Abstract: A current limiting fuse has a main fusible element and an auxiliary fusible element each helically wound over an insulative support member. Each end of the auxiliary element is connected to conductive metal clips or electrodes in which blocks of metal oxide varistor material are fixedly secured and placed in contact with the main fusible element. Subsequent to the initial burn back of the main fusible element, the metal oxide varistors precisely initiate electrical arcs between the terminal clips at the ends of the auxiliary fusible element and the main element at points adjacent to these terminal clips. The presence of these arcs quickly sever the main element or elements at these points thereby producing additional burnback areas in the main fusible element or elements.

Abstract: A circuit interrupting device responsive to externally generated heat and method of manufacture of such device. The device includes a pair of spaced, coaxially aligned leads each entering a thermally conductive housing from an opposite end. The inserted ends of the coaxially aligned leads are bridged by a conductive member comprising the tail of a conical spring which surrounds one of the leads and is secured at a corresponding end of the housing. The circuit-completing spring tail is secured by fusible material to the inserted ends of each of the spaced-apart leads. In a normal, closed circuit condition, the spring is under tension. Upon heating, the fusible material softens, allowing the spring tail to break away from the inserted ends of the spaced-apart leads, the retracting force of the conical spring, pulling the spring tail from the other one of the leads to open the circuit.