EP3721455B1 - Cable with a fireproof layer - Google Patents

Description

The invention relates to a cable according to the preamble of claim 1.

the DE 42 36 560 A1 shows a cable with a sheath with a corrugated layer and the US 2007/0102188 A1 shows a communication cable.

From the US 2010/0051315 A1 a cable is known in which a relatively thick jacket layer is surrounded by a thinner fire protection layer. A cable in which a relatively thick fire protection layer with flame retardant behavior is surrounded by a thinner Termigon layer shows the EP 2 811 491 A1 .

From the DE 101 31 569 A1 cables are already known that can be laid in the ground. These cables comprise a sheath which has a polyethylene jacket and a fire protection layer. The polyethylene jacket encloses a cable core. The polyethylene jacket and the fire protection layer are applied to the cable by coextrusion.

Cables with such a polyethylene jacket can be laid in the water and in the moist soil. Against this background, the polyethylene jacket has a relatively high wall thickness.

The fire protection layer, on the other hand, is made relatively thin and has a wall thickness which corresponds to only a third to a quarter of the wall thickness of the polyethylene jacket.

In practice, however, there can be cases in which a relatively large wall thickness of a fire protection layer should be present or even an outer cable sheath should consist exclusively of flame-retardant material.

In principle, the following applies: The greater the wall thickness of the fire protection layer, the greater the resistance of a cable to fire, and the greater the thickness of a polyethylene jacket, the greater the mechanical stability of the outer cable jacket, which is important when laying the cable, but also thermomechanically Load cycle is required during operation.

If, however, a relatively thick fire protection layer is applied to an already relatively thick polyethylene jacket, the cable can be too bulky, too heavy and / or difficult to handle.

At the same time, however, there are also relatively high demands on the stability of the outer cable sheath so that it can withstand intrinsic mechanical loads resulting from the structural design of the cable.

For example, there are constructions in which a film is provided lying radially inside the outer cable sheath, which serves as a vapor or liquid barrier, in particular as a water vapor barrier, and can act in an unfavorable manner relative to the outer cable sheath.

If the film has an overlap area, notch effects can act on the outer cable sheath from the inside to the outside, so that it can break or tear. The invention is therefore based on the object of specifying a cable for laying in the ground, in the air or in pipes, but also in buildings, which is as stable as possible against mechanical influences with a compact structure and yet shows the highest possible resistance in the event of fire.

The present invention achieves the aforementioned object by the features of claim 1.

First of all, it was recognized that an overlapping area of a film can have an unfavorable effect radially outwards on an outer cable sheath, so that it can break or tear.

It was then recognized that this is the case in particular in constructions in which the outer cable sheath consists exclusively of flame-retardant material, if the fire protection requirements so require. It has also been recognized that this very combination, consisting of a film as a water vapor barrier and a pure fire protection layer above it, does not withstand the mechanical demands on the cable, or only to a limited extent.

It has also been recognized that high mechanical requirements are also placed on a cable with a metal jacket, which can have a smooth or corrugated surface. A cable that has a jacket layer and an overlying fire protection layer can be significantly improved in terms of stability compared to a cable that has only one fire protection layer.

According to the invention, it has finally been recognized that the wall thickness of a sheath layer, which consists in particular of pure polyethylene, can be selected to be smaller than the wall thickness of the fire protection layer, even if on a sheath or an outer cable sheath during installation or also in the thermomechanical load cycle during operation.

It has also been recognized that the fire protection layer, although it is more brittle than a layer made of pure polyethylene due to its filling with flame-retardant fillers, can nevertheless mechanically stabilize such a layer.

In particular, it has been recognized that a film can develop notch effects at the end of its overlap region. A relatively thin cladding layer, in particular made of pure polyethylene, can, however, withstand these notch effects surprisingly well, even if it is thin and if the thin, inner cladding layer is surrounded by a relatively thick, outer fire protection layer. The fire protection layer, which is relatively brittle per se, can stabilize a thin cladding layer surprisingly well against notch effects.

The notch effect at the overlap area of the film is mitigated by a thin jacket layer over the film; at the same time, the jacket layer provides a suitable substructure for the fire protection layer applied over it in coextrusion with regard to the mechanical stability requirements.

