Abstract: A compact, high breaking capacity fuse that includes a top and bottom insulative layer and a single piece fusible element disposed between the top and bottom insulative layer. The top and bottom insulative layers include cavities that are aligned at assembly to form a chamber in which a fusible element portion of the single piece fusible element is disposed. The single piece fusible element additionally includes terminal portions that extend along outer surfaces of the top and bottom insulative layers.

Abstract: Provided herein is a fuse that includes a conductive member, two shielding portions arranged on the conductive member, and a case. The conductive member includes a two bars on each end of the conductive member and an element (e.g., melting portion) that integrally connects the two bars. The two shielding members are disk shaped and are situated on the conductive member between the element and the two bars. The case encloses the element and the two shielding members.

Abstract: Provided is a current fuse that can improve the rating while also preventing explosive scattering of metal in association with arc discharge and enabling reliable cutting off of a circuit. The current fuse (1) includes an insulating substrate (2), a main fuse element (3) disposed on the insulating substrate (2), and a sub-fuse element (4) disposed on the insulating substrate (2) and having a higher melting point than the main fuse element (3). The main fuse element (3) and the sub-fuse element (4) are connected in parallel.

Abstract: A compact, high breaking capacity fuse that includes a top and bottom insulative layer and a single piece fusible element disposed between the top and bottom insulative layer. The top and bottom insulative layers include cavities that are aligned at assembly to form a chamber in which a fusible element portion of the single piece fusible element is disposed. The single piece fusible element additionally includes terminal portions that extend along outer surfaces of the top and bottom insulative layers.

Abstract: The present invention provides a protection device which includes a laminar element 16 which is formed of an insulation resin and has at least one throughhole; electrically conductive metal thin layers 22 and 28 which are positioned on each of main surfaces of the laminar element, and a fuse layer 40 which is positioned on a side surface defining said at least one throughhole and electrically connects the electrically conductive metal thin layers. The fuse layer includes a first metal layer 41 consisting of a metal having a higher melting point and a second metal layer 42 consisting of a metal having a lower melting point. The protection device of the present invention allows a larger amount of a current to flow therethrough and can provide a protection from an excessive current.

Abstract: The present invention provides a protection device which includes a laminar element 16 which is formed of an insulation resin and has at least one throughhole; electrically conductive metal thin layers 22 and 28 which are positioned on each of main surfaces of the laminar element, and a fuse layer 40 which is positioned on a side surface defining said at least one throughhole and electrically connects the electrically conductive metal thin layers. The fuse layer includes a first metal layer 41 consisting of a metal having a higher melting point and a second metal layer 42 consisting of a metal having a lower melting point. The protection device of the present invention allows a larger amount of a current to flow therethrough and can provide a protection from an excessive current.

Abstract: A medium voltage controllable fuse that provides fast activation in response to both low current and high current faults, and at load currents in response to an external condition detected by an external sensing device. The controllable fuse includes a high-current fault interrupting section, a low-current fault interrupting section, and a trigger element responsive to a fuse controller.

Abstract: A fuse is provided that includes a housing and a first lead and a second lead. The fuse further includes a fuse element having a current capacity. The fuse element forms a part of an electrical pathway between the first lead and the second lead. The fuse also includes a switch unit in communication with the housing and in series with the fuse element. The switch unit has an open state and a closed state. When the switch unit is in the closed state, the electrical pathway is connected to form a closed pathway between the first lead and the second lead, and when the switch unit is in the open state, the electrical pathway is disconnected to provide an open circuit between the first lead and the second lead.

Abstract: A fuse is provided that includes a housing and a first lead and a second lead. The fuse further includes a fuse element having a current capacity. The fuse element forms a part of an electrical pathway between the first lead and the second lead. The fuse also includes a switch unit in communication with the housing and in series with the fuse element. The switch unit has an open state and a closed state. When the switch unit is in the closed state, the electrical pathway is connected to form a closed pathway between the first lead and the second lead, and when the switch unit is in the open state, the electrical pathway is disconnected to provide an open circuit between the first lead and the second lead.

Abstract: A cryogenic current limiting fuse is disclosed together with a method of manufacturing a cryogenic current limiting fuse, the cryogenic current limiting fuse comprising a first cryogenic composite and a second cryogenic composite wherein at least one of the first and the second cryogenic composites has a non-linear and increasing resistivity with respect to at least one of temperature and current.

