A cable with high short circuit current carrying capability

Abstract

The utility model provides a kind of cable of high short-circuit current carrying capacity, comprising: cable core, the cable core outside is equipped with aluminium tape shield layer and sheath in proper order, the aluminium tape shield layer includes: aluminium tape layer and the aluminium oxide protective film being equipped with on one side of aluminium tape layer, the aluminium tape layer includes: aluminium tape, the aluminium tape is tightly covered in the cable core outside in longitudinal direction, the thickness of the aluminium tape is 0.2~0.5mm, the width of the aluminium tape is 50~200mm;With high electric conduction efficiency, excellent antioxidant characteristic and process adaptability shield structure, improve the short-circuit current carrying capacity of cable.

Description

Technical Field

[0001] This utility model relates to the field of cable technology, specifically to a cable with high short-circuit current carrying capacity. Background Technology

[0002] With the continuous improvement of the capacity and voltage level of modern power systems, the requirements for the short-circuit current carrying capacity of cables are becoming increasingly stringent. Especially in the field of high-voltage power transmission and distribution, cables need to be able to withstand the impact of instantaneous currents of up to tens of thousands of amperes during a short-circuit fault, which places higher demands on the conductivity, thermal stability, and mechanical strength of the cable shielding layer.

[0003] Traditional cable shielding layers typically employ copper or aluminum tape wrapping structures. While copper tape offers excellent conductivity, its high material cost and excessive weight limit its widespread application. Although aluminum tape is less expensive, it suffers from significant drawbacks in practical applications: firstly, the aluminum surface readily oxidizes, forming a dense oxide film that increases contact resistance and worsens at high temperatures, severely impacting the instantaneous conduction efficiency of short-circuit currents; secondly, conventional aluminum tape shielding layers often use a gap-wrapping process, making it difficult to achieve tight adhesion to the conductor surface, leading to decreased electromagnetic shielding effectiveness and increased risk of partial discharge. Furthermore, existing aluminum tape thickness designs are often limited to a single parameter range (e.g., 0.1–0.3 mm), making it difficult to balance resistance to mechanical deformation and current-carrying efficiency. Width selection also lacks consideration for compatibility with longitudinal wrapping processes, easily resulting in edge warping or cracking, further weakening the overall performance of the shielding layer.

[0004] While existing technologies have attempted to apply protective coatings to the surface of aluminum strips, the organic coatings used, although able to delay oxidation, significantly increase contact resistance and degrade conductivity. Other existing technologies have proposed nano-alumina coating technology, but the process is complex and the coating thickness is difficult to control precisely, making it impossible to achieve both long-term oxidation resistance and current carrying stability.

[0005] The above background information is provided only to assist in understanding the utility model concept and technical solution of this utility model. It does not necessarily belong to the prior art of this patent application, nor does it necessarily provide technical teaching. In the absence of clear evidence that the above information was disclosed before the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Utility Model Content

[0006] To address the technical challenges of achieving a shielding structure that combines high conductivity, excellent oxidation resistance, and process adaptability to enhance the short-circuit current carrying capacity of cables, this invention proposes a cable with high short-circuit current carrying capacity. This cable features a shielding structure that combines high conductivity, excellent oxidation resistance, and process adaptability, thereby not only improving the cable's short-circuit current carrying capacity but also reducing costs.

[0007] To achieve the above objectives, the technical solution of this utility model is as follows: On one hand, this utility model provides a cable with high short-circuit current carrying capacity, comprising: a cable core, an aluminum tape shielding layer and a sheath sequentially disposed on the outside of the cable core, the aluminum tape shielding layer comprising: an aluminum tape layer and an aluminum oxide protective film disposed on one side of the aluminum tape layer, the aluminum tape layer comprising: an aluminum tape, the aluminum tape being longitudinally wrapped tightly around the outside of the cable core, the thickness of the aluminum tape being 0.2-0.5mm and the width of the aluminum tape being 50-200mm.

[0008] This utility model provides a cable with high short-circuit current carrying capacity, which has a shielding structure that combines high conductivity, excellent oxidation resistance and process adaptability, thereby not only improving the cable's short-circuit current carrying capacity but also reducing costs.

[0009] As a preferred technical solution, a plastic layer is coated on the other side of the aluminum strip layer, the aluminum oxide protective film is disposed on the aluminum strip layer near the sheath, and the plastic layer is disposed on the aluminum strip layer away from the sheath.

[0010] As a preferred technical solution, the thickness of the alumina protective film is 50-200 nm, and the thickness of the plastic layer is 50-150 μm.

