A cable 2 has an outer sheath on which a layer of selectively activatable material such as a layer of thick-film conductive polymer is sprayed to form a resistive element. A layer of thermochromic ink is printed on top of this. Electric current passed through the resistive element provides heating to the ink and causes it to warm and change color.

An electrically powered tool down in a borehole is suspended from a cable that also supplies electrical power to the tool. The cable has a conducting member of sufficient tensile strength to support the majority of the weight of the tool and an insulating layer surrounding the conducting member.

A cable for dielectric optical waveguides has the dielectric optical waveguides arranged in segmented compartments. Tensile members are provided in the core of the cable and/or externally of the segmented compartments. This particular cable construction prevents the dielectric optical waveguides being subjected to excessive tensile stress.

A cable comprises at least one layer of strands (10) with each strand covered with an individual sheath (20) of rubber or plastics material. The sheaths are so shaped (16, 17, 18) that the sheaths of adjacent strands interlock. This provides a layer in which the strands have a generally fixed spatial relationship both to each other and within the cable. This reduces inter-strand forces, so increasing cable life, and also provides a dimensionally stable cable.

An article of manufacture comprising (i) a plurality of electrical conductors, each surrounded by one or more layers of a composition comprising (a) one or more polyolefins and, blended therewith, (b) a mixture containing one or more alkylhydroxyphenylalkanoyl hydrazines and one or more defined functionalized hindered amines; and (ii) hydrocarbon cable filler grease within the interstices between said surrounded conductors.

Disclosed are durable corrosion resistant wellbore electrical cables including a coated electrical conductor, a polymeric protective layer for trapping coating flakes, a first insulating jacket disposed adjacent to the polymeric protective layer and having a first relative permittivity. A second insulating jacket is disposed adjacent to the first insulating jacket and has a second relative permittivity that is less than the first relative permittivity. Another aspect of the invention is a method...

A cable construction comprises the following components: (i) a plurality of insulated electrical conductors having interstices therebetween, said insulation comprising (a) one or more polyolefins selected from the group consisting of polyethylene, polypropylene, and mixtures thereof, and, blended therewith, (b) a mixture containing one or more alkylhydroxy-phenylalkanoyl hydrazines and one or two functionalized hindered amines; (ii) hydrocarbon cable filler grease within the interstices; and (ii...

A cable construction comprising the following components: (i) a plurality of insulated electrical conductors having interstices therebetween, said insulation comprising (a) one or more polyolefins selected from the group consisting of polyethylene, polypropylene, and mixtures thereof, and, blended therewith, (b) a mixture containing one or more alkylhydroxy-phenylalkanoyl hydrazines and one or two functionalized hindered amines; (ii) hydrocarbon cable filler grease within the interstices; and (i...

A duct for electrical cables comprises a plurality of filiform elements arranged substantially parallel to one another according to the longitudinal development of the duct. The duct of the invention includes, for at least a portion of its length, a plurality of structural modules, which are arranged in a transverse direction with respect to said filiform elements and are set at a distance from one another in succession according to the longitudinal development of the duct. The supporting module...

An article of manufacture comprising (i) a plurality of electrical conductors, each surrounded by one or more layers of a composition comprising (a) one or more polyolefins and, blended therewith, (b) a mixture containing one or more alkylhydroxyphenylalkanoyl hydrazines and one or more functionalized hindered amines; and (ii) hydrocarbon cable filler grease within the interstices between said surrounded conductors.