Flexible fibre optic cable.

The invention relates to an optical cable according to the preamble of claim 1. In excavators and conveyor belts, which constitute portable power consumer, not only the power supply via flexible cable must be ensured, but also the transmission of information. Information today is transmitted via optical fibers, because they are economical and unrivaled in terms of noise immunity.

The invention has for its object to provide a longitudinally watertight, metal-free and flexible optical cable containing a reinforcement to protect the message part against external damage. This object is achieved in an optical cable of the type mentioned according to the invention by the features listed in the characterizing part of claim 1.

Areas of application of the invention are preferably of opencast mining where the cable can be used as a highly flexible, mobile cable. In particular, the cable against penetrating sweat, which may arise during welding, protected. The cable must be in particular metal-free, as it should be routed together with power cables.

The cable consists of a central strength member, by up to 8 optical conductors can be stranded. The cable core is filled to the longitudinal water tightness example with petrolatum and surrounded by a Glaszugentlastung. The shell forms an approximately 2 mm thick polyurethane layer, whereby the cable has a total of about 10 cm thickness. to give a low flexural stiffness in the loose, meandering laying order the cable, a plastic encased, high tensile strength, but soft and non-elastic yarn is used as a central tension member. Due to the fact the optical fiber is enclosed with a solid shell, which rests directly on the fiber and has about 0.9 mm diameter. This low cross-sensitivity to pressure and therefore a low influence of compressive forces is achieved on the fiber attenuation. These veins are relatively loosely stranded with short blow to the central element in order to ensure the appropriate fiber storage in the cable under tension and thermal stress. The cable core is preferably filled with petrolatum and amplified by a two-ply layer of strength members of glass filament and upholstered simultaneously. This two-layer armouring is designed with respect to the lay length that the cable remains torsion at traction. Nevertheless, it is very easy to bend.

The jacket was made of polyurethane (PUR). This material is excellent in abrasion resistance, oil resistance and cold bend expensive than polyvinyl chloride (PVC) and was adjusted with respect to the flame retardant mixture. In particular, this mixture is resistant to sweat, so that welding work carried out in the vicinity of the cable can werder.