Direct current cable
By using non-crosslinked polypropylene material and flat aluminum sleeve design, the problem of crosslinked polyethylene material being unable to be recycled and operating temperature is solved, and cables with high current carrying capacity and high temperature operation are achieved, with good bending performance and insulation performance.
Patent Information
- Application Number
- CN202422498778.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-16
- Publication Date
- 2025-08-22
- Estimated Expiration
- 2034-10-16
AI Technical Summary
The existing crosslinked polyethylene DC cables cannot be recycled and reused after their lifetime expires, and the operating temperature can only reach 70℃, resulting in a short cable life, low conveying capacity, poor economy, and easy to be broken down.
A three-layer coextruded structural insulating layer with non-crosslinked polypropylene material as the matrix is designed with the outer layer of the flat aluminum sleeve and the hot melt adhesive layer to achieve the recyclability of the cable and the operating temperature to 90℃, enhancing insulation and bending performance.
The DC cable is recyclable and reusable, the current carrying capacity is increased by 15%-25%, the operating temperature is increased to 90℃, reducing the possibility of breakdown, and excellent bending performance.
Smart Images
Figure CN223260366U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of DC cables, in particular to a DC cable. Background Art
[0002] With the development of new energy, new electricity and new technologies, the distribution network has also quietly undergone a trend of DC-AC-AC / DC hybrid development at the current stage. DC power supply technology has become the focus of research at home and abroad for its high power supply quality and excellent power supply capacity.
[0003] Currently, cross-linked polyethylene (XLPE) is used as the base material for the insulation layer of DC cables due to its excellent electrical, mechanical, and thermal properties. However, XLPE is a thermoset material and therefore cannot be directly recycled after the cable reaches the end of its life. Incineration, pyrolysis, and landfilling not only consume large amounts of energy but also have significant negative environmental impacts, making them unsuitable for environmental protection. Furthermore, during operation, the insulation layer in a DC cable experiences a sharp increase in conductivity as the temperature rises, which in turn increases the electric field strength within the insulation layer. If the electric field strength during operation exceeds the insulation's withstand field strength, the DC cable may break down. Currently, DC cables made of XLPE can only operate at temperatures of 70°C, significantly lower than the 90°C operating temperature designed for my country's DC systems. This results in low transmission capacity and poor transmission economics. Temperatures exceeding 70°C can also cause the DC cable to break down.
[0004] Therefore, there is an urgent need for a DC cable to solve the above technical problems. Utility Model Content
[0005] The purpose of the utility model is to provide a DC cable that is recyclable and has a high current carrying capacity, an operating temperature of up to 90°C, reduces the possibility of cable breakdown, and has good bending performance.
[0006] To achieve this purpose, the present invention adopts the following technical solutions:
[0007] A DC cable, comprising:
[0008] Conductor layer;
[0009] an insulating layer, covering the outer periphery of the conductor layer; the insulating layer comprises a three-layer co-extruded structure consisting of a non-cross-linked conductor shielding layer, a non-cross-linked insulating layer, and a non-cross-linked insulating shielding layer, wherein the non-cross-linked conductor shielding layer, the non-cross-linked insulating layer, and the non-cross-linked insulating shielding layer are sequentially arranged from the inside to the outside, and the base material is non-cross-linked polypropylene;
[0010] a semiconductive buffer layer, coated on the outer peripheral surface of the insulating layer;
[0011] A metal sheath layer, wherein the metal sheath layer is a flat aluminum sheath, and the inner wall surface of the flat aluminum sheath is attached to the outer peripheral surface of the semi-conductive buffer layer;
[0012] The outer layer includes a three-layer co-extruded structure consisting of a hot melt adhesive layer, an outer sheath and a semi-conductive electrode, and the hot melt adhesive layer, the outer sheath and the semi-conductive electrode are arranged in sequence from the inside to the outside, and the outer layer is bonded to the outer peripheral surface of the flat aluminum sleeve through the hot melt adhesive layer.
[0013] In some possible implementations, the thickness of the non-cross-linked conductor shielding layer is greater than or equal to 0.8 mm and less than or equal to 2.0 mm; and / or,
[0014] The thickness of the non-cross-linked insulating layer is greater than or equal to 9 mm and less than or equal to 31 mm; and / or,
[0015] The thickness of the non-cross-linked insulating shielding layer is greater than or equal to 0.6 mm and less than or equal to 1.5 mm.
