Fire resistant flame retardant medium voltage fire resistant cable
By employing a combination design of tightly stranded copper conductors, multi-layer co-extruded cross-linked insulation, ceramicized silicone rubber, and metal sheath in medium-voltage cables, the problem of loose interlayer protection in medium-voltage cables at high temperatures is solved, achieving excellent fire resistance, heat insulation, and mechanical protection performance, ensuring stable operation of the cable under fire conditions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HENAN HUAXING WIRES & CABLES
- Filing Date
- 2026-04-02
- Publication Date
- 2026-06-12
AI Technical Summary
Existing medium-voltage fire-resistant cables are prone to loosening between protective layers at high temperatures, causing heat to be transferred along weak points, resulting in poor fire resistance and structural stability, and a lack of continuous and effective structural connections.
It adopts a copper tightly stranded conductor and a three-layer co-extruded cross-linked insulation structure. The outer layer is set with a ceramicized silicone rubber extrusion isolation layer, an inorganic fire-resistant oxygen barrier layer and a corrugated metal sheath fireproof layer to form a continuous and dense covering structure. A low-smoke halogen-free flame-retardant outer sheath and a halogen-free flame-retardant nylon outer sheath are set on the outside to form a multi-layer progressive protection.
It effectively blocks heat transfer in high-temperature environments, maintains structural stability and electrical performance, improves the fire resistance and thermal insulation performance and mechanical protection of cables, ensures that cables are not easily combustible and do not produce toxic gases under fire conditions, and extends service life.
Smart Images
Figure CN122201907A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of medium-voltage cable technology, and specifically relates to a fire-resistant and flame-retardant medium-voltage fireproof cable. Background Technology
[0002] With the continuous increase in power system capacity and the acceleration of urbanization, cables, as an important carrier of electrical energy transmission, have been widely used in building power distribution, rail transit, industrial manufacturing and large public facilities. Especially in high-rise buildings, underground spaces and densely populated places, cables not only undertake conventional power supply tasks, but also undertake the power supply functions of fire protection power supply, emergency lighting and safety control systems. Their operational reliability is directly related to the safety and emergency protection capabilities of the power system. Compared with low-voltage cables, medium-voltage cables have obvious advantages in power transmission capacity and power supply stability, and can effectively reduce line voltage loss, so they have gradually been widely used.
[0003] Against this backdrop, in order to improve the operational reliability of cables under extreme conditions such as fires, existing medium-voltage fire-resistant cables typically achieve their protective function by sequentially setting multiple layers of flame-retardant and fire-resistant structures outside the insulated core. However, these structures often adopt a layered approach, with different functional layers achieving their protective effect mainly through simple stacking. There is a lack of effective structural connection between different protective layers, resulting in insufficient continuity of the overall protection path. Under high temperatures or flames, local gaps or loose fits can easily occur between each protective layer, causing heat to be transferred along the weak points of the structure. This leads to a decrease in protective performance and structural stability, making it difficult to simultaneously ensure both fire resistance and operational reliability under complex operating conditions.
[0004] Therefore, there is an urgent need for a fire-resistant and flame-retardant medium-voltage fireproof cable to solve the problems of lack of continuous and effective structural connection, loose interlayer fit under high temperature, attenuation of protective performance, heat transfer along weak parts of the structure, and poor fire resistance stability in the existing technology. Summary of the Invention
[0005] In view of this, the present invention proposes a fire-resistant and flame-retardant medium-voltage fireproof cable, which solves the existing technical problems of lack of continuous and effective structural connection, easy loose interlayer fit under high temperature, attenuation of protective performance, heat transfer along weak parts of the structure, and poor fire resistance stability in the field of medium-voltage cable technology.
