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EP-3886121-B1 - FIRE-RESISTANT CABLE

EP3886121B1EP 3886121 B1EP3886121 B1EP 3886121B1EP-3886121-B1

Inventors

  • GIACCARELLO, Davide
  • Moda, Alessio

Dates

Publication Date
20260506
Application Date
20200325

Claims (14)

  1. A fire-resistant cable (10) with a cable longitudinal axis (cx), comprising: - at least one conductor or group of conductors (1; 1A, 1B, 1C, 1D); - at least one protection layer (2) formed around and enclosing said conductor or group of conductors (1; 1A, 1B, 1C, 1D); - an inner jacket layer (3) formed around and enclosing said at least one protection layer (2); the at least one conductor or group of conductors (1; 1A, 1B, 1C, 1D), the at least one protection layer (2) and the inner jacket layer (3) forming the core (100) of the fire-resistant cable (10), which is surrounded by an outer jacket layer (7); characterized in that; between the core (100) of the fire-resistant cable (10) and the outer jacket layer (7) at least one shielding layer (4) is formed around the core (100) of the fire-resistant cable (10), which shielding layer (4) is provided with transfer ports (40) that allow transfer of gaseous and/or non-gaseous material emitted by the core (100) of the fire-resistant cable (10); wherein the shielding layer (4) consists of turns of a tape that preferably has a thickness in the range of approximately 0.05 mmm to 0.2 mm.
  2. A fire-resistant cable (10) according to claim 1, wherein the least one protection layer (2) consists of fire resistant material such as solid high-density polyethylene (HDPE).
  3. A fire-resistant cable (10) according to claim 1 or 2, wherein the least one protection layer (2) is formed from turns of a tape preferably wrapped in opposing directions with respect to the cable longitudinal axis (cx).
  4. A fire-resistant cable (10) according to claim 1, 2 or 3, wherein the at least one inner jacket layer (3) consists of plastic material, preferably thermoplastic elastomeric material that protects the inner layers and conductors against mechanical and chemical impact.
  5. A fire-resistant cable (10) according to one of the claims 1 - 4, wherein a plurality of conductors or groups of conductors (1; 1A, 1B, 1C, 1D) are individually contained in the at least one protection layer (2) and are embedded in common in the inner jacket layer (3).
  6. A fire-resistant cable (10) according to one of the claims 1 - 5, wherein at least one outer protection layer (6A, 6B) is enclosing the core (100) of the fire-resistant cable (10), which outer protection layer (6A, 6B) is provided with transfer ports (60A, 60B).
  7. A fire-resistant cable (10) according to one of the claims 1 - 6, wherein the transfer ports (40) of the shielding layer (4) and/or the transfer ports (60A, 60B) of the at least one outer protection layer (6A, 6B) are provided as perforations, holes, weakening lines with material reduction or as slits that will open under pressure.
  8. A fire-resistant cable (10) according to one of the claims 1 - 7, wherein the transfer ports (40) of the shielding layer (4) have a length or diameter in the range from 0.25 mm to 2.5 mm and/or wherein transfer ports (40) cover an area in the range of 1% - 10% of the area of the shielding layer (4).
  9. A fire-resistant cable (10) according to one of the claims 1 - 8, wherein the transfer ports (40) of the shielding layer (4) are arranged in equal distances from one another or preferably in equal distances along a line, such as a helical line extending along the longitudinal axis (cx) or wherein the transfer ports (40) of the shielding layer (4) are arranged in groups in equal distances from one another or in groups preferably in equal distances along a line, such as a helical line extending along the longitudinal axis (cx).
  10. A fire-resistant cable (10) according to one of the claims 1 - 9, wherein the transfer ports (40) of the shielding layer (4) are arranged preferably in equal distances along a line, such as a helical line extending along the longitudinal axis (cx) and inclined thereto by an angle of approximately 120°.
  11. A fire-resistant cable (10) according to one of the claims 1 - 10, wherein the shielding layer (4) consists of plastic or metal or a combination thereof or wherein the shielding layer (4) comprises an inner and/or an outer plastic layer preferably consisting of polyester and a metal layer preferably consisting of aluminum.
  12. A fire-resistant cable (10) according to one of the claims 1 - 11, wherein turns of the tape are helically applied with an overlap between subsequent tape turns in the range of preferably 20% to 30% and wherein the tape comprises the transfer ports (40) preferably arranged on at least one line that extends in parallel, coaxially or offset, to the center axis of the tape.
  13. A fire-resistant cable (10) according to one of the claims 1 - 12, further comprising an electromagnetic shielding layer (5).
  14. A fire-resistant cable (10) according to one of the claims 1 - 13, further comprising at least one additional preferably perforated protection layer or preferably perforated structural element (8, 9) contained in the core (100) of the fire-resistant cable (10).

