Multi-core bundle low smoke halogen-free flame-retardant intrinsically safe control cable

Abstract

The utility model relates to the technical field of electric wire and cable, and concretely relates to a multi-core bundle stranded low-smoke halogen-free flame-retardant intrinsic safety type control cable, which comprises: a conductor stranding unit at a central position, which constitutes an inner layer cable core structure; a plurality of conductor stranding units stranded outside the inner layer cable core structure, which constitute an outer layer cable core structure; a shielding layer, which is wrapped on the outer wall of the outer layer cable core structure; and an outer insulation layer, which is wrapped on the outer wall of the shielding layer. Through the reverse stranding design of the inner wire core and the supporting core of the conductor stranding unit and the secondary reverse re-stranding of the conductor stranding unit in the outer layer cable core structure, the torque inside the cable is effectively balanced, the overall softness and bending fatigue resistance of the cable are improved, the wire cores in the same conductor stranding unit are set to a uniform color, different units are set to different colors, and digital markers are additionally provided, so that quick and accurate wire core identification is realized and the on-site troubleshooting and maintenance efficiency is greatly improved.

Description

Technical Field

[0001] This utility model relates to the field of wire and cable technology, and more specifically to a multi-core stranded low-smoke halogen-free flame-retardant intrinsically safe control cable. Background Technology

[0002] In environments with explosive gases, such as oil, chemical, and coal mines, intrinsically safe control cables serve as the nerve center connecting field instruments, sensors, and the control system. To ensure safety, these cables must meet stringent intrinsic safety standards, meaning that by limiting the cable's distributed inductance and capacitance, the energy of any electrical spark generated under any fault condition is insufficient to ignite a specific gas. Existing technologies often employ thin conductors, twisted-pair shielding, and low-dielectric-constant insulation materials to achieve this goal.

[0003] Meanwhile, given the high fire safety requirements of the aforementioned environments, low-smoke halogen-free flame-retardant (LSZH) materials are commonly used for insulation and sheathing to reduce toxic smoke release and prevent flame spread in the event of a fire. However, in actual engineering installation and maintenance, especially in confined spaces and areas requiring frequent relocation for maintenance, technicians face numerous challenges: First, the complex multi-layered structures designed to meet electrical performance requirements often result in high cable rigidity, and repeated bending and dragging can easily cause fatigue damage to the internal cores and shielding layers, affecting their long-term reliability; second, when system signals malfunction, accurately locating the fault point among dozens of cores with limited markings is extremely time-consuming and laborious, extending the exposure time of personnel in hazardous environments.

[0004] Therefore, there is still room for improvement in the existing cable structure in terms of flexibility, fatigue resistance, and field maintainability. Summary of the Invention

[0005] To address the technical problems existing in intrinsically safe control cables in the prior art, this utility model proposes a multi-core stranded low-smoke halogen-free flame-retardant intrinsically safe control cable, comprising: A conductor stranded unit in the center constitutes the inner core structure; Multiple conductor stranded units stranded outside the inner core structure constitute the outer core structure. A shielding layer, covering the outer wall of the outer cable core structure; An outer insulating layer, covering the outer wall of the shielding layer; The conductor stranding unit includes a support core and multiple wire cores stranded outside the support core. In the outer core structure, multiple conductor stranding units are stranded outside the conductor stranding unit, and the stranding direction of the wire cores is opposite to the stranding direction of the conductor stranding unit. A hollow filler strip is provided between the inner cable core structure and the outer cable core structure, and a flame-retardant elastic filler strip is provided between the outer cable core structure and the outer insulation layer.

[0006] Preferably, the conductor stranding unit includes a support core and 4-5 right-hand strands stranded outside the support core, with adjacent strands being tangent, and the support core comprising flame-retardant PP rope.

[0007] Preferably, the conductor core includes an inner stranded conductor layer, an outer stranded conductor layer, and an inner insulation layer, wherein the stranding directions of the inner stranded conductor layer and the outer stranded conductor layer are opposite.

