Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B7/00—Insulated conductors or cables characterised by their form
  • H01B7/17—Protection against damage caused by external factors, e.g. sheaths or armouring
  • H01B7/29—Protection against damage caused by extremes of temperature or by flame
  • H01B7/295—Protection against damage caused by extremes of temperature or by flame using material resistant to flame
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
  • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
  • H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
  • H01B3/46—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes silicones

Definitions

• the present invention relates to a fire-resistant security cable.
• the present invention relates to a fire-resistant cable, which comprises at least two electrical conductors surrounded by a common insulating layer.
• the present invention relates to a substantially flat fire-resistant cable, which comprises at least two electrical conductors which are adjacent to one another, and which are surrounded by a common insulating layer.
• the safety cables are in particular power transmission or data transmission cables, such as for control or signaling applications.
• the fire-resistant safety cables must, during a fire, maintain an electrical function. Preferably, said cables must also not spread the fire. Said security cables are used, for example, for emergency exit lighting and elevator installations.
• the fire resistant cables must meet criteria set in particular by the French standard NF C 32-070. According to this standard, the cable is deposited horizontally in a tubular furnace which is mounted in temperature up to 920 0 C for 50 minutes. The cable must not present a short circuit during this rise in temperature and for 15 minutes at 920 0 C. During all this time, to simulate falling objects during a fire, the cable is subjected periodically to a shock by a metal bar to shake the cable.
• the cables satisfying the test defined by NF C 32-070, paragraph 2-3 belong to category CRl.
• Criteria similar to those defined in the French standard NF C 32-070 are also defined by international standards, such as IEC 60331, or European standards, such as EN 50200.
• JP 01-1 17204 and JP 01-030106 disclose two flat fire-resistant cables, said cables comprising several conductors surrounded by an insulator and an outer sheath of polyethylene, the insulating layer of each electrical conductor being made of mica ribbons.
• a fire-resistant cable which is provided with an insulating layer made of mica ribbons has several disadvantages.
• such a cable may have a gap (or space revealing the conductor) at the level of the mica ribbon envelope, resulting in a defect in the protection of conductors leading to a short circuit.
• Fire resistant cables having a substantially round cross section are also known.
• Such cables may comprise more than two insulated conductors, at least one insulated conductor being superimposed on the others so as to ensure a round cross section of the cable.
• the document EP 942 439 describes a security cable, round, fire-resistant and halogen-free, comprising at least one conductor, an insulator around each conductor and an outer sheath, empty spaces being provided between said sheath and said insulation of each electrical conductor.
• the insulation of each conductor is made of a composition formed of a polymeric material containing at least one ceramic-forming filler and able to transform at least superficially in the ceramic state at high temperatures corresponding to fire conditions .
• the outer sheath is made of a polyolefinic composition containing at least one charge of metal hydroxide.
• the outer sheath is usually transformed, under the action of a fire, into ashes that can hinder the transformation of the polymeric material of the ceramic insulator, resulting in cracks in the conductor insulation.
• the superposition of the insulated conductors can cause a significant increase in the size of the cracks, resulting from a crushing of (s) layer (s) insulating (s) contaminated (s) by said ash.
• These disadvantages lead to a reduction of the insulating protection by the insulating layer (s) of the cable and to an increase in the risk of short-circuiting the conductors.
• These risks concern, in particular, superposed isolated elements.
• these ashes can lead to an increase in the volume and surface conductivity of the insulation, which affects the proper operation of the cable.
• objects such as a beam or elements of a building structure may fall and strike the cable and thus damage the cable and alter the mechanical strength of the ceramic insulation. or in the process of ceramic transformation of each driver.
• the fall of such an object can lead to an insulated conductor being compressed between said object and another conductor of the same cable, resulting in damage to the insulator transformed into ceramic or during ceramic transformation, and thus causing short circuit of the two conductors.
