Super-flexible 27.5 kV high-speed rail traction power supply cable

Abstract

The utility model discloses a super-flexible 27.5 kV high-speed rail traction power supply cable, which is suitable for the technical field of cables. The cable comprises a circular stranded copper conductor, a conductor shielding layer, an ethylene propylene rubber insulating layer, a semi-conductive insulating shielding layer, a low-density polyethylene isolation sleeve, a halogen-free low-smoke flame-retardant glass fiber belt and an aluminum wire armor layer, wherein the periphery of the circular stranded copper conductor is surrounded by the conductor shielding layer, the ethylene propylene rubber insulating layer and the semi-conductive insulating shielding layer are wrapped outside, a semi-conductive water-blocking belt and a metal shielding layer are arranged outside the semi-conductive water-blocking belt and the metal shielding layer, and the low-density polyethylene isolation sleeve and the halogen-free low-smoke flame-retardant glass fiber belt and the aluminum wire armor layer are wrapped outside. A double-layer flame-retardant wrapping tape and a low-smoke halogen-free sheath are wrapped outside, and a nylon outer sheath is arranged on the outermost layer; on the premise that the whole cable structure meets various performance requirements of high-speed rail operation, through the flexible design of structural materials of all parts, the weight of the cable is reduced as much as possible, the installation convenience is greatly improved, the installation and construction cost is reduced, and the cable conforms to the efficient and economic development trend of modern high-speed rail construction and is worthy of popularization and application. The method has wide application prospects and remarkable economic benefits and social benefits.

Description

Technical Field

[0001] This utility model relates to the field of cable technology, and in particular to an ultra-flexible 27.5kV high-speed rail traction power supply cable. Background Technology

[0002] To address the shortcomings of commonly used cables, such as poor flexibility, weak impact resistance, poor oil resistance, and inability to withstand high and low temperatures, and to make them more suitable for high-speed trains, a utility model patent with publication number CN103077783A discloses a "production process for cables used in high-speed trains." This utility model relates to the field of cable manufacturing, specifically a production process for cables used in high-speed trains. The process involves layering and repeatedly twisting multiple fine tin-plated copper wires of the same diameter in the same direction to form a conductor cable core. An inner and outer insulation layer is then simultaneously extruded onto the conductor cable core, using one or both of phosphate ester and magnesium hydroxide as flame retardants. However, this cable has drawbacks, including low production efficiency, potential aging and degradation of certain materials under extreme environments, poor fatigue resistance, and reduced service life.

[0003] To improve the voltage withstand performance and flexibility of cables during long-term surge current operation, and also to extend their service life, a utility model patent with publication number CN201749721U discloses a "power cable for high-speed electrified railways." The cable features a single-core conductor formed by multiple strands of tin-plated soft copper wire twisted together at its center. A non-woven fabric insulating layer is wrapped around the conductor. On the insulating layer, three layers are co-extruded: a conductor semi-conductive layer, an insulation layer, and an insulating semi-conductive layer. On the insulating semi-conductive layer, in sequence, are: a metal shielding layer formed by tin-plated copper wire braiding, an extruded inner sheath, and a sealed metal sheath formed by longitudinal welding and corrugation. The outermost layer of the cable is extruded with an outer sheath. Although this cable is stable and reliable with good fatigue resistance, its insulation performance is easily affected.

[0004] In summary, existing high-speed rail power supply cables typically have the following drawbacks: insufficient cable flexibility, poor fatigue resistance, and easily affected insulation performance. Summary of the Invention

[0005] The purpose of this utility model is to solve the problems in the existing technology and propose an ultra-flexible 27.5kV high-speed rail traction power supply cable, which can solve a series of problems such as insufficient flexibility, poor fatigue resistance, and easy impact on insulation performance of existing cables.

[0006] To achieve the above objectives, this utility model proposes an ultra-flexible 27.5kV high-speed rail traction power supply cable. The cable's structural layers, from the inside out, include: a circular stranded copper conductor, a conductor shielding layer, an EPDM rubber insulation layer, a semi-conductive insulation shielding layer, a wrapped semi-conductive resistive water-resistant tape, a metal shielding layer, a low-density polyethylene isolation sleeve, a wrapped halogen-free, low-smoke, flame-retardant fiberglass tape, an aluminum wire armor layer, a wrapped double-layer flame-retardant tape, and a low-smoke, halogen-free sheath. The circular stranded copper conductor is surrounded by a conductor shielding layer, and the outer side of the conductor shielding layer is made of EPDM rubber. The rubber insulation layer consists of an ethylene propylene rubber insulation layer, an outer semi-conductive insulating shielding layer, an outer semi-conductive resistive water tape, an outer metal shielding layer, an outer low-density polyethylene isolation sleeve, an outer halogen-free, low-smoke, flame-retardant fiberglass tape, an outer aluminum wire armor layer, an outer double-layer flame-retardant wrapping tape, and an outer low-smoke, halogen-free sheath.

