35kV flame-retardant polypropylene insulated power cable

Abstract

The utility model relates to the technical field of wires and cables, in particular to a 35kV flame-retardant polypropylene insulated power cable, which comprises a plurality of wire cores tangent in pairs, filling strips filled among the wire cores, and a cable core wrapped and fixed by a first wrapping tape into a circular cross section, the isolation sleeve is extruded on the outer wall of the cable core; the outer wall of the isolation sleeve is coated with the armor layer; and the outer wall of the armor layer is coated with the fire retardant layer. According to the utility model, the cable core is formed by wrapping the filling strip and the wire core together, the filling strip adopts an extrusion structure and comprises an outer layer with good heat conduction capability and an inner layer with good elasticity, and the outer layer structure of the filling strip can be used as a heat conduction channel from the wire core to the outside of the cable, so that the heat dissipation performance of the cable can be improved; and meanwhile, the cable also has the advantages of weight reduction and good elasticity, and compared with a mode of filling glass fiber ropes, the production process is simpler, the production efficiency is favorably improved, and the comprehensive performance of the cable is improved.

Description

Technical Field

[0001] This utility model relates to the field of wire and cable technology, and more specifically to a 35kV flame-retardant polypropylene insulated power cable. Background Technology

[0002] The increasing demand for large-scale power transmission and supply in the national economy has led to the optimization of power transmission lines and the subsequent construction and upgrading of power grids. The development of 26 / 35kV polypropylene insulated power cables will generate significant market demand.

[0003] Compared to traditional cross-linked polyethylene (XLPE) cable insulation, polypropylene (PP) is a lightweight (one of the lightest plastics available), non-toxic, odorless, and tasteless milky-white, highly crystalline polymer. It not only possesses excellent electrical properties but also superior heat resistance (allowing cables to operate at temperatures above 105°C for extended periods). Because polypropylene does not require cross-linking treatment to achieve high mechanical strength and is a typical thermoplastic, it is recyclable, meeting the development needs of environmentally friendly cable insulation and representing a greener, more sustainable material.

[0004] However, polypropylene has a lower thermal conductivity than polyethylene, resulting in poor heat dissipation. In addition, to meet fire resistance requirements, fiberglass ropes are usually used to fill the outside of the cable core. Therefore, the heat generated during cable operation is difficult to dissipate in time, resulting in a temperature difference between the inside and outside of the insulation layer, which in turn affects the electrical performance and safety of the cable. Utility Model Content

[0005] To address the technical problems existing in the current electric wire and cable technology, the first aspect of this utility model proposes a 35kV flame-retardant polypropylene insulated power cable, comprising:

[0006] Multiple tangent wire cores and filler strips between the wire cores are wrapped and fixed by the first wrapping tape to form a cable core with a circular cross-section.

[0007] An isolation sleeve is extruded onto the outer wall of the cable core;

[0008] An armor layer, covering the outer wall of the isolation sleeve;

[0009] A fire-resistant layer, covering the outer wall of the armor layer;

[0010] The outer sheath is extruded onto the outer wall of the fire-retardant layer;

[0011] The filler strip is configured to have a predetermined cross-sectional shape. The filler strip includes an inner layer structure and an outer layer structure. The outer layer structure is located outside the inner layer structure. The surface of the outer layer structure is in contact with the outer wall of the wire core and the inner wall of the first wrapping tape. The outer layer structure includes a composite thermally conductive layer, and the inner layer structure includes a foaming layer.

[0012] Preferably, the outer layer structure includes a polyethylene extrusion layer or a polyvinyl chloride extrusion layer.

[0013] Preferably, the polyethylene extrusion layer or the polyvinyl chloride extrusion layer contains thermally conductive particles.

[0014] Preferably, the thermally conductive particles include graphite particles or ceramic particles.

[0015] Preferably, the inner layer structure includes a polyethylene foam extrusion layer.

[0016] Preferably, the wire core includes a conductor, a three-layer co-extruded inner shielding layer, a polypropylene insulation layer, and an outer shielding layer, wherein the outer wall of the outer shielding layer is wrapped with a copper strip shielding layer.

[0017] Preferably, the first wrapping tape includes alkali-free glass fiber tape, and the first wrapping tape has two wrapping layers, with each layer having an overlap rate of more than 15%.

[0018] Preferably, the armor layer comprises a galvanized steel strip with gap wrapping, wherein the galvanized steel strip has two wrapping layers, and the gap ratio of each layer is greater than 50%.

[0019] Preferably, the fire-retardant layer comprises at least two layers of fiberglass tape wrapping, each layer of fiberglass tape having a thickness greater than 0.2 mm and a wrapping overlap rate greater than 15%.

[0020] Preferably, both the isolation sleeve and the outer sheath comprise a flame-retardant polyvinyl chloride sheath.

