A 110kV power cable and its manufacturing process

Abstract

This invention relates to the field of cable manufacturing, and more particularly to a 110kV power cable and its manufacturing process. The cable comprises a conductor formed by hinged joints of several conductive cores. The conductor surface is covered with an insulation layer, and the insulation layer is covered with an inner sheath. Annular temperature-regulating shells are linearly arrayed on the surface of the inner sheath. Annular mounting shells are symmetrically fixed to both sides of the annular temperature-regulating shells, with a gap between the annular mounting shells and the inner sheath. The bottom of the annular mounting shells has linearly arrayed slots. This invention, by incorporating annular temperature-regulating shells, annular heat-conducting plates, an air chamber, a compression cylinder, and a piston block, allows for the following process: when the cable heating piston moves upward, hot air from the upper part of the first chamber is discharged, and hot air from the cable gap is drawn in from the lower part. When the cable cooling piston moves downward, the cooled air from the lower part is discharged back to the cable surface, and cold air from the outside is drawn in from the upper part. This process relies entirely on the cable's own Joule heat as a power source, achieving autonomous temperature regulation of the cable and extending the thermal aging life of the insulation material.

Description

Technical Field

[0001] This invention relates to the field of cable manufacturing, and more particularly to a 110kV power cable and its manufacturing process. Background Technology

[0002] As a key component of urban power transmission networks and large-scale industrial power supply, 110kV power cables directly affect the reliability of power supply due to their current carrying capacity and operational stability. These cables typically consist of multiple layers, including a conductive core, conductor shielding layer, insulation layer, insulating shielding layer, inner sheath, metallic armor layer, and outer sheath.

[0003] In the existing technology, the following shortcomings still exist for power cables: For example, under normal operating conditions, the current passing through the conductive core will generate Joule heat, and the insulation dielectric loss under the alternating electric field will also cause the internal temperature of the cable to rise. However, with the continuous growth of the power grid load, the cable is in a high current-carrying or even overloaded operating state for a long time, which can easily lead to a significant increase in operating temperature, which is not conducive to long-term use.

[0004] Therefore, this invention proposes a 110kV power cable and its manufacturing process to solve the above problems. Summary of the Invention

[0005] Firstly, to achieve the above objectives, the technical solution adopted by the present invention is as follows: a 110kV power cable, comprising: a conductor formed by hinged connection of several conductive cores, the surface of the conductor being covered with an insulation layer, the surface of the insulation layer being covered with an inner sheath, annular temperature regulating shells being linearly arranged on the surface of the inner sheath, annular mounting shells being symmetrically fixedly connected to both sides of the annular temperature regulating shells, a gap being left between the annular mounting shells and the inner sheath, and slots being linearly arranged at the bottom end of the annular mounting shells; A waterproof layer is provided on the annular mounting shell between two annular temperature-regulating shells, and the outer wall of the waterproof layer is flush with the outer wall of the annular temperature-regulating shell. An outer protective sleeve is disposed on the surface of the waterproof layer; Several first chambers are arrayed within an annular temperature-regulating shell. A first piston plate is slidably connected to the first chamber. A first exhaust pipe and a first intake pipe are symmetrically fixed and connected to both sides of the first chamber above the first piston plate. The first exhaust pipe and the first intake pipe are connected to the annular mounting shell. A second exhaust pipe and a second intake pipe are symmetrically fixed and connected to the bottom end of the first chamber. The pushing component pushes the first piston plate upward when the temperature of the inner sheath rises, and drives the first piston plate downward when the temperature drops.

[0006] Preferably, the pushing component includes an annular heat-conducting plate disposed on the surface of the inner sheath. Several air chambers are fixedly connected to the surface of the annular heat-conducting plate in an array. The air chambers are filled with inert gas. A compression cylinder is fixedly connected to the top of the air chamber. The top of the compression cylinder is fixedly connected to an annular temperature-regulating shell. A piston block is slidably connected inside the compression cylinder. The top of the rod of the piston block penetrates the inner wall of the annular temperature-regulating shell and is fixedly connected to a first piston plate.

