Abstract: A PTC device suitable for attachment to a terminal of a battery. The device contains a PTC component which has a shape with an outer periphery and an inner periphery which defines a first opening in the center of the PTC component. The PTC component is made from a laminar PTC resistive element which is composed of a PTC conductive polymer composition, a first laminar electrode which is attached to a first face of the resistive element, and a second laminar electrode which is attached to a second opposite face of the resistive element. Also part of the device are a first conductive lead which has a first part which is attached to the first electrode, and a second part which extends into the first opening, and a second conductive lead.

Abstract: Laminar electrical devices, in particular circuit protection devices, contain two laminar electrodes, with a PTC element between them, and a cross-conductor which passes through the thickness of the device and contacts one only of the two electrodes. This permits connection to both electrodes from the same side of the device. The device also includes layers of solder on the areas of the device through which connection is made, and separation and/or masking members which (a) reduce the danger of short circuits formed by solder flow during installation of the device and/or (b) provide a site for permanent marking of the device.

Abstract: A circuit protection system employing arrangements of PTC devices and mechanical switches. The PTC device is not involved in the circuit until a fault is sensed. A current sensing relay senses an overcurrent and directs the current to the PTC device. As the voltage across the PTC device increases, a parallel arrangement of voltage sensing relays completes the operation of the protection system, and disconnects the load until the protection system is reset. The protection system may be reset manually or remotely.

Abstract: An apparatus for sealing the end of an elongate cable such as a heating cable includes (1) a housing with a first open end and a second open end and a strain relief element positioned within the housing, (2) a flexible container which can be positioned over the cable end and (i) is of generally tubular shape, (ii) has an interior surface and an exterior surface, (iii) has a first open end and a second closed end, and (iv) contains a sealant; and (3) a cap which can be mated with the housing at the second open end, and cover the flexible container. The apparatus has excellent moisture-resistant properties even after repeated exposure to high temperatures, is reenterable, and can be readily mounted on a substrate such as a pipe.

Abstract: An apparatus for sealing a core of an elongate cable in which a polymeric core of an insulating or a conductive polymer is positioned between first and second elongate electrodes. The apparatus is a container which has a first portion with an open end into which the cable can be inserted and a second partially closed end which has first and second openings. The first portion also contains a sealant, e.g. a grease or a gel. A first removable guide tube is inserted through the first opening and a second removable guide tube is inserted through the second opening, the first and second guide tubes being suitable for insertion of the first and second elongate electrodes, respectively. The apparatus allows insertion of the elongate electrodes after the polymer has been removed from them, without allowing contact between the electrodes and the sealant.

Abstract: A connector for connecting an end of a first elongate electrical heating cable to an end of a first elongate electrical component such as another heating cable or a power cable. The connector includes first and second shell members which can be in a mated or demated configuration and which, when mated, form a shell having a first inlet port for the first heating cable and a second inlet port for the first electrical component. In addition, the connector includes an element for connecting electrodes of the first heating cable to elongate members of the first electrical component and a sealing assembly for holding the first heating cable in position in the first inlet port. The sealing assembly includes a hollow cylindrical ring from which gripping elements in the form of fingers extend perpendicular to the plane of the ring, a nut for making connection to the first inlet port, and a grommet which is held by the fingers and which grips the first heating cable.

Abstract: A conductive polymer composition which has a resistivity at 20.degree. C. of at most 1.0 ohm-cm and a PTC anomaly of at least 10.sup.4 contains at most 64% by volume of a crystalline polymeric component and at least 36% by volume of a particulate conductive filler. A preferred conductive filler is carbon black having a DBP number of 60 to 120 cm.sup.3 /100 g. Compositions of the invention, as well as other conductive polymer compositions are preferably prepared by a method in which the polymeric component and the filler are blended in a first step at a temperature greater than the melting temperature of the polymer, the mixture is then cooled, and the mixture is then mixed in a second step. The resulting composition has a PTC anomaly that is at least 1.2 times the PTC anomaly of the first mixture.

Abstract: An electrical plug for connecting an electrical cable such as an electrical heating cable to an electrical power outlet. Contained within the housing of the plug are first and second contact members which comprise a first prong and a second prong, respectively, each prong being suitable for insertion into a socket of an electrical power outlet. A cutting module and a cutting element which fits within the cutting module are used to remove polymer, e.g. insulation or a conductive polymer composition, from the first and second electrodes of the cable at the end of the cable in order to make electrical connection from the electrodes to the first and second contact members. Present within the cutting module are first and second electrode-contact sections positioned on the concave arcuate inner surface of the wall of a cavity in the cutting module. The electrode-contact sections can be electrically connected to the first and second contact members.

Abstract: A tape covering for elongate substrates such as metal pipes is provided. At least one edge of the tape is chamfered. and in preferred embodiments the angle of the chamfer is no greater than 25.degree. especially no greater than 7.degree.. In other preferred embodiments the tape comprises a backing layer and an adhesive layer, both of which preferably include a chamfered edge, the chamfer preferably extending through both the backing layer and the adhesive layer. The tape is preferably heat recoverable, and the adhesive, if present, heat activatable. The tape may be installed according to a preferred method of the invention using induction heating, preferably at such high frequency that the ratio of the thickness of the substrate to the skin depth is at least 25:1.