According to a variant of the cable, the wall thickness of the jacket layer in a first section could be greater than the wall thickness of the fire protection layer and could be less in a second section. The first section can then be laid in an open area, in particular in the ground, and the second section in an interior area, in particular in a building.

The cable is designed as a hybrid cable, which is suitable for several applications. Higher fire protection requirements in a building and lower fire protection requirements in the open air can thus be satisfied with a single cable.

Only the jacket layer could therefore be present in a first section, but no fire protection layer, both the jacket layer and the fire protection layer being provided in a second section. This saves expensive material for the fire protection layer.

Against this background, it is conceivable that the sections merge continuously into one another, the wall thickness ratios continuously reversing along the cable. A sudden reversal is also conceivable. A section of the inversion of the wall thickness ratios and / or the other sections could or could be identified by a marking so that the cable is laid correctly.

The wall thickness of the cladding layer could be at most 45%, preferably at most 25%, particularly preferably at most 10% of the wall thickness of the fire protection layer.

A metallic foil could be provided as the foil lying radially inside the jacket layer and the fire protection layer. The metallic foil could be purely metallic or comprise a metallically vapor-deposited or coated plastic carrier layer. The film could also have an adhesive layer. The film serves as a water vapor barrier.

The foil could be designed as an aluminum foil. Aluminum is easy to process and light.

The overlap area of the said film could extend over an arc segment of 10 ° to 45 °. The length of the arc segment depends on the manufacture of the cable.

A smooth metal jacket or a corrugated jacket could be provided as the metal jacket lying radially inside and beyond the jacket layer and the fire protection layer. A metal jacket increases the stability of a cable. Smooth or corrugated metal jackets can be made of lead, aluminum or other metallic materials, in particular sheet metal, with a smooth surface or in a corrugated design as a so-called corrugated jacket. In contrast to layered jackets, these designs are characterized by the fact that they have no overlapping area.

The metal jacket could be made of aluminum or lead. These two metals have proven particularly useful in practice. A corrugated jacket is preferably made of aluminum. In general, however, a corrugated jacket could also be made from sheet metal.

The wall thickness of the jacket layer, which consists in particular of pure polyethylene, could be in the range 0.3-1 mm. These wall thicknesses have proven to be advantageous in order to withstand notch effects and movements of a foil, in particular an aluminum foil.

The wall thickness of the fire protection layer could be in the range 0.5-5 mm. These wall thicknesses have proven to be advantageous in order to support a cladding layer against notch effects and movements of a film and at the same time to meet the fire protection requirements.

The jacket layer over the film or a metal jacket could be made of polyethylene or comprise polyethylene. Polyethylene, High-density polyethylene (HDPE) in particular is particularly suitable for cables to be laid in the ground.

The jacket layer could not have any fire-retardant and / or flame-retardant materials or fillers. This makes the jacket layer very stable, elastic and not brittle. As an alternative or in addition, the jacket layer could be made of pure polyethylene. Polyethylene is well suited for underground cables.

A further thin, electrically conductive layer could optionally be provided lying radially outside the fire protection layer. In this way, damage or errors in the laying of the cable can be detected. The wall thickness of this electrically conductive layer could be approx. 0.1-0.3 mm.

The cable described here could be used as a high-voltage cable and / or high-voltage cable for voltages in the range 1 kV to 500 kV for laying in the ground and / or at least in sections within buildings. The cable is sufficiently mechanically stable and can withstand fires well.

The fire protection layer can be made of or have any suitable material. The material is flame-retardant and / or generates as little smoke as possible in the event of a fire. The material is halogen-free. The material could comprise polyethylene and / or ethylene vinyl acetate in which about 20% -40% fillers are contained. Calcium carbonate, magnesium hydroxide or aluminum hydroxide can be present as fillers. The above-described jacket layer without flame-retardant fillers, in particular made of pure polyethylene, preferably does not have one of these or all of these fillers.

