Abstract: Ignition cables which contain a layer of a melt-extruded conductive polymer. The conductive polymer is preferably the sole current-carrying component of the cable. The polymeric component in the conductive polymer is a fluoropolymer, preferably a vinylidene fluoride copolymer having a crystallinity index of 10 to 23% and/or a DSC heat of melting of 4.7 to 9.5 J/g. Preferably, the sole conductive filler in the conductive polymer is a carbon black.

Abstract: An elongate electrode, usually an anode, is provided, suitable for use in an impressed current corrosion protection system. The electrode comprises a central elongate core, usually a metal such as copper, an optional conductive polymeric composition surrounding the metal core and having a higher electrical resistivity than the core, but being in electrical contact with the core, a flexible jacket, for example, a fabric braid containing within it particulate coke, and tensioning wraps positioned around the flexible jacket. The purpose of the tensioning wraps is to compact the coke particles relative to their compaction in the absence of the tensioning wraps.

Abstract: A melt-extrudable conductive polymer composition which contains a polymer, a particulate conductive filler, and a particulate nonconductive filler. When a standard strip heater is made from the composition and tested in a UL VW-1 test, it has comparable performance to a heater made from a second composition which is the same as the composition but which does not contain the nonconductive filler. When tested in a standard arcing fault test, the standard heater will trip a fuse in less time than is required by the second heater, i.e. in less than 30 seconds. In some embodiments, the composition also comprises a flame retardant, preferably a halogenated flame retardant. When strip heaters prepared from these compositions are tested in a standard arc propagation test, an arc will not propagate. A preferred nonconductive filler is Sb.sub.2 O.sub.3.

Abstract: A system for detecting leaks from buried pipes which transport fluids other than water. The system includes a pipe for transporting the fluid, a fluid-wicking member which lies beneath the pipe, is wetted by the fluid when the fluid leaks from the pipe, and is permeable to water, and a fluid sensor which contacts the fluid-wicking member and is capable of detecting the fluid.

Abstract: A housing contains a PTC element which can be easily inserted and removed. Conductive metal retaining elements of the housing are secured to the base of the housing, and retain the PTC element with a generally planar portion parallel to the electrodes of the PTC component. The retaining elements also have slidable contact between the elements and the top of the housing so as to modify the elastic deformation of the element and allow for insertion and removal of the PTC element.

Abstract: Novel polyester compositions, particularly suitable for the insulation of wires, contain an aromatic polyester, especially polybutylene terephthalate. The presence of certain tin (II) compounds, for example tin (II) oxide, oxalate, phthalate, pyromellitate, or phosphite, reduces the flammability and smoke generation of such compositions. The presence of an aliphatic polyester, and optionally a thermoplastic elastomer, can also improve the properties of such compositions.

Abstract: An electrical device (1) in which an element (7) composed of a conductive polymer is positioned in contact with the surface layer of one or more metal electrodes (3,5). The metal electrode contains a base layer (9) which comprises a first metal, an intermediate metal layer (15) which comprises a metal that is different from the first metal, and a surface layer (17) which (i) comprises a second metal, (ii) has a center line average roughness R.sub.a of at least 1.3, and (iii) has a reflection density R.sub.d of at least 0.60. The conductive polymer composition preferably exhibits PTC behavior. The electrical devices, which may be, for example, circuit protection devices or heaters, have improved thermal and electrical performance over devices prepared with electrodes which do not meet the center line average roughness and reflection density requirements.

Abstract: Electrical circuit protection arrangements with PTC devices and mechanical switches. The combinations of this invention permit the use of mechanical switches and PTC devices to switch voltages and currents in normal circuit operations, wherein the voltage and/or current ratings of the mechanical switches and PTC devices are much less than the normal operating voltages and currents of the circuits. This feature permits the use of smaller and less expensive mechanical switches and PTC device than would otherwise be required in such circuits. The arrangements of switches and PTC devices also permit the PTC devices to limit the magnitude of the fault current passed to the circuit.

Abstract: Electrical devices, particularly circuit protection devices, contain conductive polymer elements whose edges are formed by breaking the conductive polymer element, along a desired path, without the introduction of any solid body into the element. The resulting cohesive failure of the conductive polymer produces a distinctive fractured surface. One method of preparing such devices involves etching fracture channels in the electrodes of a plaque containing a PTC conductive polymer element sandwiched between metal foil electrodes, and then snapping the plaque along the fracture channels to form individual devices.

