PTC CIRCUIT PROTECTION DEVICE

摘要

Circuit protection devices comprise a PTC conductive polymer element and means for minimizing the adverse effects of carbonaceous dust evolved by the PTC element when it is tripped. An enclosure encloses, but is spaced apart from, the PTC element. In one embodiment at least part of the interior surface of the enclosure is composed of polytetrafluoroethylene, a ceramic or another material which discourages the formation of permanent low resistance paths through carbonaceous material lying on its surface. In another embodiment the enclosure has a large internal surface area compared to the volume of the PTC element. In further embodiments, electrical leads are connected to and pass through the enclosure, and at least one of the leads is insulated along its length and/or the leads pass through opposite ends of the enclosure.