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: 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.