Medium-voltage fire-resistant cable

Abstract

The utility model relates to a medium-voltage fire-resistant cable. The medium-voltage fire-resistant cable comprises a cable core and a protection unit. The cable core comprises a wire core, a first wrapping layer and a filling layer; the protection unit is arranged on the periphery of the filling layer and sequentially comprises an outer sheath, a second wrapping layer, an armor layer, a first oxygen isolation layer, a mineral fireproof layer and a second oxygen isolation layer from outside to inside. The mineral fireproof layer is filled between the first oxygen barrier layer and the second oxygen barrier layer, and the mineral fireproof layer can be decomposed under a heating condition to reduce the temperature of the cable core. The mineral fire-resistant layer does not need high-temperature vulcanization, damage to the cable core is avoided, the service life and long-term reliability of the medium-voltage fire-resistant cable are improved, the first oxygen barrier layer and the second oxygen barrier layer have fire resistance, the mineral fire-resistant layer can be decomposed under the heating condition, the cooling effect is achieved, and the service life of the medium-voltage fire-resistant cable is prolonged. The fire-resistant performance of the medium-voltage fire-resistant cable is improved through the synergistic effect of fire insulation, heat insulation and cooling.

Description

Technical Field

[0001] The present application relates to the technical field of power cables, and in particular to medium voltage fire-resistant cables. Background Art

[0002] Medium voltage cable is a type of power transmission cable, usually used to transmit medium voltage (1kV-35kV) electricity. Medium voltage cable has the advantages of large transmission capacity, low line loss and easy installation. It is widely used in urban power grids, industrial electricity, mining power transmission and other fields.

[0003] In the related art, medium voltage fire-resistant cables mostly use ceramic silicone rubber as the fire-resistant layer. Ceramic silicone rubber will sinter into porcelain at a certain flame temperature to isolate the flame temperature, and the fire-resistant method is single. In addition, ceramic silicone rubber needs to be extruded by a rubber extruder and then vulcanized at high temperature, which has certain requirements for cable manufacturing processes and equipment. In addition, the insulating core of ceramic silicone rubber is easily expanded by heat during the vulcanization process, resulting in an overly tight bond between the insulating shielding layer and the metal shielding layer. After the insulating core cools, obvious metal copper tape marks will be produced on the surface of the insulating shielding layer. In severe cases, the insulating core will be deformed, which to a certain extent affects the long-term operating stability and life of the cable. Summary of the invention

[0004] Based on this, it is necessary to provide a medium voltage fire-resistant cable to address the above technical problems so as to improve the fire resistance and service life of the cable.

[0005] The present application provides a medium voltage fire resistant cable, the medium voltage fire resistant cable comprising:

[0006] A cable core, the cable core comprising a wire core, a first wrapping layer and a filling layer, the outer periphery of the wire core is wrapped with the first wrapping layer, and the filling layer is arranged on the outer periphery of the first wrapping layer; and

[0007] The protection unit is arranged on the periphery of the filling layer. The protection unit includes an outer sheath, a second wrapping layer, an armor layer, a first oxygen insulation layer, a mineral fire-resistant layer and a second oxygen insulation layer from the outside to the inside. The mineral fire-resistant layer is filled between the first oxygen insulation layer and the second oxygen insulation layer and the mineral fire-resistant layer can be decomposed under heating conditions to reduce the temperature of the protection unit.

[0008] In one embodiment, the outer sheath is made of halogen-free, low-smoke, and highly flame-retardant material.

[0009] In one embodiment, the armor layer is an anti-corrosion electro-galvanized stainless steel strip.

[0010] In one embodiment, the first wrapping layer and the second wrapping layer are both formed by wrapping glass fiber cloth.

[0011] In one embodiment, the mineral refractory layer is formed by extruding a mixture of magnesium hydroxide and silicate.

[0012] In one embodiment, the first oxygen-isolating layer and the second oxygen-isolating layer are both made of halogen-free, low-smoke, and highly flame-retardant materials.

[0013] In one embodiment, the oxygen index of the first oxygen barrier layer and the second oxygen barrier layer is ≥40.

[0014] In one embodiment, the filling layer is formed by inorganic paper filling.

