Fireproof early warning cable

Abstract

The utility model discloses a fire-resistant early warning cable, and aims to solve the defect that the existing cable lacks early warning. The cable comprises three cable cores, an early warning optical fiber and a functional layer wrapped outside the cable cores, the three cable cores are attached pairwise, the three cable cores are clamped to form a central space, the early warning optical fiber is arranged in the central space and attached to each cable core, the functional layer comprises a fireproof layer, a fireproof oxygen barrier layer, an oxygen barrier layer, an armor layer and an outer sheath, and the outer sheath is arranged in the fireproof layer. Glass fiber wrapping layers are arranged between the adjacent functional layers and on the inner side of the fireproof layer. According to the cable, hidden dangers of the cable can be found in time through the built-in optical fiber, and the cable has reliable fireproof performance, so that the hidden dangers on the cable can be detected in time, power supply can be maintained in a fire disaster, and in addition, a failure area of the cable can be determined through the built-in optical fiber in a post-accident stage to help to restore the fire behavior.

Description

Technical Field

[0001] This utility model relates to the field of cable technology, and more specifically, to a fire-resistant early warning cable. Background Technology

[0002] With the rapid development of the national economy, the requirements for safety levels in public places are becoming increasingly stringent. Cables, playing a vital role in important locations such as large buildings, shopping malls, hospitals, and colleges, as well as in systems like railways, are facing increasingly stringent safety requirements. For example, the demand for cables meeting high flame retardant and fire-resistant properties has risen significantly, and the safety of cables during use has become a widespread concern. Especially in areas where cables are densely laid, fires are highly likely to occur, placing high demands on the flame retardant and fire-resistant properties of cables in these locations.

[0003] Ordinary flame-retardant cables can only provide short-term flame-retardant effects after a fire, and they also generate a lot of heat, toxic gases, and smoke, causing people to inhale large amounts of harmful gases and lose their awareness of escape due to the high temperature environment. In addition, they cannot guarantee the normal power supply of the line, causing elevators, emergency lighting, automatic alarms, and disaster relief systems to malfunction, thus affecting the chances of escape. Utility Model Content

[0004] With increased public awareness of fire safety, people have clearly recognized the importance of using fire-resistant power supply lines that can maintain power supply in a fire environment and reduce the generation of heat, toxic gases, and smoke during a fire, thereby increasing the chances of escape. To further improve safety and prevent problems before they occur, there is an urgent need for a technological means to promptly detect potential hazards in cables, providing early warnings to reduce property damage and ensure the safety of life and property.

[0005] This invention overcomes the shortcomings of existing cables that lack early warning capabilities, and provides a fire-resistant early warning cable. It can detect cable hazards in a timely manner through built-in optical fibers and has reliable fire-resistant performance. Thus, it can detect cable hazards in a timely manner and maintain power supply during a fire. In addition, in the post-accident stage, it can also determine the failure area of ​​the cable through built-in optical fibers to help reconstruct the fire situation.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A fire-resistant early warning cable includes three cable cores, an early warning optical fiber, and a functional layer wrapped around the cable cores. The three cable cores are bonded together in pairs, forming a central space. The early warning optical fiber is disposed in the central space and bonded to each cable core. The functional layer includes a fire-resistant layer, a fire-resistant oxygen barrier layer, an oxygen barrier layer, an armor layer, and an outer sheath. A glass fiber wrapping layer is also provided between adjacent functional layers and on the inner side of the fire-resistant layer.

[0008] This application places the optical fiber in the central space inside three cable cores, and the optical fiber is simultaneously attached to each cable core, thereby enabling the reception of vibrations from the cable cores. The principle of temperature detection by the optical fiber is as follows: when laser light propagates in the optical fiber, it interacts with the fiber molecules to generate backscattered Raman light. The intensity of the anti-Stokes light is temperature-sensitive, while the Stokes light is temperature-independent; the temperature value can be calculated from the intensity ratio of the two. The principle of abnormal vibration detection by the optical fiber is as follows: external vibrations cause deformation of the fiber core, leading to a phase change in the transmitted light wave. An interferometer converts the phase difference into light intensity fluctuations, which are then converted into electrical signals by a photodetector. By analyzing the time-domain signal, the source of the disturbance can be located.

[0009] The external functional layers include redundant fire-resistant layers, fire-resistant oxygen-barrier layers, and oxygen-barrier layers. During combustion, these layers prevent the further spread of the fire by isolating oxygen, heat, and flames, and limit the flame's propagation along the cable. By selecting appropriate materials, the insulation capacity of the cable core can be guaranteed, protecting the integrity of the circuit. Properties such as flame spread length, peak heat release rate, total heat release, combustion growth rate index, smoke production rate, total smoke production, as well as the particle size distribution of combustion droplets, smoke toxicity level, and corrosivity level can all meet combustion requirements.

