Flame-retardant fireproof low-voltage power cable for nuclear power station

Abstract

The utility model relates to the technical field of cables, in particular to a flame-retardant fire-resistant low-voltage power cable for a nuclear power plant, which comprises a cable core, the cable core is sequentially sleeved with a wrapping layer and an outer protective layer from inside to outside, the cable core comprises a plurality of wire cores formed by mutually twisting, the wire cores are used for electric conduction, the wrapping layer wraps the outer sides of the plurality of wire cores, and the outer protective layer is used for protecting the outer protective layer. A filling layer is arranged between the plurality of wire cores and the wrapping layer, the wrapping layer comprises a ceramic fiber belt and a halogen-free low-smoke high-flame-retardant cloth belt, the halogen-free low-smoke high-flame-retardant cloth belt is wound on the plurality of wire cores, the ceramic fiber belt is wound on the halogen-free low-smoke high-flame-retardant cloth belt, a warning wire is arranged in the filling layer, the resistance value of the warning wire and the temperature change linearly, and the resistance value of the warning wire and the temperature change linearly. And the outer protective layer is formed by extruding a halogen-free low-smoke high-flame-retardant polyolefin material. The cable has the effects of flame retardance, fire resistance and convenience in monitoring.

Description

Technical Field

[0001] This application relates to the field of cable technology, and in particular to a flame-retardant and fire-resistant low-voltage power cable for nuclear power plants. Background Technology

[0002] A cable is a conductor made of one or more mutually insulated conductors and an outer insulating protective layer. It is used to transmit electricity or information. Cables are usually made of multiple insulated conductors twisted together, with an outer insulating protective layer. Their main function is to transmit electricity or signals. Their core characteristics are internal conductivity and external insulation, making them the primary means of transmitting electrical energy in nuclear power plants.

[0003] Common power cables use polymer insulation materials that are flammable. During the transmission of electrical energy, the cables may catch fire due to accidents, and the fire will produce a lot of thick smoke. This can cause the fire to spread along the cable, and the thick smoke will affect the evacuation of people and subsequent fire rescue, which is a shortcoming. Utility Model Content

[0004] In order to improve the problems caused by traditional cables during use, this application provides a flame-retardant and fire-resistant low-voltage power cable for nuclear power plants.

[0005] This application provides a flame-retardant and fire-resistant low-voltage power cable for nuclear power plants, which adopts the following technical solution:

[0006] A flame-retardant and fire-resistant low-voltage power cable for nuclear power plants includes a cable core. The cable core is wrapped with a wrapping layer and an outer sheath from the inside out. The cable core includes multiple stranded wires for conducting electricity. The wrapping layer is wrapped around the outside of the multiple strands. A filler layer is provided between the multiple strands and the wrapping layer. The outer sheath is extruded from a halogen-free, low-smoke, high-flame-retardant polyolefin material.

[0007] By adopting the above technical solution, when a fire occurs in the external environment of the cable, the high temperature and open flame will first act on the outer sheath. Since the outer sheath is made of halogen-free, low-smoke, and highly flame-retardant material, it can withstand high temperatures. Therefore, in the initial period of the fire, the outer sheath will not be ignited or produce dense smoke. At the same time, it will not release toxic gases in the high-temperature environment, which facilitates the evacuation of personnel and the subsequent fire rescue process, and reduces the possibility of the fire spreading along the cable.

[0008] Optionally, the wrapping layer includes a ceramic fiber tape and a halogen-free, low-smoke, high-flame-retardant fabric tape, wherein the halogen-free, low-smoke, high-flame-retardant fabric tape is wound around multiple of the wire cores, and the ceramic fiber tape is wound around the halogen-free, low-smoke, high-flame-retardant fabric tape.

[0009] By adopting the above technical solutions, the temperature resistance of ceramic fiber tape is above 1000℃, and the material has low thermal conductivity. At the same time, the main raw material of halogen-free, low-smoke, and high-flame-retardant cloth tape is inorganic material, which is not easy to burn. The combined use of ceramic fiber tape and halogen-free, low-smoke, and high-flame-retardant cloth tape forms a protective layer for the cable core, which greatly improves the flame retardant performance of the cable and enables the cable core to work normally.

[0010] Optionally, the wire core includes a conductor, and the conductor is fitted with an insulation layer and a heat insulation layer from the inside out, and the halogen-free, low-smoke, high flame-retardant fabric tape is wrapped around the outside of the heat insulation layer.

[0011] By adopting the above technical solutions, the insulation layer reduces the possibility of short circuits caused by accidental contact of the conductor with water, while the halogen-free, low-smoke, and highly flame-retardant fabric tape reduces the possibility of direct contact between open flames and the insulation layer, further reducing the possibility of the insulation layer being ignited.