[0021] Compared with the prior art, the advantages of this utility model are:

[0022] This invention involves wrapping a filler strip around the cable core to form the cable core. The filler strip has an extruded structure, comprising an outer layer with good thermal conductivity and an inner layer with good elasticity. The outer layer of the filler strip serves as a heat conduction channel from the cable core to the outside of the cable, improving the cable's heat dissipation performance. At the same time, the cable also has the advantages of weight reduction and good elasticity. Compared with the method of filling with fiberglass rope, the production process is simpler, which helps to improve production efficiency and enhance the overall performance of the cable. Attached Figure Description

[0023] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings, wherein:

[0024] Figure 1 This is a schematic diagram of the structure of the 35kV flame-retardant polypropylene insulated power cable shown in this utility model.

[0025] Figure 2 This is a schematic diagram of the wire core shown in this utility model. Detailed Implementation

[0026] To better understand the technical content of this utility model, specific embodiments are provided below in conjunction with the accompanying drawings.

[0027] Combination Figure 1 As shown, the first aspect of this utility model proposes a 35kV flame-retardant polypropylene insulated power cable, including a cable core, an isolation sleeve 4, an armor layer 5, a fire-retardant layer 6, and an outer sheath 7. The cable core is formed by wrapping multiple tangent wire cores 1 and filling strips between the wire cores 1 with a first wrapping tape 3 to form a circular cross section.

[0028] like Figure 2 As shown, the wire core 1 includes a conductor 11, an inner shielding layer 12 formed by three co-extrusions, a polypropylene insulation layer 13, and an outer shielding layer 14, with a copper tape shielding layer 15 wrapped around the outer wall of the outer shielding layer 14.

[0029] Conductor 11 is a type II compacted round copper conductor. The inner shielding layer 12, polypropylene insulation layer 13 and outer shielding layer 14 are formed by three-layer co-extrusion of polypropylene semi-conductive shielding material, polypropylene insulation material and polypropylene semi-conductive shielding material. Since the three materials are all made of polypropylene matrix, their processing conditions are basically the same, which is conducive to the control and adjustment in the production process and improves production efficiency and product quality.

[0030] Thus, polypropylene insulation material has good dielectric and heat resistance properties, which can prevent accidents such as creepage, leakage or breakdown. At the same time, the inner and outer layers of polypropylene semi-conductive shielding material can form equipotential with the cable conductor and metal shielding layer, uniformly distribute the interface electric field, suppress excessive local field strength, and prevent partial discharge.

[0031] Furthermore, a copper strip shielding layer 15 is provided on the outer wall of the outer shielding layer 14. The copper strip shielding layer 15, together with the insulation layer and the filler strip, forms an effective heat dissipation channel, which can improve the heat dissipation performance of the cable.

[0032] The filler strip is configured to have a predetermined cross-sectional shape. For example, when three wire cores 1 are twisted together, the filler strip is configured to adapt to the gap shape formed by the three wire cores 1, and when four wire cores 1 are twisted together, the filler strip is configured to adapt to the gap shape formed by the four wire cores 1.

[0033] In an optional embodiment, the filler strip includes an inner layer structure 22 and an outer layer structure 21. The outer layer structure 21 is located outside the inner layer structure 22. The surface of the outer layer structure 21 is in contact with the outer wall of the wire core 1 and the inner wall of the first wrapping tape 3. The outer layer structure 21 includes a composite thermally conductive layer, and the inner layer structure 22 includes a foaming layer.

[0034] Thus, the filler strip has the advantages of heat conduction and weight reduction, which can improve the heat dissipation performance of the cable, while making the cable filling more uniform and dense, which helps to reduce the voids inside the cable and improve the electrical and insulation performance of the cable.

[0035] The outer layer of the double-layer co-extruded filler strip is doped with thermally conductive particles, such as graphite and ceramic particles, which can effectively improve the thermal conductivity of the material.

[0036] In an optional embodiment, the outer layer structure 21 includes a polyethylene extrusion layer or a polyvinyl chloride extrusion layer. The polyethylene extrusion layer or the polyvinyl chloride extrusion layer contains thermally conductive particles. Optionally, the thermally conductive particles include graphite particles or ceramic particles.

[0037] In this way, the thermal conductivity of the filler strip can be improved by using thermally conductive particles, which can more effectively conduct the heat generated inside the cable to the outside, thereby improving the reliability and service life of the cable.

[0038] Furthermore, the inner layer structure 22 includes a polyethylene foam extrusion layer.

[0039] Thus, this double-layer co-extruded filler strip combines the strength of the outer layer with the elasticity of the inner layer, enabling the cable to better resist deformation and damage when subjected to external forces. Compared with the existing technology of filling with fire-retardant rope, the production process of this filler strip is simpler and can be automated through continuous extrusion, which also helps to ensure the quality and consistency of the filler strip.

[0040] Furthermore, the first wrapping tape 3 includes an alkali-free glass fiber tape, and the first wrapping tape 3 has two wrapping layers, with each layer having an overlap rate of more than 15%.

[0041] By wrapping the filler strip and core 1 with alkali-free glass fiber tape, the cable core structure becomes compact and round, while the alkali-free glass fiber tape has good flame-retardant properties.

[0042] Furthermore, the isolation sleeve 4 is extruded onto the outer wall of the cable core, and the isolation sleeve 4 can be a 90°C flame-retardant polyvinyl chloride sheath.

