Termite-resistant fire resistant power cable

Abstract

The present application relates to the technical field of power cable, and discloses an ant termite fireproof power cable.The cable comprises a plurality of conductors wrapped with insulation layers to form an insulated core, a filling layer for covering the insulated core to form a round cable core, a conductor shielding layer for covering the filling layer, a mica tape fireproof layer for covering the conductor shielding layer, an ant termite fireproof assembly comprising a protection layer spirally wound outside the fireproof layer and an expansion strip embedded in the protection layer, a buffer layer for covering the ant termite fireproof assembly, a steel tape armoring layer for covering the buffer layer and an outer sheath for covering the steel tape armoring layer.The protection layer is formed by a plurality of fan-shaped retainers connected in an axial spiral manner, the retainers are provided with grooves for placing the expansion strips, and the outer walls of the retainers are provided with guide strips matched with guide grooves to realize stable connection.The expansion strips are expanded to fill the gaps and provide thermal insulation when a fire occurs, and the fireproof layer maintains insulation.The protection layer, the steel tape armoring layer and the outer sheath cooperate to realize ant termite prevention and structural stability, thereby ensuring the safety and reliability of the cable operation.

Description

Technical Field

[0001] This invention relates to the field of power cable technology, and in particular to a termite-proof and fire-resistant power cable. Background Technology

[0002] As a critical carrier of power transmission, the safety, reliability, and service life of power cables directly affect the stable operation of power systems. In practical applications, power cables, especially those laid underground or in conduits, often face various external environmental challenges.

[0003] Among these, the fire resistance performance of power cables is of paramount importance. In fire accidents, power cables need to maintain circuit integrity and power supply capacity for a long time to ensure the normal operation of critical equipment such as fire protection and emergency lighting, and to buy valuable time for personnel evacuation and rescue. In existing technologies, fire-resistant cables usually use mica tape wrapping as the fire-resistant layer, but its external structure is prone to deformation and collapse at high temperatures, leading to the failure of the fire-resistant layer and exposing the internal conductors of the cable, thereby causing short circuits or power outages. In addition, the internal structure of existing fire-resistant cables lacks effective support and expansion flame-retardant mechanisms at high temperatures. Once the outer structure is damaged, the direct exposure of the internal medium will accelerate the damage and shorten the fire resistance time of the line.

[0004] Therefore, designing a power cable that can maintain structural integrity and power supply capacity during a fire is a pressing technical problem that needs to be solved in the current cable technology field. Existing technologies generally lack a power cable that can provide a comprehensive solution in terms of termite resistance, fire resistance, and structural stability. Summary of the Invention

[0005] The technical problem to be solved by this invention is that existing power cables are prone to collapse and deformation in the event of a fire. To address this, we propose a termite-proof and fire-resistant power cable.

[0006] To achieve the above objectives, this application adopts the following technical solution: a termite-proof and fire-resistant power cable, comprising, from the inside out: multiple conductors, each conductor covered with an insulation layer to form an insulated core; a filler layer, covering the multiple insulated cores to form a circular cable core; a conductor shielding layer, covering the filler layer; a fire-resistant layer, covering the conductor shielding layer; a protective component, comprising a protective layer spirally wound around the fire-resistant layer and an expansion strip embedded in the protective layer; a buffer layer, covering the protective component; a steel tape armor layer, covering the buffer layer; and an outer sheath, covering the steel tape armor layer.

[0007] Preferably, the protective layer is formed by spirally connecting multiple retainer units along the cable axis. The cross-section of the retainer is fan-shaped, and its inner sidewall is attached to the outer wall of the fire-resistant layer. The retainer has a through groove running from front to back, and an expansion strip is set in the groove. The retainer is made of silicon steel or thermosetting engineering plastic. The thermosetting engineering plastic is one of phenolic resin, glass fiber reinforced epoxy resin, or polyimide.

[0008] Preferably, the outer wall of the cage is provided with mutually cooperating guide structures, the guide structures including guide strips provided on one side of the outer wall and guide grooves provided on the other side of the outer wall; when multiple cages are spirally connected, the guide strip of one cage is embedded in the guide groove of the adjacent cage to form a stable annular structure.

[0009] Preferably, the cross-section of the guide bar and the guide groove is rectangular, and the ends of the guide bar are chamfered or pointed to facilitate insertion and engagement with the guide groove of the adjacent cage.

