Abstract: A circuit protection device for protecting an electrical circuit from a voltage transient, e.g. a voltage transient caused by an electrostatic discharge, lightning or a nuclear electromagnetic pulse, comprises a threshold switching element formed from an amorphous composition comprising germanium, selenium and optionally antimony, and a pair of electrodes in contact with the composition. The devices generally exhibit a good balance of physical properties including switching speed, energy required to latch them in their low resistance state, high resistance state (off) resistance, threshold voltage and capacitance, which enables them to be used successfully to protect electrical circuits from such transients.

Abstract: A marker assembly 1 comprises a support layer 2 that has a surface which is provided with a porous coating 3 of a curable material, e.g. a particulate epoxy coating. The coating may be printed on using for example an ink jet printer to form indicia 6, and may be cured after the indicia have been formed in order to render them substantially indelible. The opposite side of the support layer 2 may be provided with suitable means for supporting the maker on a surface, e.g. a layer 4 of adhesive. The marker may be formed from a dimensionally stable or dimensionally heat-recoverable material.

Abstract: An article for protecting a multiconductor connector comprising a container containing a layer of gel. In one embodiment the container can be moved relative to the container to compress the gel to seal the connector. In another embodiment the gel layer contains a plurality of holes which tend to close when the gel is compressed.

Abstract: A high voltage connector is provided for interconnecting a power cable to an apparatus such as a transformer. The cable is securely coupled to the connector, which is then mounted on to the transformer bushing. The bushing and cable electrical contacts inside the connector are spaced apart, and electrical connection is achieved therebetween by inserting a continuity plug into a socket of the connector. Electrical isolation between the cable and transformer may be effected without physically moving either piece of equipment, by removing the continuity plug and replacing it with another plug that introduces sufficient electrical insulation between the equipment contacts to allow operating and test voltages to be applied to one of the cable and transformer without flashover occurring to the other of said pieces of equipment. Other interchangeable plugs may provide earthing for a selected one of the pieces of equipment, also without requiring physical movement of the equipment.

Abstract: A circuit protection device comprising a chalcogenide glass threshold switching element connected or arranged to be connected between a current carrying line and earth, and a capacitor connected in a series with the switching element.

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: Cohesive flexible curable adhesive coatings formed from a dispersion of first and second powdered curing components, preferably reactive at ambient temperatures, in a solution of a binder, the binder content being not more than 15%, preferably not more than 2.5% by weight of the dried composition. Also claimed are curable compositions having a specific advantageous reactive particle size distribution; specific epoxy-amine adduct curing agents; and specific polyalkylene oxide binders.

Abstract: A method for the preparation of a variety of engineering polymers and copolymers, in particular aromatic polymers and copolymers which comprises reacting a stannylated reactant containing a first monomeric or polymeric moiety with an electrophilic reactant, usually a di(acid chloride) containing a second monomeric or polymeric moiety. The intermediate and second compound react by way of a condensation reaction to eliminate the tin and polymerize together the first and second moieties. Some novel polymers and copolymers can be prepared using this method.

Abstract: Friedel Crafts preparation of arylene ether (especially arylene ether ketone) oligomers with an exceptionally high degree of isomeric purity and freedom from by-products can be achieved by adding to the Lewis acid reaction system a protic controlling agent selected from ROX, water, RCOOX, RSO.sub.3 X, and ROY, wherein R is organic, X is hydrogen or metal, and Y is metal.Contrary to conventional expectation, the protic agent does not significantly acylate or alkylate the Friedel Crafts reaction product, and controlling agents of relatively low molecular weight, e.g., benzoic acid, can surprisingly be selected to produce dispersions of the resulting oligomers.