[0007] Preferred options also include: Several second chambers are arrayed within an annular temperature-regulating shell and located between two first chambers respectively. Second piston plates are symmetrically and slidably connected within the several second chambers. A first spring is fixedly connected between the second piston plates and the second chambers. Flame retardant is filled within the second chambers. Two drain pipes, with their ends respectively fixedly connected to the second chamber and the annular mounting shell; The limiting component is used to limit the elastic reset of the first spring when the cable temperature does not exceed the threshold. When the cable temperature exceeds the threshold, the limiting component releases the limiting on the second piston plate. Under the action of the first spring, the second piston plate compresses the flame retardant in the second chamber.

[0008] Preferably, the limiting component includes: A first locking block and a second locking block are slidably connected to the side wall of the second piston plate, and a second spring is fixedly connected between the first locking block and the second piston plate; The second chamber has a slot on its side wall that communicates with the first chamber, and the first locking block is located in the slot. The second locking block is slidably connected to the side wall of the first piston plate, and a third spring is fixedly connected between the second locking block and the first piston plate.

[0009] Preferably, a first one-way valve and a second one-way valve are respectively provided in the first exhaust pipe and the first intake pipe, and a third one-way valve and a fourth one-way valve are respectively provided in the second exhaust pipe and the second intake pipe.

[0010] Preferably, it also includes a metal container disposed inside the second air intake pipe, the metal container being filled with paraffin wax.

[0011] Preferably, a fifth one-way valve is provided inside the drain pipe.

[0012] Preferably, a mesh is provided inside the slot, which allows gas to pass through.

[0013] Preferably, the annular mounting shell, the annular temperature regulating shell, and the annular heat-conducting plate are all assembled from two semi-annular shells.

[0014] Secondly, this invention also proposes a process for manufacturing kV power cables, including the following steps: Step 1: Concentrically strand multiple metal conductive wire cores using a frame stranding machine to form a round, tightly compressed conductor; Step 2: The conductor insulation layer is extruded sequentially over the conductor, and then the inner sheath is extruded over the insulation layer. The sheath is then cross-linked and cooled through a continuous vulcanization pipeline. Step 3: Assemble the annular mounting shell, annular temperature regulating shell, and annular heat-conducting fin onto the inner sheath using snaps or bolts; Step 4: Wrap a double layer of water-blocking tape around the outer surface of the annular mounting shell between two adjacent annular temperature-regulating shells and apply a hot-melt waterproof adhesive to form a waterproof layer.

[0015] Step 5: Use heat and rolling to make the outer wall of the waterproof layer flush with the outer wall of the annular temperature regulating shell, and use a scraper to trim excess material to ensure a smooth and continuous surface; Step 6: Pass the cable continuously through the extruder head to extrude the outer protective sleeve. Control the extruder head temperature, screw speed and traction speed during extrusion to ensure that the outer protective sleeve tightly covers the waterproof layer and the outer surface of the annular temperature regulating shell, forming a complete outer sheath. Step 7: Test the prepared cable.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention, by setting up an annular temperature regulating shell, an annular heat-conducting plate, a gas chamber, a compression cylinder, and a piston block, allows the inert gas to expand and drive the piston upward when the cable heats up, expelling the hot air from the upper part of the first chamber and drawing in the hot air from the gap between the cables. When the cable cools down, the piston moves downward, expelling the cooled air from the lower part back to the cable surface and drawing in cold air from the outside. This process relies entirely on the Joule heat of the cable itself as a power source, enabling autonomous regulation of the cable temperature and extending the thermal aging life of the insulation material.

[0017] This invention uses a metal container filled with paraffin wax. As the piston moves upward to draw in hot air from the cable gap, the hot airflow first flows over the surface of the metal container and undergoes forced heat exchange with the paraffin wax inside. The paraffin wax absorbs heat and melts, making the temperature of the air entering the lower part of the first chamber significantly lower than the temperature of the cable surface. When the piston moves downward, the pre-cooled air is discharged back into the cable, thereby further improving the heat dissipation effect.

[0018] This invention, by setting up a second chamber, a second piston plate, a first spring, and a drain pipe, allows the first piston plate to move up to its highest position when the cable temperature exceeds a threshold due to overload or external fire. The second locking block is pushed into the locking slot and pushes out the first locking block, releasing the restriction on the second piston plate. The first spring instantly releases its stored energy, spraying flame retardant onto the heating surface through the drain pipe, the annular mounting shell, and the slot, thus suppressing any possible internal electric arc or external fire spreading to the cable.