Abstract: A circuit protection device which comprises first and second laminar electrodes; a laminar PTC conductive polymer resistive element sandwiched between the electrodes; a third laminar conductive member which is secured to the same face of the PTC element as the second electrode but is separated therefrom; and an electrical connector which connects the third conductive member and the first electrode. This permits connection to both electrodes from the same side of the device, so that the device can be connected flat on a printed circuit board, with the first electrode on top, without any need for leads. The connector is preferably a cross-conductor which passes through an aperture in the PTC element, because this makes it possible to carry out the steps for preparing the devices on an assembly which corresponds to a number of individual devices, with division of the assembly as the final step.

Abstract: Improved tape assemblies for delivering electrical devices to work stations at which the devices are installed. Each of the devices comprises a laminar electrical component sandwiched between two laminar metal members, and is preferably a PTC circuit protection device. In the assemblies, the electrical components are discrete components, but they are contacted by, and linked together through, laminar metal members which, after the assembly has been divided into separate devices, provide leads which contact and extend away from the electrical component. Preferably the metal members are prepared by cutting and forming a single strip of metal. Preferably the assembly is free from any longitudinally continuous carrier strip which much be discarded after the devices have been separated from each other. Preferably, the assemblies are sufficiently flexible to be wrapped around a reel and unwrapped at the work station.

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: Apparatus and method for reading an identification mark on a semi-conductor wafer. The wafer includes a marking area which bears a relief mark. The marking area is illuminated by a segmented light source and is viewed by a viewing device. The viewing device sees a dark segment and an adjacent lighted segment which preferably surrounds the dark segment, and the mark appears as a light image in the dark segment. Preferably the segmented light source is a diffuse light source with an opaque patch at its center. The method is particularly effective for reading soft marks with low profiles.

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: A switching device for a telecommunications channel. The device comprises a voltage detector, a switch, and a storage device. The voltage detector produces an output voltage if the voltage between the lines of the channel exceeds a predetermined level, for example 110 volts. The switch can increase an impedance in one of the lines (preferably causing open circuit) in response to an input voltage. The first storage device, for example a capacitor, produces the input voltage when it reaches a charge V.sub.2 ; is initially at a voltage V.sub.1, for example zero, that is less than V.sub.2 ; after charging by the output voltage from the voltage detector, is at a voltage V.sub.3 greater than V.sub.2 ; and discharges from V.sub.3 to V.sub.1 in the absence of the output voltage. The voltage detector comprising a low-pass filter such that an AC signal on the channel produces an output voltage that charges the first storage device to a charge below V.sub.2.

Abstract: An overcurrent protection system which will give a rapid response to overcurrents which cause a reduction in the voltage across the load, e.g. a partial or complete short across the load, and which will preserve the trip endurance of a PTC device used in the protection system. The new system maintains the trip endurance of the PTC device by removing the source voltage from the PTC, while still keeping the circuit protection arrangement in a fault state, thereby continuing to protect the load.

Abstract: A circuit protection device for protecting batteries is formed from a resistive element composed of a PTC conductive polymer composition and two electrodes. The device has a resistive element thickness of 0.025 to 0.20 mm; a crosslinking level equivalent to 1 to 20 Mrads; a surface area of at most 120 mm.sup.2 ; a resistance at 20.degree. C., R.sub.20, of at most 0.030 ohm; and a resistivity at 20.degree. C., .rho..sub.20, of at most 2.0 ohm-cm. Devices of the invention are sufficiently small to be easily inserted into an assembly comprising a battery, particularly a rechargeable battery, and the device. Such assemblies are used for powering portable electronic equipment such as cellular telephones.

Abstract: Insulated electrical cables which are suitable for use in gasoline fuel tanks comprise a stranded conductor which is blocked by a polysulfide and is covered by polyamide insulation.

Abstract: Insulated wires and cables, especially local area network (LAN) cables, in which the conductors are covered by foamed insulation made from a composition containing an ECTFE polymer having a crystallinity of at least 50% by weight, and, dispersed in the ECTFE polymer, particles of a PTFE polymer having a crystallinity of at least 50%, the ratio by weight of the ECTFE polymer to the PTFE polymer being 1:1 to 9:1.

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.