Show in the drawing

Fig. 1

a schematic sectional view of a cable which has a film with an overlap area,

Fig. 2a

an enlarged sectional view of a further cable, which has two sections, wherein a section is shown in which the wall thickness of the cladding layer is less than the wall thickness of the fire protection layer,

Figure 2b

an enlarged sectional view of another cable, which has two sections, wherein a section is shown in which the wall thickness of the cladding layer is greater than the wall thickness of the fire protection layer,

Fig. 3

a schematic longitudinal sectional view of the cable according to Figures 2a and 2b , in which there are different wall thickness ratios of the cladding layer and the fire protection layer in two sections,

Fig. 4

a schematic longitudinal sectional view of a further cable which has a section without a fire protection layer, and

Fig. 5

a sectional view of a further cable which has a metal jacket.

Fig. 1 shows a cable, namely an underground cable, for laying in the ground, in the air or in pipes, but also in buildings, comprising a cable core K and a sheath. The sheath surrounds the cable core. In this specific case, the sheath functions as an outer cable sheath.

In the specific case, the cable core includes the components that are identified with the reference numerals 1 to 5. The cable further comprises windings 6, 8 and shield wires 7.

The cable includes a sheath. In the specific case, the casing includes the components that are identified with the reference numerals 9 to 13. The sheath surrounds the inner cable structure, which comprises the components with the reference numerals 1 to 8.

The shell has a film 9, a jacket layer 12 made of polyethylene (HDPE) and a flame-retardant and / or fire-retardant fire protection layer 13. The jacket layer 12 and the fire protection layer 13 are coextruded. No additional adhesive is provided between the jacket layer 12 and the fire protection layer 13 in order to bond them together.

The wall thickness 12a of the jacket layer 12 made of polyethylene is less than the wall thickness 13a of the fire protection layer 13, the film 9 having an overlap area 11 being provided radially inside and beyond the jacket layer 12 made of polyethylene. The film 9 has two ends 10 which overlap one another. The film 9 is a separate component and is separate from the jacket layer 12 made of polyethylene. The film 9 lies radially further inward than the jacket layer 12 and the fire protection layer 13.

Fig. 2a, Fig. 2b and Fig. 3 show an alternative cable, which in sections has the same structure as the cable according to FIG Fig. 1 However, the wall thickness 12a of the jacket layer 12 made of polyethylene in a first section A is greater than the wall thickness 13a of the fire protection layer 13. In a second section B, the wall thickness 12a of the jacket layer 12 made of polyethylene is then less than the wall thickness 13a of the fire protection layer 13 .

The wall thickness ratios are continuously reversed in a transition section C. In all sections A, B, C, the jacket layer 12 made of polyethylene and the fire protection layer 13 are coextruded.

Fig. 4 shows a further alternative cable, which in sections has the same structure as the cable according to FIG Fig. 1 having, wherein in a first section A only the cladding layer 12 is present and no fire protection layer. Both the jacket layer 12 and the fire protection layer 13 are present in a second section B.

The cable core K of the cables shown here can be constructed in the usual way. It can have conductors 1 made of copper or aluminum. A ladder can be round. A conductor can be stranded or formed in segments. In the specific case according to Fig. 1 , Fig. 2 and Fig. 5 the conductor 1 is shown round and stranded made of copper or aluminum. The conductor 1 is surrounded by insulation 4, preferably made of polyethylene. Furthermore, shielding wires 7 made of copper or aluminum can be provided to control short circuits. It is also conceivable that optical fibers are provided.

The in Fig. 1 , Figures 2a and 2b The overlap area 11 shown extends over an arc segment of 10 ° to 45 °. A metallic foil is provided as the foil 9 lying radially inside and on the other side of the cladding layer 12. The foil 9 is designed as an aluminum foil.

The wall thickness 12a of the jacket layer 12 made of polyethylene is 1 mm in Fig. 1 . The wall thickness 13a of the fire protection layer 13 is 3 mm in Fig. 1 . The jacket layer 12 is made of polyethylene. Specifically, the jacket layer 12 is made of high-density polyethylene (HDPE).

An electrically conductive layer can optionally be provided lying radially outside the fire protection layer 13. This layer can go through Applying a conductive material, in particular graphite, can be generated. In this case the graphite can be polished in. The conductive layer can be extruded onto the fire protection layer by a further coextrusion of a conductive layer.

Fig. 5 shows another embodiment of a cable.