[0019] This invention utilizes a mesh membrane. When the temperature threshold is not exceeded, the mesh membrane remains intact, allowing cooling gas to pass through and diffuse evenly onto the inner sheath surface, preventing localized hot spots. When localized combustion occurs or the temperature rises sharply beyond the mesh membrane's tolerance temperature, the mesh membrane near the ignition point preferentially melts or burns, allowing the flame retardant sprayed from the second chamber to flow out from the damaged area and quickly cover the core area of ​​the fire source. This avoids the flame retardant being diluted and diverted by unignited areas, thereby improving fire extinguishing efficiency. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the present invention. Figure 1 ; Figure 2 This is a schematic diagram of the overall structure of the present invention. Figure 2 (Hidden waterproof layer and outer protective cover); Figure 3 This is a schematic diagram showing the connection between the annular temperature regulating shell and the annular mounting shell of the present invention; Figure 4 This is a schematic diagram showing the connection between the annular temperature-regulating shell and the annular heat-conducting sheet in this invention; Figure 5 This is a first cross-sectional view of the annular temperature-regulating shell in this invention; Figure 6 This is a second cross-sectional view of the annular temperature-regulating shell in this invention; Figure 7 This is a schematic diagram showing the connection between the first piston plate and the second locking block in this invention; Figure 8 This is a schematic diagram showing the connection between the second piston plate and the first snap-fit ​​block in this invention; Figure 9 This is a flowchart of the cable manufacturing process in this invention.

[0021] In the diagram: 1. Wire; 2. Insulation layer; 3. Inner sheath; 4. Waterproof layer; 5. Outer protective sheath; 6. Annular temperature regulating shell; 7. Annular mounting shell; 8. Groove; 9. First chamber; 10. First piston plate; 11. Second locking block; 12. Third spring; 13. First exhaust pipe; 14. First one-way valve; 1401. First air inlet pipe; 15. Second one-way valve; 1501. Second exhaust pipe; 16. Third one-way valve; 1601. Second air inlet pipe; 17. Fourth one-way valve; 1701. Metal container; 1702. Annular heat-conducting plate; 18. Air chamber; 19. Compression cylinder; 20. Piston block; 21. Second chamber; 22. Second piston plate; 23. First spring; 24. First locking block; 25. Second spring; 25. Locking groove; 27. Drain pipe; 28. Fifth one-way valve; 2801. Detailed Implementation

