Abstract: A photopolymerisable system is disclosed which can be polymerised by exposure to UV light, for example, to form a solid, light-transmitting sheet material having volume refractive index variations defining an optical diffuser or a hologram, for example. The system includes a silicone monomer, prepolymer, macromonomer or co-monomer capable of undergoing free radical initiated polymerization and further includes a photoinitiator.

Abstract: A photopolymerisable system is disclosed which can be polymerised by exposure to UV light, for example, to form a solid, light-transmitting sheet material having volume refractive index variations defining an optical diffuser or a hologram, for example. The system includes a silicone monomer, prepolymer, macromonomer or co-monomer capable of undergoing free radical initiated polymerization and further includes a photoinitiator.

Abstract: A light diffuser, hologram or other light modifying structure is manufactured by exposing to UV light, a layer, on said substrate, of a photopolymerisable system which includes a silicone monomer, prepolymer, macromonomer or co-monomer, either the silicon monomer or another monomer in the system being ethylenically unsaturated and the system further including a photoinitiator so that the system is capable of undergoing free radical initiated polymerization, upon exposure to UV light to form a light diffusing sheet or hologram, for example. The method, when used to form an optical diffuser may include exposure of the system through an optical aperture mask or may simply comprise blanket exposure directly to UV radiation without the interposition of an optical mask.

Abstract: A reflective diffuser of light in one embodiment comprises an extruded, drawn, rolled or otherwise stretched or extended sheet comprising a matrix of a first plastics material incorporating inclusions of a second, different material, substantially insoluble in the first material, resulting in small scale surface irregularities on at least one surface of the sheet. The textured surface having such irregularities is rendered reflective or partly reflective, for example by metallisation, eg. by vapour deposition or other particle deposition of metal, such as vacuum sputtering. By controlling the extent to which the sheet is stretched preferentially in one direction during manufacture, the extent to which the diffuser has asymmetric diffusing properties can be readily controlled. Instead of metallising the extended sheet itself, the textured surface of the latter may be used as a mould or die surface for the production of a textured surface on another, eg.

Abstract: A light reflecting and light diffusing sheet material useful, inter alia, as a back-reflector for liquid crystal displays (LCDs), comprises a sheet of light diffusing material having a light reflecting coating or backing. In a preferred embodiment, the reflective backing comprises a light-reflecting sheet formed separately from the light-diffusing sheet and juxtaposed with a rear surface of the sheet.

Abstract: An electrical insulator comprising a cylindrical core (2) of an insulating refractory material, such as porcelain, onto a portion of the curved surface of which a sleeve (8) of insulating polymeric material is fitted. Metal end-caps (4), for electrically connecting the insulator, are fitted to the ends of the porcelain core such that there is an exposed portion (10) of the curved surface of the core between the sleeve and each end-cap. Thus, any damaging electrical activity which takes place at the metal end-caps is directed primarily onto the surface of the porcelain core (2), and not onto the surface of the electrically vulnerable polymeric sleeve (8), which serves to protect mechanically the relatively brittle porcelain core. Optionally, the polymeric sleeve (8) may have a convoluted or a shedded outer surface (12) to increase the leakage path length of the insulator, or to prevent the formation of a continuous moisture path, or both.

Abstract: The invention provides a high voltage capacitor suitable for measuring the voltage of an overhead power line. The capacitor dielectric is mounted directly on to the power line conductor, which serves as one electrode of the capacitor. The other electrode of the capacitor is mounted on to the outer surface of the dielectric, and is protected at each side by a guard ring. Stress control is provided between the outer capacitor electrode and the guard rings and also at the outer edges of the guard rings. The capacitor may be enclosed in an earthed housing, which can contain one or more current transformers. The apparatus can be used for fault detection and location, and may be used in combination with a power cable or a switch.

Abstract: The invention provides an electrical insulator comprising a cylindrical core (2) of an insulating refractory material, such as porcelain, onto a portion of the curved surface of which a sleeve (8) of insulating polymeric material is fitted. Metal end-caps (4), for electrically connecting the insulator, are fitted to the ends of the porcelain core such that there is an exposed portion (10) of the curved surface of the core between the sleeve and each end-cap. Thus, any damaging electrical activity which takes place at the metal end-caps is directed primarily onto the surface of the porcelain core (2), and not onto the surface of the electrically vulnerable polymeric sleeve (8), which serves to protect mechanically the relatively brittle porcelain core. Optionally, the polymeric sleeve (8) may have a convoluted or a shedded outer surface (12) to increase the leakage path length of the insulator, or to prevent the formation of a continuous moisture path, or both.

Abstract: The invention is a wire-stripping arrangement having recoverable material preferably in the form of heat-recoverable metal which is arranged to be capable upon recovery of cutting into the wire insulation and then to strip the insulation.

Abstract: A fibre optic cable is helically wound on to an overhead high voltage conductor, and has an electrically non-tracking outer jacket and is filled with protective material, or has a conductive outer jacket. The cable is guided off the conductor inside a conductive housing, and then to earth potential along the inside of a non-tracking shedded or convoluted tube.