[0006] To achieve the above-mentioned technical objectives, the specific technical solution adopted by the present invention is as follows: A fire-resistant and flame-retardant medium-voltage fireproof cable includes a copper compacted stranded conductor. The copper compacted stranded conductor is concentrically surrounded by an inner semiconductive shielding layer, an XLPE insulation layer, and an outer semiconductive shielding layer, forming a three-layer co-extruded cross-linked insulation structure. The outer semiconductive shielding layer is covered by a wrapped shielding layer composed of multiple copper wires. A ceramicized silicone rubber extruded insulating layer is concentrically covered outside the wrapped shielding layer. The ceramicized silicone rubber extruded insulating layer and the wrapped shielding layer form a continuous and dense covering structure. An inorganic fire-resistant oxygen barrier layer is concentrically covered outside the continuous and dense covering structure. A flame-retardant glass fiber tape, forming a circumferential constraint, is concentrically wound around the outside of the inorganic fire-resistant oxygen barrier layer. The outer layer of the fiber-reinforced material is concentrically covered with a corrugated metal sheath fireproof layer that forms a sealed fit with the inorganic fire-resistant oxygen barrier layer. This continuous and dense covering structure serves as the inner matrix, thus forming a progressive fire protection structure from the inside out with the inorganic fire-resistant oxygen barrier layer and the corrugated metal sheath fireproof layer. This provides multi-layered continuous barrier in the radial direction. The corrugated metal sheath fireproof layer is concentrically covered with a low-smoke halogen-free flame-retardant outer sheath, which in turn is concentrically covered with a halogen-free flame-retardant nylon outer sheath. This creates a tightly bonded, layered covering structure between the low-smoke halogen-free flame-retardant outer sheath and the halogen-free flame-retardant nylon outer sheath, thus forming an outer thermal barrier for the corrugated metal sheath fireproof layer when exposed to a fire source.
[0007] Furthermore, the ceramicized silicone rubber extruded isolation layer fills the gaps formed between multiple copper wires inside the wrapped shielding layer. Through the formed continuous and dense covering structure, the ceramicized silicone rubber extruded isolation layer becomes the inner continuous support interface of the inorganic fire-resistant oxygen barrier layer and the wrinkled metal sheath fireproof layer.
[0008] Furthermore, the wrapping shielding layer is composed of multiple copper wires wrapped around the circumference of the outer semiconductive shielding layer, with gaps continuously distributed circumferentially between adjacent copper wires, and the average width of the corresponding gaps is no greater than 4mm.
[0009] Furthermore, the ceramicized silicone rubber extruded isolation layer forms a continuous filling state in the gap between adjacent copper wires, and the ceramicized silicone rubber and the wrapped shielding layer form a gapless bonding structure. The thickness of the ceramicized silicone rubber extruded isolation layer is not less than 1.5mm to ensure the integrity of its filling of the gaps formed between multiple copper wires inside the wrapped shielding layer.
[0010] Furthermore, the inorganic refractory oxygen barrier layer adopts a coating layer structure that extends continuously along the axial direction of the copper compacted stranded conductor, and the inner surface of the inorganic refractory oxygen barrier layer forms a continuous surface contact interface with the outer surface of the ceramicized silicone rubber extruded isolation layer.
[0011] Furthermore, flame-retardant glass fiber tape is wrapped around the outer periphery of the inorganic fire-resistant oxygen barrier layer in an overlapping manner, forming a circumferential tightening constraint on the inorganic fire-resistant oxygen barrier layer.
[0012] Furthermore, the corrugated metal sheath fireproof layer is formed by longitudinally wrapping, welding and corrugating copper strips with a thickness of 0.5mm to 1.0mm, thereby forming a continuous corrugated sleeve structure.
[0013] Furthermore, the inner diameter of the trough of the corrugated metal sheath fireproof layer is 1mm to 1.5mm larger than the outer diameter of the inorganic fire-resistant oxygen barrier layer. This can provide radial expansion space for the internal structure under heating conditions, thereby preventing the inorganic fire-resistant oxygen barrier layer and its inner structure from being squeezed and deformed.
