Societa Cavi Pirelli S.p.a.

Industrie Pirelli S.p.a.

Pirelli Cavi E Sistemi S.p.a.

Gianmario Lanfranconi

Bernardino Vecellio

Gianni Miramonti

Giuseppe Monti

Giorgio Grasso

Paolo G Priaroggia

Franco Peruzzotti

Claudio Bosisio

Enrico Dotti

Bruno Parmigiani

Carlo Marin

Piero Metra

Elio Occhini

Andrea Borroni

Pietro Metra

Mass-impregnated electrical cable, particularly for carrying high voltage direct current, having an insulation in which, around the insulating layer impregnated with an insulating fluid, a containing layer is provided broadly includes at least one winding of a tape of a semiconducting elastomeric material, which exerts an effective action of containing the insulating fluid, while preventing formation of micro-cavities within the impregnated insulating layer. The material constituting the tape has high physical-chemical resistance to the degrading action of the components of the insulating fluid, both in the cold state and, in particular, at the operating temperature of the cable.

High voltage direct current electrical cable with mass-impregnated insulation

A cable for conveying both electrical power and optical signals, the cable having an electric conductor with insulation therearound, a sheath around the insulation, a one or two part protective layer around the insulation, a tube within the protective layer and at least one optical fiber loosely received in the tube. The protective layer can have armoring therearound and in this case, the radial thickness of the protective layer is from two to four times the diameter of the tube.

Combined electrical power and optical fiber cable

A direct current electric cable with a conductor, a semi-conductive screen around and contacting the conductor, a plurality of layers of insulation formed by tapes of insulating material around the semi-conductive screen, a further semi-conductive screen around the layers of insulation and a metal sheath around the further semi-conductive screen, the layers of insulation being impregnated with a non-migrating, insulation composition having a dropping point temperature at least 5.degree. C. above the maximum operating temperature of the cable and having an electronegative gas dissolved therein, the gas having a coefficient of diffusion in the composition in the range from 3.times.10.sup.-5 to 3.times.10.sup.-6 cm.sup.2 /sec at temperatures below the dropping point temperature of the composition.

Direct current cable insulation with insulating composition including

A granulator for forming granules of cross-linkable plastic compounds in which a screw extruder extrudes the compound into the smaller diameter end of a funnel-shaped, annular conduit, the other end of the conduit facing a die with circular arrays of through-holes. The compound which passes through the through-holes is cut into granules by rotating blades having air nozzles which remove particles of the compound from the blades. The granules are received in a chamber from which they are removed pneumatically. Where the annular conduit meets the die, there are channels within and outside of the arrays of through-holes which lead to the outside of the granulator and which provide conduits for removal of compound which does not directly impinge on the entrances of the through-holes which are specially shaped to avoid accumulation of the compound between the through-holes.

Granulator for cross-linkable plastic

Joint for cables with an extruded insulation

A joint between a pair of electrical cables of different types, such as an oil filled cable and a cable with extruded insulation. Both cable ends have tapered insulation and stepped layers outwardly of the insulation and the conductor of one cable is mechanically and electrically connected to the conductor of the other cable by a rod surrounded by a body of insulation. Portions of the insulation at opposite ends of the body and the tapered insulations are respectively covered by insulation applied thereto during installation of the joint. The tapered insulation of the oil filled cable is enclosed by a housing in fluid tight engagement with the body and the sheath of the oil filled cable and filled with the oil of the oil filled cable. The insulation surrounding a portion of the body and the tapered insulation of the cable with extruded insulation is adhesively bonded to such portion of the body.

Joint for interconnecting two electrical cables of different types

In laying an electric cable underwater, the finishing end of the cable is brought ashore by laying the cable end portion (from the cable laying ship) along a course parallel to the shore and as close to the shore as the ship can reach, then pulling the cable end to shore using a rope, pulling the cable end along the shore to the intended landing point, and then pulling the cable end in-land along the intended laying line until the whole cable is positioned along this line. Buoyancy devices are attached at intervals to the cable end portion for the duration of the landing process, to facilitate the sliding movement of the cable over the bottom.

Process for bringing ashore the ends of underwater cables at arrival

Method and apparatus for replacing flammable, insulating oil in an oil-filled electric cable by non-flammable, insulating oil in which the flammable oil is withdrawn at least from the cable oil duct under vacuum and with heating of the cable to its maximum operating temperature and thereafter, the flammable oil which was withdrawn is replaced by non-flammable oil. During operation of the cable, oil which flows out of the cable during heating of the cable is sent to a first reservoir, through a check valve and during subsequent cooling, such oil is replaced by non-flammable oil from a second reservoir containing non-flammable oil and connected to the cable duct by a check valve. Also, an oil-filled cable having its insulation impregnated with flammable, insulating oil or a mixture of such oil with non-flammable, insulating oil and having an oil duct filled with a non-flammable, insulating oil which is different from the flammable oil.

Method and apparatus for replacing flammable oil in an electrical cable

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.

Process for laying a submarine cable

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.

High voltage direct current cable with impregnated tape insulation

A product by process for reducing micro-voids in cross-linked cable insulation without reducing the voltage breakdown strength thereof in which process the insulation, after cross-linking, is heated at a temperature in the range from about 120.degree. C. to about 150.degree. C. and under a pressure less than 10 mm. Hg for a period from about 8 hours to 48 hours. Also, a cable having such insulation which has micro-voids less than about 10.sup.2 per mm.sup.3 and a perforation gradient greater than the perforation gradient of a cable which has not been so treated.

Electric cables of reduced micro-voids in the extruded insulation

A process for reducing micro-voids in cross-linked cable insulation without reducing the voltage breakdown strength thereof in which process the insulation, after cross-linking, is heated at a temperature in the range from about 120.degree. C. to about 150.degree. C. and under a pressure less than 10 mm. Hg for a period from about 8 hours to 48 hours. Also, a cable having such insulation which has micro-voids less than about 10.sup.2 per mm.sup.3 and a perforation gradient greater than the perforation gradient of a cable which has not been so treated.

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Trezzo d'Adda, Italy

Gianmario Lanfranconi