[0016] In some possible implementations, the inner wall surface of the flat aluminum sleeve is in contact with and pressed against the outer peripheral surface of the semiconductive buffer layer.
[0017] In some possible implementations, the head and tail ends of the flat aluminum sleeve are welded by argon arc welding to form a butt weld.
[0018] In some possible implementations, the outer wall of the flat aluminum sleeve at the butt weld is recessed inward to form a groove, and the thickness of the groove is less than or equal to 0.3 mm; or,
[0019] The inner wall of the flat aluminum sleeve at the butt weld is bulged inward to form a bulge, and the thickness of the bulge is less than or equal to 0.6 mm.
[0020] In some possible implementations, the thickness of the metal sheath layer is greater than or equal to 2.0 mm and less than or equal to 4.0 mm.
[0021] In some possible implementations, the thickness of the hot melt adhesive layer is greater than or equal to 0.4 mm and less than or equal to 1.2 mm; and / or,
[0022] The thickness of the outer sheath is greater than or equal to 2 mm and less than or equal to 8 mm; and / or,
[0023] The thickness of the semiconductive electrode is greater than or equal to 0.15 mm and less than or equal to 0.6 mm.
[0024] In some possible implementations, the flat aluminum sleeve is made of soft aluminum in a fully annealed state, and has a tensile strength of less than or equal to 95 N / mm.
[0025] In some possible implementations, the peeling force of the material of the hot melt adhesive layer is greater than or equal to 16 N / mm.
[0026] In some possible implementations, the yield strength of the material of the outer sheath is greater than or equal to 15 MPa.
[0027] Beneficial effects of the utility model:
[0028] The DC cable provided by the present invention includes a conductor layer, an insulating layer, a semi-conductive buffer layer, a metal sheath layer and an outer layer. The base materials of the non-cross-linked conductor shielding layer, the non-cross-linked insulating layer and the non-cross-linked insulating shielding layer are all non-cross-linked polypropylene, which enables the cable to have the processing characteristics of non-cross-linked extrusion, making it recyclable and reusable, and the operating temperature can reach 90°C, reducing the possibility of the cable being broken down. The non-cross-linked conductor shielding layer, the non-cross-linked insulating layer and the non-cross-linked insulating shielding layer are a three-layer co-extrusion structure, so that the non-cross-linked conductor shielding layer and the non-cross-linked insulating shielding layer can be tightly combined with the non-cross-linked insulating layer, which can enhance the insulation performance. The metal sheath layer is a flat aluminum sheath, and the inner wall surface of the flat aluminum sheath is attached to the outer peripheral surface of the semi-conductive buffer layer, so that the contact resistance between the metal sheath layer and the semi-conductive buffer layer is small, thereby avoiding the semi-conductive buffer layer from being burned, and further reducing the possibility of the cable being broken down. The hot melt adhesive layer, outer sheath and semi-conductive electrode are three-layer co-extruded structures, and the outer sheath is bonded to the outer peripheral surface of the flat aluminum sleeve through the hot melt adhesive layer. Through co-extrusion and bonding, the outer sheath and the flat aluminum sleeve can be tightly bonded, making the flat aluminum sleeve less likely to bend and wrinkle, making the minimum bending radius of the cable relatively smaller, and thus improving the bending performance. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Figure 1 It is a structural schematic diagram of the DC cable provided by the utility model.
[0030] In the picture:
[0031] 1. Conductor layer;
[0032] 2. Insulation layer; 21. Non-cross-linked conductor shielding layer; 22. Non-cross-linked insulation layer; 23. Non-cross-linked insulation shielding layer;
[0033] 3. Semiconducting buffer layer;
[0034] 4. Metal sheath layer;
[0035] 5. Outer layer; 51. Hot melt adhesive layer; 52. Outer sheath; 53. Semi-conductive electrode. DETAILED DESCRIPTION
[0036] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all of its components.
[0037] In the description of this utility model, unless otherwise specified or limited, the terms "connected," "connect," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on the specific circumstances.
[0038] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.
[0039] In the description of this embodiment, the terms "upper," "lower," "right," and other orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for ease of description and simplified operation. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used solely for descriptive purposes and have no special meaning.