Abstract: An article (2) in which at least part of a surface (8) of a polymeric element has an embossed pattern (6). The article may be either heat-recoverable or non-heat-recoverable. If the article is heat-recoverable, when heated the article recovers and the embossed surface becomes substantially smooth. The change in surface texture can be used to indicate that sufficient heat has been applied to the article to achieve adequate recovery and/or to adequately melt an attached adhesive layer (10). In another embodiment, the article (2) is in the form of a patch (14) which can be used to secure the opposing longitudinal edges of heat-recoverable article which is in the form of a wraparound sheet.

Abstract: A maintenance termination unit (MTU) for use in telephone circuits. The MTU comprises a switching arrangement which can be connected between sets of terminal equipment in a communications channel comprising a pair of lines. The switching arrangement comprises: a DC voltage window detector circuit which, in use, is connected between the lines and is responsive to a voltage between the lines; and series switching circuits, which, in use, are connected in the lines. The arrangement may also include a shunt switching circuit, which, in use, is connected between the lines. The arrangement includes low pass filters associated with the switching circuits. The DC voltage window detector circuit will actuate the switching circuits when the DC voltage between the lines is within respective predetermined bands, but will not actuate the switching circuits when the DC voltage between the lines is not within the respective predetermined bands.

Abstract: A circuit protection arrangement comprises a series switching circuit that is intended to be connected in a line of the circuit and will switch to an open state when subjected to an overcurrent, and a shunt switching circuit that is open under normal operating conditions but will shunt the overcurrent across the load of the circuit or to ground when triggered by the series switching circuit. Preferably the series switching circuit comprises a switching transistor (4) that is controlled by a control transistor (6), and the shunt switching circuit comprises a shunt switching transistor (9) that is controlled by a shunt control transistor (11) which is itself controlled by the series switching circuit. The shunt switching circuit may be connected to ground or it may be connected to a back-up load or voltage foldback device such as a triac.

Abstract: An apparatus for sealing the end of an elongate cable such as an electrical heating cable which comprises a clip-shaped insert positioned within a tubular-shaped housing. Gripping members and pre-gripping members project from the interior surfaces of the arms of the insert and act to grip a cable when it is inserted into the device. A locking mechanism on the insert engages locking teeth on the housing and serves to hold the insert in position. A conformable gel component may be present. The apparatus provides high pullout force, as well as environmental sealing, for cables such as electrical heating cables or power cables.

Abstract: A switching arrangement that can be connected in a communications channel comprising a pair of lines, between sets of terminal equipment, which comprises:(i) a pair of series switching circuits, each of which can be series connected in one of the lines and will open when subjected to an overcurrent in its associated line; and/or(ii) one or more shunt switching circuits connected between the lines, or between one or both the lines and earth, and will close when subjected to an overvoltage in its associated line;wherein the or each switching circuit can be remotely actuated by means of a test signal sent along the channel.

Abstract: Wrapped covering material, e.g. tape is applied around an elongate substrate, such as a pipe, using an apparatus comprising a hollow frame mounted on rollers that is rotatable about the substrate, a delivery device for holding the covering material, mounted on the frame, and pressure rollers designed to press down on the covering material.

Abstract: A conductive polymer composition containing a particulate conductive filler dispersed in a polymeric component. The polymeric component comprises a first polymer which (i) is present in an amount 25 to 75% by weight of the total polymeric component, and (ii) is polyethylene, and a second polymer which (i) is present in an amount 25 to 75% by weight of the total polymeric component, and (ii) comprises units derived from a first monomer which is ethylene and a second monomer which is an alkyl acrylate having the formula --CH.sub.2 .dbd.CHCOOC.sub.m H.sub.2m+1 --, where m is at least 4. The resulting composition is useful in preparing electrical devices, e.g. circuit protection devices, which have lower resistivities, higher PTC anomalies, and better thermal and electrical stability than devices comprising conventional conductive polymer compositions.

Abstract: A conductive polymer composition containing a particulate conductive filler dispersed in a polymeric component. The polymeric component comprises a first polymer which (i) is present in an amount 25 to 75% by weight of the total polymeric component, and (ii) is polyethylene, and a second polymer which (i) is present in an amount 25 to 75% by weight of the total polymeric component, and (ii) comprises units derived from a first monomer which is ethylene and a second monomer which is an alkyl acrylate having the formula --CH.sub.2 .dbd.CHCOOC.sub.m H.sub.2m+1, where m is at least 4. The resulting composition is useful in preparing electrical devices, e.g. circuit protection devices, which have lower resistivities, higher PTC anomalies, and better thermal and electrical stability than devices comprising conventional conductive polymer compositions.

Abstract: An article is provided for applying a temperature indicating composition (8) on to the surface of a heat recoverable substrate. The article comprises the following four layers: backing layer (2), release layer (4), indicating composition (8), and heat-activatable adhesive layer (10). The conversion temperature of the temperature indicating composition (8) is higher than the melting temperature of the release layer (4), and the melting temperature of the release layer (4) is the same as or higher than the activation temperature of the adhesive (10).

Abstract: A conductive polymer wraparound sleeve is used to enclose a joint between district heating pipes. It is wrapped so that longitudinal edges thereof overlap, and it acts as a source of heat to seal the overlapping longitudinal edges. Elongate electrodes, preferably metal bars provided on a carrying strip, are positioned along the overlap and connected to a power source to cause electrical current to flow circumferentially across the overlap region to cause bonding of the overlap.

Abstract: A method of making a planar polymeric circuit protection device arranges for the current between two electrodes (4, 6) to flow parallel to the surface of a sheet (2) of conductive polymeric material, rather than through its thickness. The resistance and tripping current levels of the device can be finely controlled and set at comparatively low levels.