Abstract: An optical fiber water sensor includes a mandrel having a convex or concave shape adjacent to an optical fiber which is adjacent to a water swellable material held in a reservoir. Upon coming in contact with water, the material swells and deforms a section of the optical fiber about a contour defined by the mandrel thus attenuating a signal propagating through the fiber which is detected by an optical detector to indicate the presence of water.

Abstract: An assembly capable of enclosing and sealing an intermediate section of an optical fiber includes a plurality of sealing mechanisms arranged such that the assembly can be entered to gain access to electronic components for servicing without affecting an environment occupied by optical fiber broken out of an optical fiber cable. Accordingly, physical integrity of the exposed fiber, and its associated connectors and splices, is not compromised. The assembly further includes a plurality of card cages, each of which has its own integral backplane having socket connectors which allow for connection to an adjacent card cage backplane within the assembly. During initial deployment of the assembly where less than all card cages for maximum capacity are initially required to be deployed, segmenting the backplane reduces the first installed cost of the assembly.

Abstract: Circuit protection systems which comprise a PTC resistor and a second resistor, e.g. a thick film resistor, which is thermally and electrically connected to the PTC resistor have a break current I.sub.B and a hold current I.sub.H such that the ratio I.sub.B /I.sub.H is at most 20. Suitable PTC resistors are conductive polymer devices which comprise a PTC element which has been radiation crosslinked under conditions such that the average dose rate is at most 3.0 Mrad/minute or during which no part of the PTC element which is in contact with the electrodes reaches a temperature greater than (T.sub.m -60).degree.C., where T.sub.m is the melting point of the polymeric component of the conductive polymer.

Abstract: Circuit protection devices which comprise a PTC conductive polymer element and a second electrical component which is thermally coupled to the PTC element and which, when a fault causes the current in the circuit to become excessive, generates heat which is transferred to the PTC element, thus reducing the time taken to "trip" the PTC element. The second component is for example a voltage-dependent resistor which is connected in series with the PTC element under the fault conditions and is thus protected from damage. Alternatively, the second component is a thick film resistor which is connected in series with the PTC element.

Abstract: Circuit protection devices which comprise a PTC conductive polymer element and a second electrical component which is thermally coupled to the PTC element and which, when a fault causes the current in the circuit to become excessive, generates heat which is transferred to the PTC element, thus reducing the time taken to "trip" PTC element. The second component is for example a voltage-dependent resistor which is connected in series with the PTC element under the fault conditions and is thus protected from damage. Alternatively, the second component is a thick film resistor which is connected in series with the PTC element.

Abstract: Circuit protection devices which comprise a PTC conductive polymer element and a second electrical component which is thermally coupled to the PTC element and which, when a fault causes the current in the circuit to become excessive, generates heat which is transferred to the PTC element, thus reducing the time taken to "trip" the PTC element. The second component is for example a voltate-dependent resistor which is connected in series with the PTC element under the fault conditions and is thus protected from damage. Alternatively, the second component is a thick film resistor which is connected in series with the PTC element.

Abstract: A device assembly in which a plurality of PTC circuit protection devices are connected in series. Assemblies of this type are useful in providing protection under voltage conditions which would be unsafe for an individual protection device. In a preferred system the device assembly is connected in series with a circuit breaker.

Abstract: Disclosed is a positive temperature coefficient of resistance (PTC) crosslinked polymeric composition comprising a first polymeric material exhibiting high green strength prior to crosslinking and elastomeric behavior subsequent to cross-linking, and a second polymeric material comprising a thermoplastic, both said materials having dispersed therein conductive particles, e.g., carbon black, and further, said composition exhibiting a rise in resistance with increased temperature at temperatures above the melting point of either material.

Abstract: A self-regulating heating article comprising a layer of material exhibiting a positive temperature coefficient of resistance (PTC) and said PTC layer having at least partially contiguous therewith at least one layer of constant wattage output material. The article operates such that when connected to an electric power source, the current flows through at least a portion of the thickness of the PTC layer and of the constant wattage layer.

Abstract: Disclosed is a positive temperature coefficient of resistance (PTC) crosslinked polymeric composition comprising a first polymeric material exhibiting high green strength prior to crosslinking and elastomeric behavior subsequent to cross-linking, and a second polymeric material comprising a thermoplastic, both said materials having dispersed therein conductive particles, e.g., carbon black, and further, said composition exhibiting a rise in resistance with increased temperature at temperatures above the melting point of either material.

Abstract: A self-regulating heating article comprising a layer of material exhibiting a positive temperature coefficient of resistance (PTC) and said PTC layer having at least partially contiguous therewith at least one layer of constant wattage output material. The article operates such that when connected to an electric power source, the current flows through at least a portion of the thickness of the PTC layer and of the constant wattage layer. In a preferred embodiment, upon heating the article, a change in dimensions as well as activation of an adhesive occurs.

