Large-specification water-blocking halogen-free low-smoke flame-retardant environment-friendly medium-voltage power cable

Abstract

The utility model relates to the technical field of power cables, in particular to a large-specification water-blocking halogen-free low-smoke flame-retardant environment-friendly medium-voltage power cable, which comprises a cable core with a circular cross section formed by wrapping a plurality of mutually twisted wire cores and a filling layer filled among the wire cores by a water-blocking wrapping tape, the outer wall of the cable core is coated with the waterproof layer; the woven flame-retardant aramid yarn reinforcing layer is arranged on the outer wall of the waterproof layer in a sleeving manner; the halogen-free low-smoke flame-retardant polyolefin outer sheath is extruded on the outer wall of the woven flame-retardant aramid yarn reinforcing layer; wherein the wire core comprises a conductor, a conductor shielding layer, an insulating layer, an insulating shielding layer and a metal shielding layer. A copper wire sparse winding shielding layer is adopted outside the insulation of the wire core, a large effective cross section value can be achieved, the cable core ensures longitudinal water resistance of the cable by filling a water-blocking rope, and meanwhile, the purpose of full water resistance of the cable is achieved by longitudinally wrapping a metal composite belt outside a cabling wrapping belt and extruding a flame-retardant polyethylene sheath with waterproof performance at the same time.

Description

Technical Field

[0001] This utility model relates to the field of power cable technology, and more specifically to a large-diameter water-blocking, halogen-free, low-smoke, flame-retardant, environmentally friendly medium-voltage power cable. Background Technology

[0002] Power cables with rated voltage of 3.6 / 6~26 / 35kV typically refer to medium-voltage flame-retardant and environmentally friendly power cables. They are suitable for power transmission and distribution lines with rated voltage of 3.6 / 6kV~26 / 35kV and are mainly used for power distribution. They are widely used in urban power grids, mines, chemical plants, substations and other places, and can be used for fixed installation in the air, indoors, cable trenches, tunnels or underground.

[0003] Power cables with rated voltages of 3.6 / 6~26 / 35kV mainly consist of a structural conductor, an insulation layer, a metallic shielding layer, and a sheath. The structural conductor typically uses copper or aluminum as the conductor material, possessing good conductivity and mechanical strength, capable of carrying the rated current and transmitting electrical energy. The insulation layer can use cross-linked polyethylene or polyethylene as the insulation material, possessing excellent electrical and mechanical properties, effectively isolating the conductor from the external environment, and preventing leakage and short circuits. The main function of the metallic shielding layer is to uniformly distribute the electric field and reduce partial discharge. Shielding methods include copper wire braiding shielding, copper tape wrapping shielding, loose copper wire shielding, or aluminum alloy wire braiding shielding, etc. For large specifications (500mm²), 2 Cables with high current carrying capacity (and above) also generate a large electromagnetic field. When the short-circuit current exceeds a certain value, the copper tape shielding layer can no longer meet the requirements, while using loosely wound copper wire provides better shielding and current conduction. The sheath layer is usually made of materials such as polyvinyl chloride (PVC), polyethylene (PE), or polyolefin, which has good corrosion resistance, weather resistance, and mechanical protection properties, protecting the internal structure of the cable from the influence of the external environment.

[0004] With the rapid development of the power industry towards rivers and seas and the increasing demand for power cables, power cables are being used more widely in large power plants and transmission lines, subways, river crossings, and sea crossings. When laid in humid or watery environments, higher requirements are placed on the water-blocking performance of the cables, making water-blocking performance increasingly important for medium-voltage power cables. Utility Model Content

[0005] To address the technical problems existing in existing large-diameter water-blocking medium-voltage power cables, the first aspect of this utility model proposes a large-diameter water-blocking, halogen-free, low-smoke, flame-retardant, and environmentally friendly medium-voltage power cable, comprising:

[0006] A cable core with a circular cross-section is formed by wrapping multiple twisted cores together with a filler layer between the cores with a water-blocking tape.

[0007] A water-blocking layer is wrapped around the outer wall of the cable core;

[0008] A flame-retardant aramid fiber reinforcement layer is woven and fitted onto the outer wall of the water-blocking layer;

[0009] A halogen-free, low-smoke, flame-retardant polyolefin outer sheath is extruded onto the outer wall of the braided flame-retardant aramid fiber reinforcing layer.