Abstract: A Full-Range fuse element assembly includes an insulative former having opposite first and second ends and electrically conducting connectors coupled to ends of the former. A plurality of fuse elements extend between the first connector and the second connector about the insulative former, and each of the fuse elements include a low current interrupting fuse element portion extending from the first connector and a high current limiting fuse element portion extending from the second connector. An insulative sleeve surrounds each of the low current interrupting fuse element portions, and each sleeve includes an end adjacent a respective one of the high current limiting fuse element portions. Each of the low current interrupting fuse element portions includes a weak spot located proximate the second end of a respective one of the sleeves.

Abstract: A dual element fuse includes a first conductive fuse coupler portion and an overload fusing assembly coupled to the first conductive fuse coupler portion. The overload fusing assembly includes a barrel having a flange at one end thereof, a trigger received within said barrel and positioned in a pre-operated position by a fusing alloy, and a conductive coil surrounding the barrel predominately in an area adjacent the flange. The conductive coil is connected between the first conductive fuse coupler portion and the flange, thereby concentrating heat generated in the conductive coil toward the flange.

Abstract: A fusing device with an adjustable current rating. The fusing device has a common conductive trace, a plurality of individual conductive traces, and a plurality of fusible links. Each fusible link electrically connects the common conductive trace with a corresponding individual conductive trace, and each fusible link has a current rating. The current ratings of the plurality of fusible links are substantially identical to each other or different. Each fusible link can have one or more fusible elements. The fusible elements can be coupled in parallel or in series. Optionally, at least one fusible element can be trimmed through an intermediate terminal. Fusible links can be disposed in a same surface of a substrate or in different surfaces of the substrate.

Abstract: A non-venting current limiting fuse for mounting in a cutout comprises a high current fuse component and a low current fuse component housed in separate compartments of a housing and connected in series. Interruption of a low current overload results in operation of the low current fuse component only, with the high current component being unaffected. The low current fuse component is removable from the housing such that when a low current overload situation exists, the low current fuse component can be simply removed and replaced without the need for replacement of the more costly high current fuse component.

Abstract: A safety fuse system includes a safety fuse including a fuse casing having a bottom surface and opposing end surfaces at each end of the bottom surface; a fuse element inside the fuse casing; a pair of electrical contacts connected to the fuse element, the electrical contacts extending through openings in the bottom surface of the fuse casing to an exterior of the fuse casing; the openings being located at a distance from the opposing end surfaces so that the electrical contacts are remote from the opposing ends; a fuse holder including a fuse holder casing having a top surface, the top surface including apertures for receiving the electrical contacts of the safety fuse, the apertures being in alignment with the safety fuse openings when the safety fuse is engaged with the fuse holder; metal contacts within the fuse holder casing for receiving the electrical contacts.

Abstract: An improved high voltage, full range, current limiting fuse with enhanced ability to dear high and low fault currents, even after the fuse has been subjected to a potentially damaging current surge, includes a sand-filled tubular housing with conductive terminals at either end and a dielectric support member supported therein about which a fusible structure is spirally wound. The fusible structure is electrically connected to the terminals and includes one or more high fault current interrupting elements for clearing high fault currents to which is mounted a low fault current interrupting assembly. The low fault current interrupting assembly includes a plurality of conductive components one of which is a damage sensor portion having a melting time-current characteristic which results in the damage sensor portion melting before the one or more high fault current interrupting elements. This enables the fuse to interrupt a low current which might exist after an element-damaging surge has occurred.

Abstract: A dual element ferrule fuse includes a short circuit element and an overload element. The overload element includes a heater element which, in addition to carrying heat, is designed to partially enclose the overload element with tabs that provide a weldable surface between the element and the metallic end cap, thus eliminating the need for a separate washer. Additionally, the tabs serve to center the element in the end cap and retain the element at a certain point in the fuse body between assembly of the fuse and soldering of the cap to the weldable surface.

Abstract: A fuse comprises a housing filled with arc-quenching material, terminals at the opposite ends of said housing, and a fuse element assembly in the housing connected between the terminals. The fuse element assembly has at least one short circuit blowing section and a center-melting slow blowing section, both disposed within an unpartitioned space in the housing, so that the entire body of arc-quenching material affects the short circuit blowing section of the fuse. The slow blowing fuse section has a surrounding layer of thermoplastic material which prevents the oxidation thereof and becomes plastic at the melting temperature of the time delay element. During the fuse element melting attendant to blowout, plastic deformation allows necessary geometric change in fuse element shape and facilitates collapse of the slow blowing fuse section.

