Water-tree-resistant low-voltage environment-friendly flame-retardant cable for urban underground pipe gallery

Abstract

A water-tree-resistant low-voltage environment-friendly flame-retardant cable for an urban underground pipe gallery is characterized by comprising four wire cores, a belting layer, a tearing rope, a moisture-proof layer and a sheath, the cable is simple in structural design, the conductor adopts a 90-degree fan-shaped compressed shape, a water-blocking tape and aluminum tape longitudinal wrapping process structure is designed, and two symmetrical rip cords are added for convenient construction, so that the cable has excellent environment-friendly, moisture-proof and water-blocking performance, is insulated and resistant to water trees, and is widely applied to new construction or quality improvement and reconstruction of urban underground pipe gallery projects; the cable is very considerable in economic value and application value, greatly improves the operation safety and reliability of an urban smart power grid, is waterproof, moisture-proof, mechanical damage-resistant, corrosion-resistant and high in flame retardance, has a bending radius of 15D, is not liable to cause dark loss during installation and laying, and is convenient for later maintenance.

Description

Technical Field

[0001] This utility model relates to the field of cableway power cable technology, and in particular to a water-resistant, tree-resistant, low-voltage, environmentally friendly, and flame-retardant cable for use in urban underground utility tunnels. Background Technology

[0002] Currently, the cable system in underground utility tunnels may face the following major defects and challenges during operation, which may affect power supply reliability, safety, and maintenance efficiency:

[0003] 1. Underground utility tunnels are prone to water seepage or water accumulation. Long-term damp environment can cause water treeing in the cross-linked polyethylene insulation layer of cables, reducing the insulation performance of the cables and causing leakage or short circuits. The decline in insulation performance directly threatens power supply safety and increases the risk of breakdown.

[0004] 2. Cables in underground utility tunnels are prone to mechanical damage in their working environment, which may cause partial discharge or direct short circuits. Furthermore, their concealment makes fault location difficult.

[0005] 3. Inappropriate material selection; failure to select corrosion-resistant and flame-retardant materials suitable for the utility tunnel environment;

[0006] 4. Insufficient cable bending radius can lead to hidden structural damage inside the cable during installation.

[0007] 5. During later maintenance and repair of cables, due to the large number of pipelines gathered together and the narrow operating space, the sheath is not easy to peel off when inspecting the electrical structure.

[0008] In conclusion, the deficiencies of underground utility tunnel cables need to be comprehensively optimized from the perspectives of design, materials, and construction, and combined with green and environmentally friendly ecological technologies, in order to improve the reliability and resilience of urban underground integrated pipe networks. Summary of the Invention

[0009] This utility model addresses the problems mentioned in the background art by providing a water-resistant, low-voltage, environmentally friendly, and flame-retardant cable for urban underground utility tunnels. It is waterproof, moisture-proof, resistant to mechanical damage, corrosion-resistant, flame-retardant, has a large bending radius, is not prone to hidden damage during installation, and is convenient for later maintenance.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] A water-resistant, tree-resistant, environmentally friendly, flame-retardant cable for use in urban underground utility tunnels, characterized by comprising four conductor cores, a wrapping layer, a tear cord, a moisture-proof layer, and a sheath.

[0012] Each conductor core includes a conductor and an insulation layer. The conductor is made of several copper conductors twisted and pressed into a fan-shaped cross-section. The angular radius of the fan-shaped cross-section of the conductor is 90°. The insulation layer is extruded onto the conductor and is made of polypropylene material. The cross-section of the cable core assembly composed of all conductor cores is circular.

[0013] The wrapping layer covers the four conductor cores to form a cable core assembly. The wrapping layer is a tape composed of two layers of non-woven fabric with an expansion water-blocking powder sandwiched in between.

[0014] The moisture-proof layer is longitudinally wrapped on the wrapping layer. The moisture-proof layer is an aluminum-plastic tape. After being longitudinally wrapped on the wrapping layer, the interface is welded to form a dense protective tube. In this way, the cable core assembly and the aluminum-plastic tape of the moisture-proof layer are tightly bonded to form a radial waterproof structure. The moisture-proof layer is corrugated by a corrugating machine to a height of 0.5mm, which ensures that it will not break when the cable is bent. At the same time, it is fully bonded to the outer sheath to form a good comprehensive protective layer with excellent waterproof performance.

[0015] The sheath layer is extruded onto the moisture-proof layer. The sheath layer is a low-smoke, halogen-free polyolefin elastomer material, which is an environmentally friendly flame-retardant polymer material. The elastomer material formula is mainly EVA+AL(OH)3, and the formula does not contain heavy metal components such as lead and cadmium, so it will not cause pollution to water and soil.

[0016] A further aspect of this invention is as follows: In order to achieve water-blocking function while ensuring the flexibility and electrical performance of the material, the tape layer has a thickness of 0.25mm and is overlapped and wrapped around the outside of the cable core with an overlap rate of greater than or equal to 25%.