[0010] Preferably, the expansion strip is a rope-like or rod-like structure made of expanded vermiculite wrapped with fiber-reinforced tape, and the volume expansion rate of the expanded vermiculite in the expansion strip is not less than 300% when heated to 200°C to 300°C.

[0011] Preferably, the fiber reinforcement tape is one of glass fiber tape, ceramic fiber tape, or aramid fiber tape.

[0012] Preferably, the spiral angle of the protective layer is 8° to 35°.

[0013] Preferably, the cross-section of the steel strip in the steel strip armor layer is parallelogram or rhombus, and the steel strip is spirally wound around the outside of the buffer layer in an intermittent or overlapping manner.

[0014] Preferably, the fire-resistant layer is a mica tape wrapping layer, and the buffer layer is a wrapping non-woven fabric layer, glass fiber layer, or elastic rubber layer.

[0015] Preferably, the conductors are four strands, symmetrically distributed and integrated into a circular cable core through a filler layer.

[0016] The technical effects and advantages of this invention are as follows: In this invention, the protective layer is formed by multiple fan-shaped retainers that are spirally connected to guide bars and guide grooves with rectangular cross sections, forming a stable ring support structure. This allows the cable to effectively resist external compression and internal thermal expansion stress, preventing structural deformation. When a fire occurs, the expansion bars placed in the retainer grooves are activated by heat, and the expanded vermiculite inside expands rapidly at high temperatures, increasing in volume and filling the cavity to form a dense heat insulation layer, effectively blocking heat transfer to the interior. In addition, the mica tape fire-resistant layer closely attached to the conductor shielding layer serves as the final line of defense, maintaining insulation at high temperatures and ensuring that the line remains energized during a fire. Attached Figure Description

[0017] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings, the same reference numerals are used to refer to the same parts:

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a cross-sectional view of the overall structure of the present invention; Figure 3 This is an exploded view of the overall structure of the present invention; Figure 4 This is a schematic diagram of the protective layer structure of the present invention; Figure 5 This is an exploded view of the protective layer structure of the present invention; Figure 6 This is a schematic diagram of the steel strip armor layer structure of the present invention; Figure 7 This is a cross-sectional view of the steel strip armor layer structure of the present invention; Figure 8 For the present invention Figure 7 Enlarged view of the structure at point A in the middle.

[0019] Legend: 1. Conductor; 2. Filler layer; 3. Conductor shielding layer; 4. Fire-resistant layer; 5. Protective layer; 6. Expansion strip; 7. Buffer layer; 8. Steel strip armor layer; 9. Outer sheath; 10. Cage; 11. Groove; 12. Guide strip; 13. Guide groove; 14. Insulation layer. Detailed Implementation

[0020] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0021] Example 1: As Figures 1-8 As shown, the present invention provides a termite-proof and fire-resistant power cable, the internal structure of which, from the inside out, includes: conductor 1, insulation layer 14, filling layer 2, conductor shielding layer 3, fire-resistant layer 4, protective components, buffer layer 7, steel tape armor layer 8, and outer sheath 9.

[0022] Specifically, this power cable includes multiple conductors 1, which are made of highly conductive materials such as copper or aluminum. Each conductor 1 is covered with an insulation layer 14, which is made of insulating materials such as cross-linked polyethylene or ethylene propylene rubber to ensure electrical isolation between conductors 1. These conductors 1 covered by the insulation layer 14 constitute the insulated core.

[0023] Multiple insulated wire cores are covered by a filling layer 2. The function of the filling layer 2 is to fill the gaps between the insulated wire cores, shape the cable cores into a circle, and provide a certain buffering effect. The filling layer 2 is composed of polypropylene rope, non-woven fabric or extruded polymer filler.

[0024] A conductor shielding layer 3 is wrapped around the outside of the filling layer 2. The conductor shielding layer 3 is composed of semiconductor material. Its function is to improve the electric field distribution, uniformly distribute the electric stress inside the cable, thereby preventing the occurrence of partial discharge, protecting the insulation layer 14 from damage, and improving the operational reliability of the cable.

[0025] A fire-resistant layer 4 is wrapped around the outside of the conductor shielding layer 3. The fire-resistant layer 4 is a key component of the fire resistance performance of this cable. It adopts a mica tape wrapping structure. The mica tape has excellent high temperature resistance and insulation performance. In the event of a fire, even if the external structure is damaged, the mica tape can maintain its insulation state at high temperature, ensuring that the cable maintains power supply for a certain period of time.

