Large-section aluminum alloy solid core split conductor medium-voltage power cable and preparation method thereof

Abstract

The invention relates to a large-section aluminum alloy solid core split conductor medium-voltage power cable which comprises an insulating wire core, and a metal shielding layer, an isolation sleeve, an armor layer and an outer sheath are sequentially arranged on the outer side of the insulating wire core. Wherein the insulating wire core comprises a solid split conductor, the solid split conductor is formed by twisting a plurality of solid fan-shaped strand blocks, and an isolating layer is arranged between every two adjacent solid fan-shaped strand blocks; the semi-conductive wrapping tape is arranged on the outer side of the solid split conductor and is used for wrapping the solid split conductor; the conductor shielding layer covers the outer side of the semi-conductive wrapping tape and is used for uniformizing an electric field on the surface of the conductor; the insulating layer is arranged on the outer side of the conductor shielding layer, and the insulating shielding layer wraps the outer side of the insulating layer and is used for isolating electrical contact between the solid split conductor and the outside. According to the invention, the solid fan-shaped strand blocks are twisted to form the split conductor, so that the cable conductor is not influenced by a large-section skin effect and has larger current-carrying capacity input, and the disadvantage of twisted monofilaments can be avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and in particular to a medium-voltage power cable with a large-section aluminum alloy solid split conductor and a preparation method thereof. Background Art

[0002] This patent belongs to the field of conductor structure optimization of medium-voltage aluminum alloy power cables, and particularly relates to a new type of large-section aluminum alloy solid split conductor medium-voltage power cable. Under the current background of global energy transformation, the scarcity of copper resources has become increasingly prominent, and the strategy of "replacing copper with aluminum" has received attention due to its rich application value and prospects. On the one hand, the grade of global copper mines has declined, my country's copper resources are in short supply, and the price bottom has risen. Replacing copper with aluminum can reduce the external dependence on copper resources to a certain extent, enhance resource security capabilities, and safeguard national economic security; on the other hand, the copper-aluminum price ratio has been maintained above 3 for a long time. For cost reduction considerations, the copper-aluminum substitution effect has accelerated. It is expected that the subsequent copper-aluminum price ratio will remain high, and "replacing copper with aluminum" will become a new track for industry development.

[0003] In the field of cables, aluminum alloy cables are favored for their superior performance and low price. The utilization rate of aluminum alloy cables in developed countries in Europe and the United States is as high as 90%. Although China started late, it has developed rapidly and has grown at a rate of 3-5 times in recent years. It is expected that my country's aluminum alloy cable market will develop rapidly in the next five years. China's copper resource reserves are about 26 million tons, while the annual copper consumption is about 5 million tons. 70% of copper concentrates are imported each year. If it does not rely on imports, China's copper resources can be used for up to 5 years. In sharp contrast, my country's aluminum resource reserves are about 2.7 billion tons, which is very rich, and the annual production capacity of electrolytic aluminum exceeds 25 million tons, which is seriously oversupplied. In order to achieve aluminum instead of copper, the excess aluminum metal will be used in the cable industry with huge demand. "Aluminum instead of copper" has been clearly elevated to a national strategy by the Ministry of Industry and Information Technology of the People's Republic of China, and it has been determined to support the inclusion of aluminum alloy cables in the National "Industrial Adjustment Guidance Catalogue".

[0004] At present, the aluminum alloy conductors of cables in the industry generally adopt a compressed and twisted circular structure, but this structure cannot meet the requirements of large specifications and large-capacity transmission due to the skin effect. In addition, due to the low mechanical strength and poor creep resistance of the circular compressed and twisted structure, after the line has been running for a period of time, the contact resistance at the line crimping will be large due to loose joints and creep deformation, causing the line to overheat, which may cause power outages and equipment shutdowns, or even fires or explosions. The solid aluminum alloy conductor is softened in a high-voltage cavity to reach a hot-melt state, and then a unique cooling method is used. After cooling, the lattice of the material remains consistent, making the mechanical and electrical properties of the solid aluminum alloy conductor better than those of the twisted aluminum alloy conductor. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide a medium voltage power cable with a large cross-section aluminum alloy solid split conductor. By using solid fan-shaped strands to form split conductors, it is not only ensured that the cable conductor is not affected by the skin effect of the large cross-section and has a larger current carrying capacity, but also can effectively avoid the disadvantages of twisted monofilaments.

