CA2801931A1 - Energy and/or telecommunications cable capable of preventing fire from spreading - Google Patents

Abstract

The present invention relates to a cable (1) of energy and / or telecommunication comprising: - at least one elongated electrically conductive element (2), and - a first thermal protection layer (3) coaxially surrounding said electrically conductive element (2), characterized in that the first thermal protection layer (3) comprises glass fibers having a density of at least 0.5 g / cm3.

Description

Energy and / or telecommunication cable capable of preventing the Propagation of a fire The present invention relates to an aluminum-based cable suitable for withstand extreme thermal conditions, and more particularly suitable for avoid the spread of a fire.
The invention finds a particularly advantageous application, but non-exclusive, in the field of energy cables and / or telecommunications, which are intended to remain operational for a period of time defined when they are subjected to intense heat and / or directly to flames.
Today, one of the major challenges of the cable industry is improving the behavior and performance of cables in extreme thermal conditions, in particular those encountered during a fire. For reasons essentially of security, it is indeed essential to maximize cable capabilities to delay the propagation flames on the one hand, and resist fire on the other. A slowdown significant increase in the flames, this is the time saved for evacuate the premises and / or to implement extinguishing means appropriate. Better fire resistance gives the cable the ability to to work longer, its degradation being less rapid.
Whether electric or optical, intended for the transport of energy or for transmission of data, a cable is schematically made up of at least a conductive element extending inside at least one insulating element.
It should be noted that at least one of the insulating elements can also play the role of means of protection and / or that the cable may further comprise minus a specific protective element, forming a sheath.
In particular, a cable having an aluminum conductive element and which is installed near a flammable material must be able

2 withstand temperatures of between 750 C and 900 C
not be a fire propagator. However, these fire temperatures are higher at the melting temperature of aluminum which is of the order of 658 C.
However, it is known that among the best insulating materials and / or protection used in the cable, many of them are unfortunately also excellent flammable materials. This is particularly the case polyolefins and their copolymers, such as, for example, polyethylene, polypropylene, copolymers of ethylene and vinyl acetate, copolymers of ethylene and propylene. Anyway, in practice, this excessive flammability is totally incompatible with the fire resistance requirements previously mentioned.
In the field of cable, there are many methods for improve the fire behavior of polymers used as materials insulation and / or sheathing.
The most common solution so far has been to employ halogenated compounds as a dispersed halogenated by-product in a polymer matrix, or directly in the form of a polymer halogen as in the case of a polyvinyl chloride (PVC) for example.
However, current regulations now tend to prohibit the use of this type of substance mainly because of their toxicity and their potential corrosivity, whether at the time of manufacture of material, or during its decomposition by fire. This is all the more true that the decomposition in question can occur accidentally during a fire, but also voluntarily during an incineration. What anyway, the recycling of halogenated materials is still particularly problematic.
That's why we use more and more fireproof fillers halogenated, and in particular to metal hydroxides such as aluminum hydroxide or magnesium hydroxide. This type of solutions However, the technical disadvantages of quantities of charges to achieve a satisfactory level of efficiency, that this in terms of the ability to delay the spread of flames, fire resistance. For example, the content of metal hydroxides can , i II

3 typically reach 150 to 200% by weight relative to the total amount of resin. However, any massive incorporation of charges induces an increase considerable viscosity of the material, and consequently a decrease in noticeable extrusion speed, resulting in a significant drop in productivity.
The addition of too large quantities of fire retardant additives is also causing a significant deterioration of properties mechanical and electrical cable.
GB 2 035 666 discloses, in its prior art, a suitable cable to operate at high temperatures comprising at least one conductor aluminum or copper, coated longitudinally or helically a mineral insulating layer based on glass fibers. It is stated that this material is difficult to manipulate and that the manufacturing process is so tedious and long. On the other hand, it is stated in this document that the fiberglass layer exhibits instability of behavior at temperatures of about 400-500 C, and that around 700-800 C, the fiberglass has a viscous phase, making it less insulating.
Thus, the purpose of the present invention is to overcome the disadvantages of the prior art by proposing a power cable and / or telecommunications fireproofing, said cable furthermore making it possible to avoid the problems of the state of the art, in particular by offering mechanical properties significantly improved while providing service functionality when of a fire.
The present invention relates to a power cable and / or telecommunication comprising:
at least one elongated electrically conductive element, and a first layer of thermal protection surrounding coaxially said electrically conductive element, characterized in that the first thermal protection layer comprises glass fibers having a density of at least 0.5 g / cm3.
It has been demonstrated that such a fiberglass layer allows to make the cable fire-resistant by limiting the spread of a fire by this one to the surrounding objects (curtains, etc.), while ensuring a service feature. Indeed, the first layer of protection thermal