[0026] The protective assembly includes a protective layer 5 spirally wound around the outside of the fire-resistant layer 4 and an expansion strip 6 embedded within the protective layer 5. The protective layer 5 is formed by multiple retainer units 10 spirally connected along the cable axis. Figure 3 and Figure 4 As shown, each retainer 10 has a fan-shaped cross-section, with its inner wall tightly fitted to the outer wall of the fire-resistant layer 4, forming a ring-shaped support structure. This fan-shaped design and tight fit minimize the possibility of termite intrusion and provide a solid physical barrier. Furthermore, as... Figure 5As shown, each retainer 10 has a through-groove 11 inside, and an expansion strip 6 is disposed within the groove 11. The expansion strip 6 is a rope-like or rod-like structure made of expanded vermiculite wrapped with fiber-reinforced tape. The fiber-reinforced tape can be selected from glass fiber tape, ceramic fiber tape, or aramid fiber tape to provide sufficient mechanical strength and high-temperature resistance. Expanded vermiculite is characterized by a volume expansion rate of not less than 300% in the temperature range of 200°C to 300°C. This means that when the cable encounters a fire, the expanded vermiculite will expand rapidly, filling the interior of the retainer 10 and any tiny gaps that may exist between the retainers 10, forming a dense and heat-insulating carbonized layer, effectively blocking heat from being transferred to the internal fire-resistant layer 4 and the insulation layer 14. This significantly improves the fire resistance and power supply capacity of the cable. The fan-shaped retainer 10 and its internal groove 11 not only effectively restrict the movement of the expansion strip 6 and ensure the directionality of the expansion effect, but also make the entire protective layer 5 structure more compact and stable, resisting external impact and internal stress, preventing structural deformation, and further enhancing the cable's termite-proof and fire-resistant performance. The spiral angle of the protective layer 5 is preferably 8° to 35°. Within this angle range, sufficient wrapping density and termite-proof performance can be ensured, while also taking into account the convenience of the production process and the bending performance of the cable. The retainer 10 is made of silicon steel or thermosetting engineering plastic, and the thermosetting engineering plastic is one of phenolic resin, glass fiber reinforced epoxy resin, or polyimide.

[0027] The protective component is covered with a buffer layer 7. The function of the buffer layer 7 is to absorb external impact and bending force, and to provide a smooth transition support for the subsequent steel belt armor layer 8, so as to avoid the steel belt armor layer 8 directly contacting the protective layer 5 and causing wear. The buffer layer 7 can be a non-woven fabric layer, a glass fiber layer or an elastic rubber layer in the form of wrapping. These materials all have good cushioning and insulation properties.

[0028] Outside the buffer layer 7 is the steel tape armor layer 8, which is the main mechanical protection structure of the cable. It can effectively resist external mechanical impact and termite bites. The cross-section of the steel tape in the steel tape armor layer 8 can be designed as a parallelogram or a rhombus. These two shapes of steel tape can form a tighter structure when wound, improving the resistance to compression and torsion. The steel tape is spirally wound on the outside of the buffer layer 7 in a gap-like or overlapping manner. When using gap-like winding, a certain gap is left between the steel tapes, which makes the cable have better bending flexibility. When using overlapping winding, the steel tapes overlap each other to form a stronger continuous protective layer, providing higher mechanical strength. Through the synergistic effect of the protective components and the steel tape armor layer 8, a double protection is formed inside and out to jointly resist termite infestation and provide more comprehensive protection for the cable.

[0029] The outermost layer is the outer sheath 9, which provides the cable with moisture protection, corrosion protection, UV protection and final mechanical protection. The outer sheath 9 is usually made of polyvinyl chloride, polyethylene or low smoke halogen-free materials to meet the requirements of different operating environments.

[0030] Example 2: Based on Example 1, this example further describes in detail the connection method of the cage 10 unit in the protective layer 5.

[0031] like Figure 3 and Figure 4 As shown, to ensure the protective layer 5 forms a stable annular structure, the outer wall of the retainer 10 is provided with a cooperating guide structure. This guide structure includes a guide strip 12 on one side of the outer wall and a guide groove 13 on the other side of the outer wall. When multiple retainer 10 units are spirally connected along the cable axis, the guide strip 12 of one retainer 10 can be precisely embedded into the guide groove 13 of the adjacent retainer 10. Through this plug-in cooperation method, a highly stable and continuous annular structure is formed. This structure effectively enhances the overall rigidity and compressive strength of the protective layer 5, preventing deformation or loosening of the structure under external stress or internal thermal expansion force. At the same time, this guide connection also makes the installation and assembly process of the retainer 10 more standardized and efficient.

