Large-current flexible flat cable

Abstract

The invention discloses a large-current flexible flat cable which comprises a conductor, a wrapping tape layer, a fireproof layer, an insulating layer, an armor layer and an outer sheath which are sequentially arranged from inside to outside, the conductor is a flat conductor formed by doubling copper wires, the wide side nominal size of the flat conductor is 10-200 mm, the narrow side nominal size of the flat conductor is 0.8-4.5 mm, the edge of the flat conductor is provided with a round corner, and the outer sheath is provided with an outer sheath. And the radius of the fillet is 0.2-0.5 time of the size of the narrow edge. The large-current flexible flat cable has the advantages that the sectional area of the conductor is large, the transmission loss is low, the occupied space is small, the laying cost of a bridge can be reduced, the product safety and stability are high, and in addition, the invention further discloses a manufacturing method of the large-current flexible flat cable.

Description

Technical Field

[0001] This invention relates to the field of flat cable technology, and in particular to a high-current flexible flat cable. Background Technology

[0002] In global power engineering construction, there is an increasing demand for low-voltage cables for long-distance, high-current power transmission in applications such as photovoltaic power generation, energy storage, and new energy charging piles. The global market for high-current low-voltage cables is showing a continuous growth trend.

[0003] For example, in Chinese patent literature, patent number CN 202010337625.2 disclosed on September 18, 2020, a flexible flat cable resistant to nuclear electromagnetic high current. This application includes several insulated cores and a sheath disposed outside the insulated cores. The insulated cores include conductors arranged from the inside out, an insulation layer extruded outside the conductors, and a shielding layer. The conductors are several horizontally arranged adjacent sub-conductors.

[0004] The shortcomings of existing technologies lie in the fact that high-current, low-voltage cables are typically laid in tightly packed cable trays. Due to the limited space and high degree of enclosure in these trays, the operating temperature of the cables is high during high-power transmission, leading to overall cable heating and increased power loss. Especially in high-temperature summer environments, cable losses can reach 10% with increased power consumption, placing greater demands on the flame retardancy and high-temperature resistance of the cables. Therefore, special requirements are placed on the materials and structure of the cables, which conventional multi-segment low-voltage cables cannot meet. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this invention provides a high-current flexible flat cable with a large conductor cross-sectional area, low transmission loss, and small space occupation.

[0006] To achieve the above objectives, the present invention adopts the following technical solution.

[0007] A high-current flexible flat cable includes, from the inside out, a conductor, a wrapping tape layer, a fire-resistant layer, an insulation layer, an armor layer, and an outer sheath. The conductor is a flat conductor formed by parallel copper wires. The nominal size of the wide side of the flat conductor is 10-200 mm, and the nominal size of the narrow side is 0.8-4.5 mm. The edge of the flat conductor is rounded, and the radius of the rounded corner is 0.2-0.5 times the size of the narrow side.

[0008] The conductor is a structure made up of multiple small copper wires spliced ​​together, which increases the conductor's cross-sectional area and makes it more flexible. This reduces the skin effect and proximity effect on the conductor surface, resulting in energy loss of only 1% of the transmitted power during transmission, compared to 10% for conventional wires and cables. Compared to traditional low-voltage multi-segment cables, a single flexible flat cable can carry a current of up to 1800A, which is 6 to 10 times higher than conventional cables. More significantly, compared to the large footprint and space required for traditional multi-segment cable trays, high-current, low-voltage flexible flat cables require only 40-60% of the space and floor space, greatly reducing construction costs for businesses and users. Due to its superior electrical performance and economic benefits, high-current, low-voltage flexible flat cables are the optimal choice in photovoltaics, energy storage, new energy, construction, and power grids.

[0009] Preferably, the wrapping tape layer is made of plain weave nonwoven fabric with an overlap of 0.1 to 0.12 mm in nominal thickness and an overlap width of not less than 5 mm. The wrapped plain weave nonwoven portion conforms to the surface of the flat conductor. This ensures the fire resistance of the wrapping tape layer.