[0017] A further aspect of this invention is that, in order to facilitate the operation when peeling off the moisture-proof layer and the sheath, a tear rope is provided on each side of the cross-section of the cable core assembly between the wrapping layer and the moisture-proof layer.

[0018] The beneficial effects of this utility model are: the cable structure is simple, the conductor adopts a 90-degree fan-shaped compaction shape, and the design incorporates a water-blocking tape + aluminum tape longitudinal wrapping process. For ease of construction, two symmetrical tear ropes are added, giving the cable excellent environmental protection, moisture-proof, and water-blocking performance. The cable insulation is resistant to water treeing and can be widely used in new or upgraded urban underground utility tunnel projects. Its economic and application value is considerable, greatly improving the safety and reliability of urban smart grid operation. It is waterproof, moisture-proof, resistant to mechanical damage, corrosion-resistant, and flame-retardant. The bending radius can reach 15D. It is not easy to suffer hidden damage during installation and laying, and subsequent maintenance is convenient. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of an embodiment of the present utility model. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Example

[0021] like Figure 1 As shown, a water-resistant, tree-resistant, low-voltage, environmentally friendly, flame-retardant cable for urban underground utility tunnels includes four conductor cores, a wrapping layer 3, a tear cord 4, a moisture-proof layer 5, and a sheath 6.

[0022] Each conductor core includes a conductor 1 and an insulation layer 2. The conductor 1 is formed by twisting and pressing several copper conductors together, and has a fan-shaped cross-section. The angular radius of the fan-shaped cross-section of the conductor 1 is 90°. The insulation layer 2 is extruded onto the conductor 1 and is made of polypropylene material. The cross-section of the cable core assembly formed by all conductor cores is circular.

[0023] The wrapping layer 3 covers the four conductor cores to form a cable core assembly. The wrapping layer 3 is a tape composed of two layers of non-woven fabric with an expansion water-blocking powder sandwiched in between.

[0024] The moisture-proof layer 5 is longitudinally wrapped around the wrapping layer 3. The moisture-proof layer 5 is an aluminum-plastic tape. After being longitudinally wrapped around the wrapping layer 3, the interface is welded to form a dense protective tube. In this way, the cable core assembly and the aluminum-plastic tape of the moisture-proof layer 5 are tightly bonded to form a radial waterproof structure. The moisture-proof layer 5 is 0.5mm high after being corrugated by a corrugating machine, which ensures that it will not break when the cable is bent. At the same time, it is fully bonded to the outer sheath 6 to form a good comprehensive protective layer with excellent waterproof performance.

[0025] The sheath layer 6 is extruded onto the moisture-proof layer 4. The sheath layer 6 is a low-smoke, halogen-free polyolefin elastomer material, which is an environmentally friendly flame-retardant polymer material. The elastomer material formula is mainly EVA+AL(OH)3, and the formula does not contain heavy metal components such as lead and cadmium, so it will not cause pollution to water and soil.

[0026] In order to achieve water-blocking function while ensuring the flexibility and electrical performance of the material, the tape layer 3 has a tape thickness of 0.25mm, and is overlapped and wrapped around the outside of the cable core assembly with an overlap rate of greater than or equal to 25%.

[0027] To facilitate the operation when peeling off the moisture-proof layer and the sheath, a tear rope 4 is provided on each side of the cross-section of the cable core assembly between the wrapping layer and the moisture-proof layer.

Claims

1. A water-tree resistant, environmentally friendly, flame-retardant cable for use in urban underground utility tunnels, characterized in that... It includes four conductor cores, a wrapping layer, a tear cord, a moisture-proof layer, and a sheath; Each conductor core includes a conductor and an insulation layer. The conductor is made of several copper conductors twisted and pressed into a fan-shaped cross-section. The angular radius of the fan-shaped cross-section of the conductor is 90°. The insulation layer is extruded onto the conductor and is made of polypropylene material. The cross-section of the cable core assembly composed of all conductor cores is circular. The wrapping layer covers the four conductor cores to form a cable core assembly. The wrapping layer is a tape composed of two layers of non-woven fabric with an expansion water-blocking powder sandwiched in between. The moisture-proof layer is longitudinally wrapped on the wrapping tape layer. The moisture-proof layer is an aluminum-plastic tape. After being longitudinally wrapped on the wrapping tape layer, the joint is welded to form a dense protective tube. The moisture-proof layer is 0.5mm high after being corrugated by a corrugating machine. The sheath layer is extruded onto the moisture-proof layer, and the sheath layer is a low-smoke halogen-free polyolefin elastomer material.

2. The water-resistant, tree-resistant, environmentally friendly, flame-retardant cable for urban underground utility tunnels as described in claim 1, characterized in that... The tape layer has a thickness of 0.25 mm and is overlapped and wrapped around the outside of the cable core with an overlap rate of ≥25%.

3. A water-resistant, tree-resistant, environmentally friendly, flame-retardant cable for urban underground utility tunnels as described in claim 1 or 2, characterized in that... Between the wrapping layer and the moisture-proof layer, a tear rope is provided on each side of the cross-section of the cable core assembly.

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