[0032] Preferably, the guide strip 12 and the guide groove 13 have rectangular cross-sections, which simplifies the structural design and manufacturing process. To further improve the convenience and stability of the insertion fit, the end of the guide strip 12 can be chamfered or pointed. The chamfered design allows the guide strip 12 to slide smoothly into the guide groove 13, reducing installation resistance; the pointed design can guide the insertion more accurately, ensuring a tight connection and reducing connection defects that may be caused by process deviations. Through this design, the protective layer 5 provides termite and fire resistance functions while also possessing extremely high structural stability and easy assembly characteristics.

[0033] Example 3: Based on Example 1, this example further defines the structure of conductor 1 and related filling layer 2.

[0034] In this embodiment, there are four conductors 1, which are symmetrically arranged and integrated through a filler layer 2 to form a regular circular cable core. For example, a triangular or fan-shaped arrangement can be used, and the gaps are filled and shaped by the filler layer 2. Three of the four conductors are phase wires and one is a neutral wire. The filler layer 2 tightly integrates these insulated cores into a circular cable core, which not only helps maintain the overall circular cross-section of the cable and facilitates uniform wrapping of subsequent layers, but also increases the cable's compactness and compressive strength. The symmetrical distribution helps the cable maintain balanced electrical and mechanical properties during operation.

[0035] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. A termite-proof and fire-resistant power cable, characterized in that, From the inside out, the cable comprises: multiple conductors, each covered with an insulation layer to form an insulated core; a filler layer, covering the multiple insulated cores to form a circular cable core; a conductor shielding layer, covering the filler layer; a fire-resistant layer, covering the conductor shielding layer; a protective assembly, comprising a protective layer spirally wound around the fire-resistant layer and an expansion strip embedded within the protective layer; a buffer layer, covering the protective assembly; a steel tape armor layer, covering the buffer layer; and an outer sheath, covering the steel tape armor layer. The protective layer is formed by multiple retainer units spirally connected along the cable axis, the retainer having a fan-shaped cross-section, and its inner wall fitting against the outer wall of the fire-resistant layer. The cage has a through groove running from front to back, and the expansion strip is disposed within the groove. The cage is made of silicon steel or thermosetting engineering plastic, and the thermosetting engineering plastic is one of phenolic resin, glass fiber reinforced epoxy resin, or polyimide. The outer wall of the cage has a mutually cooperating guide structure, which includes a guide strip disposed on one side of the outer wall and a guide groove disposed on the other side of the outer wall. When multiple cages are spirally connected, the guide strip of one cage is embedded in the guide groove of the adjacent cage to form a stable annular structure. The expansion strip is a rope-like or rod-like structure made of fiber-reinforced tape wrapped with expanded vermiculite. When the expanded vermiculite in the expansion strip is heated to 200°C to 300°C, its volume expansion rate is not less than 300%.

2. The termite-proof and fire-resistant power cable according to claim 1, characterized in that: The guide bar and guide groove have rectangular cross-sections, and the ends of the guide bar are chamfered or pointed to facilitate insertion and engagement with the guide grooves of adjacent cages.

3. The termite-proof and fire-resistant power cable according to claim 1, characterized in that: The fiber-reinforced tape is one of glass fiber tape, ceramic fiber tape, or aramid fiber tape.

4. The termite-proof and fire-resistant power cable according to claim 1, characterized in that: The spiral angle of the protective layer is 8° to 35°.

5. The termite-proof and fire-resistant power cable according to claim 1, characterized in that: The steel strip of the steel strip armor layer has a parallelogram or rhombus cross-section, and the steel strip is spirally wound around the outside of the buffer layer in an intermittent or overlapping manner.

6. The termite-proof and fire-resistant power cable according to claim 1, characterized in that: The fire-resistant layer is a mica tape wrapping layer, and the buffer layer is a wrapping non-woven fabric layer, glass fiber layer, or elastic rubber layer.

7. The termite-proof and fire-resistant power cable according to claim 1, characterized in that: The conductor consists of four strands, symmetrically distributed, and integrated into a circular cable core through the filling layer.

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