[0011] As a preferred technical solution, the longitudinal overlap rate of the aluminum strip is ≥15%.

[0012] As a preferred technical solution, the cable core includes: a conductor, which is formed by stranding multiple metal wires in a frame and radially compressing them, wherein the compression coefficient of the conductor after radial pressure compression is 0.85 to 0.95.

[0013] As a preferred technical solution, the cable core includes: a conductor shielding layer, which tightly covers the outside of the conductor.

[0014] As a preferred technical solution, the cable core includes: a water-tree resistant insulation layer, which covers the outside of the conductor shielding layer.

[0015] As a preferred technical solution, the cable core includes: an insulating shielding layer, which covers the outside of the water-tree resistant insulating layer; the conductor shielding layer, the water-tree resistant insulating layer, and the insulating shielding layer are co-extruded into one integral layer with no gaps between the layers.

[0016] As a preferred technical solution, the cable core includes a semi-conductive resistive water strip, which is wrapped around the outside of the insulating shielding layer.

[0017] As a preferred technical solution, the sheath is a polyethylene sheath or a low-smoke halogen-free flame-retardant polyolefin sheath.

[0018] The cable with high short-circuit current carrying capacity provided by this utility model has the following beneficial effects: 1) The present invention provides a cable with high short-circuit current carrying capacity, which has a shielding structure that combines high conductivity, excellent oxidation resistance and process adaptability, which not only improves the short-circuit current carrying capacity of the cable, but also reduces the cost.

[0019] 2) This utility model provides a cable with high short-circuit current carrying capacity, featuring an aluminum strip thickness of 0.2–0.5 mm and a width of 50–200 mm, resulting in a cross-sectional area of ​​10–100 mm². 2 Compared to traditional copper tape shielding solutions, the conductive cross-sectional area is increased; the longitudinal overlap rate of the aluminum tape is ≥15%, and combined with a width design of 50-200mm, it can maintain continuous and tight contact under different cable cross-section specifications, with a contact resistance ≤0.02Ω·m. 3 The skin effect loss is reduced by 30%; the surface roughness Ra of the alumina protective film is ≤2μm, which forms a uniform electric field distribution between the film and the insulating layer, reducing the partial discharge and improving the conductivity. Aluminum strips with an alumina protective film exhibit spontaneous passivation capabilities in corrosive environments (such as soils with a pH of 4–10), with a corrosion rate ≤0.01 mm / year, demonstrating more than 5 times the oxidation resistance compared to uncoated aluminum strips; the difference in thermal expansion coefficient between the protective film and the aluminum substrate is ≤2 × 10⁻⁶. -6 / ℃, no cracks are generated under temperature fluctuations from -40℃ to 130℃; it has excellent antioxidant properties; The aluminum strip width of 50-200mm can be adapted to the continuous longitudinal wrapping of cable cores with a cross-sectional area of ​​8-240mm, and has good process adaptability. Aluminum density (2.7g / cm³) 3 It costs only 30% of copper, and the material cost is reduced by 40% for the same conductive cross-section. Attached Figure Description

[0020] Figure 1 A schematic diagram of the structure of a cable with high short-circuit current carrying capacity provided by this utility model; Among them, 1-conductor; 2-conductor shielding layer; 3-water tree resistant insulation layer; 4-insulating shielding layer; 5-semi-conducting resistive water tape; 6-aluminum tape shielding layer; 7-sheath. Detailed Implementation

[0021] The preferred embodiments of this utility model are described in detail below with reference to the accompanying drawings.

[0022] like Figure 1As shown, this utility model provides a cable with high short-circuit current carrying capacity, comprising: a cable core, an aluminum tape shielding layer 6 and a sheath 7 sequentially disposed on the outer side of the cable core, the aluminum tape shielding layer comprising: an aluminum tape layer and an aluminum oxide protective film disposed on one side of the aluminum tape layer, the aluminum tape layer comprising: an aluminum tape, the aluminum tape being longitudinally wrapped tightly around the outer side of the cable core, the thickness of the aluminum tape being 0.2-0.5mm and the width of the aluminum tape being 50-200mm.

[0023] The thickness of the aluminum strip is preferably 0.2mm, 0.35mm and 0.5mm. Due to space limitations and for the sake of brevity, this utility model will not exhaustively list the specific values ​​included in the range. The width of the aluminum strip is preferably 50mm, 125mm, and 200mm. Due to space limitations and for the sake of brevity, this utility model will not exhaustively list the specific values ​​included in the range.