[0010] Preferably, the cable core comprises, from the inside out, a current-conducting core, a semi-conductive conductor shielding layer, an insulation layer, a semi-conductive insulating shielding layer, a semi-conductive resistive water buffer layer, and a metallic shielding layer. The semi-conductive conductor shielding layer eliminates the concentration of the electric field on the conductor surface and smooths the electric field at the interface between the conductor and the insulation layer. The semi-conductive insulating shielding layer homogenizes the electric field on the surface of the insulation layer and prevents discharge at the interface between the insulation and the metallic shielding layer. The semi-conductive resistive water buffer layer prevents damage to the insulation shielding and insulation layer from the metallic shielding layer under high temperature and high pressure conditions and under the condition of thermal expansion and contraction of the insulation. The metallic shielding layer normally carries capacitive current, acts as a channel for short-circuit current during a short circuit, reduces interference with external magnetic fields by shielding the electric field, homogenizes the electric field, and serves as the neutral line in a three-phase four-wire system, bearing unbalanced current. The metallic shielding layer also has a radial water-blocking function.

[0011] As a preferred option, the gap between the cable core and the functional layer is filled with alkali-free glass fiber rope to ensure the roundness of the three-core cable and to conduct heat away in high-temperature environments. It also has excellent flame-retardant properties.

[0012] Preferably, the current-conducting core is formed by layering and compacting several circular single wires, with a compaction coefficient ≥0.9. The geometry of the circular single wires is fixed, suitable for medium and high voltage cables. During stranding, compaction is performed layer by layer (such as the central layer, second layer, outer layer, etc.). Each layer is compressed once by a die, rather than being stranded and then compacted as a whole. This ensures that the ratio of the actual cross-sectional area of ​​the circular single wire to the calculated outline area of ​​the outer diameter of the current-conducting core after stranding and compaction is greater than or equal to 0.9, meeting the performance requirements of medium and high voltage cables.

[0013] Preferably, the insulation layer is made of cross-linked polyethylene. Cross-linked polyethylene has high power frequency resistance and pulse breakdown strength, very low dielectric loss and insulation resistance, excellent resistance to treeing and partial discharge, certain mechanical strength and flexibility, creep resistance, chemical stability and solvent resistance, and long-term stable insulation performance.

[0014] Preferably, the refractory layer is formed by wrapping a ceramic refractory strip around a glass fiber wrapping layer. The ceramic refractory strip can form a crust under combustion conditions, blocking the entry of flames and heat, and protecting the integrity of the insulation.

[0015] As a preferred option, the material of the fire-resistant oxygen barrier layer is ceramicized halogen-free polyolefin. It can also form a crust to ensure that the flame, heat and oxygen are blocked under the condition of combustion, preventing the flame cable from burning further, protecting the insulation from the heat and flame, ensuring the integrity of the insulation and the line, and meeting the requirement of the cable line being intact within 180 minutes of fire supply time.

[0016] Preferably, the material of the oxygen barrier layer is halogen-free polyolefin.

[0017] Preferably, the outer sheath is made of halogen-free polyolefin. Under fire conditions, halogen-free polyolefin exhibits superior heat release and smoke production characteristics, including flame spread length, peak heat release rate, total heat release, combustion growth rate index, smoke production rate, total smoke production, as well as properties such as the level of combustion droplets, smoke toxicity level, and corrosiveness level, all of which meet combustion requirements.

[0018] Preferably, the armor layer is formed by wrapping steel strips or wires around the glass fiber wrapping layer. The armor layer provides mechanical properties to withstand external mechanical tension and reduce the tensile stress on other functional layers.

[0019] Preferably, the two ends of the early warning optical fiber extend beyond the ends of the outer sheath and are connected to optical fiber connectors at both ends. The optical fiber connectors are connected to external detection equipment for monitoring temperature and vibration anomalies.

[0020] Compared with the prior art, the beneficial effects of this utility model are:

[0021] (1) By using built-in optical fibers, cable hazards can be detected in a timely manner, helping to find risk points in time and reduce the probability of accidents;

[0022] (2) It has good fire resistance properties and is important in reducing heat and the generation of toxic gases and smoke during a fire, thereby increasing the chance of escape;

[0023] (3) Maintain power supply for a considerable period of time during a fire to support the normal use of escape equipment and fire extinguishing equipment;

[0024] (4) Good protective performance combined with optical fiber built into the core of the cable can determine the failure area of ​​the cable, thereby helping to restore the fire situation. Attached Figure Description

[0025] Figure 1 This is a cross-sectional schematic diagram of the present invention;

[0026] In the picture:

[0027] 1. Early warning fiber optic cable; 2. Conductor core; 3. Semiconductor shielding layer; 4. Insulation layer; 5. Semiconductor insulating shielding layer; 6. Semiconductor resistive water buffer layer; 7. Metal shielding layer; 8. Alkali-free fiberglass rope; 9. Fiberglass wrapping layer; 10. Fire-resistant layer; 11. Fire-resistant oxygen barrier layer; 12. Oxygen barrier layer; 13. Armoring layer; 14. Outer sheath. Detailed Implementation

[0028] The present disclosure will be further described below with reference to the accompanying drawings and embodiments.