Description

The present invention relates to a fire-resistant cable. Fire-resistant cables typically comprise a structure of layers that fulfill various functions in order to ensure operability of the fire-resistant cable in case of fire for as long as possible. Such layers may have fire resistant or fire retardant functions or also mechanical functions for maintaining the geometrical structure of the structural elements of the fire-resistant cable. EP0770259B1 discloses a fire-resistant cable with an inner layer of fire-resistant material over which is spirally wrapped an electrically insulating covering tape of an inorganic fire-resistant material with adjacent turns of the tape overlapping one another. EP3301687B1 discloses a fire-resistant cable with a conductor, a first fire-protection layer formed by tightly wrapped tape turns around said conductor, a second fire-protection layer formed by tightly wrapped tape turns around said first fire-protection tape, a conductor insulation layer enclosing said second fire-protection layer and an outer jacket layer surrounding said conductor insulation layer. With tightly wrapping insulation tapes around conductors and protection layers, fire resistance is maintained over a longer period of time up to a point where the cable gets typically instantaneously destroyed and is inoperable. CN110797146A discloses a low-smoke flame-retardant safety communication cable, with conductors that are wrapped with a flame-retardant wrapping structure consisting of a molten flame-retardant material layer, which is coated with an aluminum plastic sheath. The aluminum plastic sheath is enclosed by a porous polyurethane foam plastic heat insulation layer. WO2019085492A1 discloses a high-speed photoelectric composite cable that includes layers woven from a silver-plated copper wire. US4625187A and EP0917242A1 disclose cables which permit the signal carried by the cable to radiate through apertures in the outer conductor. EP0917242A1 states that a common requirement of such radiating coaxial cabled is resistance to flame propagation. In radiating co-axial cable having a foam dielectric, flame propagation may be encouraged if the dielectric melts and escapes through the radiating apertures. The problem of the present invention is to provide an improved fire-resistant cable that in case of fire is maintaining operability for a further extended period of time. The improved fire resistance shall be achieved practically without any additional effort or expenditure. Manufacturing processes and layer material used for conventional cables shall be further applicable. The inventive solution shall be applicable for any cable structure that has been defined according to given requirements and specifications. Further, the inventive solution shall be applicable for any type of cable, including electrical cables and optical cables used for example in the field of telecommunication, or for cables used for the transfer of energy. The problem is solved by a fire-resistant cable according to claim 1. Further preferred embodiments of the fire-resistant cable are defined in dependent claims. The fire-resistant cable, which has a cable longitudinal axis, comprises at least one conductor or group of conductors;at least one protection layer formed around and enclosing said conductor or group of conductors;at least one inner jacket layer formed around and enclosing said at least one protection layer; and which at least one conductor or group of conductors, the at least one protection layer and the inner jacket layer form the core of the fire-resistant cable, which is surrounded by an outer jacket layer. According to the invention, between the core of the fire-resistant cable and the outer jacket layer a shielding layer is formed around the core of the fire-resistant cable, which shielding layer is provided with transfer ports that allow transfer of gaseous and/or non-gaseous material emitted by the core of the fire-resistant cable. Hence, the fire-resistant cable comprises at least one conductor or group of conductors, preferably groups of conductors forming individual cable sections along which electrical or optical signals, such as signals of a communication protocol, or electrical energy is transferred. The individual electrical conductor or the conductors of the group or groups of conductors are preferably made from stranded copper and/or aluminium wires or from a conductive polymer or a superconductor or a carbon steel conductor or a metal alloy. Optical conductors may be made of silica. The at least one protection layer is preferably a fire-protection layer formed around and enclosing the individual conductors or groups of conductors. The protection layer is preferably made from plastic material having excellent dielectric constant property as normally used for insulating of conductors. Preferably, the protection layer is made from solid high-density polyethylene (HDPE). This material may be self-extinguishable or