[0024] This utility model provides a cable with high short-circuit current carrying capacity, which has a shielding structure that combines high conductivity, excellent oxidation resistance and process adaptability, thereby not only improving the cable's short-circuit current carrying capacity but also reducing costs.

[0025] Preferably, such as Figure 1 As shown, a plastic layer (not shown) is covered on the other side of the aluminum strip layer. The aluminum oxide protective film is disposed on the aluminum strip layer on the side close to the sheath 7, and the plastic layer is disposed on the aluminum strip layer on the side away from the sheath 7. This structural design achieves improved corrosion resistance and lifespan while maintaining high conductivity of the aluminum strip shielding layer through the functional complementarity of the aluminum oxide film and the plastic layer, and the overall cost is reduced compared with the copper strip solution.

[0026] Preferably, such as Figure 1 As shown, the thickness of the alumina protective film is 50–200 nm, and the thickness of the plastic layer is 50–150 μm. The preferred thicknesses of the alumina protective film are 50 nm, 125 nm, and 200 nm; however, for space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​within these ranges. Similarly, the preferred thicknesses of the plastic layer are 50 μm, 100 μm, and 150 μm; however, for space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​within these ranges. When the thickness of the alumina protective film is 50–200 nm, its surface resistivity can be reduced to 1–5 Ω·sq. -1It achieves effective attenuation of high-frequency electromagnetic waves (8-30GHz) through reflection and absorption mechanisms, with a shielding effectiveness (SE) of 60-70dB, thus improving electromagnetic shielding effectiveness. The dense alumina layer with a thickness of ≥50nm has a porosity of <2%, which can block the penetration of corrosive media such as moisture and chloride ions, thereby reducing the corrosion rate. The plastic layer with a thickness of 50-150μm provides sufficient mechanical support, absorbs the shear stress generated by cable bending, and avoids the aluminum strip layer from breaking.

[0027] Preferably, such as Figure 1 As shown, the longitudinal overlap rate of the aluminum strip is ≥15%, and the overlapping area forms a continuous conductive channel with a contact resistance ≤0.02Ω·m, which ensures low contact resistance, suppresses the skin effect, and improves the conductivity of the cable.

[0028] Preferably, such as Figure 1 As shown, the cable core includes: a conductor 1, which is formed by stranding multiple metal wires in a frame and radially compressing them. The compression coefficient of the conductor after radial pressure compression is 0.85 to 0.95. The compression coefficient is defined as the ratio of the cross-sectional area of ​​the conductor after compression to the original loose cross-sectional area. The preferred compression coefficients of the conductor after radial pressure compression are 0.85, 0.90, and 0.95. Due to space limitations and for the sake of brevity, this utility model will not exhaustively list the specific values ​​included in the range. The high compression coefficient of the conductor after radial pressure compression of 0.85 to 0.95 significantly reduces the air gap between the metal wires, improves the conductor filling density, reduces the skin effect, and improves the current carrying capacity for the same cross-sectional area. The close contact reduces the DC resistance of the conductor, thereby reducing power transmission loss.

[0029] Preferably, such as Figure 1 As shown, the cable core includes: a conductor shielding layer 2, which tightly covers the outside of the conductor 1. The conductor shielding layer 2 is made of a semi-conductive material with uniform thickness, which can effectively smooth the electric field distribution and reduce corona discharge. Preferably, such as Figure 1 As shown, the cable core includes a water-tree resistant insulation layer 3, which covers the outside of the conductor shielding layer 2. The water-tree resistant insulation layer 3 enables the cable to meet the conditions for long-term operation in a humid environment, avoids line accidents caused by water tree breakdown, improves the service life of the cable, and ensures the insulation performance and electrical reliability of the cable.

[0030] Preferably, such as Figure 1As shown, the cable core includes: an insulating shielding layer 4, which covers the outside of the water-tree resistant insulating layer 3; the conductor shielding layer 2, the water-tree resistant insulating layer 3, and the insulating shielding layer 4 are co-extruded into a single integrated structure with no gaps between the layers; the insulating shielding layer 4 is made of a semi-conductive material and is tightly bonded to the water-tree resistant insulating layer 3, further optimizing the electric field distribution and improving the electrical performance of the cable; the gapless interlayer structure reduces the amount of partial discharge and suppresses partial discharge.

[0031] Preferably, such as Figure 1 As shown, the cable core includes a semi-conductive resistive water strip 5, which covers the outside of the insulating shielding layer 4. The semi-conductive resistive water strip 5 is disposed between the insulating shielding layer 4 and the aluminum strip shielding layer 6, and can form a smooth electric field transition with the insulating shielding layer 4 and the aluminum strip shielding layer 6, avoiding the electric field concentration at the edge of the insulation layer and reducing the risk of partial discharge.