• the present invention relates to a safety cable, fire resistant, said cable comprising: - at least two electrical conductors, said electrical conductors being separated from each other by at least one space;
• insulating layer surrounding the electrical conductors and filling said space or spaces, said insulating layer being constituted from at least one polymeric material able to transform at least superficially into the ceramic state at high temperatures in fires, and
• halogen-free cable is meant a cable of which all the components are not substantially halogenated. Even more preferentially, the constituents do not comprise any halogenated compound.
• the cable comprises a common insulating layer which surrounds the conductors and fills the spaces, a space separating two adjacent conductors. Said common insulating layer thus forms a mechanically integral envelope inside which the electrical conductors are included.
• the outer contour of the insulating layer of the cable substantially follows the shape of the envelope of the conductors, resulting in inclusion of the conductors in the insulating layer.
• the insulating layer of the cable preferably has a thickness which is substantially constant on the extrados of the electrical conductors and which can be reduced to a minimum value sufficient to give the cable the typical protection of an insulating layer of cable .
• a common insulating layer according to the invention has the advantage of avoiding, during a fire, any insertion of residual ash from the sheath between each insulated conductor during the ceramic transformation of the insulator, and reducing the appearance of cracks. It also allows a better mechanical cohesion of the conductors between them once the insulation transformed into ceramic. This thus reduces the risk of short circuit between electrical conductors while maintaining the integrity of the cable.
• the material of the outer sheath preferably comprises an ethylene / vinyl alcohol copolymer (or EVA), a polysiloxane, a polyolefin such as polyethylene, polyvinyl chloride (or PVC), or a mixture thereof.
• EVA ethylene / vinyl alcohol copolymer
• the material of the outer sheath may further comprise mineral fillers capable of turning into residual ash under the effect of high temperatures of a fire, such as chalk, kaolin, metal oxides such as hydrated alumina, or metal hydroxides as magnesium hydroxide, the metal oxides or hydroxides may serve as flame retardant fillers.
• the material of the outer sheath may optionally be expanded so as to improve in particular the impact resistance of the cable, shock to which it may be subjected following the fall of an object during the fire.
• the outer sheath may be in the form of a single layer or of several layers of polymeric material (s), for example, 2, 3 or 4 layers.
• polymeric material for example, 2, 3 or 4 layers.
• the insulation is constituted in particular from at least one polymeric material able to be transformed at least superficially into the ceramic state at high temperatures in the fires, especially in the interval ranging from 400 0 C to 1200 0 C.
• This transformation in the ceramic state of the polymeric material of the insulator ensures the maintenance of the physical integrity of the cable and its electrical operation in the conditions of the fire .
• the polymeric material of the insulating layer is preferably a polysiloxane such as a cross-linked silicone rubber.
• the insulating layer may further preferably comprise a ceramic-forming filler under the effect of high fire temperatures, such as silica or metal oxides.
• the polymeric material of the insulating layer may be foamed.
• the insulation may be in the form of a single layer or multiple layers of polymeric material (s), such as 2 or 3 or more layers.
• the cable according to the invention comprising at least two conductors included in the same insulating layer, may further comprise a stuffing material between said insulating layer and the outer sheath.
• the stuffing material is preferably selected from an ethylene / vinyl alcohol (or EVA) copolymer, a polysiloxane, a polyolefin such as polyethylene, polyvinyl chloride (or
• the stuffing material may further comprise mineral fillers capable of being converted into residual ash under the effect of high temperatures of a fire, such as chalk, kaolin, metal oxides such as hydrated alumina, or metal hydroxides such as magnesium hydroxide, metal oxides or hydroxides that can be used as flame retardant fillers
• the cable according to the invention may be, in cross section, round or substantially flat.
• a substantially flat cable is a cable which has, in cross section, at least two substantially flat faces and substantially parallel to the plane comprising the axes of the conductors.
• the flat cable has a substantially rectangular outer profile, and more preferably it comprises, in cross section, at least two substantially planar faces and substantially parallel to the plane comprising the axes of the conductors and two substantially rounded lateral portions which are connected to said two faces.