[0010] The wire core includes a conductor, a conductor shielding layer, an insulation layer, an insulation shielding layer, and a metal shielding layer. The metal shielding layer includes a copper wire unwound layer and a copper strip layer, and a water-absorbing structural layer is provided between the copper wire unwound layer and the copper strip layer.

[0011] Preferably, the absorbent structural layer includes a non-woven fabric tape wrapping structural layer, the non-woven fabric tape including a non-woven fabric layer and an absorbent layer, the absorbent layer facing the copper wire loosely wrapped layer.

[0012] Preferably, the wrapping overlap rate of the nonwoven fabric tape is 15-30%.

[0013] Preferably, the average spacing between adjacent copper wires in the copper wire loose winding layer is 2.5 to 3.5 mm, and the maximum gap is no more than 5 mm.

[0014] Preferably, the filling layer comprises a water-resistant filling rope.

[0015] Preferably, the water-blocking tape includes a double-sided water-blocking tape, which comprises a sandwich structure consisting of a polyester fiber nonwoven fabric, a highly absorbent and expandable layer, and a polyester fiber nonwoven fabric.

[0016] Preferably, the water-blocking layer comprises a metal composite strip layer and a flame-retardant polyethylene sheath layer, wherein the metal composite strip layer covers the outer wall of the cable core, and the flame-retardant polyethylene sheath layer is extruded onto the outer wall of the metal composite strip layer.

[0017] Preferably, the metal composite strip layer comprises longitudinally wrapped metal composite strips, and the gaps in the metal composite strips are welded to form a sealing structure.

[0018] Preferably, the cross-sectional dimension of the conductor is greater than or equal to 500 mm. 2 .

[0019] Preferably, the braided flame-retardant aramid yarn reinforcing layer comprises braided flame-retardant aramid yarn with a braiding angle of 45% and a braiding density greater than 90%.

[0020] Compared with the prior art, this utility model proposes In the design of large-specification water-blocking, halogen-free, low-smoke, flame-retardant, and environmentally friendly medium-voltage power cables, the insulation of the conductor core is protected by a loosely wound copper wire shielding layer, which can achieve a relatively large effective cross-sectional value. Compared with other shielding methods, the continuity is more reliable, which can prevent the electromagnetic field generated by itself from interfering with the surrounding environment during use, and also limit the influence of external electromagnetic fields on the interior.

[0021] In this application, the copper wire loose winding layer inside the cable core adopts a water-absorbing structure layer to increase the longitudinal water-blocking capacity. The cable core is filled with water-blocking rope to ensure the longitudinal water-blocking of the cable. At the same time, by longitudinally wrapping the metal composite tape outside the cable wrapping tape and extruding a flame-retardant polyethylene sheath with waterproof performance, the radial water-blocking performance of the cable itself is guaranteed, thereby achieving the purpose of full water blocking of the cable.

[0022] This application ensures that the cable has excellent halogen-free, low-smoke, flame-retardant, and environmentally friendly performance by using asbestos-free fibers and raw and auxiliary materials that comply with the RoHS environmental directive, thus meeting the certification requirements of the HJ 2501-2010 standard "Technical Requirements for Environmental Labeling Products: Wires and Cables". 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.

[0024] Figure 1 This is a schematic diagram of the structure of the large-specification water-blocking, halogen-free, low-smoke, flame-retardant, environmentally friendly medium-voltage 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 and Figure 2 As shown, the large-diameter water-blocking, halogen-free, low-smoke, flame-retardant, and environmentally friendly medium-voltage power cable according to the embodiments of this utility model, especially refers to medium-voltage power cables with rated voltages of 3.6 / 6 to 26 / 35kV, and particularly those with a cross-sectional area of ​​500mm². 2 Medium-voltage cables of 6 and above have a structure including a cable core, a water-blocking layer, a braided flame-retardant aramid fiber reinforcing layer 6, and a halogen-free, low-smoke, flame-retardant polyolefin outer sheath 7.

[0028] Combination Figure 1As shown, multiple intertwined wire cores 1 and the filling layer 2 between the wire cores 1 are wrapped together by a water-blocking tape 3 to form a cable core with a circular cross-section. The water-blocking layer covers the outer wall of the cable core, the braided flame-retardant aramid fiber reinforcing layer 6 is sleeved on the outer wall of the water-blocking layer, and the halogen-free low-smoke flame-retardant polyolefin outer sheath 7 is extruded on the outer wall of the braided flame-retardant aramid fiber reinforcing layer 6.

