Raychem Limited

Manoochehr Mohebban

Chi-Ming Chan

Jeffrey A Bennett

Nachum Rosenzweig

Neil L Holt

Peter L Larsson

Pradeep Barma

Stephen E Sheehan

James L Fergason

Robert Parker

Dennis C Siden

Lester T Toy

Wayne Montoya

Eugen L Kurjatko

Willem M Versteegh

Conductive polymer composition

A composition which comprises a matrix polymer and, distributed therein, a particulate conductive filler. At least some of the filler particles are composed of a conductive polymer composition and/or the matrix comprises a sintered polymer. The matrix polymer and the filler particles and the method of distributing the particles are such that the particles maintain their identity in the matrix. For example, the particles are preferably highly cross-linked so that they have a hot modulus of at least 250 psi if the composition is prepared by melt extrusion or another process involving a high degree of shear; or a low-shear process such as sintering can be used. Preferably the matrix polymer is capable of coating the filler particles; for example, the matrix polymer and the filler polymer may be chemically similar. The invention is particularly useful for preparing compositions which have high resistivities, eg. 1000 ohm.cm or more, and which can be prepared with a high degree of reproduceability. The compositions can exhibit PTC, ZTC or NTC behavior, depending on the nature of the conductive filler, and their resistivity is dependent on the electric field. The compositions are particularly useful as resistive materials in sheet heaters and as stress-grading materials for high voltage apparatus.

A double-walled article in the form of a tube having a small volume filling of a friction-reducing liquid or solid between its two walls. The article is able to revolve over a substrate by relative sliding motion between its two walls, to provide environmental or electrical protection.

Tubular article

An electrical apparatus having a liquid crystal fault indicator, comprising: an electrical component subject to electrical fault; a smectic liquid crystal display having an indicating element having a first and a second visual state, said indicating element being capable of transitioning from the first to the second visual state upon the application of an electric field sufficient to realign the smectic liquid crystal material contained therein and remaining in the second visual state after the removal of the electric field and further being capable of transitioning from the second to the first visual state upon heating to at least a delatching temperature Td sufficient to destroy the electric field induced alignment of the smectic liquid crystals; and fault signal means for providing, upon the occurrence of a fault, a prescribed input sufficient to cause said indicating element to transition from a visual state indicative of an unfaulted condition to a visual state indicative of a faulted condition.

Liquid crystal electrical fault indicators

A liquid crystal display (LCD) is connected in series with a capacitor having a capacitance C.sub.0 such that

Liquid crystal display having a capacitor for overvoltage protection

Liquid crystal display with particular relationship of the capacitances

A voltage tester, particularly for relatively low voltage A.C., comprises a device having a contact for electrical connection to an electrical component, and a contact that may be touched by an operator through whom capacitive connection may be made to earth. The device includes liquid crystal displays powered by the voltage under test via a voltage multiplier.

Device for A.C. voltage testing using a voltage multiplier and LCD

Method for remotely detecting an electric field using a liquid crystal

The conductors of multi-conductor, medium voltage, power cables, at locations where the cable insulation has been removed, are insulated by positioning between the conductors or cores, an insert, at least the surface of which comprises a first void-filling material capable of forming a substantially void-free interface with each conductor, placing a second void-filling material over the conductors and recovering a dimensionally recoverable polymeric sleeve over the resulting assembly. The method is particularly useful to provide insulation between conductors of a joint between two multi-conductor, medium voltage power cables.

Insulating multiple-conductor cables using coated insert means

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Foster City, CA, United States of America

Manoochehr Mohebban