[0014] Furthermore, the thickness of the low-smoke halogen-free flame-retardant outer sheath is not less than 1.8 mm, and the thickness of the halogen-free flame-retardant nylon outer sheath is 0.1 mm to 0.2 mm. The low-smoke halogen-free flame-retardant outer sheath and the halogen-free flame-retardant nylon outer sheath form a continuous double-layer covering structure along the radial direction.
[0015] Furthermore, the inner semiconductive shielding layer, the XLPE insulating layer, and the outer semiconductive shielding layer are formed by three-layer co-extrusion in one step, and are chemically cross-linked to form an integrated structure, thereby forming a continuous insulating layer system structure without interface delamination. The thickness of the inner semiconductive shielding layer is 0.8mm to 1.2mm, the thickness of the XLPE insulating layer is 10.5mm, and the thickness of the outer semiconductive shielding layer is 1.0mm to 1.4mm.
[0016] In this invention, the key to this application lies in sealing the internal gaps of the copper wire wrapping shielding layer by extruding a ceramicized silicone rubber isolation layer, so that the wrapping structure forms a continuous and dense whole, and on this basis, it forms a continuous protective path that is sequentially connected with the outer inorganic fire-resistant oxygen barrier layer and the corrugated metal sheath fireproof layer, thereby forming an inseparable synergistic protective relationship between multiple protective layers.
[0017] By adopting the above technical solution, the present invention can also bring the following beneficial effects: 1. This invention discloses a fire-resistant and flame-retardant medium-voltage fireproof cable. By setting a low-smoke halogen-free flame-retardant outer sheath and a halogen-free flame-retardant nylon outer sheath to form a double-layer covering structure, it provides effective mechanical protection and reduces the impact of external compression, abrasion and oil erosion on the cable structure. Through the low-smoke halogen-free flame-retardant outer sheath and the halogen-free flame-retardant nylon outer sheath, it is not easy to burn under fire conditions and does not produce toxic and harmful gases and corrosive smoke, reducing the harm of fire to personnel and equipment. At the same time, the halogen-free flame-retardant nylon outer sheath has good wear resistance and strength, improves service life, and has the advantages of excellent flame-retardant protection performance, environmental adaptability and mechanical protection capabilities.
[0018] 2. This invention discloses a fire-resistant and flame-retardant medium-voltage fireproof cable. It forms a multi-layered fireproof structure from the inside out by sequentially setting a ceramicized silicone rubber extruded isolation layer, an inorganic fire-resistant oxygen barrier layer, and a corrugated metal sheath fireproof layer outside the wrapped shielding layer. The ceramicized silicone rubber extruded isolation layer forms a ceramicized hard shell under high-temperature conditions. The inorganic fire-resistant oxygen barrier layer remains stable under high-temperature conditions and blocks heat transfer. The corrugated metal sheath fireproof layer has a high melting point and good mechanical strength, forming a stable support. This delays heat transfer into the multi-layered fireproof structure under fire conditions, ensuring the structural integrity and electrical continuity of the XLPE insulation layer. It possesses excellent fire-resistant and heat-insulating performance, structural stability, and fire protection capabilities.