[0029] As can be seen, the cable core is treated with a water-blocking layer and a reinforcing layer, which gives the cable better water-blocking ability and tensile strength, especially suitable for use in humid and watery environments. It also effectively reduces the probability of insulation damage and sheath breakage caused by cable stress, and improves the safety and service life of the cable.

[0030] Among them, the halogen-free, low-smoke, flame-retardant polyolefin outer sheath 7 has the advantages of safety and environmental protection, heat and cold resistance, and good flame retardancy. In particular, it does not contain halogens and will not produce toxic and harmful gases when burning, which is environmentally friendly and meets the environmental protection requirements of modern society.

[0031] The cables proposed in this utility model are made of asbestos-free fibers and environmentally friendly raw and auxiliary materials that comply with the RoHS environmental directive, ensuring that the cables have excellent environmental performance.

[0032] The wire core 1 includes a conductor 11, a conductor shielding layer 12, an insulation layer 13, an insulation shielding layer 14, and a metal shielding layer. The metal shielding layer includes a copper wire loose winding layer 15 and a copper strip layer 17.

[0033] Optionally, the cross-sectional dimension of conductor 11 is greater than or equal to 500 mm. 2 The insulation layer is made of polyethylene or cross-linked polyethylene, and the conductor shielding layer 12 and the insulating shielding layer 14 are made of semi-conductive materials.

[0034] The conductor shielding layer 12, the insulation layer 13, and the insulation shielding layer 14 are formed by three-layer co-extrusion.

[0035] To increase the longitudinal water-blocking capacity of the copper wire loose layer 15, optionally, a water-absorbing structure layer 16 is provided between the copper wire loose layer 15 and the copper strip layer 17. The water-absorbing structure layer 16 includes a non-woven fabric wrapping structure layer, and the non-woven fabric includes a non-woven fabric layer and a water-absorbing layer, with the water-absorbing layer facing the copper wire loose layer 15.

[0036] In this way, the water-absorbing structure layer 16 can absorb the water vapor that enters the copper wire unwound layer 15, so as to ensure the water-blocking ability of the wire core 1.

[0037] Preferably, the average spacing between adjacent copper wires in the copper wire loose winding layer 15 is 2.5 to 3.5 mm, and the maximum gap is no more than 5 mm.

[0038] In this way, a better shielding effect can be achieved by evenly arranging the copper wires.

[0039] Optionally, the wrapping overlap rate of the nonwoven tape is 15-30%. The absorbent layer can be selected from at least one of starch-based absorbent swelling layer, cellulose-based absorbent swelling layer, and superabsorbent resin layer, which meets the requirements of water absorption and retention while also complying with environmental protection requirements.

[0040] In an optional embodiment, the filler layer 2 includes a water-blocking filler rope. The water-blocking filler rope fills around the core 1 to provide a water-blocking environment for the core 1, preventing moisture from being transferred from the cable joint or radially into the core 1.

[0041] Furthermore, the water-blocking tape 3 includes a double-sided water-blocking tape, wherein the double-sided water-blocking tape comprises a sandwich structure consisting of a polyester fiber nonwoven fabric, a highly absorbent and swellable layer, and a polyester fiber nonwoven fabric.

[0042] The super absorbent swelling layer can be selected from at least one of starch-based super absorbent swelling layer, cellulose-based super absorbent swelling layer, and super absorbent resin layer.

[0043] Furthermore, the water-blocking layer includes a metal composite strip layer 4 and a flame-retardant polyethylene sheath layer 5. The metal composite strip layer 4 covers the outer wall of the cable core, and the flame-retardant polyethylene sheath layer 5 is extruded onto the outer wall of the metal composite strip layer 4.

[0044] Optionally, the metal composite strip layer 4 includes longitudinally wrapped metal composite strips, with the gaps between the metal composite strips welded to form a sealing structure. Thus, a water-blocking metal shell is formed by the longitudinally wrapped metal composite strips, providing reliable radial water-blocking capability.