[0029] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0030] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0031] In this disclosure, terms such as "upper," "lower," "left," "right," "front," "back," "vertical," "horizontal," "side," and "bottom" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are merely relational terms determined for the convenience of describing the structural relationship of the various components or elements in this disclosure, and do not specifically refer to any component or element in this disclosure, nor should they be construed as limiting this disclosure.

[0032] In this disclosure, terms such as "fixed connection," "connected," and "linked" should be interpreted broadly, indicating a fixed connection, an integral connection, or a detachable connection; a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can determine the specific meaning of these terms in this disclosure based on the specific circumstances, and they should not be construed as limitations on this disclosure. Example

[0033] A fire-resistant early warning cable, reference Figure 1 As shown, the cable includes three cable cores, an early warning optical fiber 1, and a functional layer surrounding the cable cores. The three cable cores are bonded together in pairs, forming a central space. The early warning optical fiber 1 is positioned in the central space and bonded to each of the cable cores. Both ends of the early warning optical fiber 1 extend approximately 0.5 to 1 meter beyond the outer sheath 14 and are connected to optical fiber connectors. These connectors are connected to external detection equipment for monitoring temperature and vibration anomalies.

[0034] The gap between the cable core and the functional layer is filled with alkali-free glass fiber rope 8, which ensures the roundness of the three-core cable and has the function of conducting heat away in high-temperature environments. Secondly, it also has excellent flame retardant properties.

[0035] The functional layers include a fire-resistant layer 10, a fire-resistant oxygen barrier layer 1211, an oxygen barrier layer 12, an armor layer 13, and an outer sheath 14. A glass fiber wrapping layer 9 is also provided between adjacent functional layers and on the inner side of the fire-resistant layer 10.

[0036] The cable core consists of, from the inside out, a current-conducting core 2, a semi-conductive conductor shielding layer 3, an insulation layer 4, a semi-conductive insulating shielding layer 5, a semi-conductive resistive water buffer layer 6, and a metallic shielding layer 7. The semi-conductive conductor shielding layer 3 eliminates the concentration of the electric field on the conductor surface and smooths the electric field at the interface between the conductor and the insulation layer 4. The semi-conductive insulating shielding layer 5 homogenizes the electric field on the surface of the insulation layer 4 and prevents discharge at the interface between the insulation and the metallic shielding layer 7. The semi-conductive resistive water buffer layer 6 can prevent damage to the insulation shielding and insulation layer 4 by the metallic shielding layer 7 under high temperature and high pressure conditions and under the condition of thermal expansion and contraction of the insulation. The metallic shielding layer 7 normally carries capacitive current, acts as a channel for short-circuit current during a short circuit, reduces interference with external magnetic fields by shielding the electric field, homogenizes the electric field, and serves as the neutral line in a three-phase four-wire system, bearing unbalanced current. The metallic shielding layer 7 also has a radial water-blocking function.

[0037] The current-conducting core 2 is formed by layering and compacting several circular single wires together, with a compaction coefficient ≥0.9. The geometric shape of the circular single wires is fixed, suitable for medium and high voltage cables. During stranding, each layer is compacted layer by layer (e.g., center layer, second layer, outer layer, etc.). Each layer is compressed once using a die, rather than being compacted as a whole after all layers are stranded. This ensures that the ratio of the actual cross-sectional area of ​​the circular single wire to the calculated outline area of ​​the outer diameter of the current-conducting core 2 after stranding and compaction is greater than or equal to 0.9, meeting the performance requirements of medium and high voltage cables. The insulation layer 4 is made of cross-linked polyethylene. Cross-linked polyethylene has high power frequency resistance, pulse breakdown strength, very low dielectric loss and insulation resistance, excellent resistance to treeing and partial discharge, certain mechanical strength and flexibility, creep resistance, chemical stability and solvent resistance, and long-term stable insulation performance.