[0032] Preferably, such as Figure 1 As shown, the sheath 7 is a polyethylene sheath or a low-smoke halogen-free flame-retardant polyolefin sheath, which is extruded and wrapped around the outside of the aluminum strip shielding layer by an extruder to protect the internal wire core from mechanical damage, while also having good weather resistance and fire resistance.

[0033] Example 1

[0034] like Figure 1 As shown, this utility model provides a cable with high short-circuit current carrying capacity, comprising: a conductor 1, wherein the conductor 1 is formed by stranding multiple metal wires in a frame-type stranded manner and radially compacting them, the compaction coefficient of the conductor after radial pressure compaction is 0.90, and the conductor 1 is provided with a conductor shielding layer 2, a water-tree resistant insulation layer 3, an insulation shielding layer 4, a semi-conductive water-resistant tape 5, an aluminum tape shielding layer 6, and a sheath 7 from the inside to the outside. The aluminum tape shielding layer 6 includes: an aluminum tape layer and an aluminum oxide protective film provided on one side of the aluminum tape layer, the aluminum tape layer including: an aluminum tape, the aluminum tape being longitudinally wrapped tightly around the outside of the cable core, the thickness of the aluminum tape being 0.25mm, and the width of the aluminum tape being 120mm. A plastic layer is applied to the other side of the aluminum strip layer. The aluminum oxide protective film is disposed on the aluminum strip layer near the sheath 7, and the plastic layer is disposed on the aluminum strip layer away from the sheath 7. The thickness of the aluminum oxide protective film is 120 nm, and the thickness of the plastic layer is 100 μm. The longitudinal overlap rate of the aluminum strip is ≥15%. The conductor shielding layer 2, the water-tree resistant insulation layer 3, and the insulation shielding layer 4 are co-extruded into a single integrated structure with no gaps between the layers. The sheath 7 is a polyethylene sheath or a low-smoke halogen-free flame-retardant polyolefin sheath. This shielding structure has high conductivity, excellent oxidation resistance, and process adaptability, which not only improves the short-circuit current carrying capacity of the cable but also reduces costs.

[0035] Example 2

[0036] The rest is the same as in Example 1, except that the thickness of the aluminum strip is 0.30 mm.

[0037] Comparative Example 1 The rest is the same as in Example 1, except that the aluminum strip shielding layer is replaced with a copper strip shielding layer, and the thickness of the copper strip is 0.12mm.

[0038] Experimental methods The performance of the aluminum strip shielding layer in Examples 1-2 and the copper strip shielding layer in Comparative Example 1 was tested using the following experimental methods: I. Short-circuit current (kA / 1s) test method Experimental setup: A high current generator (output capacity ≥100kA / 1s) is linked with a power frequency / pulse waveform generator, and the sample is held by a copper clamp; Test steps: ① Preset short-circuit current parameters (frequency 50Hz, pulse width 1s); ② Trigger short-circuit impact and simultaneously capture current waveform (sampling rate ≥ 1MS / s); ③ Record the peak current density (unit: kA / mm²) 2 ) and temperature rise curve (infrared thermal imager frame rate ≥1kHz); Judgment criteria: The material shows no melting or fracture, and the instantaneous current density is ≥250A / mm². 2 (Copper-based materials).

[0039] II. Short-circuit current boosting capability (%) assessment 1. Conductive network optimization verification Cross-section improvement test: ① Calculate the minimum cross-sectional area according to the IEC 60949 formula; High-frequency impedance suppression: ① Vector network analyzer (1MHz-3GHz) measures skin depth δ; ② After structural optimization, the skin depth is reduced by ≥20% (e.g., copper wire braiding replaces copper strip wrapping). 2. Multiphysics coupling test: Composite loading system: ① Circular electromagnetic loading device (magnetic field strength ≥ 0.5T); ② Pulsed current source (rise rate ≥ 10) 9 A / s); ③ Distributed fiber optic temperature measurement system (response time ≤ 1ms); Performance improvement metrics: Short-circuit withstand time increased by ≥20% for the same cross-section; Current density increased by ≥15% under the same temperature rise conditions; 3. Shielding effectiveness verification Triaxial method test: ① Deploy CoMet test sleeves and network analyzers; ② Measure the surface transfer impedance Zt (frequency range 10kHz~3GHz); ③ After optimization, the Zt value is reduced to less than 30% of the original value.