[0015] In one embodiment, the wire core includes a conductor and a shielding layer, wherein the shielding layer is wrapped around the outer surface of the conductor.

[0016] In one embodiment, the shielding layer includes a metal shielding layer, an insulating shielding layer, an insulating layer and a conductor shielding layer. The first winding layer is wrapped around the outer periphery of the metal shielding layer, and the metal shielding layer, the insulating shielding layer, the insulating layer and the conductor shielding layer are wrapped around the outer surface of the conductor from the outside to the inside in sequence.

[0017] The above-mentioned medium-voltage fire-resistant cable is achieved by filling a decomposable mineral fire-resistant layer between the first oxygen insulation layer and the second oxygen insulation layer. The mineral fire-resistant layer does not need to be vulcanized at high temperature to avoid damage to the wire core, thereby improving the service life and long-term reliability of the medium-voltage fire-resistant cable. The mineral fire-resistant layer can decompose under heating conditions, so that when encountering high temperatures, the mineral fire-resistant layer can undergo a decomposition reaction. This process will absorb a certain amount of heat and have a cooling effect. The first oxygen insulation layer and the second oxygen insulation layer are flame retardant. The first oxygen insulation layer, the mineral fire-resistant layer and the second oxygen insulation layer can isolate flame combustion and isolate heat transfer to the wire core, thereby improving the fire resistance of the medium-voltage fire-resistant cable through the synergistic effects of fire insulation, heat insulation and cooling. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 is a schematic diagram of a medium voltage fire-resistant cable in an embodiment of the present application. DETAILED DESCRIPTION

[0019] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0020] In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0021] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0022] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0023] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0024] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0025] Referring to Fig. 1 , Fig. 1 shows a schematic diagram of a medium voltage fire resistant cable in an embodiment of the present application. In some embodiments, the medium voltage fire resistant cable 100 includes a cable core 10 and a protection unit 20 .

[0026] The cable core 10 is the core part of the cable 100, and is used to transmit current, and the current is transmitted from the power source to the target device or load through the cable core 10. Specifically, the cable core 10 includes a wire core 11, a first wrapping layer 12, and a filling layer 13, wherein the outer periphery of the wire core 11 is wrapped with the first wrapping layer 12, and the filling layer 13 is arranged on the outer periphery of the first wrapping layer 12.

[0027] The core 11 is a key part of the cable core 10 for transmitting current, and is usually made of high-quality conductive materials such as copper or aluminum to ensure good conductivity and conductive performance. The first sheath 12 is directly wrapped around the outer periphery of the core 11, so that the twisted core 11 can be tied and wrapped to form, avoiding looseness of the core 11, and at the same time helping the core 11 to keep round, facilitating the subsequent layout of multiple groups of cores 11. The filling layer 13 is filled between the first sheath 12 and the protective unit 20, playing a supporting and filling role, making the structure of the cable 100 more solid and stable.

[0028] Specifically, the wire cores 11 can be arranged into multiple groups according to actual needs. For example, the cable core 10 in the present application includes three groups of wire cores 11 , each wire core 11 is wrapped with a first wrapping layer 12 , and a filling layer 13 is filled between the multiple groups of wire cores 11 and between the wire cores 11 and the protective unit 20 .

[0029] Furthermore, the filling layer 13 is formed by filling with inorganic paper. Inorganic paper materials generally have excellent fire resistance. Under high temperature conditions, inorganic paper materials are not easy to burn and can effectively resist flames and high temperatures, providing additional fire protection for the medium voltage fire resistant cable 100. Thus, the filling layer 13 helps to slow down the speed at which the flame spreads from the protection unit 20 to the cable core 10, thereby improving the safety of the medium voltage fire resistant cable 100. In other embodiments, the filling layer 13 can also be formed by filling with polypropylene material.

[0030] The protection unit 20 is used to provide overall protection for the cable core 10. For example, the protection unit 20 can provide mechanical protection to prevent the cable 100 from external physical damage, such as extrusion, stretching, shearing, etc., to ensure that the structure of the cable core 10 inside the cable 100 is not damaged and the current transmission is not interfered with; for example, the protection unit 20 has good fire resistance and can slow down the spread of fire when a fire occurs, thereby protecting the internal structure of the cable 100 and the safety of the environment surrounding the cable 100.