[0040] like Figure 1As shown, the utility model provides a DC cable, comprising a conductor layer 1, an insulating layer 2, a semi-conductive buffer layer 3, a metal sheath layer 4, and an outer layer 5. The insulating layer 2 is coated on the outer periphery of the conductor layer 1; the insulating layer 2 comprises a three-layer co-extruded structure consisting of a non-cross-linked conductor shielding layer 21, a non-cross-linked insulating layer 22, and a non-cross-linked insulating shielding layer 23. The non-cross-linked conductor shielding layer 21 is used to prevent local discharge caused by gaps between the surface of the conductor layer 1 and the surface of the non-cross-linked insulating layer 22, and the non-cross-linked insulating shielding layer 23 is used to prevent local discharge caused by gaps between the semi-conductive buffer layer 3 and the non-cross-linked insulating layer 22. The non-cross-linked conductor shielding layer 21, the non-cross-linked insulating layer 22, and the non-cross-linked insulating shielding layer 23 are arranged in sequence from the inside to the outside, and the base material is non-cross-linked polypropylene.
[0041] The semiconductive buffer layer 3, covering the outer surface of the insulating layer 2, protects the conductor layer 1 and insulating layer 2 within the cable from external mechanical damage. It also provides a certain buffering effect, preventing the cable from being subjected to excessive mechanical stress during operation. Furthermore, due to its semiconductive properties, the semiconductive buffer layer 3 also provides a path for short-circuit currents. The semiconductive buffer layer 3 can be a semiconductive water-blocking tape, which not only performs the above functions but also has a water-blocking function. The metal sheath layer 4 can be used to carry short-circuit current. The metal sheath layer 4 is a flat aluminum sheath, and the inner wall surface of the flat aluminum sheath is adhered to the outer peripheral surface of the semi-conductive buffer layer 3; the outer layer 5 includes a three-layer co-extrusion structure consisting of a hot-melt adhesive layer 51, an outer sheath 52 and a semi-conductive electrode 53. The hot-melt adhesive layer 51 serves as an anti-corrosion layer for the metal sheath layer 4, and the outer sheath 52 serves as a protective layer for the cable. The cable can resist external mechanical impact through the outer sheath 52. The semi-conductive electrode 53 serves as grounding protection for the cable. The hot-melt adhesive layer 51, the outer sheath 52 and the semi-conductive electrode 53 are arranged in sequence from the inside to the outside, and the outer layer 5 is bonded to the outer peripheral surface of the flat aluminum sheath through the hot-melt adhesive layer 51.
[0042] The base materials of the non-cross-linked conductor shielding layer 21, non-cross-linked insulation layer 22, and non-cross-linked insulation shielding layer 23 are all non-cross-linked polypropylene. First, this gives the cable the processing characteristics of non-cross-linked extrusion, making it recyclable and reusable. Second, it can achieve a temperature resistance rating of 105°C, thereby increasing the operating temperature from 70°C to 90°C under DC conditions, reducing the possibility of cable breakdown. According to calculations, it can also increase the cable's current carrying capacity by 15% to 25%. Finally, the cable has excellent extrusion performance and can be used with specialized extrusion equipment in medium voltage, high voltage, and ultra-high voltage applications. In addition, the non-cross-linked conductor shielding layer 21, non-cross-linked insulation layer 22, and non-cross-linked insulation shielding layer 23 are a three-layer co-extruded structure, allowing the non-cross-linked conductor shielding layer 21 and non-cross-linked insulation shielding layer 23 to be tightly integrated with the non-cross-linked insulation layer 22, thereby enhancing insulation performance.
[0043] The metal sheath layer 4 is a flat aluminum sheath, and the inner wall surface of the flat aluminum sheath is attached to the outer peripheral surface of the semi-conductive buffer layer 3, so that the contact resistance between the metal sheath layer 4 and the semi-conductive buffer layer 3 is small, and the semi-conductive buffer layer 3 is prevented from being burned, further reducing the possibility of the cable being broken down. The metal sheath layer 4 is a flat aluminum sheath, which can also improve the current carrying capacity of the cable. In addition, the outer layer 5 includes a three-layer co-extrusion structure consisting of a hot melt adhesive layer 51, an outer sheath 52 and a semi-conductive electrode 53, and the outer layer 5 is bonded to the outer peripheral surface of the flat aluminum sheath through the hot melt adhesive layer 51. Through co-extrusion and bonding, the outer sheath 52 can be tightly bonded to the flat aluminum sheath, making the flat aluminum sheath less likely to bend and wrinkle, making the minimum bending radius of the cable relatively smaller, and making the bending performance better.