[0010] Preferably, the fire-resistant layer consists of one or two layers of white calcined mica with a nominal thickness of 0.12 mm or 0.14 mm, overlapped and wrapped, with an overlap width of not less than 5 mm. It possesses excellent high-temperature resistance, flame retardancy, and electrical insulation properties. The wrapped mica tape can pass the fire resistance test in BS6387, with a maximum test temperature of 1100 degrees Celsius, maintaining the integrity of the circuit. The circuit integrity fire resistance test passes the fire resistance tests in N, NJ, and NS sections of GB / T 19666.

[0011] Preferably, the insulation layer is made of soft polyvinyl chloride or cross-linked polyethylene extruded onto the outside of the fire-resistant layer. The nominal thickness of the extruded insulation is 0.7-3.0 mm, the average thickness of the insulation layer is not less than the nominal thickness, and the thickness of the thinnest point of the insulation layer is not less than 90% of the nominal thickness. Extruded insulation has high electrical insulation performance and is resistant to both low and high temperatures.

[0012] Preferably, the armor layer is made of steel strip, with the gap between the steel strips controlled between 40% and 50% of the strip width, and the thinnest point of the steel strip not less than 90% of the nominal thickness. The steel strip overlap should be uniform, without any missing strips or curling edges, and the joints should be flat, without weld holes, cuts, or other defects. It should have tensile, compressive, and interference resistance capabilities, providing mechanical protection for the conductor when subjected to external mechanical stress.

[0013] Preferably, the armor layer is made of steel wire braided armor with a braiding density of ≥8. The copper wire braided layer is made of 0.30mm diameter steel wire with a braiding angle range of 40° to 50° and a braiding density of not less than 80%. At 30MHz, the measured transfer impedance does not exceed 250Ω / km. It has strong anti-interference capabilities and also increases bending and tensile strength.

[0014] Preferably, the armor layer is made of aluminum alloy flat wire interlocking armor, with the diameter of the flat wire controlled between 1 and 3 millimeters, and the speed of the interlocking armor controlled between 9 and 15 meters per minute.

[0015] Preferably, the sheath layer is a polyvinyl chloride (PVC) or low-smoke halogen-free polyolefin outer sheath extruded outside the armor layer. PVC and polyolefin have excellent weather resistance, chemical resistance, and aging resistance, as well as good flame retardancy. In addition, the polyolefin sheath also has low smoke, halogen-free, and low toxicity properties, fully meeting environmental protection requirements. The cable can pass the bundled burning tests of GB / T19666, which are classified as Class A, Class B, and Class C flame retardant standards.

[0016] A method for manufacturing the aforementioned high-current flexible flat cable, characterized by comprising the following steps: A. Conductor fabrication: The conductor is made of oxygen-free copper rod with a copper content of 99.95% and a resistivity of less than 0.017241Ω.mm / m. After continuous annealing and drawing, the multiple drawn copper wires are combined and then shaped into a flat conductor using a fixed mold. B. Wrapping tape layer production: Plain weave non-woven fabric is used, and the tensile strength of the plain weave non-woven fabric reaches 60Mpa or more. The flat conductor is wrapped by overlapping wrapping, and the wrapping overlap width is not less than 5mm. C. Refractory layer construction: Wrap mica tape around the conductor after it has been wrapped with wrapping tape, with an overlap width of not less than 5mm. D. Insulation layer fabrication: The insulation layer is made of soft polyvinyl chloride or cross-linked polyethylene. The flat conductor after the fire-resistant layer is wrapped passes through a flat die head that is adapted to its shape. The flat die head extrudes the insulation layer on the outside of the fire-resistant layer. E. Armor layer fabrication: Fabricate an armor layer on the surface of the insulation layer; F. Outer Sheath Fabrication: The outer sheath is extruded and formed on the outside of the armor layer using a flat die head. The outer sheath is made of polyvinyl chloride or low-smoke halogen-free polyolefin material.

