Raychem Limited

Burton E Miller

Andrew N Au

Hugh Duffy

Alan J Gotcher

Robert W Fouts, Jr

Robert Bremner

Apparatus for automatically disconnecting a conductive polymer heater if an arcing fault occurs. A sensor conductor is incorporated into the heater, so that if an arcing fault occurs, the current through the sensor conductor increases and triggers a safety circuit to disconnect the heater. The sensor conductor is preferably insulated by an organic polymer which pyrolyses if an arcing fault occurs and thus permits current to flow between the sensor conductor and an electrode of the heater.

Electrical heaters

Conductive polymer compositions comprises a polymeric material having dispersed therein (a) conductive particles composed of a highly conductive material and (b) a particulate filler. The compositions exhibit a positive temperature coefficient of resistivity and undergo a large increase in resistivity as the temperature increases above a certain value. The compositions are useful in preparing electrical devices such as current limiting devices, heaters, EMI shields and the like.

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Sunnyvale, CA, United States of America

Burton E Miller