Raychem Limited

Raynet Corporation

David A Horsma

Stephen Hunter Diaz

Shou-Mean Fang

Bernard J Lyons

Robert Smith-Johannsen

Guillaume Peronnet

Andrew N Au

William D Carlomagno

Timothy E Fahey

Teddy J Hammack

Hundi Panduranga Kamath

Marc F Moisson

Thomas A Kridl

Nelson M Shen

Lester T Toy

Wendell W Moyer

Lowell I Koht

Donald Del Fava

Charles H Camphouse

Wells Whitney

Damian Kaczorowski

Robert J Naidoff

Narendra Kulkarni

Gregory P Hayward

Francis De Blauwe

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.

Optical fiber water sensor

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. Finally, multiple alarms are provided for the assembly to alert a central office that a cover of the assembly has been removed and a humidity level within a vicinity of the broken out fiber cable exceeds a predetermined level.

Sealed optical fiber closures

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.

Electrical device comprising conductive polymers

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.

Composite circuit protection devices

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.

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.

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.

Assemblies of PTC circuit protection devices

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.

Self regulating heating device employing positive temperature

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.

Layered self-regulating heating article

Positive temperature coefficient of resistance compositions

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.

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.

Self-heating article with deformable electrodes

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.

Method of encapsulation

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 than

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Palo Alto, CA, United States of America

David A Horsma