[0007] Preferably, the conductor is made of tin-plated copper wire, which has good flexibility and conductivity; the stranding ratio of each layer is optimized to significantly improve the flexibility of the conductor while ensuring the uniformity of current transmission.

[0008] Preferably, the conductor shielding layer comprises a semiconductor nylon strip and a semiconducting conductor shielding strip, with the semiconductor nylon strip located inside the semiconducting conductor shielding strip. The semiconducting nylon strip possesses excellent flexibility and semiconducting properties, which not only further enhances the stability of the conductor structure but also helps to achieve a uniform electric field distribution, reduce the electric field intensity on the conductor surface, and decrease the occurrence of corona discharge.

[0009] Preferably, all three layers of the insulation layer are made of soft ethylene propylene rubber. Due to its excellent electrical insulation properties, flexibility and aging resistance, ethylene propylene rubber is an ideal choice for the insulation and shielding layer of high-speed rail traction power supply cables. Nanoscale silica particles are uniformly added to the ethylene propylene rubber material of the inner and outer shielding layers to effectively enhance the mechanical properties and corona resistance of the shielding layer.

[0010] Preferably, the inner shielding layer is tightly fitted to the semi-conductive nylon tape wrapped around the conductor, and the outer shielding layer is located outside the insulation layer. Together, they create a uniform electric field, preventing local electric field concentration in the insulation layer and protecting the insulation layer from electric field damage.

[0011] Preferably, the metal shielding layer is made of copper wire in a loose winding manner. This loose winding method greatly improves the flexibility of the cable while ensuring the shielding effect. Subsequently, soft copper tape is used for gap wrapping to further enhance the shielding effect and the flexibility of the cable.

[0012] Preferably, the low-density polyethylene insulating sleeve is made of soft linear low-density polyethylene material; this material has good flexibility, chemical stability and waterproof performance, and can effectively isolate the internal structure of the cable from the external environment, protecting the inside of the cable from external factors.

[0013] Preferably, the metal armor is made of non-magnetic aluminum wire that has undergone annealing and softening treatment; the annealing and softening treatment gives the aluminum wire good flexibility, while the non-magnetic properties prevent additional electromagnetic interference in the strong electromagnetic environment of high-speed rail operation.

[0014] Preferably, the aluminum wires are closely arranged around the cable core to provide the necessary mechanical protection for the cable while maximizing the cable's flexibility so that it can adapt to various bending requirements during high-speed rail operation.

[0015] Preferably, the outer sheath is made of a soft, low-smoke, halogen-free material, which has good flexibility and is also environmentally friendly with low smoke and halogen-free properties. The thickness of the outer sheath is reasonably determined according to the cable's operating environment and mechanical protection requirements, and has excellent wear resistance, chemical corrosion resistance and waterproof performance. An appropriate amount of plasticizers and other additives are added to the outer sheath material.

[0016] The beneficial effects of this utility model are:

[0017] 1) Structural optimization: Through innovative optimization of the conductor structure, including improvements in stranding process and wrapping with semi-conductive nylon tape, the flexibility of the cable has been significantly improved, which can perfectly adapt to the complex working conditions such as frequent bending and vibration during high-speed rail operation, greatly reducing the risk of cable damage caused by mechanical stress and effectively ensuring the stable operation of the high-speed rail power supply system.

[0018] 2) Performance improvement: The three-layer co-extrusion structure of soft ethylene propylene rubber material, combined with the addition of nano-level reinforcing particles, effectively improves the electrical insulation performance and corona resistance of the cable, ensuring stable and reliable operation of the cable under high voltage environment, greatly reducing the probability of electrical faults, and improving the safety and stability of high-speed rail power supply.

[0019] 3) Improved efficiency and reduced costs: The uniquely designed metal shielding structure, consisting of loosely wound copper wires and soft copper strips with gaps, along with a flexible linear low-density polyethylene isolation sleeve, not only effectively enhances the shielding effect but also further improves the cable's flexibility. The outer sheath is made of soft, low-smoke, halogen-free material, possessing excellent environmental performance, abrasion resistance, chemical corrosion resistance, and waterproof performance. This comprehensively improves the cable's overall performance and service life in complex environments, while reducing maintenance costs.