[0017] These features and advantages of the present invention will be disclosed in detail in the following specific embodiments and accompanying drawings. Attached Figure Description

[0018] The present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0019] Figure 1This is a schematic diagram of the structure of a high-current flexible flat cable proposed in one embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram of the cross-section of a high-current flexible flat cable proposed in one embodiment of the present invention.

[0021] In the diagram: 1. Conductor, 2. Wrapping tape layer, 3. Fire-resistant layer, 4. Insulating layer, 5. Armoring layer, 6. Outer sheath. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be explained and described below with reference to the accompanying drawings. However, the following embodiments are only preferred embodiments of the present invention and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments in the implementation methods without creative effort are all within the protection scope of the present invention.

[0023] Figure 1 and Figure 2 As shown, one embodiment of the present invention proposes a high-current flexible flat cable, which includes a conductor 1, a wrapping tape layer 2, a fire-resistant layer 3, an insulation layer 4, an armor layer 5, and an outer sheath 6 arranged sequentially from the inside to the outside. The conductor 1 is a flat conductor 1 formed by parallel copper wires. The nominal size of the wide side of the flat conductor 1 is 10-200 mm, and the nominal size of the narrow side is 0.8-4.5 mm. The edge of the flat conductor 1 is provided with rounded corners, and the radius of the rounded corners is 0.2-0.5 times the size of the narrow side.

[0024] The surface of the flat conductor 1 after fabrication should be smooth, free of oil stains, burrs that damage the insulation, and any protruding or broken single wires. A single flat conductor 1, when placed vertically, can carry a current of 200-1800 A, with a bending diameter between 3-8 mm. To increase the overall current carrying capacity of conductor 1, the flat conductors 1 can be arranged in double or multiple overlapping layers. The overlapping of conductors 1 should be tight and compact, with minimal relative displacement. This increases the cross-sectional area of ​​conductor 1, making it more flexible and reducing the skin effect and proximity effect on the conductor surface. Compared to multi-layered conductors 1, using flat conductors first increases the surface area of ​​conductor 1, accelerating heat dissipation. This results in energy loss during transmission of only 1% of the transmitted power, compared to 10% for conventional wires and cables. It also reduces the relative volume of the cable, making the structure more compact and installation easier. The cable is no longer installed using copper lugs, but rather using direct bolts for fixing, which is more efficient, convenient, and safer for construction workers.

[0025] The wrapping layer consists of a thin, lightweight plain-weave nonwoven fabric with a nominal thickness of 0.11 mm, overlapped and wrapped with a minimum overlap width of 5 mm. The tensile strength of the plain-weave nonwoven fabric must reach at least 60 MPa. The wrapped nonwoven fabric should adhere tightly to the surface of the flat conductor 1. The fire-resistant layer 3 consists of one or two layers of white calcined or 0.14 mm nominal thickness phlogopite, overlapped and wrapped with a minimum overlap width of 5 mm. The wrapped mica tape should adhere tightly to the outside of the flat conductor 1. The wrapped mica tape must pass the fire resistance test in BS6387, with a maximum test temperature of 1100 degrees Celsius, maintaining the integrity of the circuit. The circuit integrity fire resistance test passes the fire resistance tests in GB / T 19666 (N, NJ, NS).

[0026] The insulation layer 4 is formed by extruding soft polyvinyl chloride or cross-linked polyethylene insulation onto the outside of the fire-resistant layer 3. The nominal thickness of the extruded insulation is 0.7-3.0 mm, and the insulation thickness varies depending on the nominal cross-sectional area of ​​the conductor 1. The average thickness of the insulation layer 4 is not less than the nominal thickness, and the thickness at the thinnest point of the insulation layer 4 is not less than 90% of the nominal thickness. Cross-linked ethylene-propylene rubber (EPR) material is used as the insulation layer 4, and the insulation extruded by the extruder should tightly cover the fire-resistant layer 3. The surface of the extruded insulation should be smooth and flat, with uniform color. The extruded insulation should be subjected to a power frequency spark withstand voltage test, and the conductors 1 at both ends of the core should be reliably grounded during the test. The insulation has excellent cold resistance and still maintains good flexibility.

