Irradiated cross-linked halogen-free flame-retardant Class A fire-resistant low-voltage double-insulated power cable

Abstract

This utility model relates to the field of wire and cable technology, specifically to an irradiated cross-linked halogen-free flame-retardant Class A fire-resistant low-voltage double-insulated power cable, comprising: multiple stranded cores, each core including a conductor, a fire-resistant layer, an inner insulation layer, and an insulation layer; a cable core with a circular cross-section, formed by a filling layer filling the spaces between the cores and a sheathing layer; and a metal shielding layer covering the outer wall of the cable core. This application utilizes a composite structure of a nano-ceramic coating and a ceramicized silicone rubber inner insulation layer on the conductor surface, combined with the synergistic effect of aluminosilicate fire-resistant paper, to form a continuous heat insulation barrier at high temperatures. This effectively blocks the flame penetration path, significantly extends the fire resistance time, and meets fire resistance standards. Simultaneously, the dense and high-temperature resistant nano-ceramic coating on the conductor surface inhibits contact between corrosive media such as salt spray and moisture and the conductor, while also suppressing the increase in resistivity caused by high-temperature oxidation. This makes it suitable for highly corrosive environments such as offshore platforms.

Description

Technical Field

[0001] This utility model relates to the field of wire and cable technology, and more specifically to an irradiated cross-linked halogen-free flame-retardant Class A fire-resistant low-voltage double-insulated power cable. Background Technology

[0002] In critical fire-fighting scenarios such as high-rise buildings and traffic tunnels in modern cities, fire-resistant cables need to provide continuous power for several hours in emergencies to ensure the operation of core functions such as escape route lighting and smoke extraction systems. Traditional fire-resistant cables typically employ an insulation layer design with a high filler of inorganic materials to achieve flame-retardant properties. While these cables may pass vertical burning and smoke density tests in laboratory standards, they reveal significant hidden dangers in practical engineering applications.

[0003] For example, in salt spray corrosive environments such as offshore oil platforms, the embrittlement of traditional insulation layers and the corrosion of metal shielding layers have a superimposed effect. Platform operation and maintenance records show that cables that have been in service for more than 3 years have repeatedly caused grounding faults due to insulation cracking during emergency startup, forcing the system to switch to backup lines and exposing the power supply redundancy defects of critical facilities. Therefore, how to balance the mechanical durability and fire resistance of cables is an urgent problem to be solved. Utility Model Content

[0004] To address the technical problems existing in fire-resistant low-voltage power cables in the prior art, this utility model proposes an irradiated cross-linked halogen-free flame-retardant Class A fire-resistant low-voltage double-insulated power cable, comprising:

[0005] Multiple strands of wire twisted together, each strand comprising a conductor, a fire-resistant layer, an inner insulation layer, and an insulation layer;

[0006] The filler layer between the wire cores is wrapped together with the wrapping layer to secure the cable core, which has a circular cross-section.

[0007] A metal shielding layer is wrapped around the outer wall of the cable core;

[0008] The inner sheath layer is extruded onto the outer wall of the metal shielding layer;

[0009] The outer sheath layer is extruded onto the outer wall of the inner sheath layer;

[0010] The fire-resistant layer includes a nano-ceramic coating applied to the outer layer of the conductor, the inner insulation layer includes a ceramicized silicone rubber inner insulation layer extruded onto the outer wall of the nano-ceramic coating, and the insulation layer includes an irradiated cross-linked halogen-free insulation layer.

[0011] Preferably, the thickness of the nano-ceramic coating is 20-30 μm, and the outer layer of the nano-ceramic coating is wrapped with a layer of aluminosilicate refractory paper.

[0012] Preferably, the outer wall of the ceramicized silicone rubber inner insulating layer is covered with a layer of aluminosilicate refractory paper.

[0013] Preferably, the thickness of the ceramicized silicone rubber inner insulating layer is 1.2 to 1.5 mm.

[0014] Preferably, the filling layer includes halogen-free flame-retardant fiberglass braided filling rope filling between multiple cores and halogen-free flame-retardant fiberglass braided filling rope filling between the cores and the wrapping layer.

[0015] Preferably, the wrapping layer comprises a double-layer ceramicized glass fiber tape wrapping structure, wherein the thickness of each ceramicized glass fiber tape layer is greater than 1.2 mm.

[0016] Preferably, the wrapping layer includes an inner ceramicized fiberglass tape wrapping layer, a middle layer, and an outer ceramicized fiberglass tape wrapping layer. Both the inner and outer ceramicized fiberglass tape wrapping layers are ceramicized fiberglass tape wrapping layers, and the wrapping overlap rate is greater than 55%. The middle layer includes longitudinally wrapped aluminosilicate refractory tape.