Abstract: A fuse for use in a high-voltage circuit which has a first fusible element through which most of a current in the fuse flows in a normal state of the fuse and which further breaks into two pieces when overcurrent flows therethrough and further has a second fusible element provided around the first fusible element and adapted to burn in response to the overcurrent for further melting to remaining pieces of the first fusible element in such a manner as to enlarge the distance between the remaining pieces of the first fusible element to an extent sufficient to prevent occurence of a surplus arc therebetween. Further, material of material the first fusible element has a smaller electrical resistance, a larger cross-sectional area and a lower melting point than that of the second fusible element.

Abstract: An improved current-limiting section is provided for an interrupting device. A main-current-path section of the interrupting device carries substantially all of the normal, load current while only a negligible portion of the current flows through a higher-impedance current-limiting section. Upon operation of the interrupting device, the contacts of a switch in the main-current section are rapidly separated to create one or more gaps. Upon the creation of the one or more gaps, the current is transferred into the current-limiting section. The current-limiting section includes a plurality of fusible elements. The fusible elements are thin, elongated, conductive ribbons.

Abstract: A low fault current interrupting fuse assembly for a full range current limiting fuse of the type having a high fault current interrupting fuse element connected in series with the low fault current interrupting fuse assembly, said assembly including a first fuse element having a high melt temperature characteristic and a second fuse element having a low melt temperature characteristic, the first and second fuse elements being connected in parallel and having different diameters to provide current interruption at different time-current characteristics under low fault current conditions.

Abstract: An exothermically assisted electric fuse, having at least one exothermic body disposed in heat transfer relationship with at least a portion of each fusible element of the fuse, a triggering circuit for initiating an exothermic reaction in response to an overcurrent through the fuse, and a containment body partially enclosing the exothermic body for directing the heat energy released by the exothermic reaction. The containment body is disposed so as to confine and direct the heat energy in a direction which is substantially perpendicular to a plane containing the portion of the fusible element which is in heat transfer relationship with the exothermic body. In a preferred embodiment of such a fuse, the fusible element is wound around a support so that the fuse windings form the general shape of a cylinder, and the containment body is disposed so that the heat energy is directed in a radial direction with respect to the cylinder formed by the fuse windings.

Abstract: A current limiting fuse with less-inverse time-current characteristics characterized by a tubular housing having electrical terminals at each end, a fusible structure in the housing and interconnected between the terminals, the fusible structure comprising first fusible portions of silver alloy and second fusible portions of tin alloy intermediate the first fusible portions, and an arc-extinguishing filler around the second fusible portion.

Abstract: An inductively compensated trigger conductor for use in a chemically augmented fuse, of the type in which current flow through the fuse generates a magnetic field, employs at least one loop of electrically conductive material to inductively couple the trigger conductor to the magnetic field of the fuse. This inductive coupling increases the electrical inductance of the trigger circuit, and allows the fuse to be constructed so that the current division between the fuse conductor and the trigger conductor is constantly proportional, or at least more nearly so. When employed in a fuse which also includes a non-magnetic fuse support structure, a trigger device, and a means for chemically augmenting the separation of the fuse conductor into more than one segment during current interruption, the trigger circuit of this invention provides triggering action which is responsive only to the level of current flowing through the fuse, and not to a high rate of rise of current.

Abstract: A fuse link for use in a fast acting current limiting fuse also exhibiting a superior arc quenching capability consisting of a thin copper ribbon placed in series with a thin silver ribbon. The copper section provides a faster heating capability to the fuse while the silver section assures a lower arcing capability. The copper section has a series of apertures along the surface thereof which apertures are semicircular in configuration at the top and bottom of the copper section and separated by a circular aperture in between located in the center of the link. The silver section has top and bottom trapezoidal apertures which are separated by a smaller diameter circular aperture at the center of the link. The copper and silver links are placed in series between fuse terminals and are connected by both a mechanical and electrical connection to afford a reliable bond between the dissimilar metals constituting each of the separate links.

Abstract: This high voltage fuse comprises a pair of spaced terminals and a fusible conductive element connected between the terminals. At spaced locations along the length of the fusible element, there are bodies of a material that exothermically reacts when heated to a predetermined temperature. Connected between the terminals independently of the fusible element is a triggering circuit. The bodies of exothermic material are connected in good heat-transfer relationship with the triggering circuit and the fusible element so that the heating effect of current through the triggering circuit upon disruption of the fusible element causes the material of said bodies to exothermically react and thus cause further disruption of the fusible element at additional locations respectively located adjacent said bodies.