[0012] Optionally, the insulating layer is made of silicone rubber.

[0013] By adopting the above technical solution, when the insulation layer is accidentally ignited, the surface of the insulation layer can form a crust under flame conditions, so that the insulation layer after the surface is burned can automatically prevent the flame from continuing to burn into the interior of the insulation layer, thereby allowing the conductor to be completely wrapped, so that the conductor can still play a good electrical insulation role in the event of a fire.

[0014] Optionally, the conductor is made of multiple strands of soft copper wire twisted together.

[0015] By adopting the above technical solution, the conductor made by stranding is more flexible than the solid conductor, which is more conducive to improving the bending performance of the cable, thus facilitating the winding and laying of the cable.

[0016] Optionally, a shielding layer is provided between the outer protective layer and the wrapping layer, and a heat insulation layer is provided between the shielding layer and the outer protective layer. The heat insulation layer is formed by wrapping aerogel felt around the shielding layer.

[0017] By adopting the above technical solutions, the mutual influence of the conductor on the surrounding cables is reduced when the conductor transmits current. At the same time, the aerogel felt can effectively reduce the diffusion of temperature from the outer sheath to the shielding layer, reducing the possibility of damage to the shielding layer.

[0018] Optionally, the insulation layer is provided with multiple layers of metal mesh from the inside out, and a separating metal line is provided between two adjacent metal meshes. Both the metal mesh and the separating metal line are located inside the outer protective layer.

[0019] By adopting the above technical solution, during the extrusion molding process of the outer protective layer, the halogen-free, low-smoke, and highly flame-retardant polyolefin material will fill the grid space of the multi-layer metal mesh. When the outer protective layer is ignited at high temperature, the multi-layer metal mesh can effectively bind the halogen-free, low-smoke, and highly flame-retardant polyolefin material, reducing the possibility of the halogen-free, low-smoke, and highly flame-retardant polyolefin material falling off in the high-temperature environment, thereby enabling the outer protective layer to protect the insulation layer for a long time.

[0020] Optionally, an alarm wire is provided within the filling layer, and the resistance of the alarm wire changes linearly with temperature.

[0021] By adopting the above technical solution, during the cable installation process, workers can connect professional testing equipment to the warning conductor. When the resistance of the warning conductor changes due to high temperature, workers can use the professional testing equipment to understand in a timely manner the high temperature environment of the cable and the damage caused to the filling layer. This allows workers to predict the working condition of the cable in a timely manner and carry out timely maintenance.

[0022] In summary, this application includes at least one of the following beneficial technical effects:

[0023] 1. When a fire occurs in the external environment of the cable, the high temperature and open flame will first act on the outer sheath. Since the outer sheath is made of halogen-free, low-smoke, and highly flame-retardant material, it can withstand high temperatures. Therefore, in the initial time of the fire, the outer sheath will not be ignited or produce dense smoke. At the same time, it will not release toxic gases in the high-temperature environment, which facilitates the evacuation of personnel and the subsequent fire rescue process, and reduces the possibility of the fire spreading along the cable.

[0024] 2. During the extrusion molding process of the outer sheath, the halogen-free, low-smoke, high-flame-retardant polyolefin material will fill the grid space of the multi-layer metal mesh. When the outer sheath is ignited at high temperature, the multi-layer metal mesh can effectively bind the halogen-free, low-smoke, high-flame-retardant polyolefin material, reducing the possibility of the halogen-free, low-smoke, high-flame-retardant polyolefin material falling off in the high-temperature environment, so that the outer sheath can protect the insulation layer for a long time.

[0025] 3. During cable installation, workers connect professional testing equipment to the warning conductor. When the resistance of the warning conductor changes due to high temperature, workers can use the professional testing equipment to understand in a timely manner the high temperature environment of the cable and the damage caused to the filling layer. This allows workers to predict the working condition of the cable in a timely manner and carry out maintenance promptly. Attached Figure Description

[0026] Figure 1 This is a structural schematic diagram of an embodiment of this application.

[0027] Figure 2This is a cross-sectional view used in the embodiments of this application to illustrate the positional relationship between the conductor, the filler layer, and the ceramic fiber tape.

[0028] Explanation of reference numerals in the attached diagram: 1. Cable core; 11. Wire core; 111. Conductor; 112. Insulation layer; 113. Heat insulation layer; 12. Filler layer; 2. Wrapping layer; 21. Ceramic fiber tape; 22. Halogen-free, low-smoke, high flame-retardant cloth tape; 3. Outer sheath; 4. Shielding layer; 5. Thermal insulation layer; 6. Metal mesh; 7. Separating metal wire; 8. Warning wire. Detailed Implementation

[0029] The following is in conjunction with the appendix Figures 1-2 This application will be described in further detail.