[0017] Preferably, the metal shielding layer comprises a longitudinally wrapped copper-plastic composite strip or a longitudinally wrapped aluminum-plastic composite strip.

[0018] Preferably, the inner sheath layer comprises a low-smoke halogen-free polyolefin sheath layer, and the outer sheath layer comprises an irradiated crosslinked halogen-free polyolefin sheath layer.

[0019] Compared with the prior art, the advantages of this utility model are:

[0020] This application utilizes a composite structure of a nano-ceramic coating and an inner insulating layer of ceramicized silicone rubber on the surface of a conductor, combined with the synergistic effect of aluminosilicate fire-resistant paper, to form a continuous heat insulation barrier at high temperatures. This effectively blocks the flame penetration path, significantly extends the fire resistance time, and meets fire resistance standards. At the same time, the nano-ceramic coating on the conductor surface is dense and high-temperature resistant, which can inhibit the contact between corrosive media such as salt spray and moisture and the conductor, while also inhibiting the increase in resistivity caused by high-temperature oxidation. This makes it suitable for highly corrosive environments such as offshore platforms.

[0021] This application employs a double-layer ceramicized fiberglass tape wrapping structure and a halogen-free flame-retardant fiberglass yarn filling rope design, which enhances the tensile strength and structural stability of the cable, effectively disperses external stress, inhibits the propagation of insulation layer cracks, and extends service life. In addition, the aluminosilicate fire-resistant paper coating layer forms a rigid skeleton at high temperatures, offsetting the thermal expansion stress of the conductor, preventing short circuits or core breaks caused by loose stranded conductors, and ensuring the functional integrity of the cable under extreme conditions. Attached Figure Description

[0022] 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:

[0023] Figure 1 This is a schematic diagram of the structure of the irradiated cross-linked halogen-free flame-retardant Class A fire-resistant low-voltage double-layer insulated power cable shown in this utility model;

[0024] Figure 2 This is a schematic diagram of the cross-sectional structure of the irradiated cross-linked halogen-free flame-retardant Class A fire-resistant low-voltage double-layer insulated power cable shown in this utility model.

[0025] Figure 3 This is a schematic diagram of the wire core structure shown in this utility model;

[0026] Figure 4 This is a schematic diagram of the structure of the wrapping layer shown in this utility model. Detailed Implementation

[0027] To better understand the technical content of this utility model, specific embodiments are provided below in conjunction with the accompanying drawings.

[0028] Combination Figure 1 and Figure 2 As shown, this utility model proposes an irradiated cross-linked halogen-free flame-retardant Class A fire-resistant low-voltage double-insulated power cable, including a cable core, a metal shielding layer 4, an inner sheath layer 5, and an outer sheath layer 6.

[0029] The cable core includes multiple cores 1, a filling layer 2, and a wrapping layer 3. The multiple cores 1 are twisted together, and multiple filling ropes are filled between the cores 1 to form the filling layer 2. The cores 1 and the filling ropes are wrapped together by the wrapping layer 3 to form a cable core with a circular cross-section.

[0030] In optional embodiments, such as Figure 3 As shown, the wire core 1 includes a conductor 11, a fire-resistant layer 12, an inner insulation layer 13, and an insulation layer 14.

[0031] The refractory layer 12 includes a nano-ceramic coating coated on the outer layer of the conductor 11, the inner insulation layer 13 includes a ceramicized silicone rubber inner insulation layer extruded on the outer wall of the nano-ceramic coating, and the insulation layer 14 includes an irradiated cross-linked halogen-free insulation layer.

[0032] Optionally, the insulation layer 14 is made of cross-linked ethylene-vinyl acetate copolymer. High-energy irradiation causes the polymer molecular chains to form a three-dimensional cross-linked structure, which effectively resists molecular chain slippage caused by external stress, thereby reducing the generation and propagation of cracks.

[0033] Furthermore, conductor 11 is a type 6 tin-plated copper conductor with a multi-layer stranded structure. Preferably, the tin plating thickness on the surface of the copper conductor is greater than 3 μm to suppress the increase in resistivity caused by high-temperature oxidation.

[0034] In an optional embodiment, the thickness of the nano-ceramic coating is 20–30 μm.

[0035] Specifically, a metal alkoxide is mixed with an ethanol solvent and a nitric acid catalyst to form a uniform sol. The conductor 11 is then passed through the sol bath at a predetermined speed to form a wet film. The wet film is further heat-treated at 80-120°C for 1-2 minutes to evaporate the solvent and form a gel. Finally, the film is sintered at 400-600°C in an inert atmosphere for 10-30 minutes to obtain a dense nano-ceramic layer.