Abstract: Articles which are heat-recoverable, or which can be rendered heat-recoverable or which have been heat-recovered, comprise a member composed of a conductive polymer and, attached to said member, at least two electrodes, at least one of which is an electrode comprising a plurality of pliable conductive elements, e.g., a braided tube. By connecting the electrodes to a source of electrical power, current is caused to pass through and heat the conductive polymer member. The heat generated can be used to provide all or part of the heat necessary to cause recovery of the heat-recoverable article. The conductive polymer preferably exhibits PTC behavior, thereby regulating the maximum temperature to which the article can be heated.

Abstract: A method of encapsulating a substrate, especially a splice in a telephone cable, comprises (1) preparing an assembly comprising the substrate; an enclosure, preferably a heat-shrinkable enclosure, around the substrate; sealing material within the enclosure; and a heater within the enclosure; and (2) using said heater to change the viscosity of the sealing material. Preferably the heater is a PTC heater, especially one which is attached to thermoplastic sealing material in the form of a sheet or tape. In this way a desired distribution of heat through the assembly can be obtained so that extended heating times can be used.

Abstract: Conductive polymer compositions which have improved voltage stability and which preferably exhibit PTC behavior. The compositions comprise a carbon black dispersed in a crystalline copolymer of an olefin and at least 10% by weight of an olefinically unsaturated comonomer containing a polar group. The carbon black has a particle size greater than 18 millimicrons, preferably greater than 30 millimicrons, a d-spacing greater than 360 and a surface area which is less than1.2S+e.sup.S/50where S is the DBP absorption of the carbon black. The carbon black is preferably present in amount at least 15% by weight of the composition. Particularly useful devices including such compositions are self-regulating heaters.

Abstract: A self-regulating heating article comprising a layer of material exhibiting a positive temperature coefficient of resistance (PTC) and said PTC layer having at least partially contiguous therewith at least one layer of constant wattage output material. The article operates such that when connected to an electric power source, the current flows through at least a portion of the thickness of the PTC layer and of the constant wattage layer. In a preferred embodiment, upon heating the article, a change in dimensions as well as activation of an adhesive occurs.

Abstract: The invention relates to novel electrical devices which are useful for example as heaters and temperature sensors, and which comprise at least two electrodes, at least one PTC element, at least one relatively constant wattage element, and at least one current-directing element which directs the current, when the device is first connected to a source of electrical power, so that the effective initial resistance of the device is greater than it would be in the absence of said element. Thus the invention provides a solution to the problem of current inrush in application of PTC devices in which substantial current passes through the device at operating temperatures. The invention also includes the use of the novel devices in applications in which current inrush is not a problem.

Abstract: The invention relates to novel electrical devices which are useful for example as heaters and temperature sensors, and which comprise at least two electrodes, at least one PTC element, at least one relatively constant wattage element, and at least one current-directing element which directs the current, when the device is first connected to a source of electrical power, so that the effective initial resistance of the device is greater than it would be in the absence of said element. Thus the invention provides a solution to the problem of current inrush in applications of PTC devices in which substantial current passes through the device at operating temperatures. The invention also includes the use of the novel devices in applications in which current inrush is not a problem.

Abstract: The formation of a hermetic seal in an assembly resulting from the connection or encapsulation of one or more substrates such as cables by one or more dimensionally-recoverable covering members such as heat-recoverable sleeves is checked by detecting the increase in air pressure which occurs during heating of the assembly once a hermetic seal has been made. To this end, a covering member is provided with an aperture which communicates with a detection device such as a balloon or a manometer and with a space within the assembly in which there is a build up of air pressure.

Abstract: Novel methods for sealing a closure member to a substrate make use of pressure generated in a chamber to create and/or maintain a seal between a closure member and a substrate. The chamber has a flexible wall which is urged towards the substrate by the pressure. Where the substrate has a hollow interior which is maintained at superatmospheric pressure, e.g. a pressurized telephone cable, a fluid passage is preferably provided between the interior and the closed chamber after the seal has been formed, thus taking the closure member out of peel with the substrate. A preferred closure member is an inflatable bag which has sealing material on selected portions of one surface thereof, so that it can be wrapped around the substrate to form a hollow enclosure around the substrate. After placing a restraining means around the wrapped closure member, the closure member is inflated, thus improving the seal around the enclosure.

Abstract: A self-regulating heating article comprising a layer of material exhibiting a positive temperature coefficient of resistance (PTC) and said PTC layer having at least partially contiguous therewith at least one layer of constant wattage output material. The article operates such that when connected to an electric power source, the current flows through at least a portion of the thickness of the PTC layer and of the constant wattage layer. In a preferred embodiment, upon heating the article, a change in dimensions as well as activation of an adhesive occurs.