[0022] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0023] Firstly, such as Figures 1 to 9 The 110kV power cable shown includes: A conductor 1 is formed by hinged joints of several conductive cores. The surface of the conductor 1 is covered with an insulating layer 2. The surface of the insulating layer 2 is covered with an inner sheath 3. Annular temperature-regulating shells 6 are linearly arranged on the surface of the inner sheath 3. Annular mounting shells 7 are symmetrically fixed to both sides of the annular temperature-regulating shells 6. A gap is left between the annular mounting shells 7 and the inner sheath 3. The bottom of the annular mounting shells 7 has slots 8 linearly arranged. A waterproof layer 4 is set on the annular mounting shell 7 between two annular temperature-regulating shells 6. The outer wall of the waterproof layer 4 is flush with the outer wall of the annular temperature-regulating shell 6. An outer protective sleeve 5 is set on the surface of the waterproof layer 4. Several first chambers 10 are arrayed within an annular temperature-regulating shell 6. A first piston plate 11 is slidably connected to each first chamber 10. A first exhaust pipe 14 and a first intake pipe 15 are symmetrically fixed and connected to both sides of the first chamber 10 above the first piston plate 11. The first exhaust pipe 14 and the first intake pipe 15 are connected to the annular mounting shell 7. A second exhaust pipe 16 and a second intake pipe 17 are symmetrically fixed and connected to the bottom end of the first chamber 10. The push component pushes the first piston plate 11 to move upward when the temperature of the inner sheath 3 rises, and drives the first piston plate 11 to move downward when the temperature drops. The actuating component includes an annular heat-conducting plate 18, which is disposed on the surface of the inner sheath 3. Several air chambers 19 are fixedly connected to the surface of the annular heat-conducting plate 18. The air chambers 19 are filled with inert gas. A compression cylinder 20 is fixedly connected to the top of the air chamber 19. The top of the compression cylinder 20 is fixedly connected to the annular temperature-regulating shell 6. A piston block 21 is slidably connected inside the compression cylinder 20. The top of the rod of the piston block 21 penetrates the inner wall of the annular temperature-regulating shell 6 and is fixedly connected to the first piston plate 11. A first one-way valve 1401 and a second one-way valve 1501 are respectively installed in the first exhaust pipe 14 and the first intake pipe 15, and a third one-way valve 1601 and a fourth one-way valve 1701 are respectively installed in the second exhaust pipe 16 and the second intake pipe 17. In existing technologies, under normal operating conditions, the current flowing through the conductive core of a cable generates Joule heat. Simultaneously, insulation losses under alternating electric fields also cause the internal temperature of the cable to rise. However, with the continuous increase in power grid load, cables operating under high current-carrying capacity or even overload conditions for extended periods are prone to significant temperature increases, which is detrimental to long-term use. This technical solution can address these issues, and the specific operation is as follows: When the cable conductor core generates Joule heat by passing current, causing the internal temperature of the cable to rise, the annular heat-conducting plate 18 that is in close contact with the surface of the inner sheath 3 will transfer the heat to the air chamber 19 and the compression cylinder 20, causing the inert gas filled in the compression cylinder 20 to expand due to heat and increase in volume, thereby pushing the piston block 21 to move upward along the compression cylinder 20. Since the top of the piston block 21 is fixedly connected to the first piston plate 11, the first piston plate 11 slides upward synchronously in the first chamber 10. At this time, the volume above the first piston plate 11 gradually decreases, the internal gas pressure increases, the first one-way valve 1401 in the first exhaust pipe 14 is opened, the second one-way valve 1501 in the first intake pipe 15 is closed, the upper gas is discharged into the annular mounting shell 7 through the first exhaust pipe 14, and then discharged to the inner sheath 3 of the cable through the slot 8 at the bottom of the annular mounting shell 7, thereby reducing the problem of the inner sheath 3. As the first piston moves upward, the volume below the first piston plate 11 gradually increases, the internal gas pressure decreases, the fourth one-way valve 1701 in the second intake pipe 17 is opened, and the third one-way valve 1601 in the second exhaust pipe 16 is closed. As a result, the hot air in the gap between the inner sleeve 3 and the annular mounting shell 7 is drawn into the lower space of the first chamber 10 through the second intake pipe 17 and temporarily stored.

[0024] As the temperature continues to rise, the piston block 21 continues to move upward, and the above process continues, causing hot air to be continuously drawn from near the inner sheath 3 into the area below the first piston plate 11. At the same time, the original cold gas is discharged from the top, thus replacing the hot air inside the cable in turn, which helps to reduce the cable temperature.

[0025] When the cable load decreases or the ambient heat causes the temperature of the inner sheath 3 to drop, the inert gas in the compression cylinder 20 contracts upon cooling. The piston block 21 drives the first piston plate 11 to move downward. At this time, the volume of the lower space of the first piston plate 11 decreases and the pressure increases. The third one-way valve 1601 in the second exhaust pipe 16 is opened, and the previously drawn-in hot air in the lower space (which has radiated some heat to the outside through the shell and has a lower temperature) is discharged through the second exhaust pipe 16 and returns to the gap on the surface of the inner sheath 3. This airflow will further carry away the residual heat of the inner sheath 3 during the flow process and eventually dissipate through the slot 8. Meanwhile, the volume of the upper space of the first piston plate 11 increases and the pressure decreases. The second one-way valve 1501 in the first air inlet pipe 15 is opened, and the cooled air is drawn back into the upper part of the first chamber 10 through the slot 8, the annular mounting shell 7, and the first air inlet pipe 15 to store cooling medium for the next heating cycle.

[0026] As a further embodiment of the present invention, it also includes a metal container 1702, which is disposed inside the second air inlet pipe 17 and filled with paraffin wax. Specifically, during the process of drawing in gas through the second air inlet pipe 17, the gas passes through the metal container 1702 and exchanges heat with the paraffin wax inside the metal container 1702, thereby rapidly reducing the temperature of the air below the first piston plate 11. When the first piston plate 11 is reset, the cooled air below the first piston plate 11 re-enters the cable to further improve the heat dissipation effect.

