Flame and fire retardant aerial insulated cable

Abstract

The utility model discloses a kind of flame-retardant fire-resisting overhead insulated cables, it includes conductor, the conductor is sleeved with fire resistance layer, the fire resistance layer is sleeved with insulating layer, the insulating layer is sleeved with sheath layer, the fire resistance layer includes inner layer heat-absorbing foaming layer and outer layer carbonization catalytic layer.The utility model is by being provided with fire resistance layer of double-layer composite structure, efficient synergic protection under fire condition is realized, inner layer heat-absorbing foaming layer occurs heat-absorbing decomposition reaction under high temperature effect, a large number of heat absorption and foaming expansion, form heat shield, effectively delay heat transfer to conductor, guarantee conductor still can maintain normal operating temperature in fire initial stage, outer layer carbonization catalytic layer is catalyzed to form dense, solid carbonization layer under high temperature, the carbonization layer has good heat insulation, oxygen isolation and anti-molten droplet performance, can effectively block the direct erosion of flame and the impact of high temperature heat flow, by co-extrusion process composite as a whole, avoid interlayer separation.

Description

Technical Field

[0001] This utility model relates to the field of insulated cable technology, specifically to a flame-retardant and fire-resistant overhead insulated cable. Background Technology

[0002] Overhead insulated cables have extremely high requirements for flame retardancy and fire resistance. Current technologies often employ adding large amounts of inorganic flame retardants (such as aluminum hydroxide and magnesium hydroxide) to the insulation or sheathing materials. However, high filler content can lead to a decrease in the cable's mechanical properties (such as flexibility) and electrical performance. Another common method is to wrap mica tape around the conductor as a fire-resistant layer. However, mica tape is brittle and hard, easily cracking or even falling off when the cable is bent during installation, affecting fire resistance reliability, and the production process is inefficient. Existing technologies disclose several utility model patents in the field of wire and cable technology. Among them, utility model patent CN215496123U discloses a low-smoke fire-resistant and flame-retardant cable for rail transit. The low-smoke fire-resistant and flame-retardant cable for rail transit includes a first shielding layer; a semiconductor electrically buffered water-blocking layer, which is sleeved on the first shielding layer; a first flame-retardant layer, which is sleeved on the semiconductor electrically buffered water-blocking layer; a first fire-resistant layer, which is sleeved on the first flame-retardant layer; armor, which is sleeved on the first fire-resistant layer; a sheath, which is sleeved on the armor; and a control signal transmission mechanism, which includes three phase-to-phase transmission mechanisms disposed within the first shielding layer. The low-smoke fire-resistant and flame-retardant cable for rail transit provided by this utility model has the advantages of high temperature resistance, corrosion resistance, strong flame-retardant performance, and control signal transmission function.

[0003] However, the above method still has the following drawbacks in actual use: ceramicized silicone rubber material is expensive, and as an integral structure, its expansion ratio and char strength are sometimes difficult to meet the long-term protection requirements in extreme fire environments, and there is room for further performance improvement. Utility Model Content

[0004] The purpose of this invention is to provide a flame-retardant and fire-resistant overhead insulated cable to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a flame-retardant and fire-resistant overhead insulated cable, comprising a conductor, a fire-resistant layer outer sleeve of the conductor, an insulation layer outer sleeve of the fire-resistant layer, and a sheath layer outer sleeve of the insulation layer. The fire-resistant layer comprises an inner heat-absorbing foam layer and an outer char-forming catalytic layer. The fire-resistant layer consists of an inner heat-absorbing foam layer and an outer char-forming catalytic layer from the inside out. The inner heat-absorbing foam layer and the outer char-forming catalytic layer are composited together by a co-extrusion process.

[0006] As a further preferred embodiment of this technical solution, the inner surface of the inner heat-absorbing foam layer is in contact with the outer surface of the conductor.

[0007] As a further preferred embodiment of this technical solution, the outer surface of the outer carbonization catalyst layer is in contact with the inner surface of the insulating layer.

[0008] As a further preferred embodiment of this technical solution, the refractory layer is wrapped around the conductor by a longitudinal wrapping method, and the inner heat-absorbing foaming layer and the outer carbonization catalyst layer of the longitudinal wrapping portion are sealed together by a hot-melt method.

[0009] As a further preferred embodiment of this technical solution, the insulating layer is covered outside the fire-resistant layer by extrusion, and the sheath layer is covered outside the insulating layer by extrusion.

[0010] This utility model provides a flame-retardant and fire-resistant overhead insulated cable, which has the following beneficial effects: (1) This utility model achieves efficient synergistic protection under fire conditions by setting a double-layer composite fire-resistant layer. The inner heat-absorbing foaming layer undergoes a heat-absorbing decomposition reaction under high temperature, absorbs a large amount of heat and foams and expands to form a heat insulation barrier, effectively delaying the transfer of heat to the conductor and ensuring that the conductor can still maintain normal operating temperature in the early stage of fire. The outer carbonization catalytic layer catalyzes the formation of a dense and solid carbonized layer at high temperature. This carbonized layer has good heat insulation, oxygen isolation and anti-dripping properties, and can effectively block the direct erosion of flames and the impact of high temperature heat flow. The two functional materials are composited into one through co-extrusion process, with a firm interface bond, avoiding interlayer separation, ensuring the integrity and stability of the fire-resistant structure, significantly extending the continuous power supply time of the cable in a fire, and improving the safety and reliability of the cable.