• a substantially flat cable according to the present invention comprises at least two conductors surrounded by a common insulating layer, which are adjacent to each other and side by side, and their axes being in the same plane between said at least two faces.
• the arrangement of the axes of the electrical conductors in the same plane also makes it possible to increase the electrical resistance of the conductors by reducing any short-circuiting of the conductors.
• the spaces separating the adjacent conductors from each other in a flat cable are distributed transversely to the axis of the cable and have an identical dimension.
• the substantially flat fire-resistant cable of the present invention comprises a cable jacket having an outer contour substantially conforming to the shape of the insulating layer.
• the cable thus has in cross section a shape of "8".
• the sheath of the cable in cross-section, has an outer contour (or outer profile) which substantially follows the shape of the envelope of insulated conductors located inside the sheath of the cable, their axes being lying in the same plane.
• the sheath of the cable preferably has a thickness which is substantially constant on the extrados of the insulated conductors and which can be reduced to a minimum value sufficient to give the cable the typical protection of a cable sheath.
• the cable of the present invention leads to a reduction in the amount of sheath material used for making the cable, especially for the two-conductor cable. On the one hand, this reduces the manufacturing cost of the cable, and on the other hand a reduction in the incandescent period, the heat energy released during a fire and the amount of ash resulting from the combustion. of the sheath.
• these aspects are particularly advantageous because the risk of cracks being caused by the ashes during the transformation into Ceramic insulation at the high temperatures of a fire can be reduced significantly.
• the outer surface of the sheath is larger in the present invention, which allows a better heat exchange and a better and faster combustion of the sheath which will disturb less the transformation. ceramic insulation during the fire.
• Another object of the invention is a method of manufacturing the cables according to the invention comprising the extrusion of a polymeric material of the insulator - capable of transforming at least superficially in the ceramic state at high temperatures. in fires - on metallic conductors entering the same extrusion head so that the insulation material thus deposited makes each conductor thus isolated integral.
• Fig. 1 shows a cross-sectional view of a round cable with three electrical conductors according to a first embodiment.
• Fig. 2 is a cross-sectional view of a round cable with three electrical conductors according to a second embodiment.
• Fig. 3 shows a cross-sectional view of a so-called flat cable with two electrical conductors, according to a third embodiment.
• Fig. 4 shows a cross-sectional view of a so-called flat cable with three electrical conductors, according to a fourth embodiment.
• FIG. 5 shows a cross-sectional view of a so-called flat cable with two electrical conductors, according to a fifth embodiment.
• a round cable with three electrical conductors 2a, 2b and 2c, the latter extending longitudinally inside a common insulating layer 3.
• the electrical conductor 2c is superimposed on the electrical conductors 2a and 2b.
• the axes of the two conductors 2a and 2b are arranged parallel to one another in the same longitudinal median plane Pl, while the conductor 2c is placed above the conductors 2a and 2b its axis being parallel to those of the conductors 2a and 2b and being located in a longitudinal median plane P2 perpendicular to Pl.
• the conductors 2a, 2b, 2c are separated from each other by a space 5.
• the spaces 5 separating adjacent conductors have identical dimensions.
• the conductors 2a and 2b are located equidistant from the plane P2, on either side of the plane P2.
• the conductors 2a and 2b are separated by a gap 5 which preferably measures from about 0.1 mm to about 10 mm (transverse dimension).
• the cable 10 comprises a common insulating layer 3 which surrounds the three conductors 2a, 2b and 2c. Consequently, the material of the insulating layer 3 fills the spaces 5 which separate the three conductors, so as to obtain a common insulating layer 3 in the form of a mechanically integral envelope.
• the insulating layer 3 has an outer contour which substantially matches the shape of the conductor envelope, said insulating layer having a substantially constant thickness on the extrados of the conductors.
• the material of the insulator 3 is preferably a polysiloxane comprising in particular a silica-type reinforcing filler.