[0030] This application discloses a flame-retardant and fire-resistant low-voltage power cable for nuclear power plants.

[0031] Reference Figure 1 A flame-retardant and fire-resistant low-voltage power cable for nuclear power plants includes a cable core 1. The cable core 1 is wrapped with a wrapping layer 2 and an outer sheath 3 from the inside out. The outer sheath 3 is extruded from halogen-free, low-smoke, and highly flame-retardant polyolefin material. The nominal thickness of the outer sheath 3 is not less than 1.8 mm. The cable core 1 includes 2 to 5 strands 11 twisted together. The twist pitch ratio of the cable core 1 is in the range of 20 to 30.

[0032] Reference Figure 2 The wire core 11 includes a conductor 111 made of multiple strands of soft copper wire twisted together. The conductor 111 is used for conducting electricity. The twisting ratio of the multiple strands of soft copper wire is in the range of 15 to 20, and the cross-section of the conductor 111 is in the range of 1.5 mm. 2 ~6mm 2 .

[0033] Reference Figure 1 The conductor 111 is provided with an insulating layer 112 and a heat insulation layer 113 from the inside out. The insulating layer 112 is made of silicone rubber material and has a nominal thickness of 1.0 mm. The heat insulation layer 113 is formed by wrapping ceramic fibers with a nominal thickness of 0.3 mm around each insulating layer 112.

[0034] Reference Figure 1 The wrapping layer 2 is wrapped around the outside of the heat insulation layer 113 of the three wire cores 11. A filling layer 12 is arranged between the three wire cores 11 and the wrapping layer 2. The filling layer 12 can be a flame-retardant filling rope in the prior art. A warning wire 8 is threaded inside the filling layer 12. The warning wire 8 is made of metal material. The resistance of the warning wire 8 changes linearly with temperature.

[0035] When high temperature acts on the filling layer 12, the resistance of the warning wire 8 changes, and the detection equipment connected to the warning wire 8 will remind the worker of the cable's condition. When high temperature acts on the insulation layer 112, silicone rubber will form a shell on the surface to prevent the flame from continuing to burn into the insulation layer 112, thus enabling the cable to achieve flame retardancy in high-temperature environments.

[0036] Reference Figure 2 The wrapping layer 2 includes a ceramic fiber tape 21 and a halogen-free, low-smoke, high-flame-retardant fabric tape 22. The nominal thickness of the ceramic fiber tape 21 is 0.5 mm, and the nominal thickness of the halogen-free, low-smoke, high-flame-retardant fabric tape 22 is 0.3 mm. The halogen-free, low-smoke, high-flame-retardant fabric tape 22 is wrapped around the outside of the heat insulation layer 113 of the three wire cores 11, and the ceramic fiber tape 21 is wrapped around the halogen-free, low-smoke, high-flame-retardant fabric tape 22.

[0037] Reference Figure 1 and Figure 2 A shielding layer 4 is arranged between the outer sheath 3 and the ceramic fiber tape 21. A heat insulation layer 5 is arranged between the shielding layer 4 and the outer sheath 3. The heat insulation layer 5 is formed by wrapping aerogel felt around the shielding layer 4. Multiple layers of metal mesh 6 are sequentially wrapped around the heat insulation layer 5 from the inside to the outside. A separating metal line 7 is arranged between two adjacent metal meshes 6. Both the metal mesh 6 and the separating metal line 7 are prefabricated inside the outer sheath 3.

[0038] When the cable is in a fire, the high temperature and open flame will directly affect the outer sheath 3. Since the outer sheath 3 is made of halogen-free, low-smoke, high flame-retardant polyolefin material, the core 11 inside the outer sheath 3 can still work normally within the temperature resistance limit of the halogen-free, low-smoke, high flame-retardant polyolefin material, and the fire will not spread along the cable. At the same time, the outer sheath 3 will not release toxic gases in the high-temperature environment.

[0039] When the temperature caused by the fire exceeds the temperature limit of the outer sheath 3, the outer sheath 3 will be softened by the fire. However, the spatial gaps formed by the multi-layer metal mesh 6 will restrict the halogen-free, low-smoke, high-flame-retardant polyolefin material from detaching from the metal mesh 6, so that the halogen-free, low-smoke, high-flame-retardant polyolefin material will adhere to the metal mesh 6 for a long time, thereby continuously improving the temperature limit of the cable. At this time, the outer sheath 3 will not produce dense smoke.

[0040] When the insulation layer 5 is exposed to fire, it will continue to protect the structure inside the shielding layer 4. When the high temperature of the fire continues to act on the wrapping layer 2, the ceramic fiber tape 21 and the halogen-free, low-smoke, high flame-retardant fabric tape 22 will continue to prevent the high temperature from being transmitted to the filling layer 12.