[0011] (2) This utility model optimizes the overall performance of the cable by setting a longitudinal wrapping and hot-melt sealing process, as well as an extruded insulation layer and a sheath layer on the outside. The fire-resistant layer is wrapped around the conductor in a longitudinal wrapping manner, and the overlap is sealed by hot-melt process. This not only ensures the continuity and sealing of the fire-resistant layer, preventing high-temperature smoke or flames from penetrating through the joint, but also greatly enhances the flexibility and bending resistance of the cable, solving the problem of easy cracking and falling off of the traditional mica tape fire-resistant layer, and facilitating construction and laying. Attached Figure Description

[0012] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2 This is a three-dimensional cross-sectional schematic diagram of the vibration structure of this utility model.

[0013] In the diagram: 1. Conductor; 2. Refractory layer; 201. Inner heat-absorbing foaming layer; 202. Outer carbonization catalytic layer; 3. Insulation layer; 4. Sheath layer. Detailed Implementation

[0014] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.

[0015] This utility model provides a technical solution: such as Figure 1 and Figure 2 As shown, in this embodiment, it includes a conductor 1, an outer refractory layer 2, an outer insulating layer 3, and an outer sheath layer 4. The refractory layer 2 includes an inner heat-absorbing foam layer 201 and an outer char-forming catalyst layer 202. From the inside out, the refractory layer 2 consists of an inner heat-absorbing foam layer 201 and an outer char-forming catalyst layer 202. The inner heat-absorbing foam layer 201 and the outer char-forming catalyst layer 202 are composited together by a co-extrusion process. The inner surface of the heat-absorbing foam layer 201 is in contact with the outer surface of the conductor 1, the outer surface of the outer carbonization catalyst layer 202 is in contact with the inner surface of the insulation layer 3, the refractory layer 2 is covered by the conductor 1 by longitudinal wrapping, the inner heat-absorbing foam layer 201 and the outer carbonization catalyst layer 202 of the longitudinal wrapping part are sealed together by hot melting, the insulation layer 3 is covered by the refractory layer 2 by extrusion, and the sheath layer 4 is covered by the insulation layer 3 by extrusion.

[0016] like Figure 1 and Figure 2 As shown, the inner heat-absorbing foam layer 201 is composed of ethylene-vinyl acetate copolymer (EVA) as the base resin, and is filled with 50%~70% by weight of ultrafine aluminum hydroxide powder. The outer carbonization catalyst layer 202 is composed of linear low-density polyethylene (LLDPE) as the base resin, and is loaded with 20%~30% by weight of surface-modified ammonium polyphosphate (APP) catalyst. The inner heat-absorbing foam layer 201 uses EVA as the matrix and is filled with 50%-70% ultrafine aluminum hydroxide (ATH). The EVA matrix provides good processing flexibility and a char-forming basis, while the high-filling-content ultrafine ATH will endothermize and decompose in large quantities in the early stage of a fire (above 200°C), generating alumina and moisture. This process can efficiently reduce the temperature around conductor 1 and delay heat invasion. At the same time, the released water vapor can dilute combustible gases and combine with the foam layer to form an expanded foam carbon layer, providing a supporting foundation for the subsequent char-forming catalyst layer. The fire-resistant layer 2 is wrapped around the conductor 1 in a longitudinal overlapping manner, with an overlap rate of not less than 15%. The overlapping part is heated and pressurized to fuse the inner heat-absorbing foam layer 201 material to form a sealed tubular structure, ensuring that the layers are tightly bonded and without gaps. The fire-resistant layer 2 adopts a longitudinal wrapping method (overlap rate ≥15%) and is supplemented by hot-melt sealing. Compared with simple wrapping or direct extrusion, this process ensures that the fire-resistant layer 2 forms a completely sealed, seamless tubular structure that tightly wraps the conductor 1, effectively preventing high-temperature smoke or flames from directly penetrating through the interlayer gaps and attacking the conductor 1 during a fire. The hot-melt sealing fuses the inner and outer layer materials at the overlap into one, eliminating potential weak interfaces and enhancing the interlayer bonding force and structural integrity. Outside the refractory layer 22, an insulating layer 33 is extruded using an extruder. The insulating layer 33 is made of flame-retardant cross-linked polyethylene (FR-XLPE) material, and the outermost layer is extruded with halogen-free flame-retardant polyolefin material as a sheath layer 4.

[0017] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A flame-retardant and fire-resistant overhead insulated cable, comprising a conductor (1), characterized in that: The conductor (1) is covered with a refractory layer (2), the refractory layer (2) is covered with an insulating layer (3), the insulating layer (3) is covered with a sheath layer (4), the refractory layer (2) includes an inner heat-absorbing foam layer (201) and an outer char-forming catalyst layer (202), the refractory layer (2) consists of an inner heat-absorbing foam layer (201) and an outer char-forming catalyst layer (202) from the inside to the outside, and the inner heat-absorbing foam layer (201) and the outer char-forming catalyst layer (202) are composited by a co-extrusion process.

2. The flame-retardant and fire-resistant overhead insulated cable according to claim 1, characterized in that: The inner surface of the inner heat-absorbing foam layer (201) is in contact with the outer surface of the conductor (1).

3. The flame-retardant and fire-resistant overhead insulated cable according to claim 1, characterized in that: The outer surface of the outer carbonization catalyst layer (202) is in contact with the inner surface of the insulating layer (3).

4. The flame-retardant and fire-resistant overhead insulated cable according to claim 1, characterized in that: The refractory layer (2) is wrapped around the conductor (1) by a longitudinal wrapping method, and the inner heat-absorbing foam layer (201) of the longitudinal wrapping part and the outer carbonization catalyst layer (202) are sealed together by a hot-melt method.

5. The flame-retardant and fire-resistant overhead insulated cable according to claim 1, characterized in that: The insulating layer (3) is extruded over the fire-resistant layer (2), and the sheath layer (4) is extruded over the insulating layer (3).

Images