Abstract: A plastic sheath cutting and slitting hand tool for cutting and slitting a cable sheath of a cable includes a generally flat, elongated body; a handle portion adapted to be grasped by the hand; a tool portion extending outwardly from the handle portion and exposing a sheath scoring blade for scoring a plastic sheath to a controlled depth less than a nominal thickness of the sheath; and, a generally flat sheath engaging and slitting edge including a sheath slitter for engaging, spreading and slitting the plastic sheath lengthwise when the handle portion is grasped and drawn along the sheathed body from a cut of the sheath made by the sheath cutting blade.

Abstract: A seal kit for assembly into a system for sealing an elongate heating cable from ambient essentially includes a cone-shaped elastomeric grommet, several molded plastic parts, and a compression spring. The compression grommet forms a sealing interface between itself and a molded plastic enclosure body and between itself and an outer jacket of a heating cable. Cable ends are sealed within a sealed interior space of the enclosure body. A cup-shaped surface of a molded plastic part adjacently facing a congruent cone-shaped surface of the elastomeric grommet forms a slip-plane. The compression spring transfers energy to compress the elastomeric grommet and to cause it to expand radially against an interior wall of the enclosure body and against an outer jacket of the electrical cable and prevents that region of the grommet from becoming bonded over a high temperature operating interval to the inside wall of the enclosure body.

Abstract: An electrically conductive polymer composition containing a polymer mixture containing a first crystalline polymer having a weight-average molecular weight of at least 50,000 and a second crystalline polymer having a weight-average molecular weight of at most 10,000, and a particulate electrically conductive filler has good processability and exhibits a low resistivity at 20° C. and a good positive temperature coefficient (PTC) behavior.

Abstract: A laminar sensor for detecting changes on a laminar substrate. The sensor includes a laminar sheet which has a first surface and a second opposite surface, and is made from a conductive polymer composition which exhibits PTC behavior. A plurality of sensing elements are electrically connected in series on the sensor. Each sensing element is formed as an electrode pair containing a first electrode and a second electrode. The first and second electrodes may be on the same surface of the laminar sheet or on opposite surfaces of the sheet. Two electrical leads are present for connecting the sensing elements into a circuit, which may be used to detect changes in resistance which occur when a sensing element is exposed to an elevated temperature, a change in pressure, or a solvent.

Abstract: An electrical device in which a resistive element composed of a conductive polymer composition and two electrodes is made by a method in which the device is cut from a laminate of the conductive polymer composition and the electrodes, is exposed to a thermal treatment at a temperature above the melting temperature of the conductive polymer composition, and is then crosslinked.

Abstract: A PTC device which surely achieve effective space utilization while easily excluding the possibility of the formation of a short circuit. The PTC device includes a PTC component 3 comprising a first electrode 11, a second electrode 13, and a PTC element 9 disposed between these electrodes, a first electrically conductive lead 15 which is connected to the first electrode and able to connect with a button terminal of a battery, a second electrically conductive lead 18 which is connected to the second electrode, and an insulating element 23. The insulating element covers the inner periphery 7 of the PTC component, the second electrode and a portion of the second electrode and the second electrically conductive lead on the second electrode.

Abstract: An elongate heater (1) in which a resistive heating element core is surrounded by a first insulating jacket (9) and a second insulating jacket (11). In a preferred embodiment the resistive heating element core comprises a conductive polymer composition (3) and the heater passes the VW-1 flame test. The second insulating jacket (11) may be made from the same material as the first insulating jacket (9). For some applications it is preferred that the second insulating jacket be a thin film, e.g. polyester film.

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 electrical heating cable in which at least two elongate conductors are separated by an insulating spacer and are contacted by at least one elongate resistive heating strip. The heating strip, which contacts alternately the first conductor and the second conductor at contact points which are longitudinally spaced apart along the length of the strip and along the length of each of the conductors, is made from a conductive polymer composition which exhibits PTC behavior. The conductors are concentric stranded wires having a lay length L of at most 20 mm or a lay angle .beta. of at least 11.degree., or a lay length L of at most 20 mm and a lay angle .beta. of at least 10.degree..

Abstract: A thermally insulated substrate, e.g. a system of pipes, is maintained above a selected minimum temperature by means of one or more electrical heaters, preferably elongate self-regulating heaters. Each heater is successively switched on for a heat-up period and then off for a cool-down period. The durations of these periods are successively determined by reference to the ambient air temperature adjacent the substrate at an earlier time, e.g. at the end of the previous cool-down period. The method is particularly useful for temperature-maintenance systems in which a number of heaters are used to heat a complex system of pipes. The durations of the heat-up and cool-down periods for each heater (or for a group of two or more heaters) are separately determined by means of a single microprocessor.

Abstract: A failure indicator device for a surge arrester (2) employs a conventional explosive disconnector (10). Operation of the disconnector (10) due to earth fault current passing through the arrester (2) causes an arc to be formed. Movement of the disconnector (10) away from the arrester (2) is guided and limited by a support arrangement (18, 20) that subsequently provides a solid and permanent conductive path to earth (6) from the arrester terminal (12), thus extinguishing the arc.

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 104 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: Two-component curable adhesive for blocking automotive wiring bundles, the respective components preferably amine-terminated polyamide Part A, and acrylate, anhydride or epoxy Part B, being contained in separate sheets which are inter-leaved with one another. The concentration of the reactive components in the sheets is chosen to cause the adhesive to flow on initial heating and then to cure to resist further flow at elevated temperatures in service. Apparatus, kits and method for blocking cables or wire bundles using the adhesive are also claimed.

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: 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 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 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 of an electrical plug. 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. The cutting element comprises a cutting wedge which has (a) a convex arcuate outer surface which complements the inner surface of the wall of the cutting module, and (b) piercing means suitable for penetrating the polymer.

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: 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: 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.