4 prevents the electrically conductive element from melting, especially when this one is made of aluminum. Thus, the thermal barrier formed by the layer in glass fibers will prevent fusion of said electrically conductive element and, therefore, will also prevent the ignition of materials surrounding areas that may result from molten aluminum droplets while allowing the cable to work despite the fire.
The first layer of fiberglass makes it easier to resist fire compared to the fiberglass layer described in the document GB 2,035,666.
In a preferred embodiment, the first layer may include at least one fiberglass ribbon. Said ribbon surrounds in particular helically the electrically conductive element.
The fiberglass ribbon can cover the element electrically driver with a recovery rate of around 15% - 20%.
The first layer of the invention may have a density of from less than 0.8 g / cm3, and preferably at least 1 g / cm3.
The first layer may have a density of at most 2 g / cm3, and preferably at most 1.5 g / cm3.
In a particularly preferred manner, the first layer may have a density ranging from 1.0 to 1.5 g / cm3.
The first layer of the invention can be advantageously used as a thermal barrier, especially against flames. She allows to maintain the integrity of the electrically conductive element for a at least 800 C, and preferably at least 1000 C. It avoids thus the fusion of the electrically conductive element during a fire.
Advantageously, the first layer of the invention may have a thermal conductivity of not more than 0.25 W / m C (watt per meter-degree Celsius).
Preferably, the thickness of the first layer varies from 0.10 mm to 0.40 mm. For example, if the first layer only includes one fiberglass ribbon, the thickness will be of the order of 0.10 mm and if it comprises two, the thickness will be of the order of 0.40 mm.
Preferably, the first layer (fiberglass) has a mass per unit area ranging from 120 to 160 g / m2.

The electrically conductive element of the invention can be a material selected from aluminum (AI) or an aluminum alloy. The alloy aluminum can be selected from copper aluminum, aluminum nickel, and copper-plated and nickel-plated aluminum, or a combination thereof.

5 The element electrically conductive may be for example of the type single-stranded or multi-stranded.
Advantageously, the cable of the invention may comprise a second layer surrounding said first layer. This second layer can be formed by extrusion or by taping according to known techniques of the skilled person so as to be composed of one or more underlays, such as preferably two.
Preferably, the second layer is electrically insulating and can be of a material selected from synthetic rubber, such as silicone rubber, and a polyolefin, such as, for example, copolymers of ethylene ethylene-vinyl acetate (EVA), or one of their combinations.
Advantageously, the thickness of the second layer varies from 0.5 mm to 3.0 mm.
When the cable of the invention comprises said second layer, the first layer can be directly in physical contact with the element electrically conductive, and said second layer can be directly in physical contact with the first layer. Said cable can also include a protective sheath surrounding the second layer.
In a particularly preferred embodiment, the power cable and / or telecommunication is an isolated electrical conductor in which the elongated electrically conductive element is a central element.
The present invention also relates to the use of a cable such described above to limit the spread of a fire.
For a better understanding of the invention, the description will reference to an accompanying drawing, which is for illustrative and no limiting.

