Abstract: The invention is predicated on the use of synthetic resins as materials for fuse casings or fuse tubes because synthetic resins are relatively easily deformable. This invention is particularly applicable in connection with fuse tubes made of polyester resin and glass fibers. Such tubes lend themselves to making solderless fuse terminals, i.e. electrically conductive joints between the ferrules, or fuse caps, and the fusible element, or elements, inside the fuse tube. The fusible element is located inside the casing or fuse tube and bent over the rim thereof, and has a portion that engages the outer surface of the casing.

Abstract: A cartridge type fuse having a casing. A pair of terminal plugs is press-fitted into the ends of said casing and conductively interconnected by a fusible element. Each of said pair of terminal plugs has a knurled lateral wall. A pair of annular fasteners is mounted on said casing each adjacent one of the ends thereof. Said fasteners press the wall of said casing radially inwardly into firm engagement with said knurled lateral walls of said pair of terminal plugs. The casing preferably includes an outermost ply of woven glass cloth, an innermost ply of woven glass cloth, and at least one intermediate ply of relatively loose non-woven fibers sandwiched between said outermost ply and said innermost ply, and the constituent plies of said casing are preferably integrated by polyester resin.

Abstract: A ribbon-type fusible element is subdivided by equidistant points of equally reduced cross-section into a plurality of serially connected fusible element sections. These include first angularly bent fusible element sections comprising two half-sections, second fusible element sections being planar and arranged in spaced relation from the first fusible element sections, a planar support for the second fusible element sections; and third fusible element sections which are angularly bent and conductively interconnect the first and the second fusible element sections. The above planar support includes a portion that extends in a direction longitudinally of the fusible element and transverse arms that are in registry with the second fusible element sections. Fastener means project through said transverse arms and said second fusible element sections. As a result, the sections of the fusible element situated between contiguous fasteners are fixedly supported.

Abstract: An electric fuse having a tubular casing, an arc-quenching filler, a pair of terminal plugs closing the ends of the casing and fusible elements conductively interconnecting said pair of terminal plugs. The thermal duty imposed upon said arc-quenching filler is equalized so that equal amounts of filler are caused to absorb approximately equal amounts of heat. This is achieved by immobilizing the positions of the fusible elements and by giving them such a shape that heat dissipation is substantially equalized. In other words, the position of the fusible elements relative to the casing must be in such a way that they are not displaced when the fuse is filled with pulverulent arc-quenching filler, and the arc path of one of the fusible elements must be separated as much as possible from the arc path of the other fusible element.

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: An electric protective device capable of handling both short-circuit currents and minor overload currents of impermissible duration. The device for interrupting small overload currents of impermissible duration includes a cylinder, a plunger inside said cylinder, a spring biasing said plunger, heater means, a solder joint conductively connected to said heater means and said plunger, and a body of material evolving gases under the heat of an arc surrounding said solder joint, adjacent portions of said plunger and adjacent portions of said heater means.The process of manufacturing this device is preferably performed in two steps, namely arranging adjacent the solder joint of the device a sleeve-shaped body of melamine and an inorganic filler in a highly viscous putty-like form, and thereafter allowing said body to harden completely.

Abstract: In fuses embodying this invention each of the terminal elements has a port for the passage of fluid through the casing of the fuse during normal operation thereof, i.e. while the fuse is carrying current. A tubular fusible element conductively interconnects said port in each of said terminal elements. The fuse further includes a toroidal body of quartz sand filling the space between said casing and said tubular fusible element. The fusible element has perforations covered by annular structures of electric insulating material precluding said quartz sand from penetrating into said tubular fusible element during the normal operation of said fuse. The fuse is further provided with a pair of check valves which open during normal operation of said fuse and then allow the flow of fluid through said tubular fusible element and close on occurrence of a build-up of a predetermined amount of pressure inside of said tubular fusible element and then inhibit said flow of fluid.

Abstract: An electric fuse has an undulated fusible element provided with a plurality of aligned, spaced perforations. A straight rod preferably of a gas-evolving material extends through said plurality of perforations. The rod increases significantly the dimensional stability of the fusible element structure and contributes at the same time significantly to arc-extinction, if made of a gas-evolving material.

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.