[0045] Furthermore, a flame-retardant polyethylene sheath layer 5 is disposed on the outer layer of the metal composite strip layer 4 to form a dense radial water-blocking protective layer.

[0046] In an optional embodiment, the braided flame-retardant aramid yarn reinforcement layer 6 comprises braided flame-retardant aramid yarn with a braiding angle of 45% and a braiding density greater than 90%.

[0047] In this way, the tensile strength of the cable is enhanced by braiding flame-retardant aramid yarn, which effectively reduces the probability of insulation damage and sheath breakage under stress. This is especially important for cables in humid or watery environments, thus improving the safety and service life of the cable.

[0048] 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 large size water-blocking, halogen-free, low smoke, flame-retardant, environmentally friendly medium voltage power cable, characterized in that, It comprises: A cable core with a plurality of mutually twisted wire cores (1) and a filling layer (2) filled between the wire cores (1) together wrapped by a water-blocking tape (3) to form a round cross-section; A water-blocking layer wrapped on the outer wall of the cable core; A woven aramid fiber reinforced layer (6) wrapped on the outer wall of the water-blocking layer; A halogen-free low-smoke flame-retardant polyolefin outer sheath (7) extruded on the outer wall of the woven aramid fiber reinforced layer (6); Wherein, the wire core (1) comprises a conductor (11), a conductor shielding layer (12), an insulating layer (13), an insulating shielding layer (14), and a metal shielding layer, the metal shielding layer comprises a copper wire loose winding layer (15) and a copper tape layer (17), and a water absorption structure layer (16) is arranged between the copper wire loose winding layer (15) and the copper tape layer (17).

2. Large size water-blocking, halogen-free, low smoke, flame-retardant, environmentally friendly medium voltage power cable according to claim 1, characterized in that, The water absorption structure layer (16) comprises a non-woven tape wrapping structure layer, the non-woven tape comprises a non-woven layer and a water absorption layer, the water absorption layer is selected from at least one of a starch-based water absorption and expansion layer, a cellulose-based water absorption and expansion layer, and a super absorbent resin layer, and the water absorption layer faces the copper wire loose winding layer (15).

3. Large size water-treeing resistant, halogen-free, low smoke, flame retardant, environmentally friendly medium voltage power cable according to claim 2, characterized in that, The wrapping coverage rate of the non-woven tape is 15-30%.

4. Large size water-treeing resistant, halogen-free, low smoke, flame retardant, environmentally friendly medium voltage power cable according to claim 1, characterized in that, The average distance between adjacent copper wires in the copper wire loose winding layer (15) is 2.5-3.5 mm, and the maximum gap is not greater than 5 mm.

5. Large size water-treeing resistant, halogen-free, low smoke, flame retardant, environmentally friendly medium voltage power cable according to claim 1, characterized in that, The filling layer (2) comprises a water-blocking filling rope.

6. Large size water-treeing resistant, halogen-free, low smoke, flame retardant, environmentally friendly medium voltage power cable according to claim 1, characterized in that, The water-blocking tape (3) comprises a double-sided water-blocking tape, which comprises a sandwich structure of polyester fiber non-woven fabric-high water absorption and expansion layer-polyester fiber non-woven fabric.

7. Large size water-treeing resistant, halogen-free, low smoke, flame retardant, environmentally friendly medium voltage power cable according to claim 1, characterized in that, The water-blocking layer comprises a metal composite tape layer (4) wrapped on the outer wall of the cable core and a flame-retardant polyethylene sheath layer (5) extruded on the outer wall of the metal composite tape layer (4).

8. Large size water-treeing resistant, halogen-free, low smoke, flame retardant, environmentally friendly medium voltage power cable according to claim 7, characterized in that, The metal composite tape layer (4) comprises a longitudinally wrapped metal composite tape, and the gaps of the metal composite tape are welded to form a sealed structure.

9. Large size water-treeing resistant, halogen-free, low smoke, flame retardant, environmentally friendly medium voltage power cable according to claim 1, characterized in that, The cross-sectional dimension of the conductor (11) is greater than or equal to 500 mm 2 .

10. Large size water-treeing resistant, halogen-free, low smoke, flame retardant, environmentally friendly medium voltage power cable according to claim 1, characterized in that, The woven aramid fiber reinforced layer (6) comprises woven aramid fibers, the weaving angle is 45%, and the weaving density is greater than 90%.

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