• the insulator 3 preferably comprises a single layer of polysiloxane.
• the cable 10 shown in FIG. 1 further comprises an outer sheath 4 which surrounds the insulating layer 3 so that the cross section of the cable has a circular shape.
• the outer sheath 4 preferably consists of an EVA optionally comprising fillers such as metal oxides or hydroxides.
• the cable 20 of FIG. 2 differs from that of FIG. 1 in that an additional space 21 is present between the insulated conductors 2a,
• the insulated conductors 2a, 2b, 2c are separated from each other by respective spaces 5 and the portion of the cable contained between the spaces 5 and the insulated conductors 2a, 2b, 2c defines said additional space 21.
• the spaces 5 have the shape of three segments which respectively connect the insulated conductors 2a and 2b, 2b and 2c, and 2c and 2a, said segments being made of the insulating material of the insulating layer 3.
• the insulation 3 of the cable 20 is the combination of three annular shapes, two forms being aligned and the third being above the other two and in a centered position relative to the other two. These annular shapes are connected in pairs by a segment made of insulating material, measuring, for example, from 0.1 mm to 20 mm. The insulation then has the shape of an equilateral triangle preferably with rounded vertices.
• the cable 20 has an outer sheath 4 which surrounds the insulating layer 3 and gives a round profile in cross section to the cable.
• the additional space 21 is made of the same material as that of the outer sheath 4.
• the additional space 21 may be empty, that is to say it may contain no filler material, in order to increase the separation between the conductors.
• Fig. 3 shows a flat cable 30 according to a third embodiment of the present invention.
• This cable 30 comprises two electrical conductors 2a and 2b, a common insulating layer 3 surrounding the two electrical conductors 2a and 2b, and an outer sheath 4.
• the cable has a substantially rectangular outer profile comprising two substantially plane faces 31 and 32 substantially parallel to the plane P comprising the axes of the conductors, and two substantially rounded lateral portions 33 and 34 which are connected to said two faces 31 and 32 .
• the two electrical conductors 2a, 2b are arranged parallel to each other, adjacent to each other and side by side, in the longitudinal median plane P of the cable 30.
• the electrical conductors 2a, 2b are separated by a gap 5 This gap is from about 0.1 mm to about 10 mm.
• the insulator 3 surrounds the two conductors and fills the space 5, which leads to obtaining a common insulating layer 3 in the form of a mechanically secured envelope.
• the insulating layer 3 has an outer contour which substantially matches the outer contour of the envelope of the conductors 2a and 2b, said insulating layer 3 having a thickness which is substantially constant on the extrados of the conductors.
• the material of the insulator 3 is preferably a polysiloxane comprising in particular a silica-type reinforcing filler.
• the insulator 3 comprises a single layer.
• the outer sheath 4, deposited on the insulator 3, is preferably constituted by an EVA optionally comprising fillers such as metal oxides or hydroxides.
• the cable 40 of FIG. 4 differs from that of FIG. 3 in that an additional conductor 2c is introduced inside the insulator 3, in the longitudinal median plane P of the cable 1, and in that the outer profile of the outer sheath 4 substantially matches the outer contour of the insulating layer 3, the outer sheath 4 having a thickness which is substantially constant on the upper surface of the insulating layer 3.
• the cable 50 of FIG. 5 differs from that of FIG. 3 in that the space 5, which separates the adjacent conductors 2a, 2b, is elongated by so that the distance between said conductors is increased so as to reduce the risk of short circuit.
• the space 5 measures, for example, from 0.1 mm to 20 mm.

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• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Insulated Conductors (AREA)

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• 2005
  • 2005-07-29 US US11/989,302 patent/US7829792B2/en not_active Expired - Fee Related
  • 2005-07-29 WO PCT/FR2005/001987 patent/WO2007014983A1/fr active Application Filing
  • 2005-07-29 EP EP05793412A patent/EP1911043A1/de not_active Withdrawn

Non-Patent Citations (1)

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