OPTIC FIBRE CABLE

Abstract: The optic fibre cable for transmission networks, the inside structure of said cable, being envelopped by the outer sheath (7), consists of the central tube (2) in which at least one optic fibre (1), with protection, is situated. Further, said structure consists of a tensile element, having a form of the bedding (3), and/or of the strand (4) and of the filling cover (5). On the filling cover (5), under the outer sheath (7), the fire-blocking layer (6) is situated which consists of glass-textile ribbon and/or metallic foil.

Description: Optic fibre cable Field of technics The invention relates to an optic fibre cable which is detennined for transmission networks. Prior state of the art The hitherto known optic fibre cable designs do not contain any layer which would block the fire by means of its features. Consequently, the fire protection for a wiring system, and therefore die systems functional capability, has been solved by a reserve cable putting on other place. Such a way of solution is expensive as to costs and technical realization. Another form of optic fibre cable fire protection means its placing into protective metal tubes. With this way of protection solution, the design of the cable as such, is known. A certain fire protection form means structural reinforcing of the outer cable thermal insulation where only the time limited protection is taken into account. Essence of the invention The optic fibre cable, the inside structure of which is wrapped round by outer sheath, consists of a central tube containing at least one optic fibre with a protection. Further, it consists of a traction element in a form of a bedding and/or a strand and of a filling cover. The essence of the design is rooted in that a fire blocking layer is located on the filling cover, under the outer cable sheath. This consists of a glass-textile ribbon or of a metallic foil or of a combination of them, respectively. The advantage of the optic fibre cable desing solution, according to the invention, means increased blocking against the flame propagation. This is rooted in enhancing the effectivity against fire spreading along the cable because the fire blocking layer inhibits the simultaneous burning of both outer and inside cable layers. This has been achived by separating both outer and inside inflammable materials of a cableby means of a non-combustible one or by fire blocking one, respectively. Survey of figures on drawings The cable design, according to the invention, is explained on Fig. 1 where the cable is demon- straded in cros-section and in elevation with layers. Examples on invention realization Example 1: An optic fibre cable has been made which has five optic fibres I, with a protection, loosely situated in the central tube 2. On the outer surface of the central tube 2, the bedding 3 is located in order to secure a sufficient mechanical stiffness as to tensile stress. On the bedding 3, consisting of aramid fibres, two strands 4, made of glass-laminate, are situated for tensile stress transmission and on said strands the filling cover 5 is layed. On the filling cover 5, made of a halogenless material, the fire-blocking layer 6 is located which is formed of a combination of copper metallic foil on which a glass-textile ribbon is fitted. This whole inside cable structure is envelopped by the outer sheath 7 made of halogenless material, as can be seen on Fig. 1. Example 2 The optic fibre cable has the single optic fibre j_, with a protection, located in the central tube 2. The inside cable structure is conforming with the one, given in preceding example, with the difference that the fire-blocking layer 6 consists of the wounded-around aluminium metallic foil only. On it the outer cable shieth 7, made of P.V.C., is located. Example 3 The optic fibre cable, according to the invention, has also five optic fibres I located in a central tube 2. In this case, the tensile element consists of two strands 4 only and the fire-blocking layer 6 consists of glass-textile ribbon formed by glass fibres connected by a textile coupling. The whole structure is also envelopped by outer cable shieth 7. The cable structure functioning, according to the invention, is such that during fire the organic layers gradually burn down and, at the same time, the ashes layer develops. The thennal resistance of this developping layer reduces the final optic fibre temperature and, meanwhile, does not influence die propre function of the glass cable or the optic fibre one, respectively, i.e. the light transmission. Utilization in industry The optic fibre cable, according to the invention, is determined for indoor as well as outdoor installations where an eventual fire could cause a putting out of service of connected systems or narrowing their functioning. It can be used advantageously in control and supervisory systems of technological plants especially in nuclear as well as conventional power plants, in tunnel and underground traffic, in air traffic and health matters and further in telecommunications, cable television and computer networks.

Claims: PATENT CLAIMS 1. The optic fibre cable for transmission networks, the inside structure of said cable, said structure being envelopped by the outer sheath (7), consists of the central tube (2) in which at least one optic fibre (1) with protection, is situated, said structure further consists of a tensile element, having a fonn of the bedding (3), and/or of the strand (4) and of the filling cover (5), characterized in that, die fire-blocking layer (6) is situated on the filling cover (5) under the outer cable sheath (7). 2. The optic fibre cable of Claim 1, characterized in that, the fire-blocking layer (6) consists of glass-textile ribbon and/or of metallic foil.

Inventors: KUPILIK PAVEL, KUPILIK, PAVEL
Applicants: KUPILIK PAVEL, KUPILIK, PAVEL
Application year: 1998
Main classification: G02B6
IPC codes: G02B6, H01B7