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 high voltage fuse for interrupting a wide range of currents and especially suited for low current interruption is disclosed. The fuse is comprised of a fuse element having a first and a second plurality of portions of reduced cross-sections. The second plurality of portions further comprise two or more parallel conducting paths some of which carry a portion of material which has a lower melting temperature than the melting temperature of the material of the fuse element. The parameters of the first and second plurality of reduced cross-section portions, the lower melting point material, and the fuse element itself are selected to adapt the fuse to provide proper protection for the various current conditions to which a high voltage transformer is subjected. The fuse element provides fast rupturing under short-circuit current conditions while also providing the characteristic of withstanding relatively high inrush current conditions.

Abstract: Electric fuses according to this invention aim to increase the ratio between current-carrying capacity and i.sup.2 .multidot.t values. This means, in other words, to increase the current-limiting action for any given current rating.The fusible element of such fuses comprises an axially inner substantially planar portion of silver having at least one short-circuit neck adapted to initiate circuit interruption when said neck reaches approximately the fusing temperature of silver. The fusible element of such fuses further comprises a pair of non-planar axially outer portions of copper each having a larger width and a larger surface than said axially inner portion. The axially inner portion and the axially outer portions are conductively interconnected.

Abstract: The invention involves new high voltage current limiting fuses employing composite metal fuse elements. One metal of the composite is aluminum which is of high conductivity and high melting point while the other is cadmium which is of low melting point, so that melting of the low melting point metal occurs at any and all locations along the element when its temperature reaches the said low melting point. The resulting composite exhibits properties that are not the mean of the metals employed and has a reversible resistance characteristic thus facilitating the design of the fuse for low current fault interruption.

Abstract: A composite fusible element of silver and copper includes an inlay of silver and a base formed by a thicker strip of copper than the inlay of silver. The strip of copper is severed by a pair of juxtaposed incisions, so that the entire current is carried at this particular point only by the strip of silver. Moreover, the incisions penetrate into the strip of silver, producing in it a point of reduced cross-section. The strip of copper is preferably provided with a concave groove. The strip of silver is preferably convex and fits into the concave groove of the strip of copper. The composite fusible element may include several parallel strips of silver in a joint base of copper.

Abstract: A current limiting fuse construction including a fuse element extending between electrically conductive terminals carries a body of arc-quenching filler material within a hollow casing of electrical insulating material. The filler material includes a first portion of arc quenching aluminum sulfate mixed with calcium sulfate binder, and second portion of arc quenching silica sand arranged in stratified layers, with the aluminum sulfate layer being positioned closest to a weak spot of the fuse element, and the layer of silica sand being positioned closer to an end cap of the fuse casing.

Abstract: A fuse for operation with both DC and AC currents is disclosed which consists of a composite fuse link contained in a large insulator housing. Located within the housing are first and second foil sections fabricated from a good conducting material. Each foil section is secured to a right and left terminal with its other end coupled to a central link fabricated from zinc. The central link is contained within a smaller cylinder and is surrounded by air, while the foil sections are surrounded by quartz sand or some other suitable filler material dispersed within the large housing.

Abstract: A current limiting fuse is disclosed in which a main fuse element is wound at a given pitch around a fuse spider or mandrel. An auxiliary fuse element for assisting in low current high voltage current limiting operation is wound at generally the same pitch but in a disposition of non-electrical contact on the same fuse spider or mandrel. At the ends of the auxiliary elements, sheaths of flexible glass material of known thickness and dielectric characteristics are disposed for being wound around a predetermined notch in the fuse element for greatly enhancing the flashover or arc transfer characteristic between the main fuse element and the auxiliary fuse element during a fusing operation.

Abstract: An electric fuse for elevated circuit voltages, such as, e.g. 5 to 15 KV. It includes a tubular casing or electric insulating material, terminal elements and a pulverulent arc-quenching filler. It further includes a plurality of equidistantly spaced fusible elements electrically connected in parallel, wound substantially helically in planes defining a prism and forming part of a current path conductively interconnecting the pair of terminal elements.The point of novelty consists in that the fusible elements are formed by a unitary metal stamping. That stamping also includes aligned metal bridges conductively interconnecting all the fusible elements. The preferred number of planes or sides of the aforementioned prism is four and the preferred number of bridges is n-1 for each quarter turn of the fusible elements, wherein n is the number of fusible elements connected in parallel. The bridges are arranged in spaced relation from the edges of the prism.