[0031] The protection unit 20 is arranged on the periphery of the filling layer 13, and includes an outer sheath 21, a second wrapping layer 22, an armor layer 23, a first oxygen insulation layer 24, a mineral refractory layer 25 and a second oxygen insulation layer 26 from the outside to the inside. The mineral refractory layer 25 is filled between the first oxygen insulation layer 24 and the second oxygen insulation layer 26, and the mineral refractory layer 25 can be decomposed under heating conditions to reduce the temperature of the protection unit 20.

[0032] By filling the decomposable mineral refractory layer 25 between the first oxygen insulation layer 24 and the second oxygen insulation layer 26, the mineral refractory layer 25 does not need to be vulcanized at high temperature, thereby avoiding damage to the wire core 11, and improving the service life and long-term reliability of the medium voltage fire resistant cable 100. The mineral refractory layer 25 can be decomposed under heating conditions, so that when encountering high temperatures, the mineral refractory layer 25 can undergo a decomposition reaction. This process will absorb a certain amount of heat and play a role in cooling the temperature. The first oxygen insulation layer 24 and the second oxygen insulation layer 26 are flame retardant. The first oxygen insulation layer 24, the mineral refractory layer 25 and the second oxygen insulation layer 26 can isolate flame combustion and isolate heat transfer to the wire core 11, thereby improving the fire resistance of the medium voltage fire resistant cable 100 through the synergistic effects of fire insulation, heat insulation and cooling.

[0033] In some embodiments, the outer sheath 21 is made of a halogen-free, low-smoke, and highly flame-retardant material. The outer sheath 21 is wrapped around the cable core 10 to protect the cable core 10. The halogen-free, low-smoke, and highly flame-retardant material does not contain halogen elements such as chlorine and bromine, so it will not release harmful halide gases when a fire occurs, and the amount of smoke generated when a fire burns is relatively low. It has good flame retardant properties, can effectively inhibit the spread of flames, and prevent the fire from spreading to the inside of the cable 100, thereby improving the safety of the cable 100 in the event of a fire, reducing the harm to the environment and human body, and improving the fire resistance of the medium voltage fire-resistant cable 100.

[0034] Specifically, the outer sheath 21 can be made of a flexible thermosetting halogen-free, low-smoke, highly flame-retardant polyolefin material, which is made by adding various compounding agents to polyolefin as a matrix. During the actual production process, the outer sheath 21 can be evenly extruded around the outer periphery of the second winding layer 22, ensuring good mechanical strength while having good fire resistance.

[0035] Furthermore, the second wrapping layer 22 is wrapped around the outer periphery of the armor layer 23, thereby preventing the armor layer 23 from scratching the outer sheath 21, ensuring the integrity of the outer sheath 21, improving the production quality of the cable 100, and helping to reduce dents on the outer surface of the cable 100, so that the cable 100 has good roundness.

[0036] Preferably, the first wrapping layer 12 and the second wrapping layer 22 are both formed by wrapping glass fiber cloth. Glass fiber cloth has good insulation properties, can effectively prevent current leakage or short circuit, improve the insulation level of the cable 100, ensure the safe operation of the internal circuit of the cable 100, and the glass fiber cloth wrapping layer can provide additional mechanical protection to prevent the cable 100 from external physical damage and extend the service life of the cable 100. Compared with other materials, glass fiber cloth is usually lighter, which can realize the lightweight design of the cable 100, reduce the load on the supporting structure, and reduce the installation and maintenance costs.

[0037] Generally, glass fiber cloth is a non-combustible material with good fire resistance, which can slow down the spread of fire in the event of a fire, protect the safety of the internal structure of the cable 100 and the surrounding environment, the first wrapping layer 12 can slow down the spread of fire toward the inside of the core 11, and ensure the safety of the inside of the core 11, and the second wrapping layer 22 can slow down the spread of fire toward the inside of the protection unit 20, and ensure the safety of the cable core 10, that is, the first wrapping layer 12 and the second wrapping layer 22 both have a certain flame retardancy, which helps to improve the fire resistance of the cable 100. Preferably, the first wrapping layer 12 and the second wrapping layer 22 are both halogen-free, low-smoke, and highly flame-retardant glass fiber tapes.