[0019] 3. This invention discloses a fire-resistant and flame-retardant medium-voltage fireproof cable, which adopts a copper compacted stranded conductor and a three-layer co-extruded cross-linked insulation structure formed by an inner semi-conductive shielding layer, an XLPE insulation layer, and an outer semi-conductive shielding layer. This improves conductivity and electrical insulation performance. The copper compacted stranded conductor has good conductivity, high temperature resistance, and mechanical strength. The three-layer co-extruded cross-linked insulation structure forms a continuous and dense encapsulation interface between the copper compacted stranded conductor and the XLPE insulation layer, reducing the risk of partial discharge and impurity introduction. At the same time, combined with the wrapping shielding layer, it suppresses electromagnetic interference and improves fault current conduction capability. It maintains stable operation under complex environments and extreme working conditions, and has the advantages of excellent electrical performance, anti-interference capability, and operational reliability. Attached Figure Description
[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0021] Figure 1 This is a schematic diagram of the structure of a fire-resistant and flame-retardant medium-voltage fireproof cable mentioned in this invention; Figure 2 This example illustrates a method for preparing a fire-resistant and flame-retardant medium-voltage fireproof cable. 1. Copper tightly stranded conductor; 2. Inner semiconductive shielding layer; 3. XLPE insulation layer; 4. Outer semiconductive shielding layer; 5. Wrapped shielding layer; 6. Ceramicized silicone rubber extruded isolation layer; 7. Inorganic fire-resistant oxygen barrier layer; 8. Corrugated metal sheath fireproof layer; 9. Low smoke halogen-free flame-retardant outer sheath; 10. Halogen-free flame-retardant nylon outer sheath. Detailed Implementation
[0022] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
[0023] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0024] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this invention, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using other structures and / or functionalities besides one or more of the aspects set forth herein.
[0025] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.
[0026] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details. Example
[0027] like Figure 1 and Figure 2As shown, a fire-resistant and flame-retardant medium-voltage fireproof cable includes a copper compacted stranded conductor 1. The copper compacted stranded conductor 1 is concentrically surrounded by an inner semiconductive shielding layer 2, an XLPE insulation layer 3, and an outer semiconductive shielding layer 4. The inner semiconductive shielding layer 2, XLPE insulation layer 3, and outer semiconductive shielding layer 4 are formed by a three-layer co-extrusion process in a single extrusion, and are chemically cross-linked to form an integrated structure, thus creating a continuous insulation layer system without interface delamination. The thickness of the inner semiconductive shielding layer 2 is 0.8mm to 1.2mm, the thickness of the XLPE insulation layer 3 is 10.5mm, and the thickness of the outer semiconductive shielding layer 4 is... The thickness is 1.0mm to 1.4mm; the outer semiconductive shielding layer 4 is covered with a wrapped shielding layer 5 composed of multiple copper wires, and a ceramicized silicone rubber extruded isolation layer 6 is concentrically covered outside the wrapped shielding layer 5. The ceramicized silicone rubber extruded isolation layer 6 and the wrapped shielding layer 5 form a continuous and dense covering structure. An inorganic fire-resistant oxygen barrier layer 7 is concentrically covered outside the continuous and dense covering structure. The inorganic fire-resistant oxygen barrier layer 7 adopts a covering layer structure that extends continuously along the axial direction of the copper tightly stranded conductor 1. The inner surface of the inorganic fire-resistant oxygen barrier layer 7 and the outer surface of the ceramicized silicone rubber extruded isolation layer 6 form a continuous surface contact interface.
[0028] A flame-retardant glass fiber strip is concentrically wrapped around the outer side of the inorganic fire-resistant oxygen barrier layer 7 to form a circumferential constraint. The flame-retardant glass fiber strip is wrapped around the outer periphery of the inorganic fire-resistant oxygen barrier layer 7 in an overlapping manner, forming a circumferential tightening constraint on the inorganic fire-resistant oxygen barrier layer 7. A corrugated metal sheath fireproof layer 8 is concentrically wrapped around the outside of the flame-retardant glass fiber strip, forming a sealed fit with the inorganic fire-resistant oxygen barrier layer 7. The corrugated metal sheath fireproof layer 8 is formed by longitudinal wrapping, welding and corrugating of copper strip with a thickness of 0.5mm to 1.0mm, thereby forming The continuous corrugated sleeve structure, with the inner diameter of the corrugated metal sheath fireproof layer 8 being 1mm to 1.5mm larger than the outer diameter of the inorganic fire-resistant oxygen barrier layer 7, can provide radial expansion space for the internal structure under heating conditions, thereby preventing the inorganic fire-resistant oxygen barrier layer 7 and its inner structure from being squeezed and deformed. This allows the continuous and dense covering structure to serve as the inner matrix, thus forming a fireproof protection structure that progresses from the inside out with the inorganic fire-resistant oxygen barrier layer 7 and the corrugated metal sheath fireproof layer 8, providing multi-layer continuous barrier in the radial direction.