[0008] Preferably, the inner stranded conductor layer is a 1+6 copper conductor stranded structure with a strand diameter ratio of 14~18, the outer stranded conductor layer has a strand diameter ratio of 16~20, the inner stranded conductor layer is right-handed, and the outer stranded conductor layer is left-handed.

[0009] Preferably, the inner insulation layer comprises a cross-linked polyolefin insulation layer.

[0010] Preferably, the stranding pitch ratio of the wire core outside the support core is 18~22, and the stranding direction is left-handed; the stranding pitch ratio of the conductor stranding unit located in the outer cable core structure is 20~25, and the stranding direction is right-handed.

[0011] Preferably, the shielding layer includes a semiconducting wrapping tape disposed in the inner layer and a copper wire braided shielding layer disposed in the outer layer.

[0012] Preferably, the outer insulation layer comprises a low-smoke, halogen-free, flame-retardant polyolefin insulation layer.

[0013] Preferably, all the wires in the same conductor stranded unit are the same color, while the wires in different conductor stranded units are different colors.

[0014] Preferably, all the cores in the same conductor stranding unit have different numerical markings on their surfaces.

[0015] Compared with the prior art, the advantages of this utility model are: This application effectively balances the internal torque of the cable by using the reverse twisting design of the conductor stranding unit's inner core and the supporting core, as well as the secondary reverse twisting of the conductor stranding unit in the outer cable core structure, thereby improving the overall flexibility and resistance to bending fatigue of the cable, making it suitable for working environments with frequent movement and dragging.

[0016] This application uses low-smoke halogen-free flame-retardant materials to form the outer insulation layer, and combines the design of flame-retardant elastic filler strips and hollow filler strips to further enhance the overall flame retardancy and fire resistance of the cable, and effectively suppress the spread of flames and the release of toxic fumes.

[0017] This application sets a uniform color for the wire cores within the same conductor stranding unit and sets different colors for different units, supplemented by digital markings, to achieve fast and accurate wire core identification, greatly improving the efficiency of on-site troubleshooting and maintenance. Attached Figure Description

[0018] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the structure of the multi-core stranded low-smoke halogen-free flame-retardant intrinsically safe control cable shown in this utility model; Figure 2 This is a schematic diagram of the cross-sectional structure of the multi-core stranded low-smoke halogen-free flame-retardant intrinsically safe control cable shown in this utility model. Figure 3 This is a schematic diagram of the conductor stranding unit shown in this utility model; Figure 4 This is a schematic diagram of the cross-sectional structure of the conductor stranding unit shown in this utility model. Detailed Implementation

[0019] To better understand the technical content of this utility model, specific embodiments are provided below in conjunction with the accompanying drawings.

[0020] Combination Figure 1 and Figure 2 As shown, this utility model proposes a multi-core stranded low-smoke halogen-free flame-retardant intrinsically safe control cable, including a cable core, a shielding layer 20, and an outer insulation layer 30.

[0021] The cable core includes an inner cable core structure 101 and an outer cable core structure 102. The inner cable core structure 101 consists of a centrally located... The outer core structure 102 is composed of multiple conductor stranded units 10 stranded outside the inner core structure 101.

[0022] Furthermore, the shielding layer 20 covers the outer wall of the outer cable core structure 102, and the outer insulation layer 30 covers the outer wall of the shielding layer 20.

[0023] The conductor stranding unit 10 includes a support core 11 and multiple wire cores 12 stranded outside the support core 11. In the outer core structure 102, multiple conductor stranding units 10 are stranded outside the conductor stranding unit 10, and the stranding direction of the wire cores 12 is opposite to the stranding direction of the conductor stranding unit 10.

[0024] Thus, the conductor stranding unit 10 adopts a multi-wire core bundle of 12 strands, and the outer cable core structure 102 is formed by multiple conductor stranding units 10 reverse twisting. By balancing the torque through secondary reverse twisting, the entire cable is not easy to twist when bending, the overall flexibility is greatly improved, and the stability of the core structure is guaranteed.