[0038] In some embodiments, the armor layer 23 is coated on the periphery of the first oxygen-insulating layer 24. Generally, the armor layer 23 is formed by twisting two layers of round steel wires in different directions, and based on the torsion balance design, has the ability to withstand the tension of the medium-voltage fire-resistant cable 100 during operation, prevents the cable 100 from being stretched or broken during installation and use, and provides strength protection for the medium-voltage fire-resistant cable 100. In addition, the armor layer 23 can effectively ensure that the internal structure of the cable 100 is not physically damaged by the outside, so as to improve the service life of the medium-voltage fire-resistant cable 100 and maintain the structural integrity and electrical performance of the medium-voltage fire-resistant cable 100.

[0039] Furthermore, the armor layer 23 is an anti-corrosion electro-galvanized stainless steel strip. Using the anti-corrosion electro-galvanized stainless steel strip as the armor layer 23 material can improve the corrosion resistance of the medium voltage fire-resistant cable 100, extend the service life of the medium voltage fire-resistant cable 100, and is particularly suitable for use under harsh environmental conditions, so that the medium voltage fire-resistant cable 100 can maintain an efficient and reliable working state in a wider range of application scenarios. The armor layer 23 and the second wrapping layer 22 can jointly enhance the strength of the protection unit 20.

[0040] In some embodiments, the first oxygen-insulating layer 24 is disposed on the inner side of the armor layer 23 and the outer side of the mineral fire-resistant layer 25, and the second oxygen-insulating layer 26 is disposed on the inner side of the mineral fire-resistant layer 25 and the periphery of the filling layer 13. Both the first oxygen-insulating layer 24 and the second oxygen-insulating layer 26 can isolate oxygen in the external air and reduce the contact between oxygen and the internal materials of the cable 100. When a fire occurs, oxygen is one of the necessary elements to maintain the burning of the flame. By adding the first oxygen-insulating layer 24, the spread of the flame can be effectively suppressed, and the flame retardant performance of the medium-voltage fire-resistant cable 100 in the event of a fire can be improved.

[0041] The second oxygen-isolating layer 26 is located at the innermost side of the protective unit 20, providing additional oxygen isolation, which helps to slow down the spread of flames toward the cable core 10. The first oxygen-isolating layer 24 and the second oxygen-isolating layer 26 together form a double oxygen-isolating protective layer, which increases the fire resistance of the cable 100 when a fire occurs and reduces the risk of fire.

[0042] Furthermore, the first oxygen-insulating layer 24 and the second oxygen-insulating layer 26 are both made of halogen-free, low-smoke, and highly flame-retardant materials. By using halogen-free, low-smoke, and highly flame-retardant materials to prepare the first oxygen-insulating layer 24 and the second oxygen-insulating layer 26, the cable 100 can better maintain safety performance under fire conditions, reduce the threat of fire to personnel and equipment, and meet the high requirements of modern buildings and transportation systems for fire resistance. Specifically, the first oxygen-insulating layer 24 and the second oxygen-insulating layer 26 can be made of halogen-free, low-smoke, and highly flame-retardant polyolefin materials.

[0043] Furthermore, the oxygen index of the first oxygen barrier layer 24 and the second oxygen barrier layer 26 is ≥ 40. The oxygen index is an important indicator for measuring the flame retardant performance of a material, which indicates the ratio of oxygen content to other gases in the air under specific conditions, usually expressed as a percentage.

[0044] When the oxygen index is not less than 40, it means that the burning speed of the material in the flame will be significantly reduced, because this means that the material requires a higher oxygen concentration in the air to maintain combustion. Therefore, materials with an oxygen index of not less than 40 usually show better flame retardant properties, can effectively inhibit the spread of flames, and improve safety during fires.

[0045] Using materials with an oxygen index of not less than 40 to prepare the first oxygen barrier layer 24 and the second oxygen barrier layer 26 can further enhance the fireproof performance of the medium voltage fire resistant cable 100 under fire conditions, reduce the threat of fire to personnel and equipment, and ensure the safety of the medium voltage fire resistant cable 100 in emergency situations.

