Abstract: The fusible element of a fuse that needs series multibreaks for interrupting small currents is provided with a shunt current path including an arc gap in the center region thereof. That current path does not normally carry any current on account of the presence of the arc gap in it. The shunt current path shunts a portion of the fusible element including a so-called M-effect causing overlay. When that overlay becomes operative it causes formation of an arc gap in the fusible element which, in turn, causes a voltage to appear across the arc gap. When that voltage is sufficiently high the arc gap breaks down. The ensuing arc current is too small to allow formation of series breaks in the fusible element. The fusible element or the above shunt thereof are provided with beads that evolve gases under the action of the arc.

Abstract: A composition resistor incorporates a thermal fuse inert preferably positioned at its center. The insert includes a fuse link which under normal conditions provides electrical continuity between lead wires extending from each end of the resistor. If a current overload occurs, the heat generated by the resistance material raises the temperature at the center of the resistor to the melting point of the fuse link and the fuse link opens circuit before the organic constituents of the resistor begin to decompose or ignite.

Abstract: A conventional fusible element is combined with exothermic reactive material such as PETN or a ribbon of aluminum-palladium to supply quickly released chemical energy for fast circuit interruption where the circuit-derived electrical energy available for interruption is low. An arc quenching substance preferably surrounds the fusible element. The exothermic reaction is initiated thermally or by supplementary electrical energy from a trigger circuit.

Abstract: A d-c fuse having a clearing ability ranging from currents close to the minimum fusing current to major fault currents is provided with a wide ribbon fuse link having a matrix-like system of perforations. The fuse link is wrapped around gas-evolving rod means in such a fashion as to form a gap between the longitudinal edges thereof resulting in the formation of currents of arc-quenching gas evolving from said rod means and flowing transversely across said edges of said ribbon fuse link.