[0027] Depending on the laying conditions and application environment, the armor layer 5 can be made of steel strip armor, steel wire braided armor, or aluminum alloy flat wire interlocking armor.

[0028] When the armor layer 5 is steel strip armored, a 710 armoring machine is used. The gap between the armored steel strips is controlled between 40% and 50% of the steel strip width, and the thickness of the thinnest point of the steel strip is not less than 90% of the nominal thickness. The steel strip overlap should be uniform, without any missing wraps or curling edges. The joints should be flat, without weld holes, cuts, or other defects. It should have tensile, compressive, and interference resistance capabilities, and provide mechanical protection for the conductor when subjected to external mechanical stress.

[0029] When the armor layer 5 is made of steel wire braided armor, a 64-spindle braiding machine is used, with a braiding density of ≥8. The copper wire braided layer is made of 0.30mm diameter steel wire, with a braiding angle range of 40°~50° and a braiding density of not less than 80%. At 30MHz, the measured transfer impedance does not exceed 250Ω / km. It has strong anti-interference capabilities and also increases bending and tensile strength.

[0030] When the armor layer 5 is made of aluminum alloy flat wire interlocking armor, the diameter of the flat wire is controlled between 1 and 3 mm. The diameter of the flat wire varies depending on the nominal cross-sectional area of ​​conductor 1. The interlocking armoring speed is controlled between 9 and 15 meters per minute. The armored surface should be smooth, neat, and free of burrs.

[0031] The sheath layer is a polyvinyl chloride (PVC) or low-smoke halogen-free polyolefin outer sheath 6 extruded outside the armor layer 5. PVC and polyolefin have excellent weather resistance, chemical resistance, and aging resistance, as well as good flame retardancy. In addition, the polyolefin sheath also has low smoke, halogen-free, and low toxicity properties, fully meeting environmental protection requirements. The cable can pass the bundled burning tests of GB / T 19666, which are classified as Class A, Class B, and Class C flame retardant standards.