[0006] In the first aspect, in order to solve the above technical problems, the present invention provides a large-section aluminum alloy solid core split conductor medium-voltage power cable, characterized in that it comprises: an insulating core, a metal shielding layer, an isolation sleeve, an armor layer and a sheath are arranged on the outside of the insulating core in sequence, the metal shielding layer is used to isolate electromagnetic interference and conduct leakage current and capacitive current; the isolation sleeve is arranged on the outside of the metal shielding layer to protect the insulating core; the armor layer is arranged on the outside of the isolation sleeve to prevent mechanical damage to the cable during operation; the outer sheath is wrapped and arranged on the outside of the armor layer to protect the entire cable; wherein the insulating core comprises: A solid split conductor, wherein the solid split conductor is formed by twisting a plurality of solid sector-shaped strands, and an isolation layer is provided between two adjacent solid sector-shaped strands; A semi-conductive wrapping tape is arranged on the outside of the solid split conductor and is used to wrap the solid split conductor; A conductor shielding layer, the conductor shielding layer covers the outer side of the semi-conductive tape and is used to make the electric field on the surface of the conductor uniform; An insulating layer, arranged on the outer side of the conductor shielding layer, for preventing current leakage; The insulating shielding layer is wrapped around the outer side of the insulating layer and is used to isolate the solid divided conductor from electrical contact with the outside world.

[0007] In one embodiment of the present invention, the semi-conductive tape is wrapped around the outside of the aluminum alloy solid divided conductor for at least 2 turns.

[0008] In one embodiment of the present invention, the isolation layer is crepe paper.

[0009] In one embodiment of the present invention, the solid sector-shaped strand block is made of aluminum alloy material.

[0010] In one embodiment of the present invention, the number of the solid sector-shaped strand blocks is 4, 5 or 6.

[0011] In one embodiment of the present invention, the metal shielding layer is made of copper tape wrapping or copper wire comb winding.

[0012] In one embodiment of the present invention, the insulating layer is made of cross-linked polyethylene material.

[0013] In a second aspect, in order to solve the above technical problems, the present invention provides a method for preparing a novel large-section aluminum alloy solid split conductor medium-voltage power cable, comprising the following steps: Step 1: Calculate the size of the fan-shaped stock block and design the mold; Step 2: Melt the aluminum ingot at high temperature through a rolling aluminum extruder, and extrude the strands of required size through a set die; Step 3, the strands extruded from the die are shaped by a cooling annealing process; Step 4, untwist the formed fan-shaped strands through a twisting machine and set a suitable pitch; Step 5: Use a coiling machine to combine multiple fan-shaped strands to form a solid split conductor, and use crepe paper as an isolation layer between the fan-shaped strands; Step 6: Wrap two layers of semi-conductive tape around the outside of the solid split conductor as reinforcement to prevent the conductor from loosening; Step 7: Extruding a conductor shielding layer, an insulating layer and an insulating shielding layer on the outer side of the wrapped solid split conductor through a three-layer co-extrusion process to form an insulated wire core; Step 8: Wrap the copper tape around the outside of the insulated wire core to form a metal shielding layer to isolate electromagnetic interference, conduction leakage current, and capacitive current; Step 9, an isolation sleeve is extruded on the outer side of the metal shielding layer to protect the insulated core; Step 10, wrapping a stainless steel strip around the outside of the isolation sleeve as an armor layer; Step 11: Finally, extrude the outer sheath on the outside of the armor layer.

[0014] The above technical solution of the present invention has the following beneficial effects compared with the prior art: The large-section aluminum alloy solid core split conductor medium-voltage power cable described in the present invention adopts solid fan-shaped strands to form split conductors, ensuring that the cable conductor is not affected by the skin effect of the large cross-section and has a larger current-carrying capacity input. In addition, the solid design is adopted to avoid the disadvantages of twisted single wires, and the structure of the strands twisted into a cable ensures the bending performance of the cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0016] Figure 1 This is a schematic structural diagram of a medium-voltage power cable with a large cross-section aluminum alloy solid split conductor according to a preferred embodiment of the present invention; Explanation of the reference numerals in the drawings in the specification: 1. conductor; 2. semi-conductive tape; 3. conductor shield; 4. insulation; 5. insulation shield; 6. metal shielding layer; 7. isolation sleeve; 8. armor layer; 9. outer sheath. DETAILED DESCRIPTION