[0040] The performance of the aluminum strip shielding layer in Examples 1-2 and the copper strip shielding layer in Comparative Example 1 was tested using the above experimental methods. The test results are shown in Table 1 below:

[0041] Table 1 above concludes that aluminum strip, as a functional part of the metallic shielding layer, is significantly superior to copper strip in terms of short-circuit current carrying capacity. Specifically: When the aluminum strip shielding thickness is 0.25mm, its short-circuit current carrying capacity can reach 3.04kA / 1s, which is about 242% higher than that of copper strip (0.12mm thickness, 0.89kA / 1s). When the aluminum strip shielding thickness is increased to 0.30mm, the short-circuit current carrying capacity is further improved to 3.65kA / 1s, which is about 310% higher than that of copper strip.

[0042] This fully demonstrates that aluminum strips, in the application of metallic shielding layers, not only significantly improve the short-circuit current carrying capacity but also possess enormous potential for performance optimization. This characteristic makes it the preferred functional component for medium-voltage cable metallic shielding layers, especially in power transmission applications with stringent requirements for short-circuit current carrying capacity.

[0043] In addition, using aluminum tape instead of copper tape can significantly reduce the material cost of cables, which has significant economic advantages.

[0044] The raw material cost of aluminum strip is significantly lower than that of copper strip. According to market data, the cost of aluminum is about one-third that of copper. Using aluminum strip instead of copper strip can significantly reduce material procurement costs. For example, taking an 18 / 30kV 1x630 aluminum core single-core cable as an example, aluminum alloy shielding strip can save more than 80% of the material cost compared to copper shielding strip.

[0045] Aluminum tape not only has advantages in material cost, but also further improves the economic efficiency of cables by reducing cable weight and lowering transportation and installation costs. In addition, the corrosion resistance and oxidation resistance of copper tape shielding reduces maintenance costs in long-term use. These comprehensive properties make copper tape shielding exhibit superior performance in medium-voltage cables.

[0046] It is understood that this utility model has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of this utility model. Furthermore, under the teachings of this utility model, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are protected by this utility model.

Claims

1. A cable with high short-circuit current carrying capacity, characterized in that, The cable core includes an aluminum strip shielding layer and a sheath arranged sequentially on its outer side. The aluminum strip shielding layer includes an aluminum strip layer and an aluminum oxide protective film disposed on one side of the aluminum strip layer. The aluminum strip layer includes an aluminum strip that is longitudinally wrapped tightly around the outer side of the cable core. The thickness of the aluminum strip is 0.2 to 0.5 mm, and the width of the aluminum strip is 50 to 200 mm.

2. The cable with high short-circuit current carrying capacity according to claim 1, characterized in that, A plastic layer is applied to the other side of the aluminum strip layer. The aluminum oxide protective film is disposed on the aluminum strip layer near the sheath, and the plastic layer is disposed on the aluminum strip layer away from the sheath.

3. The cable with high short-circuit current carrying capacity according to claim 2, characterized in that, The thickness of the alumina-containing protective film is 50–200 nm, and the thickness of the plastic layer is 50–150 μm.

4. The cable with high short-circuit current carrying capacity according to claim 1, characterized in that, The longitudinal overlap rate of the aluminum strip is ≥15%.

5. The cable with high short-circuit current carrying capacity according to claim 1, characterized in that, The cable core includes a conductor, which is formed by stranding multiple metal wires in a frame and radially compressing them, wherein the compression coefficient of the conductor after radial pressure compression is 0.85 to 0.

95.

6. The cable with high short-circuit current carrying capacity according to claim 5, characterized in that, The cable core includes a conductor shielding layer, which tightly covers the outside of the conductor.

7. The cable with high short-circuit current carrying capacity according to claim 6, characterized in that, The cable core includes a water-tree resistant insulation layer, which covers the outside of the conductor shielding layer.

8. The cable with high short-circuit current carrying capacity according to claim 7, characterized in that, The cable core includes: an insulating shielding layer, which covers the outside of the water-tree resistant insulating layer; the conductor shielding layer, the water-tree resistant insulating layer, and the insulating shielding layer are co-extruded into one integral layer without gaps between them.

9. The cable with high short-circuit current carrying capacity according to claim 8, characterized in that, The cable core includes a semi-conductive resistive water strip, which is wrapped around the outside of the insulating shielding layer.

10. The cable with high short-circuit current carrying capacity according to claim 1, characterized in that, The sheath is a polyethylene sheath or a low-smoke halogen-free flame-retardant polyolefin sheath.

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