[0032] As one embodiment of the present invention, a method for manufacturing the above-mentioned high-current flexible flat cable includes the following steps: A. Conductor 1 Fabrication: Conductor 1 is made of oxygen-free copper rod with a copper content of 99.95% and a resistivity of less than 0.017241 Ω·mm / m. The conductor undergoes continuous annealing and drawing. Multiple drawn copper wires are then joined together and shaped into a flat conductor 1 using a fixed mold. This flat conductor 1 is then formed through high-temperature welding and continuous drawing. The copper wire busbar is fixed on an extrusion mold. As the belt moves back and forth, the busbar moves forward through upper and lower slots, applying downward stress to compress it and increase its surface area. This increased surface area increases the current carrying capacity of the busbar, further improving the overall performance of conductor 1. The nominal dimensions of the wide side of the manufactured copper wire busbar conductor 1 are (10-200) mm, the nominal dimensions of the narrow side are (0.8-4.5) mm, and the radius of the rounded corners is (0.2-0.5) times the narrow side dimension. The surface of the flat conductor 1 after fabrication should be smooth, free of oil stains, burrs that damage the insulation, and protruding or broken single wires. The current carrying capacity of a single flat conductor 1 when placed vertically can reach (200-1800) A, and the bending diameter can reach (3-8) mm. In order to increase the overall current carrying capacity of conductor 1, the flat conductor 1 can be arranged in a double or multi-layer overlapping manner. After the conductors 1 are stacked together, they should be arranged tightly and with small relative displacement. B. Fabrication of wrapping layer 2: Plain weave non-woven fabric is used. The tensile strength of the plain weave non-woven fabric reaches 60 MPa or more. The flat conductor 1 is wrapped in an overlapping manner. The overlap width of the wrapping is not less than 5 mm. The wrapped non-woven fabric should be tightly attached to the surface of the flat conductor 1. C. Fire-resistant layer 3 fabrication: Wrap mica tape around the conductor 1 after it has been wrapped with reinforcing tape, with an overlap width of not less than 5mm; the wrapped mica tape should be tightly adhered to the outside of the flat conductor 1. Simultaneously, the wrapped mica tape must pass the fire resistance test in BS6387, with a maximum test temperature of 1100 degrees Celsius, maintaining the integrity of the circuit. The circuit integrity fire resistance test passes the fire resistance tests in N, NJ, and NS of GB / T 19666. D. Insulation Layer 4 Fabrication: Insulation layer 4 uses soft polyvinyl chloride or cross-linked polyethylene insulation. The flat conductor 1, wrapped with fire-resistant layer 3, is passed through a flat extrusion head adapted to its shape. The maximum operating temperature of conductor 1 can reach 105℃. Insulation is extruded using a self-made flat extrusion head. The nominal thickness of the extruded insulation is (0.7-3.0) mm. The insulation thickness varies depending on the nominal cross-sectional area of ​​conductor 1, but the average insulation thickness is not less than the nominal thickness, and the thinnest point thickness is not less than 90% of the nominal value. Cross-linked ethylene-propylene rubber (EPR) material is used as insulation layer 4. The insulation extruded by the extruder should tightly wrap around fire-resistant layer 3. The surface of the extruded insulation should be smooth and flat with uniform color. The extruded insulation should be subjected to a power frequency spark withstand voltage test. During the test, the conductors 1 at both ends of the core should be reliably grounded. The insulation has excellent cold resistance while maintaining good flexibility. E. Armor layer 5 fabrication: Armor layer 5 is fabricated on the surface of insulation layer 4; depending on the laying conditions and application environment, steel tape armor, steel wire braided armor, or aluminum alloy flat wire interlocking armor can be used. F. Outer Sheath 6 Fabrication: The outer sheath 6 is extruded onto the outside of the armor layer 5 using a flat die head. The outer sheath 6 is made of polyvinyl chloride (PVC) or low-smoke halogen-free polyolefin material. PVC and polyolefins possess excellent weather resistance, chemical resistance, and aging resistance, while also exhibiting good flame retardancy. Furthermore, the polyolefin sheath also features low smoke, halogen-free, and low toxicity, fully meeting environmental protection requirements. The cable can pass the flame retardant Class A, B, and C bundled burning tests in GB / T 19666.

[0033] When laying cables, because the cables are flat, they occupy little space and can be laid in cable trays. This improves the safety and reliability of cable operation, enhances performance during high-current transmission, reduces contact resistance and temperature rise, provides orderly and clear organization, facilitates classification and arrangement, makes maintenance easier, allows for convenient expansion, reduces interference, provides protective measures, ensures good heat dissipation, and allows for flexible construction. Furthermore, under the same current carrying capacity, if the flat cables disclosed in this application are used for cable tray laying, the overall weight is twice that of conventional double-section low-voltage cables.

[0034] High-current flexible flat cables improve the safety and reliability of the entire system by using high-quality insulation materials, making them particularly suitable for high-current transmission. Compared to traditional cables, high-current flexible flat cables also incorporate new technologies and processes in their design and manufacturing, significantly reducing contact resistance and temperature rise at the connection points and branch ports, further enhancing their performance.

[0035] The advantages of high-current flexible flat cables also include orderly and concise organization, allowing cables to be neatly organized for easy management and maintenance. Due to their overall flat shape, they can be classified according to function and application, facilitating identification and repair. Furthermore, when additional cables are needed, they can be added directly to existing flat cables without the need for rearrangement. Based on the flat copper conductor 1 of the cable, the splicing method and drilling location are determined, and the opening size is determined. Brazing is a common method. Brazing involves heating to melt the solder, which then penetrates and fills the joint of the copper conductor 1, achieving a strong connection. This method not only provides a good connection effect but also ensures stable current transmission, reducing the complexity and construction cost of cable joints. Simultaneously, the good heat dissipation performance of flat cables helps reduce the risk of cable overheating.

[0036] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes, but is not limited to, the contents described in the accompanying drawings and the specific embodiments above. Any modifications that do not depart from the functional and structural principles of the present invention will be included within the scope of the claims.

