multiple trapezoidal copper single wires layered around the circular copper single wire, and the trapezoidal copper single wires in adjacent layers are staggered; a water-blocking tape is filled between the trapezoidal copper single wires; a longitudinally wrapped aluminum-plastic composite tape layer (8) is provided between the inner sheath (6) and the outer sheath (7); the preparation method of the cable is as follows: Step 1: Prepare a multi-layer tightly compressed stranded wire conductor, and fill a water-blocking tape between each layer and between the single wires of adjacent conductors; Step 2: Extrude the conductor shield (2), insulation (3) and non-metallic insulation shield (4) on the multi-layer tightly compressed stranded wire conductor by a three-layer co-extrusion method to form a cable core; Step 3: Wind the metal shielding layer (5) around the cable core by using a flat copper wire loose winding device; Step 4: Extrude a layer of high-density polyethylene material on the metal shielding layer (5) by an extrusion process to form an inner sheath (6), and at the same time add a longitudinally wrapped aluminum-plastic composite tape layer (8) on the outside, and then extrude a layer of high-density polyethylene material to form an outer sheath (7), so as to form a comprehensive water-blocking sheath; the extrusion unit of the extrusion process includes an extrusion machine main body (9) and an extrusion head (10) fixedly installed at the output end of the extrusion machine main body (9). A first-stage cooling water tank (11) is provided at the output end of the extrusion head (10) along the extrusion direction, and a sealed pressurized outer shell (12) filled with compressed air at 0.8 Mpa is provided outside the first-stage cooling water tank (11). A vacuum pumping die hole (14) and a vacuum pump (13) with a pipeline are sequentially connected at the inlet of the extrusion head (10).

2. A method for manufacturing a medium-voltage longitudinal water-blocking cable with a large cross-section as claimed in claim 1, characterized in that, It includes the following steps: Step 1: Prepare a multi-layer tightly compressed stranded wire conductor, and fill a water-blocking tape between each layer and between the single wires of adjacent conductors; Step 2: Extrude the conductor shield (2), insulation (3) and non-metallic insulation shield (4) on the multi-layer tightly compressed stranded wire conductor by a three-layer co-extrusion method to form a cable core; Step 3: Wind the metal shielding layer (5) around the cable core by using a flat copper wire loose winding device; Step 4: Extrude a layer of high-density polyethylene material outside the metal shielding layer (5) to form an inner sheath (6) by means of an extrusion process. At the same time, add a longitudinally wrapped aluminum-plastic composite tape layer (8) on the outside, and then extrude a layer of high-density polyethylene material to form an outer sheath (7), thereby forming a comprehensive water-blocking sheath; the extrusion unit of the extrusion process includes a main extrusion machine (9) and an extrusion head (10) fixedly installed at the output end of the main extrusion machine (9). A first-stage cooling water tank (11) is arranged at the output end of the extrusion head (10) along the extrusion direction. A sealed pressurized outer shell (12) filled with compressed air at 0.8 Mpa is arranged outside the first-stage cooling water tank (11). A vacuum extraction die hole (14) and a vacuum extraction pump (13) with a pipeline are sequentially connected at the wire inlet of the extrusion head (10).

3. The preparation method of a large cross-section medium-voltage longitudinally water-blocking cable according to claim 2, wherein: In the said Step 3, the wire pay-off device of the flat copper wire winding equipment adopts a wire pay-off device with adjustable angle.

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