Abstract: Friedel Crafts preparation of arylene ether ketone polymers with an exceptionally high degree of isomeric purity and freedom from by-products can be achieved by adding to the Lewis acid reaction system a protic controlling agent selected from ROX, water, RCOOX, RSO.sub.3 X, and ROY, wherein R is organic, X is hydrogen or metal, and Y is metal. Contrary to conventional expectation, the protic agent does not significantly acylate or alkylate the polymer, and agents of relatively low molecular weight, e.g. benzoic acid, can be selected to produce dispersions of the resulting polymers. The controlling agent also apparently acts to maintain the polymer in solution until a desired molecular weight is reached.

Abstract: Organic compounds having functional groups such as aromatic ester, thioester, or carbonate groups are prepared by reacting an organometallic reactant where the metal is gallium, indium, thallium arsenic, antimony, or bismuth, with a suitable second reactant. For example, the ester ##STR1## can be prepared by reacting an organometallic derivative of hydroquinone with p-phenoxybenzoyl chloride.

Abstract: A high voltage insulator that has a helical configuration in which successive turns are axially spaced apart, and an exposed surface of insulating and substantially non-tracking material. The helical configuration provides a long creepage path length and an ability to shed water. The insulator is sufficiently rigid for it to provide a support, for example, for a high voltage cable or for a fibre optic cable.

Abstract: Polyaryletherketones are synthesized by Friedel-Crafts chemistry using a catalytic quantity of a strong acid (e.g. trifluoromethanesulphonic acid) in a solvent of lower acidity preferably comprising a second acid of strength at least equal to chloroacetic acid. Suitable second acids can be recovered for reuse, and only a small (catalytic) amount of the expensive strong acid is required.

Abstract: Melt-extruded polymeric electrolyte material for electrochemical power cells may be coextruded with other components of the cell, notably a lithium metal anode.

Abstract: High frequency attenuation cable has a core surrounded by an EMI shielding layer. The core comprises at least one inner conductor, at least one high frequency absorption layer or non-amorphous magnetic metal tape surrounding, but not necessarily adjacent to, the inner conductor, and at least one dielectric layer surrounding, but not necessarily adjacent to, the inner conductor.The constructions according to the invention enable improved attenuation at frequencies in the range of 10-100 MHz.

Abstract: An arrangement for protecting an electrical circuit from a voltage transient having a fast rise time, e.g. in the order of 20 Vns.sup.-1 comprises a number of semiconductive threshold foldback switching elements preferably formed from a chalcogenide glass, in parallel with one another between the current carrying line of the circuit and earth. An additional, non-linear, circuit protection device is connected in parallel with the switching element between the current carrying line and earth, in order to pass high frequency components of the transient to earth.

Abstract: An arrangement for protecting an electrical circuit from a voltage transient having a fast rise time, e.g. in the order of 20 Vns.sup.-1 comprises a number of semiconductive threshold foldback switching elements, preferably formed from a chalcogenide glass, in parallel with one another between a current carrying line of the circuit and earth. One or more capacitors are connected in series with the switching elements between the current carrying line and earth in order to prevent any direct currents in the current carrying line holding the switching elements in their low resistance state.

Abstract: A curable sheet comprising first and second curing reactants arranged in discrete areas of the sheet, preferably by coextrusion, in patterns such as stripes and checks. The sheet cures upon fusion of the respective areas of the curing reactants.

Abstract: A sensor array, usually a sensor matrix for sensing pressure, comprising a grid of conductors in a woven fabric, the row conductors crossing over the column conductors to form a matrix array of crossover points. The rows are separated from the columns by individually coating the conductors of one or both series with an electrically partially resistive fibrous material, so that when the conductors at any crossover point in the array are pressed closer together, the resistance between the two conductors at that crossover point decreases. By connecting the conductors to suitable electrical circuitry, the force applied at any crossover point and the location of that crossover point within the array can be determined.

Abstract: A coaxial cable pressure sensor having a partially conductive layer of fibres or particles between the inner and outer coaxial conductors whereby pressure applied to the sensor produces a detectable change in resistance of the circuit passing through the partially conductive layer. One or more of the sensors may be incorporated into a vehicle weighing system, preferably in the form of a portable "mat" which may be folded or rolled up.