[0020] The features and advantages of this utility model will be described in detail through embodiments and accompanying drawings. Attached Figure Description

[0021] Figure 1 This is a cross-sectional structural diagram of the present invention;

[0022] Figure 2 This is a schematic diagram of the structural hierarchy of this utility model;

[0023] The numbers in the diagram are: 1-Circular stranded copper conductor; 2-Conductor shielding layer; 3-Ethylene propylene rubber insulation layer; 4-Semi-conductive insulating shielding layer; 5-Wrapped semi-conductive resistive water tape; 6-Metallic shielding layer; 7-Low-density polyethylene isolation sleeve; 8-Wrapped halogen-free low-smoke flame-retardant fiberglass tape; 9-Aluminum wire armor layer; 10-Wrapped double-layer flame-retardant wrapping tape; 11-Low-smoke halogen-free sheath; 12-Nylon outer sheath. Detailed Implementation

[0024] Example 1:

[0025] See Figure 1 , 2 This utility model discloses an ultra-flexible 27.5kV high-speed rail traction power supply cable. The cable's structure, from the inside out, includes a circular stranded copper conductor 1, a conductor shielding layer 2 surrounding the outer perimeter, followed by an ethylene propylene rubber insulation layer 3, then a semi-conductive insulation shielding layer 4, then a semi-conductive resistive water tape 5, a metal shielding layer 6 outside of it, a low-density polyethylene isolation sleeve 7, then a halogen-free, low-smoke, flame-retardant fiberglass tape 8, an aluminum wire armor layer 9 on the outside, then a double-layer flame-retardant wrapping tape 10, then a low-smoke, halogen-free sheath 11, and finally a nylon outer sheath 12.

[0026] First, 2960 tin-plated copper wires with a single wire diameter of 0.40mm were selected. After stranding according to the designed stranding process, the stranding directions of each layer of copper wire were alternated, and the stranding pitch ratio of each layer was controlled within a reasonable range: 15 for the first layer, 18 for the second, and 20 for the third. After stranding, a layer of semi-conductive nylon tape, 55mm wide and 0.12mm thick, was tightly wrapped around the outside of the conductor. A three-layer co-extrusion process was used to extrude the inner shielding layer, insulation layer, and outer shielding layer in one step. Nano-sized silica particles were uniformly added to the ethylene propylene rubber material of the inner and outer shielding layers. The insulation layer thickness was designed to be 11.3mm to meet the insulation requirements of the 27.5kV voltage level. In addition to the three-layer co-extruded structure, a metal shielding layer is set. The metal shielding adopts a copper wire loose winding method with a copper wire diameter of 0.895mm and a loose winding pitch of 900mm. Subsequently, a soft copper strip with a width of 20mm and a thickness of 0.10mm is used for gap wrapping, with the gap width controlled at 70mm. The isolation sleeve is made of soft linear low-density polyethylene material with a nominal thickness of 2.0mm, which is tightly wrapped on the outside of the metal shielding layer through an extrusion process. The armor uses non-magnetic aluminum wire with a diameter of 2.5mm that has undergone annealing and softening treatment, which is tightly arranged around the cable core. The outer sheath is made of soft low-smoke halogen-free material with a designed thickness of 3.1mm, and an appropriate amount of plasticizers and other additives are added to the outer sheath material.

[0027] In this embodiment, testing revealed that the conductor structure has a moderate number of tinned copper wires and a reasonable stranding pitch ratio. Combined with the design of a loosely wound copper wire and a metal shielding layer with gaps in the soft copper strip, the cable exhibits excellent flexibility. The non-magnetic aluminum wire armor and low-smoke halogen-free outer sheath design provide excellent mechanical protection, effectively resisting external environmental erosion and mechanical damage, ensuring the cable's safety during high-speed rail operation, ensuring stable operation under high-voltage conditions, and meeting the general bending and vibration requirements of high-speed rail operation.

[0028] Example 2:

[0029] This embodiment is basically the same as Embodiment 1, except that: the number of tin-plated copper wires in the conductor structure is increased to 3280, and the diameter of a single wire is adjusted to 0.38mm; in the stranding process, the stranding pitch ratio of each layer is adjusted to 16, 17, and 19 respectively; the insulation layer thickness is increased to 11.5mm to meet more stringent insulation requirements, while the content of nano-sized silica particles in the inner and outer shielding layers is increased; the pitch of the copper wire winding is adjusted to 850mm, and the gap width of the soft copper strip is controlled at 60mm; the nominal thickness of the isolation sleeve is increased to 2.2mm; and the thickness of the outer sheath is increased to 3.2mm.

[0030] In this embodiment, the conductor structure is finer and the stranding pitch ratio is further optimized. After the copper wire loosening pitch and soft copper strip gap width of the metal shielding layer are adjusted, the flexibility is significantly improved while ensuring the shielding effect, and it can better adapt to the complex mechanical stress in high-speed rail operation. Although the performance is better, more mechanical assistance and human resources may be required during the installation process, making it suitable for special sections with extremely high requirements for electrical insulation performance.