Claims

1. A high-current flexible flat cable, characterized in that, It includes, from the inside out, a conductor, a wrapping tape layer, a fire-resistant layer, an insulating layer, an armor layer, and an outer sheath. The conductor is a flat conductor formed by twisting copper wires. The nominal size of the wide side of the flat conductor is 10-200 mm, and the nominal size of the narrow side is 0.8-4.5 mm. The edge of the flat conductor is rounded, and the radius of the rounded corner is 0.2-0.5 times the size of the narrow side.

2. The high-current flexible flat cable according to claim 1, characterized in that, The wrapping layer is made of plain weave nonwoven fabric with an overlap of 0.1 to 0.12 mm in nominal thickness and an overlap width of not less than 5 mm. The wrapped plain weave nonwoven part conforms to the surface of the flat conductor.

3. A high-current flexible flat cable according to claim 1, characterized in that, The refractory layer is made by overlapping one or two layers of white calcined mica with a nominal thickness of 0.12 mm or 0.14 mm, with the overlap width not less than 5 mm.

4. A high-current flexible flat cable according to claim 1, characterized in that, The insulation layer is formed by extruding soft polyvinyl chloride or cross-linked polyethylene insulation onto the outside of the fire-resistant layer. The nominal thickness of the extruded insulation is 0.7-3.0 mm, the average thickness of the insulation layer is not less than the nominal thickness, and the thickness of the thinnest point of the insulation layer is not less than 90% of the nominal thickness.

5. A high-current flexible flat cable according to any one of claims 1 to 4, characterized in that, The armor layer is made of steel strip armor, and the gap between the armor steel strips is controlled between 40% and 50% of the width of the steel strip. The thickness of the thinnest point of the steel strip is not less than 90% of the nominal thickness.

6. A high-current flexible flat cable according to any one of claims 1 to 4, characterized in that, The armor layer is a steel wire braided armor with a braiding density of ≥8. The copper wire braided layer is made of steel wire with a diameter of 0.30mm, with a braiding angle range of 40° to 50° and a braiding density of not less than 80%. At 30MHz, the measured transfer impedance does not exceed 250Ω / km.

7. A high-current flexible flat cable according to any one of claims 1 to 4, characterized in that, The armor layer is an aluminum alloy flat wire interlocking armor, with the diameter of the flat wire controlled between 1 and 3 millimeters, and the speed of the interlocking armor controlled between 9 and 15 meters per minute.

8. A high-current flexible flat cable according to claim 1, characterized in that, The sheath layer is a polyvinyl chloride or low-smoke halogen-free polyolefin outer sheath extruded outside the armor layer.

9. A method for manufacturing a high-current flexible flat cable according to any one of claims 1 to 8, characterized in that, Includes the following steps: A. Conductor fabrication: The conductor is made of oxygen-free copper rod with a copper content of 99.95% and a resistivity of less than 0.017241Ω.mm / m. After continuous annealing and drawing, the multiple drawn copper wires are combined and then shaped into a flat conductor using a fixed mold. B. Wrapping tape layer production: Plain weave non-woven fabric is used, and the tensile strength of the plain weave non-woven fabric reaches 60Mpa or more. The flat conductor is wrapped by overlapping wrapping, and the wrapping overlap width is not less than 5mm. C. Refractory layer construction: Wrap mica tape around the conductor after it has been wrapped with wrapping tape, with an overlap width of not less than 5mm. D. Insulation layer fabrication: The insulation layer is made of soft polyvinyl chloride or cross-linked polyethylene. The flat conductor after the fire-resistant layer is wrapped passes through a flat die head that is adapted to its shape. The flat die head extrudes the insulation layer on the outside of the fire-resistant layer. E. Armor layer fabrication: Fabricate an armor layer on the surface of the insulation layer; F. Outer Sheath Fabrication: The outer sheath is extruded and formed on the outside of the armor layer using a flat die head. The outer sheath is made of polyvinyl chloride or low-smoke halogen-free polyolefin material.

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