[0017] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0018] Reference Figure 1 As shown, the present invention discloses a large-section aluminum alloy solid core split conductor medium-voltage power cable, comprising: an insulating core, a metal shielding layer, an isolation sleeve, an armor layer and a sheath are arranged on the outside of the insulating core in sequence, the metal shielding layer is used to isolate electromagnetic interference and conduct leakage current and capacitive current; the isolation sleeve is arranged on the outside of the metal shielding layer to protect the insulating core; the armor layer is arranged on the outside of the isolation sleeve to prevent mechanical damage to the cable during operation; the outer sheath is wrapped and arranged on the outside of the armor layer to protect the entire cable; wherein the insulating core comprises: A solid split conductor, wherein the solid split conductor is formed by twisting a plurality of solid sector-shaped strands, and an isolation layer is provided between two adjacent solid sector-shaped strands; wherein the number of the solid sector-shaped strands is 4, 5 or 6; the number of the solid sector-shaped strands can be adjusted according to specific needs and specifications, providing flexibility to meet the requirements of different current carrying capacity and mechanical strength; A semi-conductive wrapping tape is arranged on the outside of the solid split conductor and is used to wrap the solid split conductor; A conductor shielding layer, the conductor shielding layer covers the outer side of the semi-conductive tape and is used to make the electric field on the surface of the conductor uniform; An insulating layer, arranged on the outer side of the conductor shielding layer, for preventing current leakage; The insulating shielding layer is wrapped around the outer side of the insulating layer and is used to isolate the solid divided conductor from electrical contact with the outside world.

[0019] In this embodiment, the semi-conductive tape is wound around the outside of the aluminum alloy solid split conductor for at least 2 turns. The design of the semi-conductive tape enhances the structural stability of the conductor, prevents the conductor from loosening, and improves the mechanical strength and electrical performance of the cable.

[0020] Preferably, the isolation layer is crepe paper. Using crepe paper as the isolation layer effectively isolates adjacent solid sector-shaped strands and prevents electrical contact between them, thereby reducing current concentration and improving the electrical safety and stability of the cable.

[0021] The solid fan-shaped strand block in this embodiment is made of aluminum alloy material. The solid fan-shaped strand block made of aluminum alloy material takes advantage of the low cost and abundant resources of aluminum alloy. At the same time, the electrical conductivity and mechanical properties of aluminum alloy are better than those of traditional copper materials, which helps to reduce costs and improve cable performance.

[0022] The metal shielding layer is made of copper tape wrapping or copper wire comb winding. The design of the metal shielding layer effectively isolates electromagnetic interference, conducts leakage current and capacitive current, and improves the electromagnetic compatibility and safety of the cable.

[0023] The insulating layer in this embodiment is made of cross-linked polyethylene material. The insulating layer prevents current leakage and also has good mechanical protection, thereby improving the durability and safety of the cable.

[0024] The cable conductor is changed from the original tightly compressed and twisted circular structure to a solid split conductor structure, which improves the disadvantage that conventional cables cannot transmit large-capacity current due to the skin effect. It can also avoid the damage and oxidation of single wires in the tightly compressed circular twisted structure, ensuring the stability of cable operation.

[0025] By adopting the split conductor structure of the present invention, the shortcomings of cable products using stranded aluminum alloy conductors are improved, the cost-effectiveness and abundant resource advantages of aluminum alloy conductors are brought into play, and the electrical connection reliability problems caused by creep and relaxation at the joints of Class 2 stranded aluminum conductors are solved, and the cables are made lighter, and transportation and laying are more convenient, providing a new cost-effective option for cable engineering.

[0026] Embodiment 2 Based on the same inventive concept as that of the first embodiment, the present invention provides a novel method for preparing a large-section aluminum alloy solid split conductor medium-voltage power cable, comprising the following steps: Step 1: Calculate the size of the fan-shaped stock block and design the mold; Step 2: Melt the aluminum ingot at high temperature through a rolling aluminum extruder, and extrude the strands of required size through a set die; Step 3, the strands extruded from the die are shaped by a cooling annealing process; Step 4, untwist the formed fan-shaped strands through a twisting machine and set a suitable pitch; Step 5: Use a coiling machine to combine multiple fan-shaped strands to form a solid split conductor, and use crepe paper as an isolation layer between the fan-shaped strands; Step 6: Wrap two layers of semi-conductive tape around the outside of the solid split conductor as reinforcement to prevent the conductor from loosening; Step 7: Extruding a conductor shielding layer, an insulating layer and an insulating shielding layer on the outer side of the wrapped solid split conductor through a three-layer co-extrusion process to form an insulated wire core; Step 8: Wrap the copper tape around the outside of the insulated wire core to form a metal shielding layer to isolate electromagnetic interference, conduction leakage current, and capacitive current; Step 9, an isolation sleeve is extruded on the outer side of the metal shielding layer to protect the insulated core; Step 10, wrapping a stainless steel strip around the outside of the isolation sleeve as an armor layer; Step 11: Finally, extrude the outer sheath on the outside of the armor layer.

