DATA CABLE

Abstract

A data cable includes a plurality of cores each having a conductor surrounded by core insulation, providing the cores with a plurality of prescribed telecommunications transmission parameters. The core insulation includes a plurality of flame-retardant layers having a mineral, electrically insulating and flame-resistant first material, for maintaining functional integrity in the event of fire.

Claims

1. A data cable, comprising: a plurality of cores; each of said cores having a conductor and core insulation surrounding said conductor to provide said cores with a plurality of prescribed telecommunications transmission parameters; and said core insulation including a plurality of flame-retardant layers having a mineral, electrically insulating and flame-resistant first material, for maintaining functional integrity in an event of fire.

2. The data cable according to claim 1, wherein said core insulation is formed as a mixed dielectric having at least one insulation layer formed of an electrically insulating second material, in addition to said flame-retardant layers.

3. The data cable according to claim 2, wherein said insulation layer is continuous.

4. The data cable according to claim 2, wherein said insulation layer is formed of a synthetic material.

5. The data cable according to claim 4, wherein said synthetic material is PE, PP or a copolymer.

6. The data cable according to claim 2, which further comprises a fire-retardant material admixed into said insulation layer.

7. The data cable according to claim 2, wherein said insulation layer has an insulation wall thickness corresponding to no more than 35% of a total wall thickness of said core insulation.

8. The data cable according to claim 7, wherein said insulation wall thickness corresponds to no more than 10% of said total wall thickness of said core insulation.

9. The data cable according to claim 2, wherein said insulation layer is applied or extruded directly onto said conductor.

10. The data cable according to claim 1, wherein said core insulation is formed exclusively of said flame-retardant layers.

11. The data cable according to claim 1, wherein said plurality of flame-retardant layers of said core insulation adjust a prescribed impedance of a given one of said cores.

12. The data cable according to claim 1, wherein said first material of each of said flame-retardant layers is mica or glass fiber.

13. The data cable according to claim 1, wherein each of said flame-retardant layers is formed as a wrapping.

14. The data cable according to claim 1, wherein each of said flame-retardant layers is applied with an overlap of no more than 20%, is applied with an overlap of no more than 10% or is applied edge to edge.

15. The data cable according to claim 13, wherein each of said flame-retardant layers is applied with an overlap of approximately 49%.

16. The data cable according to claim 13, wherein each of said plurality of flame-retardant layers of said core insulation has an edge, and said edges of different flame-retardant layers are offset from one other.

17. The data cable according to claim 1, wherein an impedance of the data cable changes by no more than 20% during a fire in order to maintain functional integrity.

18. The data cable according to claim 17, wherein said impedance is preserved during a fire for a period of at least 30 minutes or at least 90 minutes or at least 180 minutes.

19. The data cable according to claim 1, which further comprises a cable sheath surrounding said cores, said cable sheath including a layer constructed of a flame-resistant material.

20. The data cable according to claim 1, which further comprises a cable shield surrounding said cores.

21. The data cable according to claim 1, which further comprises a reinforcement surrounding said cores.

22. The data cable according to claim 1, wherein said plurality of cores are twisted and combined into a plurality of data lines, and a cable sheath commonly surrounds said plurality of data lines.

23. The data cable according to claim 22, wherein each of said data lines has a respective line shield.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0039] FIGS. 1, 2 and 3 are diagrammatic, cross-sectional views each showing a variant of a data cable; and

[0040] FIG. 4 is a fragmentary, side-elevational view of a conductor with an insulation layer and flame-retardant layer.

DETAILED DESCRIPTION OF THE INVENTION

[0041] Referring now to the figures of the drawings in detail and first, particularly, to FIGS. 1-3 thereof, there are seen embodiments of a data cable 2. The cable has a plurality of cores 4, which in the embodiment variants shown herein are respectively combined by pairs into data lines 6. In the embodiment variants shown herein, each of the data lines 6 is surrounded by a line shield 7 to shield them from one another. In each of FIGS. 1 through 3, a total of eight cores 4 are organized into four data lines 6. The data lines 6 are grouped around a central element 8, which is configured in particular as a tension-relieving device. The data cable 2 further includes a cable sheath 10, which surrounds the cores 4.

[0042] Each of the cores 4 has a conductor 12, which is surrounded by a core insulation 14. Each of FIGS. 1 through 3 now shows embodiments with different variants of this core insulation 14. For instance, the core insulation 14 in FIG. 1 has a plurality, in particular six in this case, of flame-retardant layers 16 that are banded around the conductor 12 as mica film, for example, or alternatively are wrapped around the conductor 12 as glass fiber.

[0043] By contrast, FIG. 2 shows an embodiment in which only three flame-retardant layers are applied to the conductor and are then surrounded by an additional insulation layer 18. Those layers 18 are made of a synthetic material, e.g. a polyethylene, and are produced continuously, in particular extruded.

[0044] In FIG. 3, the core insulation 14 is configured in such a way that an insulation layer 18 is initially applied directly onto the conductor 12. This insulated conductor 12 is surrounded, in particular wrapped up, by a plurality of flame-retardant layers 14, in this case three. In a non-illustrated alternative, the insulation layer 18 is disposed between two flame-retardant layers 14.

[0045] The cable sheath 10 in FIGS. 1 through 3 is multi-layered. A cable shield 19 and a flame-resistant film 20, which surround the data lines 6, are first disposed on the inner side of the cable sheath 10. Furthermore, a reinforcement 22, which in particular in this case is a steel mesh, is integrated into the cable sheath 10. In order to further improve the flame resistance of the data cable 2, a flame-resistant material is admixed with the cable sheath 10, as a result of which a flame-resistant layer 24 is formed, which in this instance additionally forms an outermost layer of the cable sheath 10.

[0046] In order to improve the flame resistance of the data cable 2, it is preferred that further layers or bandings be additionally or alternatively provided, which are disposed inwardly and/or outwardly relative to the cable shield 19. Bandings of this type are formed, for example, by mica tapes and/or glass fiber tapes.

[0047] Furthermore, the ratio of the wall thicknesses of the insulation layer 18 and the flame-retardant layers 16 can be seen in FIG. 3. For instance, the core insulation 14 has a total wall thickness G, and the insulation layer 18 has an insulation wall thickness I, wherein the insulation wall thickness I is only about one-fourth of the total wall thickness G.

[0048] FIG. 4 shows a side view of a core 4 of the data cable 2, in which one insulation layer 18 has already been applied to the conductor 12 of the core 4. That insulation layer 18 is itself wrapped in a plurality, in this case two, of flame-retardant layers 16, which in this instance are each configured as banding. Moreover, each of the flame-retardant layers 16 in this case is a mica layer, which is applied to a backing film that is wrapped around the conductor 12 and the insulation layer 18. Due to the helical wrapping, this results in an overlap 26 of two consecutive coils of a respective flame-retardant layer 16. This overlap 26 is made to be as minimal as possible. Preferably, the edges of the flame-retardant layer 16 are wound edge to edge so that there is accordingly no overlap 26.

[0049] The inner of the two flame-retardant layers 16 is shown partially with a dashed line in FIG. 4, as is the concealed overlap 26 of the outer flame-retardant layer 16, in order to emphasize that each of these is covered by the outer flame-retardant layer 16. It can clearly be seen that the overlap 26 of the outer flame-retardant layer 16 is offset in the longitudinal direction L of the core 4 relative to the overlap 26 of the first flame-retardant layer 16, and therefore there is an especially homogeneous distribution of the overlaps 26 overall and thus an especially homogeneous impedance along the data cable 2.