[0027] As a further embodiment of the present invention, it also includes a plurality of second chambers 22, which are arrayed within the annular temperature-regulating shell 6 and located between two first chambers 10 respectively. A second piston plate 23 is symmetrically and slidably connected within each of the second chambers 22. A first spring 24 is fixedly connected between the second piston plate 23 and the second chamber 22. The second chambers 22 are filled with flame retardant. Two drain pipes 28 are also included, with their ends fixedly connected to the second chambers 22 and the annular mounting shell 7 respectively. A fifth one-way valve 2801 is provided within each drain pipe 28. The limiting component is used to limit the elastic reset of the first spring 24 when the cable temperature does not exceed the threshold. When the cable temperature exceeds the threshold, the limiting component releases the limiting on the second piston plate 23. Under the action of the first spring 24, the second piston plate 23 compresses the flame retardant in the second chamber 22. The limiting assembly includes a first locking block 25, a second locking block 12 slidably connected to the side wall of the second piston plate 23, and a second spring 25 fixedly connected between the first locking block 25 and the second piston plate 23; a locking groove 27, the side wall of the second chamber 22 is provided with a locking groove 27 communicating with the first chamber 10, and the first locking block 25 is located in the locking groove 27; and a second locking block 12, the second locking block 12 slidably connected to the side wall of the first piston plate 11, and a third spring 13 fixedly connected between the second locking block 12 and the first piston plate 11. Specifically, within the normal temperature range of the cable (not exceeding the set safety threshold, such as 90°C for long-term operation or 130°C for short-term operation of a 110kV cable), the first piston plate 11 moves up and down in the first chamber 10 under the drive of the pushing component, following temperature fluctuations. At this time, the second locking block 12 on the side wall of the first piston plate 11 is located near the locking groove 27 on the side wall of the first chamber 10. Since the stroke of the first piston plate 11 has not reached the highest position corresponding to the extreme high temperature, the second locking block 12 is not aligned with the locking groove 27, so it will not interfere with the position of the first locking block 25. At this time, under the elastic force of the second spring 25, the end of the first locking block 25 is tightly locked into the locking groove 27, locking the second piston plate 23 in the initial position of the second chamber 22. At this time, the first spring 24 connected to the second piston plate 23 is in a stretched energy storage state. Since the first locking block 25 is fixed by the locking groove 27, the second piston plate 23 cannot move, and the flame retardant (such as perfluorohexanone liquid) filled in the second chamber 22 is safely sealed and will not be released. When the cable temperature continues to rise and exceeds the preset safety threshold, the first piston plate 11 moves upward to its highest position. During the movement of the first piston plate 11, the second locking block 12 aligns with the locking groove 27. Under the elastic force of the third spring 13, the second locking block 12 is quickly pushed into the locking groove 27, and pushes the first locking block 25. The first locking block 25 is pushed out of the slot 27, the second spring 25 is compressed and retracts to the side wall of the second piston plate 23. At this time, the mechanical limit of the second piston plate 23 is released. At the moment of release, the first spring 24 pushes the second piston plate 23 to move in the second chamber 22, compressing the flame retardant in the second chamber 22. The fifth one-way valve 2801 in the drain pipe 28 is opened, and the flame retardant enters the annular mounting shell 7 through the drain pipe 28. Then, it is sprayed directly onto the surface of the heated inner sheath 3 through the slot 8 at the bottom of the annular mounting shell 7 and diffuses into the gaps inside the cable, absorbing a large amount of heat and generating vaporization, thus forcibly cooling the cable. The vaporized flame retardant gas has excellent insulation and chemical inertness. Through the mechanism of isolating oxygen and capturing free radicals, it suppresses the possible internal arc or external spread of fire to the cable.

[0028] As a further embodiment of the present invention, a mesh 9 is provided in the slot 8, which allows gas to pass through. When the temperature does not exceed the threshold, the gas is evenly distributed to the surface of the cable through the mesh 9. When the temperature exceeds the threshold, the mesh 9 is destroyed by the high temperature, especially near the ignition point. At this time, the flame retardant will flow out from the destroyed area, which is conducive to extinguishing the fire in time.

