摘要:
A mineral insulated electric cable which incorporates a hydrophobic substance has, within the sheath, an additive material. This material may either 1) release carbon dioxide on reaching a predetermined temperature or 2) react with the hydrophobic material (or the degradation products thereof) or 3) react to produce oxygen. The hydrophobic material is commonly a silicone.
摘要:
This invention relates to a sealing composition for a mineral insulated electric cable termination. The sealing composition includes an inert filler such as silica flour, a low vapour pressure organic material such as a polyphenyl ether and an aerosil. This composition has improved slump resistance at high temperatures with little run out and no tendency to crack at 250°C.
摘要:
A joint formed between insulated conductors (2) of two power cables, comprising : means (4) interconnecting the conductors (3); a sleeve (5) surrounding the interconnected conductors and having ends projecting over the cable insulation to define at each end an annular gap therebetween; an insert (6) incorporated along part of the internal surface of the sleeve intermediate its ends and in electrical contact with the interconnected conductors; and a material encapsulating the joint and filling the said annular gaps; the sleeve and the encapsulating material being electrically insulating and substantially less electrically conductive than the insert.
摘要:
Système de protection d'un câble à haute tension et à courant continu, dans lequel un câble de transmission possède une polarité normale par rapport à la terre déterminée par un sens d'écoulement normal du courant. Dans l'éventualité d'une défaillance, une onde de surtension réfléchie sur la ligne peut dans certains cas donner une tension de polarité inversée à 100 % sur la ligne, ce qui provoque des dégâts du câble sauf s'il a été conçu pour supporter une telle inversion de tension (à des frais supplémentaires considérables). Selon l'invention, un redresseur à diode est connecté entre les lignes à chaque extrémité du câble dans un sens tel qu'il est polarisé de manière inverse en fonctionnement normal. Une tension inverse sur la ligne est donc limitée à la chute dans le sens direct de la diode. Comme cela provoquerait un courant de défaut de la diode très important, une résistance est montée en série avec la diode pour limiter le courant même si c'est au sacrifice d'une petite tension inverse.
摘要:
In the manufacture of a glass optical fibre preform by the chemical vapour deposition of a coating of oxide material on the surface of an elongate glass substrate (1), in particular silica and one or more dopant oxides on a vitreous silica substrate, a perforated tube (3) is disposed coaxially with the substrate (1), providing an annular reaction space between said tube (3) and the substrate (1), and at least the oxide precursor vapours, such as halides, are passed through the perforations (11) into the reaction space (5), and oxygen, optionally with an additional carrier gas, is also introduced into said space. The substrate (1), which may be a tube coated internally or a seed core coated externally, is maintained at an elevated temperature, and the coating forming reaction is caused to take place in the annular space (12) by generating energy in the space, so that a coating is formed simultaneously on the whole of the substrate surface. The energy for activating the reaction may be produced by a plasma, or a laser beam, and/or external or internal heating, and/or gas combustion in the reaction space.
摘要:
A method of forming electrical insulation comprises spraying on to a surface both a bonding material and flakes of an insulating material, more especially mica flakes having a maximum dimension significantly smaller than 1 mm, so asto form a mixture of the materials, and treating the mixture to form a compact coherent layer on the surface.
摘要:
A length of filament, such as wire or optical fibre, is loosely coiled on a flat carrier, in the form of a figure of eight the lobes of which are laid respectively in clockwise and anti- clockwise directions. The coil is formed by feeding the filament (41) downwards on to the carrier through a guiding arrangement which causes the downward path ofthefilament to rotate alternately in clockwise and anticlockwise directions. The guiding arrangement may be a figure of eight shaped double ring structure, with further guide members within the rings, or a gimbal-mounted guide member (42) which is oscillated, by two sets of reciprocating means (65, 66), about two horizontal axes at right angles to one another.
摘要:
An electrical connector for joining two or more electrical conductors, comprising a heat-shrinkable sleeve coated on at least part of its inner surface with a conductive polymer.