[0029] The corrugated metal sheath fireproof layer 8 is concentrically covered with a low-smoke halogen-free flame-retardant outer sheath 9, the thickness of which is not less than 1.8mm. The low-smoke halogen-free flame-retardant outer sheath 9 is concentrically covered with a halogen-free flame-retardant nylon outer sheath 10, the thickness of which is 0.1mm to 0.2mm. The low-smoke halogen-free flame-retardant outer sheath 9 and the halogen-free flame-retardant nylon outer sheath 10 form a continuous, radially bonded double-layer covering structure, thus providing an outer thermal barrier to the corrugated metal sheath fireproof layer 8 when exposed to a fire source. A ceramicized silicone rubber extruded isolation layer 6 fills the gaps between multiple copper wires inside the wrapping shielding layer 5, forming a continuous and dense covering structure. The ceramicized silicone rubber extruded isolation layer 6 serves as the inner continuous support interface for the inorganic fire-resistant oxygen barrier layer 7 and the corrugated metal sheath fireproof layer 8. The wrapping shielding layer 5 is composed of multiple copper wires wrapped around the outer semiconductive shielding layer 4 in the circumferential direction. A gap is formed between adjacent copper wires that is continuously distributed in the circumferential direction. The average width of the corresponding gap is not greater than 4mm. The ceramicized silicone rubber extruded isolation layer 6 forms a continuous filling state in the gap between adjacent copper wires. The ceramicized silicone rubber and the wrapping shielding layer 5 form a gapless bonding structure. The thickness of the ceramicized silicone rubber extruded isolation layer 6 is not less than 1.5mm to ensure the integrity of its filling of the gaps formed between the multiple copper wires inside the wrapping shielding layer 5.
[0030] A method for preparing a fire-resistant and flame-retardant medium-voltage fireproof cable includes the following steps: S1. Prepare copper compacted stranded conductor; Copper monofilaments conforming to GB / T3956 standard are selected, stranded, and compacted to form copper compacted stranded conductor 1, so as to ensure that the cross-sectional density and conductivity of copper compacted stranded conductor 1 meet the design requirements.
[0031] S2. Forming a three-layer co-extruded cross-linked insulation structure; An inner semiconductive shielding layer 2, an XLPE insulation layer 3, and an outer semiconductive shielding layer 4 are simultaneously extruded through a three-layer co-extrusion process outside the copper compacted stranded conductor 1, and then chemically cross-linked to form a three-layer co-extruded cross-linked insulation structure consisting of the inner semiconductive shielding layer 2, the XLPE insulation layer 3, and the outer semiconductive shielding layer 4.
[0032] S3. Form a wrap-around shielding layer; Multiple copper wires are wrapped around the outer semiconductive shielding layer 4 in the circumferential direction to form a wrapped shielding layer 5, and gaps are continuously distributed in the circumferential direction between adjacent copper wires.
[0033] S4. Form a ceramicized silicone rubber extrusion isolation layer; A ceramicized silicone rubber extrusion isolation layer 6 is coated on the outside of the wrapping shielding layer 5 by an extrusion process, so that the ceramicized silicone rubber extrusion isolation layer 6 fills the gaps formed between multiple copper wires inside the wrapping shielding layer 5 and forms a continuous and dense coating structure.