[0025] Furthermore, a hollow filler strip 103 is provided between the inner core structure 101 and the outer core structure 102, and a flame-retardant elastic filler strip 104 is provided between the outer core structure 102 and the outer insulation layer 30.

[0026] Thus, the outer core structure 102 has good resistance to compression and tension, which can effectively protect the outer core structure 102, enabling the cable to withstand dragging, compression and wear during operation, and further improving the flame retardant performance of the cable. At the same time, the hollow filler strip 103 of the inner layer improves the overall elasticity and deformability of the cable, and the cable as a whole achieves the characteristics of being flexible and having a small bending radius.

[0027] Combination Figure 3 and Figure 4 As shown, the conductor stranding unit 10 includes a support core 11 and 4 to 5 wire cores 12 twisted to the right outside the support core 11. Adjacent wire cores 12 are tangent to each other. The support core 11 includes flame-retardant PP rope.

[0028] Thus, the design of 4 to 5 conductor cores 12 allows for a larger gap between adjacent conductor stranding units 10, which can accommodate the hollow filler strip 103, laying the foundation for the cable's flexibility and high elasticity.

[0029] Combination Figure 3 and Figure 4 As shown, the conductor core 12 includes an inner stranded conductor layer 121, an outer stranded conductor layer 122, and an inner insulation layer 123. The stranding directions of the inner stranded conductor layer 121 and the outer stranded conductor layer 122 are opposite.

[0030] Thus, through the reverse twisting design of the inner and outer layers, better flexibility and bending performance can be achieved, and torque balance can be achieved. The internal conductors are almost stress-free, and the resulting twisted conductor structure is compact and not easily deformed.

[0031] In a specific embodiment, the inner stranded conductor layer 121 is a 1+6 copper conductor stranded structure with a strand diameter ratio of 14~18, the outer stranded conductor layer 122 has a strand diameter ratio of 16~20, the inner stranded conductor layer 121 is right-handed, and the outer stranded conductor layer 122 is left-handed.

[0032] Optionally, the inner insulation layer 123 may include a cross-linked polyolefin insulation layer.

[0033] Furthermore, the twisted pitch ratio of the conductor core 12 outside the support core 11 is 18~22, and the twisting direction is left-handed. The twisted pitch ratio of the conductor twisting unit 10 located in the outer cable core structure 102 is 20~25, and the twisting direction is right-handed.

[0034] In this way, by using a larger cabling section ratio, the overall flexibility of the cable can be maximized. The conductor stranding unit 10 ensures basic flexibility, while the reverse twisting makes the torque of each conductor stranding unit 10 cancel each other out, so that the internal force of the entire cable is balanced when it is bent and twisted, making it less prone to kinking and with excellent dynamic bending performance. It is especially suitable for occasions that require frequent movement and dragging.

[0035] Furthermore, the shielding layer 20 includes a semi-conductive wrapping tape disposed in the inner layer and a copper wire braided shielding layer disposed in the outer layer.

[0036] In this way, the cable core is wrapped with semi-conductive wrapping tape with a wrapping overlap rate of 30-35% and two wrapping layers. A shielding layer is then formed by braiding fine copper wire on the outer layer of the semi-conductive wrapping tape. The braiding coverage of the braided layer is greater than 90%. The copper wire braided shielding grounding has high reliability and good flexibility, meeting the usage requirements.

[0037] Furthermore, the outer insulation layer 30 includes a low-smoke halogen-free flame-retardant polyolefin insulation layer. The low-smoke halogen-free flame-retardant polyolefin insulation layer provides excellent flame-retardant, low-smoke halogen-free properties, protecting the internal structure from mechanical damage, chemical corrosion, and environmental impacts.

[0038] In the above embodiments, all the wire cores 12 in the same conductor stranding unit 10 are the same color, and the wire cores 12 in different conductor stranding units 10 are different colors. Preferably, all the wire cores 12 in the same conductor stranding unit 10 have different numerical markings on their surfaces.

