A PTC circuit protection device.

摘要

The invention relates to circuit protection devices which comprise a PTC conductive polymer element. The devices of the invention comprise two columnar electrodes and a conductive polymer element, at least a part of which is a PTC element, between the electrodes. The device is so constructed that when a fault current passes through the device and converts it to the high temperature high resistance state, a hot zone forms in the PTC element at a location away from the electrodes. In one preferred embodiment, the conductive polymer element has an intermediate portion of increased resistance, thus causing the hot zone to be located at or near the intermediate portion. Atypical device is shown in Figure 2.