[0036] Thus, by forming a dense nano-ceramic layer on the surface of conductor 11, the oxidation reaction of the conductor under high temperature in a fire can be suppressed. Under high temperature, it combines with the ceramicized layer to form a continuous heat insulation barrier, and can block the contact between moisture / corrosive media and the conductor, thereby improving corrosion resistance and meeting the requirements for use in salt spray environments.

[0037] Furthermore, an aluminosilicate refractory paper is wrapped around the outer layer of the stranded conductor coated with a nano-ceramic coating.

[0038] Thus, the coating effect of aluminosilicate fire-resistant paper can inhibit conductor oxidation, and because the fire-resistant paper forms a rigid skeleton at high temperature, it can offset the thermal expansion stress of the stranded conductor and maintain the geometry of the stranded conductor at high temperature, preventing loosening that could lead to short circuits or broken cores.

[0039] Furthermore, in combination Figure 4 As shown, the wrapping layer 3 includes a double-layer ceramicized fiberglass tape wrapping structure, with each ceramicized fiberglass tape having a thickness greater than 1.2 mm.

[0040] Specifically, the wrapping layer 3 includes an inner ceramicized fiberglass tape wrapping layer 31, a middle layer 32, and an outer ceramicized fiberglass tape wrapping layer 33. Both the inner ceramicized fiberglass tape wrapping layer 31 and the outer ceramicized fiberglass tape wrapping layer 33 are ceramicized fiberglass tape wrapping layers with a wrapping overlap rate of more than 55%. The middle layer 32 includes longitudinally wrapped aluminosilicate refractory tape.

[0041] Preferably, the thickness of the ceramicized silicone rubber inner insulating layer is 1.2 to 1.5 mm.

[0042] Furthermore, the outer wall of the ceramicized silicone rubber inner insulation layer is also covered with a layer of aluminosilicate fire-resistant paper.

[0043] Thus, through the synergistic effect of ceramicized silicone rubber and aluminosilicate inner insulation layer, the overall fire resistance time is extended. The fire-resistant paper can supplement the fire resistance at the micro-cracks in the ceramicized layer, block the path of external flame penetration, and improve the fire resistance effect.

[0044] As mentioned above, the composite structure of fire-resistant paper and ceramicized silicone rubber significantly improves the thermal insulation, oxidation resistance, and structural support compared to traditional mica tape wrapping, thus meeting the requirements for the mechanical durability and fire resistance of cables.

[0045] In an optional embodiment, the filling layer 2 includes a halogen-free flame-retardant fiberglass braided filling rope filled between multiple cores 1 and a halogen-free flame-retardant fiberglass braided filling rope filled between the cores 1 and the wrapping layer 3.

[0046] In this way, the halogen-free flame-retardant fiberglass yarn braided filler rope can bear the tensile force of the cable, reduce the adverse effects of tensile stress on the wire core, and inhibit the growth of insulation layer cracks. At the same time, the halogen-free flame-retardant fiberglass yarn braided filler rope makes the cable round and tightly filled, achieving a good flame-retardant effect.

[0047] Furthermore, the metal shielding layer 4 covers the outer wall of the cable core, the inner sheath layer 5 is extruded onto the outer wall of the metal shielding layer 4, and the outer sheath layer 6 is extruded onto the outer wall of the inner sheath layer 5.

[0048] Optionally, the metal shielding layer 4 includes a longitudinally wrapped copper-plastic composite strip or a longitudinally wrapped aluminum-plastic composite strip. The presence of the longitudinally wrapped copper-plastic composite strip or the longitudinally wrapped aluminum-plastic composite strip can improve the water-blocking effect of the shielding layer.

[0049] Optionally, the inner sheath layer 5 includes a low-smoke halogen-free polyolefin sheath layer, and the outer sheath layer 6 includes an irradiated cross-linked halogen-free polyolefin sheath layer. The low-smoke halogen-free polyolefin sheath layer has good elasticity, and the irradiated cross-linked halogen-free polyolefin sheath layer has good anti-aging properties, enabling the cable to maintain long-term integrity under the combined effects of salt spray, mechanical stress, and ultraviolet radiation, while meeting the requirements of halogen-free flame retardancy and high flexibility.

[0050] In conjunction with the above embodiments, this application, by setting a composite structure of a nano-ceramic coating and an inner insulating layer of ceramicized silicone rubber on the surface of the conductor, combined with the synergistic effect of aluminosilicate fire-resistant paper, forms a continuous heat insulation barrier at high temperatures, effectively blocking the flame penetration path, significantly extending the fire resistance time, and meeting fire resistance standards. At the same time, the nano-ceramic coating on the surface of the conductor is dense and high-temperature resistant, which can inhibit the contact between the conductor and corrosive media such as salt spray and moisture, and also inhibit the increase in resistivity caused by high-temperature oxidation, making it suitable for highly corrosive environments such as offshore platforms.