[0039] Thus, each of the multiple cores 12 in the cable core has its own unique marking, and the need for distinguishing multiple cores can be met through dual marking of color and number.

[0040] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Those skilled in the art to which this invention pertains can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of this invention shall be determined by the claims.

Claims

1. A multi-core stranded low-smoke halogen-free flame-retardant intrinsically safe control cable, characterized in that, include: A conductor stranded unit (10) located in the center constitutes the inner core structure (101). Multiple conductor stranded units (10) stranded outside the inner core structure (101) constitute the outer core structure (102). A shielding layer (20) covers the outer wall of the outer core structure (102); An outer insulating layer (30) covers the outer wall of the shielding layer (20); The conductor stranding unit (10) includes a support core (11) and multiple wire cores (12) stranded outside the support core (11). In the outer core structure (102), multiple conductor stranding units (10) are stranded outside the conductor stranding unit (10), and the stranding direction of the wire cores (12) is opposite to the stranding direction of the conductor stranding unit (10). A hollow filler strip (103) is provided between the inner core structure (101) and the outer core structure (102), and a flame-retardant elastic filler strip (104) is provided between the outer core structure (102) and the outer insulation layer (30).

2. The multi-core stranded low-smoke halogen-free flame-retardant intrinsically safe control cable according to claim 1, characterized in that, The conductor stranding unit (10) includes a support core (11) and 4 to 5 wire cores (12) twisted to the right outside the support core (11). The adjacent wire cores (12) are tangent to each other. The support core (11) includes flame-retardant PP rope.

3. The multi-core stranded low-smoke halogen-free flame-retardant intrinsically safe control cable according to claim 1, characterized in that, The core (12) includes an inner stranded conductor layer (121), an outer stranded conductor layer (122), and an inner insulation layer (123), wherein the inner stranded conductor layer (121) and the outer stranded conductor layer (122) are stranded in opposite directions.

4. The multi-core stranded low-smoke halogen-free flame-retardant intrinsically safe control cable according to claim 3, characterized in that, The inner stranded conductor layer (121) is a 1+6 copper conductor stranded structure with a strand diameter ratio of 14~18. The outer stranded conductor layer (122) has a strand diameter ratio of 16~20. The inner stranded conductor layer (121) is right-handed, and the outer stranded conductor layer (122) is left-handed.

5. The multi-core stranded low-smoke halogen-free flame-retardant intrinsically safe control cable according to claim 3, characterized in that, The inner insulation layer (123) includes a cross-linked polyolefin insulation layer.

6. The multi-core stranded low-smoke halogen-free flame-retardant intrinsically safe control cable according to claim 1, characterized in that, The strand diameter ratio of the core (12) outside the support core (11) is 18~22, and the stranding direction is left. The strand diameter ratio of the conductor stranding unit (10) located in the outer core structure (102) is 20~25, and the stranding direction is right.

7. The multi-core stranded low-smoke halogen-free flame-retardant intrinsically safe control cable according to claim 1, characterized in that, The shielding layer (20) includes a semi-conductive wrapping tape disposed in the inner layer and a copper wire braided shielding layer disposed in the outer layer.

8. The multi-core stranded low-smoke halogen-free flame-retardant intrinsically safe control cable according to claim 1, characterized in that, The outer insulation layer (30) includes a low-smoke halogen-free flame-retardant polyolefin insulation layer.

9. The multi-core stranded low-smoke halogen-free flame-retardant intrinsically safe control cable according to any one of claims 1-8, characterized in that, All the wire cores (12) in the same conductor stranded unit (10) are the same color, while the wire cores (12) in different conductor stranded units (10) are different colors.

10. The multi-core stranded low-smoke halogen-free flame-retardant intrinsically safe control cable according to claim 9, characterized in that, Different numerical markings are provided on the surface of all the cores (12) in the same conductor stranding unit (10).

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