[0044] Optionally, in this embodiment, the thickness of the non-cross-linked conductive shielding layer 21 is greater than or equal to 0.8 mm and less than or equal to 2.0 mm, so that the non-cross-linked conductive shielding layer 21 and the non-cross-linked insulating layer 22 can be in close contact, further preventing partial discharge. If the thickness of the non-cross-linked conductive shielding layer 21 is set too small, its ability to balance the strong electric field on the surface of the conductive layer 1 and its safety margin will be reduced. If the thickness of the non-cross-linked conductive shielding layer 21 is set too large, it will increase the material consumption of subsequent structures and cause resource waste.
[0045] Optionally, in this embodiment, the thickness of the non-cross-linked insulating layer 22 is greater than or equal to 9 mm and less than or equal to 31 mm. If the thickness of the non-cross-linked insulating layer 22 is set too small, the insulating layer 2 may be broken down due to the excessively high field strength. If the thickness of the non-cross-linked insulating layer 22 is set too large, the extrusion process becomes more difficult, the probability of weak point breakdown increases, and the material consumption of subsequent structures increases, resulting in waste of resources.
[0046] Optionally, in this embodiment, the thickness of the non-cross-linked insulating shielding layer 23 is greater than or equal to 0.6 mm and less than or equal to 1.5 mm, allowing the non-cross-linked insulating shielding layer 23 to be in close contact with the non-cross-linked insulating layer 22, further preventing partial discharge. If the thickness of the non-cross-linked insulating shielding layer 23 is set too small, its ability to balance the strong electric field on the surface of the non-cross-linked insulating layer 22 and its safety margin will be reduced; if the thickness of the non-cross-linked insulating shielding layer 23 is set too large, it will increase the material consumption of subsequent structures and cause resource waste.
[0047] Optionally, in this embodiment, the inner wall of the flat aluminum sleeve is in contact with and tightly abuts the outer circumference of the semiconductive buffer layer 3. Specifically, the flat aluminum sleeve is continuously rolled and compressed so that the inner wall of the flat aluminum sleeve is in contact with and tightly abuts the outer circumference of the semiconductive buffer layer 3. This arrangement improves contact between the metal sheath layer 4 and the semiconductive buffer layer 3, preventing poor contact that could cause ablation of the semiconductive buffer layer 3.
[0048] Optionally, in this embodiment, the ends of the flat aluminum sleeve are welded by argon arc welding to form a butt weld, thereby enhancing the structural strength of the flat aluminum sleeve. Optionally, the outer wall of the flat aluminum sleeve at the butt weld is inwardly recessed to form a groove, the thickness of the groove being less than or equal to 0.3 mm, or the inner wall of the flat aluminum sleeve at the butt weld is inwardly raised to form a raised portion, the thickness of the raised portion being less than or equal to 0.6 mm, to ensure uniform electric field distribution.
[0049] Optionally, in this embodiment, the thickness of the metal sheath layer 4 is greater than or equal to 2.0 mm and less than or equal to 4.0 mm, which has a higher carrying capacity for short-circuit current and enables the cable to have better bending performance.
[0050] Optionally, the thickness of the hot melt adhesive layer 51 is greater than or equal to 0.4 mm and less than or equal to 1.2 mm. This serves as a corrosion protection layer for the metal sheath layer 4 while ensuring tight adhesion between the metal sheath layer 4 and the outer sheath 52. Optionally, the thickness of the outer sheath 52 is greater than or equal to 2 mm and less than or equal to 8 mm, enhancing the cable's resistance to external mechanical impact and improving its bending properties. Optionally, the thickness of the semiconductive electrode 53 is greater than or equal to 0.15 mm and less than or equal to 0.6 mm, ensuring sufficient contact between the cable and the ground. This allows the semiconductive electrode 53 to function as an external electrode to meet cable testing requirements.
[0051] Optionally, in this embodiment, the material of the flat aluminum sheath is soft aluminum in a fully annealed state, and the tensile strength is less than or equal to 95N / mm, ensuring that the flat aluminum sheath has good ductility and impact resistance, so that the finished cable has excellent resistance to mechanical shock, and the cable has passed the free-fall flat aluminum weld mechanical impact test with a 27kg hammer and a height of 50cm.