[0029] It should be noted that the mesh 9 is made of polyester fiber nonwoven fabric or polytetrafluoroethylene (PTFE) microporous membrane with a temperature resistance rating of 220℃. Its thickness is 0.2mm to 0.5mm and its pore size is 50μm to 150μm. The mesh 9 is fixed to the inner wall of the groove 8 at the bottom of the annular mounting shell 7 by heat fusion or adhesive bonding. Within the normal operating temperature range of the cable, the membrane has stable air permeability and liquid repellency. When the cable is overloaded or the local temperature rises to more than 160℃ due to external fire, it begins to melt.

[0030] Secondly, this invention also proposes a manufacturing process for a 110kV power cable, comprising the following steps: Step 1: Concentrically strand multiple metal conductive wire cores using a frame stranding machine to form a round, tightly compressed conductor; Step 2: The insulation layer 2 of the conductor is extruded onto the outside of the conductor in sequence, and then the inner sheath 3 is extruded onto the outside of the insulation layer 2. The sheath is then cross-linked and cooled through a continuous vulcanization pipeline. Step 3: Assemble the annular mounting shell 7, the annular temperature regulating shell 6, and the annular heat-conducting plate 18 onto the inner sheath 3 using snaps or bolts; Step 4: Wrap a double layer of water-blocking tape around the outer surface of the annular mounting shell 7 between two adjacent annular temperature-regulating shells 6 and hot melt waterproof adhesive to form a waterproof layer 4. Step 5: Make the outer wall of the waterproof layer 4 flush with the outer wall of the annular temperature regulating shell 6 by heating and rolling, and use a scraper to trim excess material to ensure a smooth and continuous surface; Step 6: Pass the cable continuously through the extruder head to extrude the outer protective sleeve 5. Control the temperature of the extruder head, the screw speed and the traction speed during extrusion to ensure that the outer protective sleeve 5 tightly covers the outer surface of the waterproof layer 4 and the annular temperature regulating shell 6, forming a complete outer protective layer. Step 7: Test the prepared cable.

[0031] Specifically, multiple metal conductive cores (made of copper or aluminum) are concentrically stranded or bundled by a stranding machine at a predetermined pitch ratio to form a round, compacted conductor. During the stranding process, the cores are ensured to be tightly arranged and have a smooth, burr-free surface to meet the requirements for current carrying capacity and mechanical strength. Next, the conductor 1 is passed through a three-layer co-extrusion die head in sequence, and the conductor shielding layer and the insulation layer 2 are extruded using a dry cross-linking process. The materials are cross-linked polyethylene, XLPE and insulation shielding layer (i.e. insulation layer 2). Then, the inner sheath 3 (the material can be polyethylene PE or low smoke halogen-free polyolefin) is extruded on the outer surface of the insulation shielding layer. After extrusion, it is cross-linked through a continuous vulcanization pipeline and cooled and shaped. Then, the annular temperature regulating shell 6 and the annular mounting shell 7 are mounted on the surface of the inner sheath 3 in a linear array, ensuring that there is a gap between the annular mounting shell 7 and the inner sheath 3 as required by the design for air circulation, and that the annular heat-conducting plate 18 at the bottom of the compression cylinder 20 is tightly attached to the outer surface of the inner sheath 3, while the spacing between two adjacent sets of annular temperature regulating shells 6 remains consistent. After installation, a water-blocking tape or hot-melt waterproof adhesive is wrapped around the two annular mounting shells 7 to form a waterproof layer 4. The outer wall of the waterproof layer 4 is made flush with the outer wall of the annular temperature regulating shell 6 through a heating and rolling process to ensure a continuous and smooth surface. Then, the outer protective sleeve 5 is extruded using an extruder. The material can be polyethylene, polyvinyl chloride, or low-smoke halogen-free flame-retardant polyolefin. During the extrusion process, the pressure and temperature are controlled to ensure that the outer protective sleeve 5 tightly covers the surface of the waterproof layer 4 and the annular temperature-regulating shell 6, forming a complete cable outer sheath. Finally, the completed cable undergoes factory tests, including: partial discharge test ≤5pC; AC withstand voltage test; conductor DC resistance test; thermal cycling voltage test to verify the thermal response function of the drive component; flame retardant performance test to verify whether the second chamber 22 releases flame retardant normally at the threshold temperature; and outer sheath mechanical properties and waterproof sealing test.