Abstract: A current limiting fuse is provided with a number of discrete current limiting elements coupled electrically in parallel between a pair of conductive terminals, and a fused gap assembly in series with each current limiting element whereby full range fault current protection is provided by the fuse. Under the influence of high range fault currents, the current limiting elements operate collectively to quickly clear the fault, while low fault currents are interrupted by fusing of the fused gaps to present a plurality of parallel arc gaps in the elements, which parallel gaps function in turn to sequentially distribute the full fault to each element resulting in successive interruption by the elements and ultimate clearing of the low range fault. In a second form of the invention shiftable contact sets in each element are operably coupled with a low fault current responsive device to create the arc gaps required for sequential operation of the current limiting elements.

Abstract: An indicating composite sectionalized fuse is provided having a high-current interrupting section, and a mechanically-connected detachable low-current interrupting section in series therewith, with the low-current interrupting section including a pull-away indicating fuse-link cable, which indicates externally a blown condition of the fuse. The low-current interrupting section is replaceable, following a low-current interruption, which has no effect upon the high-current interrupting section, the latter remaining intact and may be further used. During high-current interruption, both sections are fused, and collectively contribute together to a quick interruption of the connected electrical circuit, again there being an external indicated condition of the blown condition of the fuse by an ejection of the fuse-link cable.

Abstract: Pad-mounted double-fused switchgear especially adapted for use in underground distribution systems is provided which includes an oil tank having manually operable vacuum switch apparatus therein in conjunction with closely adjacent, series-connected, combination current limiting fuse-expulsion link protective fuse structure for maintaining the required momentary electrical rating of the overall switch apparatus notwithstanding of a relatively low-rated switch element, and for providing thermal protection for the switchgear. Double-fusing within the oil tank also serves to reduce electrical duty on upstream and downstream equipment, increases the interruption rating of the switchgear, and enhances overall system coordination.

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: The fusible element of an electric fuse has a first electrical path, a second electrical path in parallel relation with the first electrical path, a weak spot in the first electrical path which can respond to a potentially-hurtful overcurrent to fuse and thereby form a first arc in the first electrical path, and a weak spot in the second electrical path longitudinally displaced from the weak spot in the first electrical path which can respond to that overcurrent to fuse and thereby form a first arc in the second electrical path. The weak spots form primary arcs as they fuse; and one important function of those primary arcs is to establish the point at which the rate of rise of the overcurrent starts to diminish, while another important function of those primary arcs is to burn the adjacent portions of the respective electrical conducting paths.

Abstract: A circuit-protecting fuse comprises an insulating housing having electrically conductive connectors on opposite ends thereof to connect the fuse in an electrical circuit and at least one fusible link in the housing connected in electrically conductive relationship at opposite ends thereof with the connectors. The fusible link has at least one area of limited cross-section defining a heat-generating section and a member of a material which produces arc quenching gas when heated to a predetermined temperature positioned on the heat-generating section, whereby when an overload condition of predetermined magnitude occurs in a circuit in which the fuse is connected, the heat-generating section melts and vaporizes, and the heat thus produced generates an amount of deionizing gas from the member to extinguish any arc which forms at the vaporized section. Seal means seals the fuse to prevent escape therefrom of flames and ionized gas the the like produced as a result of the overload condition.

Abstract: Multiple portions exhibiting relatively different heat conductance characteristics, and so arranged that heat is concentrated in the fusible element, are used to control the heat transfer in a fusible element to achieve preselected time-current fusion characteristics. A portion of the fusible element may also be made of a material exhibiting a relatively high temperature coefficient of resistance for additional control definition of the time-current characteristics.

Abstract: The fuse is of the general purpose type having a casing closed at the ends by terminal caps; a core inside the casing; a main fusible element wound about the core and connected between the caps; a pair of arcing clips mounted in spaced relation on the core adjacent the main fusible element; and, an auxiliary element also wound about the core and connecting together the arcing clips. The improvement comprises that segments of the main element passing over the arcing clips are provided with additional reduced cross-sectional necks for improving the melting response of the element upon arcing between the element and the clips.

Abstract: A fuse construction has two spaced electrical conductors with inwardly directed conductor ends. A fuse plate member has opposite plate edges secured to said conductor ends. Said fuse plate has an inner insulative sheet with opposite outer conductive sheet faces. One of the sheet faces has an electric current breaking open band adjacent one conductor and the other sheet face has a similar band adjacent the other conductor. A fusible pin passes through a central part of said insulative sheet and said conductive faces and has its pin ends secured to said conductive faces between said open bands so that said bands do not break the electric current passing between said conductors while the pin does not blow but do break said electric current when the pin blows. A method of assembly of said fuse construction is disclosed.