[0052] Optionally, in this embodiment, the hot-melt adhesive layer 51 has a peel force greater than or equal to 16 N / mm, ensuring a tighter and more secure bond between the outer sheath 52 and the flat aluminum sleeve, preventing the sleeve from bending or wrinkling. Furthermore, the outer sheath 52 has a yield strength greater than or equal to 15 MPa, enhancing the cable's bending properties. Furthermore, the outer sheath 52 is made of flame-retardant PE, which offers excellent scratch and crack resistance, as well as flame retardancy.
[0053] Obviously, the above-described embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention and are not intended to limit the manner in which the present invention is to be implemented. A person skilled in the art would be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.
Claims
1. A DC cable, characterized in that: include: Conductor layer (1); An insulating layer (2) is coated on the outer periphery of the conductor layer (1); the insulating layer (2) comprises a three-layer co-extruded structure consisting of a non-cross-linked conductor shielding layer (21), a non-cross-linked insulating layer (22) and a non-cross-linked insulating shielding layer (23); the non-cross-linked conductor shielding layer (21), the non-cross-linked insulating layer (22) and the non-cross-linked insulating shielding layer (23) are arranged in sequence from the inside to the outside, and the base material is non-cross-linked polypropylene; a semiconductive buffer layer (3) coated on the outer peripheral surface of the insulating layer (2); A metal sheath layer (4), the metal sheath layer (4) being a flat aluminum sheath, the inner wall surface of the flat aluminum sheath being attached to the outer peripheral surface of the semi-conductive buffer layer (3); The outer layer (5) comprises a three-layer co-extruded structure consisting of a hot melt adhesive layer (51), an outer sheath (52) and a semi-conductive electrode (53), wherein the hot melt adhesive layer (51), the outer sheath (52) and the semi-conductive electrode (53) are arranged in sequence from the inside to the outside, and the outer layer (5) is bonded to the outer peripheral surface of the flat aluminum sleeve through the hot melt adhesive layer (51).
2. The DC cable according to claim 1, characterized in that: The thickness of the non-cross-linked conductor shielding layer (21) is greater than or equal to 0.8 mm and less than or equal to 2.0 mm; and / or, The thickness of the non-cross-linked insulating layer (22) is greater than or equal to 9 mm and less than or equal to 31 mm; and / or, The thickness of the non-cross-linked insulating shielding layer (23) is greater than or equal to 0.6 mm and less than or equal to 1.5 mm.
3. The DC cable according to claim 1, characterized in that: The inner wall surface of the flat aluminum sleeve is in contact with and pressed against the outer peripheral surface of the semi-conductive buffer layer (3).
4. The DC cable according to claim 1, characterized in that The head and tail ends of the flat aluminum sleeve are welded by argon arc welding to form butt welds.
5. The DC cable according to claim 4, characterized in that: The outer wall of the flat aluminum sleeve at the butt weld is indented inward to form a groove, and the thickness of the groove is less than or equal to 0.3 mm; or The inner wall of the flat aluminum sleeve at the butt weld is bulged inward to form a bulge, and the thickness of the bulge is less than or equal to 0.6 mm.
6. The DC cable according to claim 1, characterized in that: The thickness of the metal sheath layer (4) is greater than or equal to 2.0 mm and less than or equal to 4.0 mm.
7. The DC cable according to claim 1, characterized in that: The thickness of the hot melt adhesive layer (51) is greater than or equal to 0.4 mm and less than or equal to 1.2 mm; and / or, The thickness of the outer sheath (52) is greater than or equal to 2 mm and less than or equal to 8 mm; and / or, The thickness of the semiconductive electrode (53) is greater than or equal to 0.15 mm and less than or equal to 0.6 mm.
8. The DC cable according to claim 1, characterized in that: The material of the flat aluminum sleeve is soft aluminum in a completely annealed state, and the tensile strength is less than or equal to 95N / mm.
9. The DC cable according to claim 1, characterized in that: The peeling force of the material of the hot melt adhesive layer (51) is greater than or equal to 16N / mm.
10. The DC cable according to claim 1, characterized in that: The yield strength of the material of the outer sheath (52) is greater than or equal to 15 MPa.