[0046] In some embodiments, the mineral fire-resistant layer 25 is located between the first oxygen-insulating layer 24 and the second oxygen-insulating layer 26, and is mainly used to enhance the fire-resistant performance of the medium-voltage fire-resistant cable 100. When a fire occurs, the mineral fire-resistant layer 25 can effectively resist high temperature and flames, prevent the fire from spreading to the cable core 10 of the cable 100, reduce the damage of the fire to the cable core 10, and slow down the spread of the flame, thereby increasing the time window for fire fighting, improving fire safety, and ensuring that the medium-voltage fire-resistant cable 100 can operate safely and reliably under fire conditions.

[0047] Generally, the mineral refractory layer 25 is made of a material with good high temperature resistance, so that the mineral refractory layer 25 maintains good structural stability under high temperature conditions, is not easy to burn, and has good heat insulation function.

[0048] Specifically in this embodiment, the mineral fire-resistant layer 25 is formed by mixing and extruding magnesium hydroxide and silicate. Magnesium hydroxide will decompose under high temperature conditions and generate magnesium oxide and water. The decomposition of magnesium hydroxide requires the absorption of heat, and the water at high temperature will be converted into water vapor, absorbing part of the high-temperature heat of the protection unit 20, so that the temperature of the protection unit 20 drops, providing high-temperature protection for the cable core 10, and increasing the fire resistance and use safety of the medium-voltage fire-resistant cable 100.

[0049] Furthermore, both magnesium oxide and silicate have good structural stability, and both magnesium oxide and silicate have good insulation, do not play a conductive role, and play a protective role on the inside of the cable 100, so that the cable 100 can be used normally. As an illustrative example only, not a limitation on the scope of protection, silicate includes but is not limited to sodium silicate, calcium silicate and magnesium silicate. In other embodiments, the mineral refractory layer 25 may also include ceramic polyolefin.

[0050] Specifically in this embodiment, the present application replaces the traditional ceramic silicone rubber with a mineral refractory layer 25, which reduces costs, and the process of extruding the mineral refractory layer 25 by a grouting machine can reduce the process difficulty and equipment cost of preparing the medium voltage fire-resistant cable 100. In addition, this process does not require high-temperature vulcanization, which effectively avoids the problem of obvious metal marks on the surface of the insulating shielding layer 1122 after the wire core 11 is cooled, thereby improving the long-term operating stability and service life of the medium voltage fire-resistant cable 100.

[0051] In some embodiments, the core 11 includes a conductor 111 and a shielding layer 112. The conductor 111 is the core part of the cable 100 for transmitting current, and is usually made of a metal material with good conductivity (such as copper or aluminum). The main function of the conductor 111 is to conduct current and provide a path for the current. The shielding layer 112 is wrapped around the outer surface of the conductor 111 to protect the conductor 111 from external electromagnetic interference and prevent the conductor 111 from radiating electromagnetic signals outward, thereby ensuring the quality and stability of the signal.

[0052] Furthermore, the shielding layer 112 includes a metal shielding layer 1121, an insulating shielding layer 1122, an insulating layer 1123 and a conductor shielding layer 1124. The first wrapping layer 12 is wrapped around the outer periphery of the metal shielding layer 1121. The metal shielding layer 1121, the insulating shielding layer 1122, the insulating layer 1123 and the conductor shielding layer 1124 are sequentially wrapped around the outer surface of the conductor 111 from the outside to the inside. The structure of the shielding layer 112 can effectively improve the anti-interference ability of the cable 100 and ensure the stability and reliability of signal transmission.

[0053] The metal shielding layer 1121 is located at the outermost part of the shielding layer 112, and is usually made of metal foil or braided mesh. Its main function is to provide electromagnetic shielding to prevent external electromagnetic interference from entering the cable 100. The insulating shielding layer 1122 is located inside the metal shielding layer 1121. As a dielectric layer, it helps to further isolate external interference and provide additional insulation protection. The insulating layer 1123 is located inside the insulating shielding layer 1122. Its main function is to provide insulation support and insulation performance between the conductor 111 and the shielding layer 112 to prevent electrical contact or short circuit between the conductor 111 and the shielding layer 112. The conductor shielding layer 1124 is located inside the insulating layer 1123 to protect the surface of the conductor 111, prevent the conductor 111 from radiating electromagnetic signals outward, and provide protection for internal signals.