Abstract: This invention relates to a clamp assembly for connecting the metal armor, screen or shielding of one power cable of a joint connecting two or more power cables, with a metal bridging element which spans the joint and is connected to the metal armor, screen or shielding of the other power cable or cables of the joint. The clamp assembly comprises a hollow metal cylinder, means for sealing the cylinder to the inner sheath of the power cable and first and second clamping means for securing the metal armor, screen or shielding of the cable and for securing the metal bridging element to the metal cylinder. The metal bridging element can be a part of a protective joint enclosure placed over the joint area.

Abstract: The substantial change in modulus with temperature of certain materials, especially memory metals, is used to make a novel connector by forcing a band made from such a material in its low modulus state up an external tapered portion of a tubular coupling member so as to deform the band which remains in position about the coupling member. To make a connection one or more substrates is(are) positioned inside the tubular coupling member and the band is brought to its high modulus state whereupon it contracts and deforms the tubular coupling member and forces it into firm connection with the substrate.

Abstract: A device for forming a mechanical and/or electrical connection between a plurality of elongate objects 1, 2, for example bus bars in electrical switchgear, comprises one or more inserts or shell members 9, 10 that can be positioned about the ends of the objects to form a tubular assembly extending between the objects.One or more memory metal drivers in the form of bands or rings 7, 8 may be provided for retaining the tubular assembly in position and forcing the shell portions against the objects 1, 2 so that a good electrical contact is formed. Preferably an annular protuberance or contact surface 12 is provided on the internal surface of the shell members 9, 10 at each end thereof, and are preferably arranged so as to be partly flattened as the bonds or rings 7, 8 contract, thereby increasing the contact area between the shell members and the objects 1, 2.

Abstract: A re-enterable cable jointing connector for electrical power distribution network cables and the method of using the connector to isolate cables physically and chemically one from another, the connector having at least two current carrying elements, each having at least three connection portions to which the individual cable cores may be attached, and having an electrically insulating body. The insulating body substantially surrounds the current carrying elements and extends at least up to the connection portions, thereby electrically insulating the current carrying elements from one another and interfacially isolating the cables from one another. Cables which are size, configuration or material incompatible may be jointed. Power cables may be optionally provided with in-line joints, branch joints or service connections by means of this compact connector.

Abstract: An enclosure for a shielded cable termination or joint comprises a protective sleeve comprising a conductive outer layer (51), an insulating inner layer (52), advantageously of substantially uniform cross-section for at least a portion of its length, and optionally a stress grading innermost layer (53). At least the insulating layer (52) and/or the stress grading layer (53) overlaps the or each cable shield, in the case of the insulating layer by an amount at least equal to the thickness of the portion of the insulating layer overlapping the cable shield end. Preferably the sleeve is installed by heat recovery.

Abstract: The substantial change in modulus with temperature of certain materials, especially memory metals, is used to make a novel connector by forcing a band made from such a material in its low modulus state up an external tapered portion of a tubular coupling member so as to deform the band which remains in position about the coupling member. To make a connection one or more substrates is (are) positioned inside the tubular coupling member and the band is brought to its high modulus state whereupon it contracts and deforms the tubular coupling member and forces it into firm connection with the substrate.

Abstract: A heat-recoverable article comprises a memory metal member to which has been imparted both thermally-recoverable and resiliently-recoverable strain. The resilient strain is retained by means of a disburdenable keeper, preferably one made from fusible or chemically degradable material, which can be removed, for example, by heating or chemical treatment, to allow resilient recovery. The article is preferably so constructed that it can be heated to obtain both thermal and resilient recovery simultaneously. One preferred form of article is a radially expanded longitudinally split tube, the keeper being positioned in the split. Such an article can be used as a connector to secure an earth lead to the sheath of a mineral-insulated cable.

Abstract: A dimensionally-recoverable article comprising a hollow resilient member which has been expanded to a dimensionally unstable configuration in which it is retained by a keeper positioned between and separating two parts of the hollow member away from the path of recovery thereof. The keeper is preferably made from a fusible or chemically degradable material so that it can be removed, for example, by heating or chemical treatment to allow the hollow member to recover towards its original configuration. One preferred form of article is a radially-expanded longitudinally split tube having the keeper positioned within the split. Such an article may be used as a connector to secure an earth lead to the sheath of a mineral-insulated cable.

Abstract: The effective transition temperature from martensite to austenite in a dimensionally heat-recoverable memory metal member can be temporarily raised by applying a stress and maintaining the applied stress at a temperature below the raised transition temperature so that the memory metal remains substantially in the martensitic state. When it is desired to utilize the member the stress is removed at a temperature above the original transition temperature. The applied stress is advantageously maintained by a disburdenable keeper. In an especially preferred embodiment the keeper comprises an aluminium tube positioned within a band or tube made from a brass memory alloy, the combined article being suitable as a connector for hydraulic pipes and the like.

Abstract: A hollow structure for use as an electrical insulator or other similar structure having outwardly disposed flanges extending circumferentially thereabout. The hollow structure includes a hollow member of heat recoverable material positionable about a central insulator core, electrical conduit, fuse or other substrate. The outwardly extending flanges are integrally formed with the hollow member and extend radially therefrom in the dimensionally heat stable state. The hollow member is designed to be expanded to a heat recoverable state for later facile positioning about an appropriate substrate. The hollow member may then be heat recovered about the substrate to become securely positioned thereon. Proper selection of the hollow member as to its dimensionally heat stable inner diameter relative to the inner diameter of the substrate results in control of the orientation of the flanges once the hollow structure has been recovered about the substrate.