[0032] The working principle of this invention is as follows: When the conductive core of the cable generates Joule heat through the current, causing the internal temperature of the cable to rise, the annular heat-conducting plate 18, which is in close contact with the surface of the inner sheath 3, will transfer the heat to the air chamber 19 and the compression cylinder 20, causing the inert gas filled in the compression cylinder 20 to expand due to heat and increase in volume, thereby pushing the piston block 21 to move upward along the compression cylinder 20. Since the top of the piston block 21 is fixedly connected to the first piston plate 11, the first piston plate 11 slides upward synchronously in the first chamber 10. At this time, the volume above the first piston plate 11 gradually decreases, the internal gas pressure increases, the first one-way valve 1401 in the first exhaust pipe 14 is opened, the second one-way valve 1501 in the first intake pipe 15 is closed, the upper gas is discharged into the annular mounting shell 7 through the first exhaust pipe 14, and then discharged to the inner sheath 3 of the cable through the slot 8 at the bottom of the annular mounting shell 7, thereby reducing the problem of the inner sheath 3. As the first piston moves upward, the volume below the first piston plate 11 gradually increases, the internal gas pressure decreases, the fourth one-way valve 1701 in the second intake pipe 17 is opened, and the third one-way valve 1601 in the second exhaust pipe 16 is closed. As a result, the hot air in the gap between the inner sleeve 3 and the annular mounting shell 7 is drawn into the lower space of the first chamber 10 through the second intake pipe 17 and temporarily stored. As the temperature continues to rise, the piston block 21 continues to move upward, and the above process continues, causing hot air to be continuously drawn from the vicinity of the inner sheath 3 into the area below the first piston plate 11. At the same time, the original cold gas is discharged from the top, thereby replacing the hot air inside the cable in turn, which helps to reduce the cable temperature. When the cable load decreases or the ambient heat causes the temperature of the inner sheath 3 to drop, the inert gas in the compression cylinder 20 contracts upon cooling. The piston block 21 drives the first piston plate 11 to move downward. At this time, the volume of the lower space of the first piston plate 11 decreases and the pressure increases. The third one-way valve 1601 in the second exhaust pipe 16 is opened, and the previously drawn-in hot air in the lower space (which has radiated some heat to the outside through the shell and has a lower temperature) is discharged through the second exhaust pipe 16 and returns to the gap on the surface of the inner sheath 3. This airflow will further carry away the residual heat of the inner sheath 3 during the flow process and eventually dissipate through the slot 8. Meanwhile, the volume of the upper space of the first piston plate 11 increases and the pressure decreases. The second one-way valve 1501 in the first air inlet pipe 15 is opened, and the cooled air is drawn back into the upper part of the first chamber 10 through the slot 8, the annular mounting shell 7, and the first air inlet pipe 15 to store cooling medium for the next heating cycle.

[0033] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A 110 kV power cable, characterized in that, include: A conductor (1) is formed by hinged joints of several conductive cores. The surface of the conductor (1) is covered with an insulating layer (2). The surface of the insulating layer (2) is covered with an inner sheath (3). The surface of the inner sheath (3) is linearly arranged with annular temperature regulating shells (6). Annular mounting shells (7) are symmetrically fixedly connected to both sides of the annular temperature regulating shells (6). A gap is left between the annular mounting shells (7) and the inner sheath (3). The bottom of the annular mounting shells (7) is linearly arranged with slots (8). Waterproof layer (4), the waterproof layer (4) is set on the annular mounting shell (7) between the two annular temperature regulating shells (6), the outer wall of the waterproof layer (4) is flush with the outer wall of the annular temperature regulating shell (6); An outer protective sleeve (5) is disposed on the surface of the waterproof layer (4); Several first chambers (10) are arrayed in an annular temperature-regulating shell (6). A first piston plate (11) is slidably connected to the first chamber (10). A first exhaust pipe (14) and a first intake pipe (15) are symmetrically fixed and connected on both sides of the first chamber (10) above the first piston plate (11). The first exhaust pipe (14) and the first intake pipe (15) are connected to the annular mounting shell (7). A second exhaust pipe (16) and a second intake pipe (17) are symmetrically fixed and connected at the bottom of the first chamber (10). The pushing component pushes the first piston plate (11) upward when the temperature of the inner sheath (3) rises, and drives the first piston plate (11) downward when the temperature drops.