[0034] S5. A multi-layered protection system is constructed through a sealed fit; An inorganic fire-resistant oxygen barrier layer 7 is extruded onto the outside of the ceramicized silicone rubber extrusion isolation layer 6, and a flame-retardant glass fiber strip is wrapped around the outer periphery of the inorganic fire-resistant oxygen barrier layer 7 to form a circumferential tightening constraint on the inorganic fire-resistant oxygen barrier layer 7. Subsequently, copper strip is used for longitudinal wrapping, welding and corrugation to form a corrugated metal sheath fireproof layer 8, so that the corrugated metal sheath fireproof layer 8 and the inorganic fire-resistant oxygen barrier layer 7 form a sealed fit relationship.
[0035] S6. Construct a double-layer encapsulation structure for external protection; The low-smoke halogen-free flame-retardant outer sheath 9 and the halogen-free flame-retardant nylon outer sheath 10 are sequentially coated on the outside of the corrugated metal sheath fireproof layer 8 by an extrusion process, so that the low-smoke halogen-free flame-retardant outer sheath 9 and the halogen-free flame-retardant nylon outer sheath 10 form a continuous and bonded double-layer coating structure, thereby completing the preparation of the fire-resistant and flame-retardant medium-voltage concentric cable.
[0036] In summary, this invention forms a multi-layered protection system that progresses from the inside out by setting a ceramicized silicone rubber extrusion isolation layer 6 outside the wrapping shielding layer 5 to form a continuous and dense covering structure, and then sequentially setting an inorganic fire-resistant oxygen barrier layer 7, a flame-retardant glass fiber tape, and a corrugated metal sheath fireproof layer 8 on its outer side. At the same time, a low-smoke halogen-free flame-retardant outer sheath 9 and a halogen-free flame-retardant nylon outer sheath 10 are set on the outer layer to form a double-layer protection structure. This enables the medium-voltage concentric cable to have good conductivity, electrical insulation, and electromagnetic shielding performance under normal operating conditions. In high-temperature environments, including fires, it can delay the transfer of heat to the internal structure and maintain structural stability. Thus, it can maintain a certain period of power continuity in high-rise buildings, underground spaces, and fire protection power supply systems, ensuring the normal operation of critical electrical equipment. It has the advantages of excellent fire resistance and heat insulation performance, high stability of continuous protection structure, good electromagnetic shielding performance, and reliable electrical operation.
[0037] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A fire-resistant and flame-retardant medium-voltage fireproof cable, characterized in that: The device includes a tightly wound copper stranded conductor. The tightly wound copper stranded conductor has a concentrically formed three-layer co-extruded cross-linked insulation structure consisting of an inner semiconductive shielding layer, an XLPE insulation layer, and an outer semiconductive shielding layer. The outer semiconductive shielding layer is covered with a wrapped shielding layer composed of multiple copper wires. A ceramicized silicone rubber extruded insulating layer is concentrically covered outside the wrapped shielding layer. The ceramicized silicone rubber extruded insulating layer and the wrapped shielding layer form a continuous and dense covering structure. An inorganic fire-resistant oxygen barrier layer is concentrically covered outside the continuous and dense covering structure. A flame-retardant glass fiber tape is concentrically wound around the outside of the inorganic fire-resistant oxygen barrier layer to form a circumferential constraint. The flame-retardant glass fiber tape is further surrounded by… A corrugated metal sheath fireproof layer is concentrically covered with an inorganic fire-resistant oxygen barrier layer, forming a sealed fit. This continuous and dense covering structure serves as the inner matrix, thus forming a progressive fire protection structure from the inside out with the inorganic fire-resistant oxygen barrier layer and the corrugated metal sheath fireproof layer, providing multi-layer continuous barrier in the radial direction. A low-smoke halogen-free flame-retardant outer sheath is concentrically covered outside the corrugated metal sheath fireproof layer, and a halogen-free flame-retardant nylon outer sheath is concentrically covered outside the low-smoke halogen-free flame-retardant outer sheath. This forms a tightly bonded, layered covering structure, thereby providing an outer thermal barrier to the corrugated metal sheath fireproof layer when exposed to a fire source.