[0038] The fire-resistant layer 10 is formed by wrapping a ceramic fire-resistant strip around the glass fiber wrapping layer 9. The ceramic fire-resistant strip can form a crust under combustion conditions, blocking the entry of flames and heat, and protecting the integrity of the insulation. The fire-resistant oxygen barrier layer 1211 is made of ceramicized halogen-free polyolefin, which can also form a crust under combustion conditions to block flames, heat, and oxygen, preventing further combustion of the flame-damaged cable, protecting the insulation from heat and flame scorching, ensuring the integrity of the insulation and the wiring, and meeting the requirement of maintaining the integrity of the cable wiring within 180 minutes of fire exposure.

[0039] The oxygen barrier layer 12 and the outer sheath 14 are made of halogen-free polyolefin. Under fire conditions, the heat release and smoke production characteristics of halogen-free polyolefin are superior, including flame spread length, peak heat release rate, total heat release, combustion growth rate index, smoke production rate, total smoke production, as well as the level of combustion droplets, smoke toxicity level, and corrosiveness level, all of which can meet the combustion requirements.

[0040] The armor layer 13 is formed by wrapping steel strips or wires around the glass fiber wrapping layer 9. The armor layer 13 provides mechanical properties to withstand external mechanical tension and reduce the tensile stress on other functional layers.

[0041] This application places the optical fiber in the central space inside three cable cores, and the optical fiber is simultaneously attached to each cable core, thereby enabling the reception of vibrations from the cable cores. The principle of temperature detection by the optical fiber is as follows: when laser light propagates in the optical fiber, it interacts with the fiber molecules to generate backscattered Raman light. The intensity of the anti-Stokes light is temperature-sensitive, while the Stokes light is temperature-independent; the temperature value can be calculated from the intensity ratio of the two. The principle of abnormal vibration detection by the optical fiber is as follows: external vibrations cause deformation of the fiber core, leading to a phase change in the transmitted light wave. An interferometer converts the phase difference into light intensity fluctuations, which are then converted into electrical signals by a photodetector. By analyzing the time-domain signal, the source of the disturbance can be located.

[0042] The external functional layers include a redundant fire-resistant layer 10, a fire-resistant oxygen-barrier layer 12, and an oxygen-barrier layer 12. During combustion, these layers isolate oxygen, heat, and flames, preventing further combustion and limiting the spread of flames along the cable. By selecting appropriate materials, the insulation capacity of the cable core can be guaranteed, protecting the integrity of the line. Properties such as flame spread length, peak heat release rate, total heat release, combustion growth rate index, smoke production rate, total smoke production, and the level of combustion droplets, smoke toxicity, and corrosivity can all meet combustion requirements.

[0043] The embodiments described above are merely preferred solutions of this utility model and are not intended to limit this utility model in any way. Other variations and modifications are possible without departing from the technical solutions described in the claims.

Claims

1. A fire resistant warning cable, characterized in that The cable comprises three cable cores, a warning optical fiber and a functional layer wrapped outside the cable cores, the three cable cores are adhered to each other, the three cable cores are clamped to form a central space, the warning optical fiber is arranged in the central space and adhered to each other with each cable core, the functional layer comprises a fireproof layer, a fireproof oxygen isolation layer, an oxygen isolation layer, an armor layer and an outer sheath, and a glass fiber wrapping layer is further arranged between adjacent functional layers and the inner side of the fireproof layer.

2. A fire resistant warning cable according to claim 1, characterised in that The cable core comprises, from inside to outside, a flow guide core, a semi-conductive conductor shielding layer, an insulation layer, a semi-conductive insulation shielding layer, a semi-conductive water-blocking buffer layer and a metal shielding layer.

3. A fire resistant warning cable according to claim 1, characterised in that The space between the cable core and the functional layer is filled with alkali-free glass fiber ropes.

4. A fire resistant warning cable according to claim 2, characterised in that The flow guide core is formed by layering and tightly pressing a plurality of round single wires, and the tight pressing coefficient of the flow guide core is greater than or equal to 0.

9.

5. A fire resistant warning cable according to claim 2, characterised in that The material of the insulation layer is cross-linked polyethylene.

6. A fire resistant warning cable according to claim 1, characterised in that The fireproof layer is formed by wrapping a ceramic fireproof belt on the glass fiber wrapping layer.

7. A fire resistant warning cable according to claim 1, characterised in that The material of the fireproof oxygen isolation layer is ceramic halogen-free polyolefin.

8. A fire resistant warning cable according to claim 1, characterised in that The material of the outer sheath is halogen-free polyolefin.

9. A fire resistant warning cable according to claim 1, characterised in that The armor layer is formed by wrapping a steel belt or a steel wire on the glass fiber wrapping layer.

10. A fire resistant warning cable according to any one of claims 1 to 9, characterised in that, Both ends of the warning optical fiber extend out of both ends of the outer sheath and are connected with optical fiber connectors at both ends.

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