[0041] The implementation principle of a flame-retardant and fire-resistant low-voltage power cable for nuclear power plants in this application embodiment is as follows: When the cable is in a fire, high temperature and open flame will directly act on the outer sheath 3. Since the outer sheath 3 is a halogen-free, low-smoke, high flame-retardant polyolefin material, the wire core 11 inside the outer sheath 3 can still work normally within the temperature resistance limit range of the halogen-free, low-smoke, high flame-retardant polyolefin material, and the fire will not spread along the cable. At the same time, the outer sheath 3 will not release toxic gases in a high-temperature environment.

[0042] When the temperature caused by the fire exceeds the temperature limit of the outer sheath 3, the outer sheath 3 will be softened by the fire. However, the spatial gaps formed by the multi-layer metal mesh 6 will restrict the halogen-free, low-smoke, high-flame-retardant polyolefin material from detaching from the metal mesh 6, so that the halogen-free, low-smoke, high-flame-retardant polyolefin material will adhere to the metal mesh 6 for a long time, thereby continuously improving the temperature limit of the cable. At this time, the outer sheath 3 will not produce dense smoke.

[0043] When the insulation layer 5 is exposed to fire, it will continue to protect the structure inside the shielding layer 4. When the high temperature of the fire continues to act on the wrapping layer 2, the ceramic fiber tape 21 and the halogen-free, low-smoke, high flame-retardant fabric tape 22 will continue to prevent the high temperature from being transmitted to the filling layer 12.

[0044] When high temperature acts on the filling layer 12, the resistance of the warning wire 8 changes, and the detection equipment connected to the warning wire 8 will remind the worker of the cable's condition. When high temperature acts on the insulation layer 112, silicone rubber will form a shell on the surface to prevent the flame from continuing to burn into the insulation layer 112, thus enabling the cable to achieve flame retardancy in high-temperature environments.

[0045] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A flame-retardant, fire-resistant, low-voltage power cable for nuclear power plants, characterized in that: The cable core (1) is provided with a wrapping layer (2) and an outer sheath (3) sequentially from the inside to the outside. The cable core (1) includes multiple strands (11) twisted together. The strands (11) are used for conducting electricity. The wrapping layer (2) is wrapped around the outside of the multiple strands (11). A filler layer (12) is provided between the multiple strands (11) and the wrapping layer (2). The outer sheath (3) is extruded from halogen-free, low-smoke, and highly flame-retardant polyolefin material.

2. A fire-retardant, fire-resistant, low-voltage power cable for nuclear power plants according to claim 1, characterized in that: The wrapping layer (2) includes a ceramic fiber tape (21) and a halogen-free, low-smoke, high-flame-retardant fabric tape (22). The halogen-free, low-smoke, high-flame-retardant fabric tape (22) is wound around multiple of the wire cores (11), and the ceramic fiber tape (21) is wound around the halogen-free, low-smoke, high-flame-retardant fabric tape (22).

3. A fire resistant, flame retardant, low voltage power cable for nuclear power plants according to claim 2, characterized in that: The core (11) includes a conductor (111), and the conductor (111) is provided with an insulation layer (112) and a heat insulation layer (113) from the inside to the outside. The halogen-free, low-smoke, high flame-retardant fabric tape (22) is wrapped around the outside of the heat insulation layer (113).

4. A fire resistant, flame retardant, low voltage power cable for nuclear power plants according to claim 3, characterized in that: The insulating layer (112) is made of silicone rubber.

5. A fire resistant, flame retardant, low voltage power cable for nuclear power plants according to claim 3, characterized in that: The conductor (111) is made of multiple strands of soft copper wire twisted together.

6. A fire-retardant, fire-resistant, low-voltage power cable for nuclear power plants according to claim 2, characterized in that: A shielding layer (4) is provided between the outer protective layer (3) and the wrapping layer (2), and a heat insulation layer (5) is provided between the shielding layer (4) and the outer protective layer (3). The heat insulation layer (5) is formed by wrapping aerogel felt around the shielding layer (4).

7. A fire resistant, flame retardant, low voltage power cable for nuclear power plants according to claim 6, characterized in that: The insulation layer (5) is provided with multiple layers of metal mesh (6) from the inside to the outside, and a separating metal line (7) is provided between two adjacent metal meshes (6). The metal mesh (6) and the separating metal line (7) are both located inside the outer protective layer (3).

8. A fire resistant, flame retardant, low voltage power cable for nuclear power plants according to claim 1, characterized in that: An alarm wire (8) is provided in the filling layer (12), and the resistance of the alarm wire (8) changes linearly with temperature.

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