2. The fire-resistant and flame-retardant medium-voltage fireproof cable according to claim 1, characterized in that: The ceramicized silicone rubber extruded isolation layer fills the gaps formed between multiple copper wires inside the wrapping shielding layer. Through the formed continuous and dense covering structure, the ceramicized silicone rubber extruded isolation layer becomes the inner continuous support interface of the inorganic fire-resistant oxygen barrier layer and the wrinkled metal sheath fireproof layer.
3. The fire-resistant and flame-retardant medium-voltage fireproof cable according to claim 2, characterized in that: The wrapping shielding layer is composed of multiple copper wires wrapped around the circumference of the outer semiconductive shielding layer, with gaps continuously distributed circumferentially between adjacent copper wires, and the average width of the corresponding gaps is no greater than 4mm.
4. The fire-resistant and flame-retardant medium-voltage fireproof cable according to claim 3, characterized in that: The ceramicized silicone rubber extruded isolation layer forms a continuous filling state in the gap between adjacent copper wires. The ceramicized silicone rubber and the wrapped shielding layer form a gapless bonding structure. The thickness of the ceramicized silicone rubber extruded isolation layer is not less than 1.5mm to ensure the integrity of its filling of the gaps formed between multiple copper wires inside the wrapped shielding layer.
5. A fire-resistant and flame-retardant medium-voltage fireproof cable according to claim 4, characterized in that: The inorganic fire-resistant oxygen barrier layer adopts a coating structure that extends continuously along the axial direction of the copper tightly stranded conductor, and the inner surface of the inorganic fire-resistant oxygen barrier layer forms a continuous surface contact interface with the outer surface of the ceramicized silicone rubber extruded isolation layer.
6. A fire-resistant and flame-retardant medium-voltage fireproof cable according to claim 5, characterized in that: The flame-retardant glass fiber tape is wrapped around the outer periphery of the inorganic fire-resistant oxygen barrier layer in an overlapping manner, forming a circumferential tightening constraint on the inorganic fire-resistant oxygen barrier layer.
7. A fire-resistant and flame-retardant medium-voltage fireproof cable according to claim 6, characterized in that: The corrugated metal sheath fireproof layer is formed by longitudinally wrapping, welding and corrugating copper strips with a thickness of 0.5mm to 1.0mm to create a continuous corrugated sleeve structure.
8. A fire-resistant and flame-retardant medium-voltage fireproof cable according to claim 7, characterized in that: The inner diameter of the trough of the corrugated metal sheath fireproof layer is 1mm to 1.5mm larger than the outer diameter of the inorganic fire-resistant oxygen barrier layer, so as to provide radial expansion space for the internal structure under heating conditions, thereby avoiding the extrusion deformation of the inorganic fire-resistant oxygen barrier layer and its inner structure.
9. A fire-resistant and flame-retardant medium-voltage fireproof cable according to claim 8, characterized in that: The thickness of the low-smoke halogen-free flame-retardant outer sheath is not less than 1.8 mm, and the thickness of the halogen-free flame-retardant nylon outer sheath is 0.1 mm to 0.2 mm. The low-smoke halogen-free flame-retardant outer sheath and the halogen-free flame-retardant nylon outer sheath form a continuous double-layer covering structure in the radial direction.
10. A fire-resistant and flame-retardant medium-voltage fireproof cable according to claim 9, characterized in that: The inner semiconductive shielding layer, XLPE insulating layer, and outer semiconductive shielding layer are formed by three-layer co-extrusion in one step, and are chemically cross-linked to form an integrated structure, thereby forming a continuous insulating layer system structure without interface delamination. The thickness of the inner semiconductive shielding layer is 0.8mm to 1.2mm, the thickness of the XLPE insulating layer is 10.5mm, and the thickness of the outer semiconductive shielding layer is 1.0mm to 1.4mm.