Abstract: A method and apparatus for forming grooves in a reinforced, thermoplastic filament and for inserting optical fibers in the grooves. The reinforced filament is pulled longitudinally through a die having rollers corresponding to the number of grooves, and the rollers are pressed against the thermoplastic material to form the grooves. The rollers may be at room temperature or may be heated to temperature above room temperature and below the melting point temperature of the thermoplastic material. The fibers are inserted in the grooves as the filament leaves the die and preferably, the filament is wrapped with a binding, e.g. a tape, after the fibers are inserted in the grooves so as to seal the grooves.

Abstract: An electric cable having a fluid-tight, metal sheath containing a plurality of cores without oil ducts, each including a conductor surrounded by insulation, and a separate tubular member adjacent and contacting two of the cores and having an oil duct of a cross-sectional area at least equal to the cross-sectional area of the sum of the oil duct cross-sectional areas normally included in each core. The spaces between the tubular member and the cores and between the cores, the tubular member and the sheath are filled with an insulating filler, and the insulation of the cores and the filler are impregnated with an insulating oil and the duct of the tubular member is filled with the insulating oil. The sheath contacts the outer surfaces of the tubular member and the cores, and the oil duct of the tubular member contains a plurality of longitudinally spaced, oil flow restrictors.

Abstract: In the laying-up of the cores of a multiple core cable in which the cores travel from a plurality of auxiliary platforms rotatably mounted on a main, rotatable platform to a laying-up member, the platforms are rotatable by separate motor drives, one for each platform, and the cores operate position sensors intermediate the auxiliary platforms and the laying-up member so as to speed up or slow down the motor drives for the auxiliary platforms dependent upon the positions of the cores as they pass from the auxiliary platforms to the laying-up member thereby eliminating residual torsion in the cores of the cable.

Abstract: An underwater electric power cable which has a minimum radius of curvature to which it can be bent without damage and which can be suspended between underwater suspension points in no greater than a predetermined length for a desired service life is layed by first laying a flexible steel rope along the desired underwater course and adjusting the rope position and length so that there are no curvatures thereof less than the minimum radius and no lengths thereof greater than the predetermined length, and then, the cable is layed alongside the rope so as to follow the configuration of the rope.

Abstract: Apparatus for inserting optical fibers into helical grooves in a plastic core advanced through a rotatable, rigid body which has conduits for guiding the fibers from bobbins mounted on a rotatable cage into the grooves, the ends of the conduits engaging the walls of the grooves which cause the body to rotate as the core is advanced, said apparatus having drive means for advancing the core separate from the drive means for the rotatable cage and having detecting and control means for detecting angular and direction of rotation differences between the cage and the rigid body and correcting such differences by control of the rotation of the cage by its drive means.

Abstract: A flameproof electrical insulating fluid and an electrical cable impregnated with such fluid, the insulating fluid being a mixture of a polymethylsiloxane having a viscosity greater than 5 centistokes at 25.degree. C. and an aromatic compound corresponding to the chemical formula: ##STR1## where R is an aliphatic radical and said aromatic compound is present in the mixture in an amount from 0.5% to 10% by weight of the total weight of the mixture. Preferably, the aromatic compound is isopropyldiphenyl.

Abstract: A direct current electric cable has its conductor insulation formed by winding a tape of a biaxially oriented polymer provided on at least one face with a film of water-repellent grease.

Abstract: An optical fiber element comprising an optical fiber surrounded and protected from mechanical stresses by three layers of plastic material, the intermediate layer having a modulus of elasticity substantially less than the moduli of elasticity of the adjacent inner and outer layers and less than one Kilogram/mm.sup.2.

Abstract: A direct current, electric, submarine cable which may be used in long lengths and at great depths and which has improved voltage breakdown characteristics with respect to voids which form in the insulation. The cable has a conductor surrounded by an inner semi-conductive screen which is surrounded by cellulose paper tape insulation which is surrounded by an outer semi-conductive screen which is surrounded by a metal sheath. The paper tape is impregnated with a compound comprising a viscous hydrocarbon oil containing a substance having polar groups, the amount of the substance being sufficient to make the volume resistivity of the compound 100 times lower than the volume resistivity of the tape with the compound therein.

Abstract: A submarine electric cable installation in which the cable is protected from damaging stresses to which it would be subjected if it were permitted to be suspended between projections on the water bottom by enclosing the portion of the cable which would normally engage the projections with a tubular stiffening means, the stiffening means having a rigidity greater than the rigidity of the cable and providing a space between it and the cable for cooling water flow. The stiffening means may comprise one or more tube and, preferably, comprises a plurality of tubes having their ends secured to the adjacent ends of other tubes, each tube comprising a pair of C-shaped shells with annular corrugations and secured together. Also, a method of applying the tubes to the cable in which the tubes are applied to the cable, as it is laid, between the laying ship and the surface of the water.

Abstract: Methods and apparatus for forming a cable element comprising a core of plastic material with helical surface grooves containing one or more optical fibers. The core has one or more reinforcing elements resistant to tension and compression and is covered with a covering of tape or thermoplastic. The core is fed to a rigid body having tongues corresponding to and entering into the grooves, and the optical fiber or fibers are fed into the grooves through through-holes in the body which extend from the exterior surface of the body to the tongues and which are inclined with respect to the axis of the core. The core feeding means may be a pay-off bobbin or a core extruder with a threading die, and by increasing the feed rate of the fibers relative to the feed rate of the core or by stretching the core in advance of the rigid body, the lengths of the fibers in the grooves may be longer than the lengths of the grooves.

Abstract: An overhead conductor unit used for transmitting high voltage, alternating current, electrical energy which comprises one conductor or several metallic wires grouped together and a thin plastic cladding, a resin or resin-rubber, around the conductor or wires. The plastic cladding includes at least one conductive composition, generally, carbon black, in an amount of 5-40 parts by weight and at least one hydrorepellent composition present in 1-10 parts by weight. The thus obtained overhead conductor unit reduces, or prevents, corona noises when the unit becomes wet.

Abstract: An overhead conductor unit used for transmitting high voltage, alternating current, electrical energy which comprises one conductor or several metallic wires grouped together and a thin plastic cladding, a resin or resin-rubber, around the conductor or wires. The plastic cladding includes at least one conductive composition, generally, carbon black in an amount of 5-40 parts by weight and at least one hydrophilic composition present in 1-10 parts by weight. The thus obtained overhead conductor unit reduces, or prevents, corona noises when the unit becomes wet.