[0031] Example 3:

[0032] This embodiment is basically the same as Embodiment 1, except that: in the conductor structure, the number of tin-plated copper wires is 1930, and the diameter of a single wire is 0.50mm; in the stranding process, the stranding pitch ratio of each layer is set to 14, 16, and 18 respectively; the insulation layer thickness is adjusted to 11.1mm, and the content of nano-sized silica particles in the inner and outer shielding layers is reduced; the pitch of the copper wire winding is increased to 950mm, and the gap width of the soft copper strip is expanded to 80mm; the nominal thickness of the isolation sleeve is adjusted to 1.8mm; the thickness of the outer sheath is adjusted to 3.0mm, and the amount of plasticizers and other additives is optimized.

[0033] In this embodiment, the conductor structure is relatively coarse, the stranding pitch is slightly lower, the copper wire of the metal shielding layer has a larger loose winding pitch, and the gap width of the soft copper strip is wider. While ensuring basic flexibility, it focuses more on simplifying the structure and reducing costs. Its flexibility is slightly inferior to the previous two embodiments. It is suitable for conventional sections where the insulation performance requirements are not extremely strict, and it is more in line with the needs of efficient and economical high-speed rail construction.

[0034] The above embodiments are illustrative of the present invention and are not intended to limit the present invention. Any simple modifications to the present invention are within the protection scope of the present invention.

Claims

1. A super-flexible 27.5kV high-speed rail traction power supply cable, characterized in that: The cable's structural layers, from the inside out, include a circular stranded copper conductor (1), a conductor shielding layer (2), an ethylene propylene rubber insulation layer (3), a semi-conductive insulating shielding layer (4), a wrapped semi-conductive resistive water tape (5), a metal shielding layer (6), a low-density polyethylene isolation sleeve (7), a wrapped halogen-free low-smoke flame-retardant fiberglass tape (8), an aluminum wire armor layer (9), a wrapped double-layer flame-retardant wrapping tape (10), and a low-smoke halogen-free sheath (11). The circular stranded copper conductor (1) is surrounded by a conductor shielding layer (2). Outside the conductor shielding layer (2) is an ethylene propylene rubber insulation layer (3), and outside the ethylene propylene rubber insulation layer (3) is... A semiconductive insulating shielding layer (4) is surrounded by a semiconductive resistive water tape (5). Outside the semiconductive resistive water tape (5) is a metal shielding layer (6). Outside the metal shielding layer (6) is a low-density polyethylene isolation sleeve (7). Outside the low-density polyethylene isolation sleeve (7) is a halogen-free, low-smoke, flame-retardant fiberglass tape (8). Outside the halogen-free, low-smoke, flame-retardant fiberglass tape (8) is an aluminum wire armor layer (9). Outside the aluminum wire armor layer (9) is a double-layer flame-retardant wrapping tape (10). Outside the double-layer flame-retardant wrapping tape (10) is a low-smoke, halogen-free sheath (11).

2. The ultra-flexible 27.5kV high-speed rail traction power supply cable as described in claim 1, characterized in that: The circular stranded copper conductor (1) is formed by stranding multiple tin-plated copper wires, with the stranding directions of each layer of copper wires alternating.

3. The ultra-flexible 27.5kV high-speed rail traction power supply cable as described in claim 1, characterized in that: The conductor shielding layer (2) includes a semiconductor nylon strip and a semiconducting conductor shielding strip, with the semiconductor nylon strip inside the semiconducting conductor shielding strip.

4. The ultra-flexible 27.5kV high-speed rail traction power supply cable as described in claim 1, characterized in that: The ethylene propylene rubber insulation layer (3) is composed of an inner shielding layer, an insulation layer and an outer shielding layer. The inner shielding layer, the insulation layer and the outer shielding layer are formed by one-time extrusion. The inner shielding layer is tightly attached to the semi-conductive nylon tape wrapped around the conductor, and the outer shielding layer is located outside the insulation layer.

5. The ultra-flexible 27.5kV high-speed rail traction power supply cable as described in claim 1, characterized in that: The metal shielding layer (6) is formed by a combination of copper wire and soft copper strip. The metal shielding layer (6) contains loosely wound copper wire, and the soft copper strip is wrapped around the outside of the copper wire.

6. The ultra-flexible 27.5kV high-speed rail traction power supply cable as described in claim 1, characterized in that: The aluminum wire armor layer (9) is made of non-magnetic aluminum wire that has been annealed and softened, and the aluminum wire is closely arranged around the cable core.

7. A flexible 27.5kV high-speed rail traction power supply cable as described in any one of claims 1 to 6, characterized in that: It also includes a nylon outer sheath (12), which is located outside the low-smoke halogen-free sheath (11).

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