[0051] This application employs a double-layer ceramicized fiberglass tape wrapping structure and a halogen-free flame-retardant fiberglass yarn filling rope design, which enhances the tensile strength and structural stability of the cable, effectively disperses external stress, inhibits the propagation of insulation layer cracks, and extends service life. In addition, the aluminosilicate fire-resistant paper coating layer forms a rigid skeleton at high temperatures, offsetting the thermal expansion stress of the conductor, preventing short circuits or core breaks caused by loose stranded conductors, and ensuring the functional integrity of the cable under extreme conditions.

[0052] 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 halogen-free flame-retardant, class A fire-resistant, low-voltage, double- layer insulated power cable crosslinked by irradiation, characterized in that, include: Multiple strands of wire (1) twisted together, wherein the wire (1) includes a conductor (11), a fire-resistant layer (12), an inner insulation layer (13) and an insulation layer (14); The filler layer (2) filling the space between the wire cores (1) is wrapped together with the wrapping layer (3) to secure the cable core with a circular cross-section; A metal shielding layer (4) covers the outer wall of the cable core; The inner sheath layer (5) is extruded onto the outer wall of the metal shielding layer (4); The outer sheath layer (6) is extruded onto the outer wall of the inner sheath layer (5); The fire-resistant layer (12) includes a nano-ceramic coating coated on the outer layer of the conductor (11), the inner insulation layer (13) includes a ceramicized silicone rubber inner insulation layer extruded on the outer wall of the nano-ceramic coating, and the insulation layer (14) includes an irradiated crosslinked halogen-free insulation layer.

2. The radiation crosslinked halogen-free flame-retardant class A fire resistant low voltage two-layer insulated power cable according to claim 1, characterized in that, The thickness of the nano-ceramic coating is 20-30 μm, and the outer layer of the nano-ceramic coating is wrapped with a layer of aluminosilicate refractory paper.

3. The radiation crosslinked halogen-free flame-retardant class A fire resistant low voltage two-layer insulated power cable according to claim 1, characterized in that, The outer wall of the ceramicized silicone rubber inner insulating layer is covered with a layer of aluminosilicate fire-resistant paper.

4. The radiation-crosslinked halogen-free flame-retardant class-A fire-resistant low-voltage two-layer insulated power cable according to claim 3, characterized in that, The thickness of the ceramicized silicone rubber inner insulating layer is 1.2 to 1.5 mm.

5. The radiation crosslinked halogen-free flame-retardant class A fire resistant low voltage two-layer insulated power cable according to claim 1, characterized in that, The filling layer (2) includes a halogen-free flame-retardant fiberglass braided filling rope filled between multiple cores (1) and a halogen-free flame-retardant fiberglass braided filling rope filled between the cores (1) and the wrapping layer (3).

6. The radiation crosslinked halogen-free flame-retardant class A fire resistant low voltage two-layer insulated power cable according to claim 1, characterized in that, The wrapping layer (3) includes a double-layer ceramicized fiberglass tape wrapping structure, with each ceramicized fiberglass tape having a thickness greater than 1.2 mm.

7. The radiation crosslinked halogen-free flame-retardant class A fire resistant low voltage two-layer insulated power cable according to claim 6, characterized in that, The wrapping layer (3) includes an inner ceramicized glass fiber tape wrapping layer (31), an intermediate layer (32), and an outer ceramicized glass fiber tape wrapping layer (33). The inner ceramicized glass fiber tape wrapping layer (31) and the outer ceramicized glass fiber tape wrapping layer (33) are both ceramicized glass fiber tape wrapping layers, and the wrapping overlap rate is greater than 55%. The intermediate layer (32) includes longitudinally wrapped aluminosilicate refractory tape.

8. The irradiated cross-linked halogen-free flame-retardant Class A fire-resistant low-voltage double-insulated power cable according to claim 1, characterized in that, The metal shielding layer (4) includes longitudinally wrapped copper-plastic composite tape or longitudinally wrapped aluminum-plastic composite tape.

9. The radiation crosslinked halogen-free flame-retardant class A fire resistant low voltage two-layer insulated power cable according to claim 1, characterized in that, The inner sheath layer (5) includes a low-smoke halogen-free polyolefin sheath layer, and the outer sheath layer (6) includes an irradiated crosslinked halogen-free polyolefin sheath layer.

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