In this cable, the wall thickness of the jacket layer 12 is less than the wall thickness of the fire protection layer 13, a metal jacket 7a being provided radially inside and beyond the jacket layer 12 and the fire protection layer 13. The metal jacket 7a can be smooth or corrugated. The metal jacket 7a can be made of aluminum or lead or sheet metal.

The wall thickness 12a of the jacket layer 12 can be smaller in sections or over the entire length of a cable than the wall thickness 13a of the fire protection layer 13.

The cables shown here are used as high-voltage cables and / or high-voltage cables for laying in the ground and / or at least in sections within buildings or outdoors or in pipes.

Reference number

1

ladder

2

Wrapping

3

inner conductive layer

4th

insulation

5

outer conductive layer

6th

Wrapping

7th

Shield wires

7a

Metal jacket

8th

Wrapping

9

foil

10

End of 9

11

Overlap area of 9

12th

Coat layer

12a

Wall thickness of 12

13th

Fire protection layer

13a

Wall thickness of 13

Claims (15)

1. Cable for laying in the ground, in the air, in pipes or buildings, comprising a cable core (K) and a sleeve which surrounds the cable core (K), wherein the sleeve has a sheath layer (12) and a flame-retardant and/or fire-retardant fire protection layer (13) and wherein the sheath layer (12) and the fire protection layer (13) are coextruded,
   characterized in that
   the wall thickness (12a) of the sheath layer (12), at least in certain portions, is lower than the wall thickness (13a) of the fire protection layer (13) which surrounds the sheath layer (12), wherein a foil (9) is provided so as to lie radially inside and beyond the sheath layer (12) and the fire protection layer (13), said foil having an overlap region (11), wherein the sheath layer (12) lies above the foil (9), or wherein a metal sheath (7a) is provided so as to lie radially inside and beyond the sheath layer (12) and the fire protection layer (13), wherein the sheath layer (12) lies above the metal sheath (7a).
2. Cable according to Claim 1, characterized in that the wall thickness (12a) of the sheath layer (12) in a first portion (A) is greater than the wall thickness (13a) of the fire protection layer (13), and is smaller in a second portion (B).
3. Cable according to Claim 1, characterized in that in a first portion (A), only the sheath layer (12) is present but no fire protection layer (13) is provided, wherein in a second portion (B), both the sheath layer (12) and the fire protection layer (13) are provided.
4. Cable according to one of the preceding claims, characterized in that the wall thickness (12a) of the sheath layer (12) is at most 45%, preferably at most 25%, particularly preferably at most 10%, of the wall thickness (13a) of the fire protection layer (13).
5. Cable according to one of the preceding claims, characterized in that a metal foil is provided as foil (9) lying radially inside and beyond the sheath layer (12) and the fire protection layer (13).
6. Cable according to Claim 5, characterized in that the foil (9) is designed as an aluminium foil.
7. Cable according to one of the preceding claims, characterized in that the overlap region (11) of the foil (9) extends over an arc segment of 10° to 45°.
8. Cable according to one of the preceding claims, characterized in that a smooth metal sheath or a corrugated sheath is provided as metal sheath (7a) lying radially inside and beyond the sheath layer (12) and the fire protection layer (13).
9. Cable according to Claim 8, characterized in that the metal sheath (7a) is manufactured from aluminium or from lead.
10. Cable according to one of the preceding claims, characterized in that the wall thickness (12a) of the sheath layer (12) lies in the range of 0.3 - 1 mm.
11. Cable according to one of the preceding claims, characterized in that the wall thickness (13a) of the fire protection layer (13) lies in the range of 0.5 - 5 mm.
12. Cable according to one of the preceding claims, characterized in that the sheath layer (12) is manufactured from polyethylene or comprises polyethylene.
13. Cable according to one of the preceding claims, characterized in that the sheath layer (12) comprises no fire-retardant and/or flame-retardant materials and/or is manufactured from pure polyethylene.
14. Cable according to one of the preceding claims, characterized in that an electrically conductive layer is provided so as to lie radially outside the fire protection layer (13).
15. Use of a cable according to one of the preceding claims as a power cable and/or high-voltage cable for laying in the ground and/or at least in certain portions inside buildings.

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