Abstract:
A current-limiting, single-element, dual-function, electric fuse has a fusible element with at least one "weak spot" of very small cross section; and the temperature of that weak spot will exceed eighty percent of the melting temperature of the material of that fusible element when that electric fuse operates at its maximum continuous current carrying capacity. An appreciable amount of the heat, which the weak spot generates in response to a low but potentially-harmful overload, will be conducted to the inner surface of the housing for the electric fuse by the arc-quenching filler; and a substantial percent of that conducted heat will pass to, and be radiated by, the exposed outer surface of that housing. The conduction of heat to the inner surface of the housing is fostered by locating the weak spot closer to that inner surface than to either terminal of the electric fuse; and the passing of that heat to the exposed outer surface of that housing is fostered by making that housing of a material which has a thermal conductivity in excess of thirty thousandths of a calorie per square centimeter of cross section per centimeter of length per second of time per degree centigrade.