2. A 110 kV power cable according to claim 1, characterized in that, The driving component includes an annular heat-conducting plate (18), which is disposed on the surface of the inner sheath (3). Several air chambers (19) are fixedly connected to the surface of the annular heat-conducting plate (18). The air chambers (19) are filled with inert gas. A compression cylinder (20) is fixedly connected to the top of the air chamber (19). The top of the compression cylinder (20) is fixedly connected to the annular temperature-regulating shell (6). A piston block (21) is sealed and slidably connected inside the compression cylinder (20). The top of the rod of the piston block (21) passes through the inner wall of the annular temperature-regulating shell (6) and is fixedly connected to the first piston plate (11).

3. A 110 kV power cable according to claim 2, characterized in that, Also includes: Several second chambers (22) are arrayed inside the annular temperature-regulating shell (6) and located between two first chambers (10). A second piston plate (23) is symmetrically and slidably connected to each of the several second chambers (22). A first spring (24) is fixedly connected between the second piston plate (23) and the second chamber (22). The second chamber (22) is filled with flame retardant. Two drain pipes (28) are fixedly connected at both ends to the second chamber (22) and the annular mounting shell (7), respectively. The limiting component is used to limit the elastic reset of the first spring (24) when the cable temperature does not exceed the threshold. When the cable temperature exceeds the threshold, the limiting component releases the limiting on the second piston plate (23). Under the action of the first spring (24), the second piston plate (23) compresses the flame retardant in the second chamber (22).

4. A 110 kV power cable according to claim 3, characterized in that, The limiting component includes: The first latching block (25) and the second latching block (12) are slidably connected to the side wall of the second piston plate (23), and a second spring (25) is fixedly connected between the first latching block (25) and the second piston plate (23). The second chamber (22) has a slot (27) on its side wall that communicates with the first chamber (10), and the first snap block (25) is located in the slot (27); The second latching block (12) is slidably connected to the side wall of the first piston plate (11), and a third spring (13) is fixedly connected between the second latching block (12) and the first piston plate (11).

5. A 110 kV power cable according to claim 4, characterised in that, The first exhaust pipe (14) and the first intake pipe (15) are respectively provided with a first one-way valve (1401) and a second one-way valve (1501), and the second exhaust pipe (16) and the second intake pipe (17) are respectively provided with a third one-way valve (1601) and a fourth one-way valve (1701).

6. A 110 kV power cable according to claim 4, characterised in that, It also includes a metal container (1702) disposed inside the second air intake pipe (17) and filled with paraffin wax.

7. A 110 kV power cable according to claim 3, characterized in that, A fifth check valve (2801) is installed inside the drain pipe (28).

8. A 110 kV power cable according to claim 1, characterized in that, A mesh (9) is provided inside the slot (8), and the mesh (9) allows gas to pass through.

9. A 110 kV power cable according to claim 1, characterized in that, The annular mounting shell (7), the annular temperature regulating shell (6), and the annular heat-conducting plate (18) are all assembled from two semi-annular shells.

10. A manufacturing process for a 110kV power cable, applicable to the 110kV power cable described in claims 1-9, characterized in that, Includes the following steps: Step 1: Concentrically strand multiple metal conductive wire cores using a frame stranding machine to form a round, tightly compressed conductor; Step 2: The insulation layer (2) of the conductor is extruded sequentially on the outside of the conductor, and then the inner sheath (3) is extruded on the outside of the insulation layer (2), and then cross-linked and cooled through a continuous vulcanization pipeline; Step 3: Assemble the annular mounting shell (7), the annular temperature regulating shell (6), and the annular heat-conducting plate (18) onto the inner sheath (3) using snaps or bolts; Step 4: Wrap a double layer of water-blocking tape around the outer surface of the annular mounting shell (7) between two adjacent annular temperature-regulating shells (6) and hot melt waterproof adhesive to form a waterproof layer (4). Step 5: Make the outer wall of the waterproof layer (4) flush with the outer wall of the annular temperature regulating shell (6) by heating and rolling, and use a scraper to trim excess material to ensure a smooth and continuous surface; Step 6: Pass the cable continuously through the extruder head to extrude the outer protective sleeve (5). Control the temperature of the extruder head, the screw speed and the traction speed during extrusion so that the outer protective sleeve (5) tightly covers the outer surface of the waterproof layer (4) and the annular temperature regulating shell (6) to form a complete outer protective layer. Step 7: Test the prepared cable.

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