[0027] Based on the preparation method in this embodiment, the medium-voltage power cable prepared by the above preparation method has a conductor structure of an aluminum alloy solid divided conductor. Compared with a circular compressed twisted structure, an oxide film is easily generated on the surface of the monofilaments of the twisted structure, resulting in a large contact resistance between the monofilaments; the monofilaments of the twisted structure are subjected to mechanical drawing, rolling, pressing and other processes, causing mechanical damage to their surface, deformation of the metal internal lattice, hardening of the conductor, increased resistivity, and decreased electrical performance; the monofilaments of the twisted structure are subjected to mechanical drawing, rolling, pressing and other processes, causing mechanical damage to their surface, decreased mechanical properties, and solid conductors will not have these situations; after the solid divided conductor is formed, the insulation performance and electromagnetic compatibility of the cable are improved through steps such as a three-layer co-extrusion process and copper tape wrapping, while the mechanical strength and electrical performance of the cable are also improved, ensuring the high quality and high performance of the cable.

[0028] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A medium voltage power cable with large cross-section aluminum alloy solid split conductor, characterized in that: include: An insulated core, wherein a metal shielding layer, an isolation sleeve, an armor layer and a sheath are arranged on the outside of the insulated core in sequence, wherein the metal shielding layer is used to isolate electromagnetic interference and conduct leakage current and capacitive current; the isolation sleeve is arranged on the outside of the metal shielding layer to protect the insulated core; the armor layer is arranged on the outside of the isolation sleeve to prevent mechanical damage during cable operation; the outer sheath is wrapped and arranged on the outside of the armor layer to protect the entire cable; wherein the insulated core comprises: A solid split conductor, wherein the solid split conductor is formed by twisting a plurality of solid sector-shaped strands, and an isolation layer is provided between two adjacent solid sector-shaped strands; A semi-conductive wrapping tape is arranged on the outside of the solid split conductor and is used to wrap the solid split conductor; A conductor shielding layer, the conductor shielding layer covers the outer side of the semi-conductive tape and is used to make the electric field on the surface of the conductor uniform; An insulating layer, arranged on the outer side of the conductor shielding layer, for preventing current leakage; The insulating shielding layer is wrapped around the outer side of the insulating layer and is used to isolate the solid divided conductor from electrical contact with the outside world.

2. A medium voltage power cable with a large cross-section aluminum alloy solid split conductor according to claim 1, characterized in that: The semi-conductive tape is wound around the outside of the aluminum alloy solid split conductor for at least 2 turns.

3. A medium voltage power cable with a large cross-section aluminum alloy solid split conductor according to claim 1, characterized in that: The isolation layer is crepe paper.

4. A medium voltage power cable with a large cross-section aluminum alloy solid split conductor according to claim 1, characterized in that: The solid sector-shaped stock block is made of aluminum alloy material.

5. The large-section aluminum alloy solid split conductor medium voltage power cable according to claim 1, characterized in that: The number of the solid sector-shaped strand blocks is 4, 5 or 6.

6. A medium voltage power cable with a large cross-section aluminum alloy solid split conductor according to claim 1, characterized in that: The metal shielding layer is made of copper tape wrapping or copper wire comb winding.

7. The large-section aluminum alloy solid split conductor medium voltage power cable according to claim 1, characterized in that: The insulating layer is made of cross-linked polyethylene material.

8. A method for preparing a novel large-section aluminum alloy solid split conductor medium-voltage power cable according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1: Calculate the size of the fan-shaped stock block and design the mold; Step 2: Melt the aluminum ingot at high temperature through a rolling aluminum extruder, and extrude the strands of required size through a set die; Step 3, the strands extruded from the die are shaped by a cooling annealing process; Step 4, untwist the formed fan-shaped strands through a twisting machine and set a suitable pitch; Step 5: Use a coiling machine to combine multiple fan-shaped strands to form a solid split conductor, and use crepe paper as an isolation layer between the fan-shaped strands; Step 6: Wrap two layers of semi-conductive tape around the outside of the solid split conductor as reinforcement to prevent the conductor from loosening; Step 7: Extruding a conductor shielding layer, an insulating layer and an insulating shielding layer on the outer side of the wrapped solid split conductor through a three-layer co-extrusion process to form an insulated wire core; Step 8: Wrap the copper tape around the outside of the insulated wire core to form a metal shielding layer to isolate electromagnetic interference, conduction leakage current, and capacitive current; Step 9, an isolation sleeve is extruded on the outer side of the metal shielding layer to protect the insulated core; Step 10, wrapping a stainless steel strip around the outside of the isolation sleeve as an armor layer; Step 11: Finally, extrude the outer sheath on the outside of the armor layer.

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