[0043] Thus, the isolation sleeve 4 can resist electrical problems such as voltage, arc and partial discharge that may occur during cable operation, and can provide additional protection in humid and corrosive environments to prevent the cable from aging or failing due to moisture.

[0044] Furthermore, the armor layer 5 covers the outer wall of the isolation sleeve 4. The armor layer 5 includes a galvanized steel strip with gap wrapping. The galvanized steel strip has two wrapping layers, and the gap ratio of each wrapping layer is greater than 50%.

[0045] Thus, the armor layer formed by the galvanized steel strip gives the cable good mechanical properties, especially improving its compressive strength and fire resistance.

[0046] Furthermore, a fire-resistant layer 6 is provided on the outer wall of the armor layer 5. The fire-resistant layer 6 includes at least two layers of fiberglass tape wrapping, each layer of fiberglass tape having a thickness greater than 0.2 mm and a wrapping overlap rate greater than 15%.

[0047] Thus, the composite structure of steel strip and fiberglass strip gives the cable good fire resistance and prevents open flames from penetrating into the cable.

[0048] Furthermore, the outer sheath 7 is extruded onto the outer wall of the fire-retardant layer 6, and the outer sheath 7 includes a 90°C flame-retardant polyvinyl chloride sheath. The 90°C flame-retardant polyvinyl chloride sheath has good aging resistance and can resist the effects of environmental factors such as long-term ultraviolet radiation, oxidation and corrosion. At the same time, it also has excellent flame-retardant properties, which can effectively prevent the spread of fire and reduce the risk of fire.

[0049] In conjunction with the above embodiments, this utility model forms a cable core by wrapping a filler strip around the wire core together. The filler strip adopts an extrusion structure, including an outer layer with good thermal conductivity and an inner layer with good elasticity. The outer layer structure of the filler strip can serve as a heat conduction channel from the wire core to the outside of the cable, which can improve the heat dissipation performance of the cable. At the same time, the cable also has the advantages of weight reduction and good elasticity. Compared with the method of filling with fiberglass rope, the production process is simpler, which helps to improve production efficiency and improve the overall performance of the cable.

[0050] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Those skilled in the art to which this invention pertains can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of this invention shall be determined by the claims.

Claims

1. A 35kV flame-retardant polypropylene insulated power cable, characterized in that, include: Multiple tangent wire cores (1) and filler strips between the wire cores (1) are wrapped and fixed by the first wrapping tape (3) to form a cable core with a circular cross section. The isolation sleeve (4) is extruded onto the outer wall of the cable core; The armor layer (5) covers the outer wall of the isolation sleeve (4); Fire-resistant layer (6) covers the outer wall of the armor layer (5); The outer sheath (7) is extruded onto the outer wall of the fire-resistant layer (6); The filler strip is configured to have a predetermined cross-sectional shape. The filler strip includes an inner layer structure (22) and an outer layer structure (21). The outer layer structure (21) is located outside the inner layer structure (22). The surface of the outer layer structure (21) is in contact with the outer wall of the wire core (1) and the inner wall of the first wrapping tape (3). The outer layer structure (21) includes a composite thermal conductive layer, and the inner layer structure (22) includes a foam layer.

2. The 35kV flame-retardant polypropylene insulated power cable according to claim 1, characterized in that, The outer layer structure (21) includes a polyethylene extrusion layer or a polyvinyl chloride extrusion layer.

3. The 35kV flame-retardant polypropylene insulated power cable according to claim 2, characterized in that, The polyethylene extrusion layer or polyvinyl chloride extrusion layer contains heat-conducting particles.

4. The 35kV flame-retardant polypropylene insulated power cable according to claim 3, characterized in that, The thermally conductive particles include graphite particles or ceramic particles.

5. The 35kV flame-retardant polypropylene insulated power cable according to claim 1, characterized in that, The inner layer structure (22) includes a polyethylene foam extrusion layer.

6. The 35kV flame-retardant polypropylene insulated power cable according to claim 1, characterized in that, The core (1) includes a conductor (11), a three-layer co-extruded inner shielding layer (12), a polypropylene insulation layer (13), and an outer shielding layer (14), the outer wall of which is wrapped with a copper strip shielding layer (15).

7. The 35kV flame-retardant polypropylene insulated power cable according to claim 1, characterized in that, The first wrapping tape (3) includes an alkali-free glass fiber tape, and the first wrapping tape (3) has two wrapping layers, with each layer having an overlap rate of more than 15%.

8. The 35kV flame-retardant polypropylene insulated power cable according to claim 1, characterized in that, The armor layer (5) includes a galvanized steel strip with gap wrapping, the galvanized steel strip having two wrapping layers, and the gap ratio of each wrapping layer being greater than 50%.

9. The 35kV flame-retardant polypropylene insulated power cable according to claim 1, characterized in that, The fire-resistant layer (6) includes at least two layers of fiberglass tape wrapping, each layer of fiberglass tape having a thickness greater than 0.2 mm and a wrapping overlap rate greater than 15%.

10. The 35kV flame-retardant polypropylene insulated power cable according to claim 1, characterized in that, Both the isolation sleeve (4) and the outer sheath (7) include flame-retardant polyvinyl chloride sheaths.

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