[0054] The medium voltage fire-resistant cable 100 in the present application can effectively prevent the flame from spreading further and play a role of fire isolation through the first oxygen isolation layer 24, the mineral fire-resistant layer 25 and the second oxygen isolation layer 26. The mineral fire-resistant layer 25 has a certain thickness and can play a certain protective role in the structure of the protection unit 20 and play a role of heat insulation. The mineral decomposition in the mineral fire-resistant layer 25 can absorb a certain amount of high-temperature heat and play a role of cooling. The comprehensiveness of the fire protection of the medium voltage fire-resistant cable 100 is improved by fire isolation, heat insulation and cooling, and the service life and fire resistance performance of the medium voltage fire-resistant cable 100 are increased.

[0055] Furthermore, the outer sheath 21 in the present application is made of halogen-free low-smoke material, which has the characteristic of self-extinguishing when burning. While meeting high flame retardancy, it does not produce halides and toxic and harmful corrosive gases, and is fully friendly to the human body and the environment. The first sheath 12 and the second sheath 22 are both made of glass fiber cloth, which has certain flame retardancy. The filling layer 13 is made of inorganic paper material to further increase the fire resistance of the cable 100. In the event of a fire, the flame and high temperature will be blocked by the outer sheath 21, the second sheath 22, the first oxygen-insulating layer 24, the mineral fire-resistant layer 25, the second oxygen-insulating layer 26, the filling layer 13 and the first sheath 12 in turn, effectively slowing down the spread of the flame, and then in the event of a fire, ensuring that the medium-voltage fire-resistant cable 100 can be powered normally, which is conducive to fire rescue and personnel escape and evacuation, reducing casualties and loss of life and property.

[0056] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0057] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A medium voltage fire-resistant cable, characterized in that: The medium voltage fire-resistant cable comprises: A cable core, the cable core comprising a wire core, a first wrapping layer and a filling layer, the outer periphery of the wire core is wrapped with the first wrapping layer, and the filling layer is arranged on the outer periphery of the first wrapping layer; and A protection unit is arranged on the periphery of the filling layer, and the protection unit includes an outer sheath, a second wrapping layer, an armor layer, a first oxygen-insulating layer, a mineral fire-resistant layer and a second oxygen-insulating layer from the outside to the inside. The mineral fire-resistant layer is filled between the first oxygen-insulating layer and the second oxygen-insulating layer, and the mineral fire-resistant layer can be decomposed under heating conditions to reduce the temperature of the protection unit.

2. The medium voltage fire-resistant cable according to claim 1, characterized in that: The outer sheath is made of halogen-free, low-smoke and highly flame-retardant material.

3. The medium voltage fire-resistant cable according to claim 1, characterized in that: The armor layer is an anti-corrosion electro-galvanized stainless steel strip.

4. The medium voltage fire-resistant cable according to claim 1, characterized in that: The first wrapping layer and the second wrapping layer are both formed by wrapping glass fiber cloth.

5. The medium voltage fire-resistant cable according to claim 1, characterized in that: The mineral refractory layer is formed by mixing and extruding magnesium hydroxide and silicate.

6. The medium voltage fire-resistant cable according to claim 1, characterized in that: The first oxygen-isolating layer and the second oxygen-isolating layer are both made of halogen-free, low-smoke and highly flame-retardant materials.

7. The medium voltage fire-resistant cable according to claim 1, characterized in that: The oxygen index of the first oxygen barrier layer and the second oxygen barrier layer is ≥40.

8. The medium voltage fire-resistant cable according to claim 1, characterized in that: The filling layer is formed by filling with inorganic paper.

9. The medium voltage fire-resistant cable according to any one of claims 1 to 8, characterized in that: The wire core comprises a conductor and a shielding layer, and the shielding layer is wrapped around the outer surface of the conductor.

10. The medium voltage fire-resistant cable according to claim 9, characterized in that: The shielding layer includes a metal shielding layer, an insulating shielding layer, an insulating layer and a conductor shielding layer. The first wrapping layer is wrapped around the outer periphery of the metal shielding layer. The metal shielding layer, the insulating shielding layer, the insulating layer and the conductor shielding layer are wrapped around the outer surface of the conductor in sequence from the outside to the inside.

Images