II

6 On this drawing :
- Figure 1 illustrates a perspective view and partially in section of an energy cable according to a preferred embodiment of the invention.
Examples of realization:
Example 1 Example of Composition of a Cable According to the Invention (figure 1) For the sake of clarity, only the essential elements for the understanding of the invention have been schematically represented, and this without respect of the scale in Figure 1.
The power cable 1, shown in FIG. 1, is a conductor insulated electrical element comprising a central conducting element 2, in particular aluminum, multi-strand type, and, successively and coaxially around this element, a first layer 3 formed of a strip (ribbon) of glass sold by the company STEVTISS or TISSTECH, or a ribbon of fiberglass marketed by SCAPA under the reference SFR10 / 103.
This ribbon covers the conductive element with a recovery rate on the order of 15% - 20% so as to ensure that the entire surface of the the conductive element is protected from flames. Above this ribbon fiberglass is deposited a second layer 4 consisting of two sub-layers layers of an extruded material based on silicone rubber: a layer white material referenced El 111 polysiloxane polymer and a black layer material referenced EM107 ethylene copolymer in the European standard for rolling stock EN 50382-1. This second layer 4 is an optional layer.
In this example, the thickness of the ribbon (ie first layer 3) is 0.12 mm and its density is 1.16 g / cm3. The thickness of the second layer 4 is of the order of 2.7 mm.
Example 2: Process for producing a cable according to the invention

7 Said multi-stranded aluminum electrical conductor is surrounded by a first layer of fiberglass tape as mentioned in Example 1. This fiberglass ribbon is then extrusion-coated with two layers of silicone rubber and polyolefin mentioned above.
Tape and extrusion techniques are well known the skilled person and will not be further explained in this request.
Experimental test The cable as described in Example 1 was subjected to a fire test.
A torch projecting a flame of 850 C was indeed positioned at proximity of the cable according to the invention for 1h so that the flame touches part of the cable. A sheet of paper has also been placed nearby cable, about 30 cm away from the flame of the torch.
It turned out that after one hour, that the second layer in silicone rubber and polyolefin got inflamed and completely burned in the area in contact with the flame but that the driver The aluminum strand remained intact thanks to the fiberglass ribbon.
Besides, this one too was intact. By the way, the paper sheet placed at 30 cm of the cable did not ignite, showing that the cable the invention is non-fire propagator.
Although the invention has been described in connection with a mode of particular achievement, it is obvious that it is by no means and that it includes all the technical equivalents of the means described as well as their combinations if they fall within the scope of the invention.

Claims (11)

1. Cable (1) of energy and / or telecommunication comprising:
at least one elongated electrically conductive element (2), and a first layer (3) of thermal protection surrounding coaxially said electrically conductive element (2), characterized in that the first layer (3) of thermal protection comprises glass fibers having a density of at least 0.5 g / cm3. Cable (1) according to claim 1, characterized in that the first layer comprises at least one fiberglass ribbon. Cable (1) according to claim 1 or 2, characterized in that the first layer has a density of at least 0.8 g / cm3, and preferably at least 1 g / cm3. 4. Cable (1) according to one of the preceding claims, characterized in that that the first layer has a density of not more than 2 g / cm3, and preferably at most 1.5 g / cm3. Cable (1) according to one of the preceding claims, characterized in that that the first layer (3) has a surface density of about 120 to 160 g / m2. Cable (1) according to one of the preceding claims, characterized in that that the thickness of the first layer (3) is of the order of 0.10 mm to 0.40 mm. Cable (1) according to one of the preceding claims, wherein the electrically conductive element (2) is made of material chosen from aluminum (Al) or an aluminum alloy. 8. Cable (1) according to one of the preceding claims, characterized in that it comprises a second layer surrounding said first layer. 9 Cable (1) according to claim 8, characterized in that the second layer is made of a material selected from synthetic rubber, and a polyolefin, or a combination thereof. Cable (1) according to one of the preceding claims, characterized in that that the first layer (3) is in direct physical contact with the electrically conductive element (2). 11. Cable (1) according to one of the preceding claims, characterized in that that it is an isolated electrical conductor in which the element electrically driver (2) is a central element.