US Patent 7932805 Fuse with fuse state indicator

A fuse includes a fuse state indicator on the exterior surface of the fuse body. The fuse state indicator includes an electrically conductive element electrically connected to and extending between the terminal elements. A temperature sensitive element proximate and in thermal contact with the electrically conductive element includes material capable of changing color when heated to a predetermined transition temperature to form a mark on the temperature sensitive element. The fuse state indicator forms a first mark on the temperature sensitive element when heat from the electrically conductive element transfers to the temperature sensitive element in response to a first overcurrent condition, and forms a second mark, distinct from the first mark, on the temperature sensitive element when heat from the electrically conductive element transfers to the temperature sensitive element in response to a second overcurrent condition distinct from the first overcurrent condition.