Abstract: An electrical transformer comprises a hollow form exhibiting high magnetic permeability and interior projections extending between separable halves of the form to provide a low magnetic leakage transformer core. Primary and secondary windings are disposed around the central projections. Furthermore, there is included means internal to the form for providing a lower permeability magnetic circuit shunt path. The internal shunt path means is typically either a cylinder or disc structure. A reduction in stray magnetic flux is desirable since it means that smaller, less expensive transformers may be constructed. The transformer of the present invention is particularly useful in electronic ballast circuits for gas discharge lamps because the magnetic shunt path acts as a current-limiting inductor. Moreover, since the transformers of the present invention do not generate external magnetic fields, flux shields are not required to maintain high efficiency.

Abstract: There is provided a core lamination for electromagnetic devices. The lamination comprises an open, substantially C-shaped frame having inwardly pointing end portions facing one another across a gap, and a central limb of a substantially rectangular shape, tightly insertable with its width into the gap between the end portions. When thus inserted, the central limb defines the space enclosed by the frame two window-like openings, each of which has a height-to-width ratio of about 3:1. The shapes and relative dimensions of the open frame and the central limb are such that they are capable of interlocking and of fully tesselating a surface delimited by two parallel edges.

Abstract: The improved structure of an inductor with an amorphous sheet core and a winding has been found. A core assembly has a pair of housing halves made of non-magnetic material with U-shaped track, in which a laminated amorphous sheet is mounted. The ends of the halves are inserted in a winding so that the ends of the cores abut with each other directly or through a gap spacer. The core halves are pressed by spring action to assemble the inductor. The core halves are produced by the steps of winding an amorphous sheet to a coil, inserting the coil in the track of the housing, and impregnating the coil with plastics.

Abstract: Laminated iron core for transformers, choke coils and the like includes a plurality of core parts overlying one another at respective mutually opposing abutment locations, the respective mutually opposing abutment locations defining a space of varying width between one another, the core parts being disposed so as to form a relatively short closed inner path and increasingly longer closed outer paths for magnetic force lines, the space having a region of relatively greater width across which the relatively short closed inner path extends.

Abstract: A core gap spacing arrangement for a transformer includes a length of twisted wire pair. The twisted pair has a relatively low packing density and is therefore compressible over a large range by using relatively low compression forces, resulting in greater ability to accurately adjust the inductance of the transformer primary winding.

Abstract: Conventionally, silicon steel strips and ferrite cores have been used as the core of a choke coil. These strips and the like have not yet been replaced with amorphous alloy because in the known amorphous magnetic alloy the pre-magnetization characteristic, the amount of heat generated, and the secular change are poor.The present invention proposes a core of a choke coil which consists of a coiled thin strip of an amorphous alloy, and has at least one cut air gap, the coiled regions of the thin strip being bound to one another at at least in the neighborhood of said at least one cut air gap, and said amorphous magnetic alloy is essentially comprised of the following composition, Fe.sub.x Mn.sub.y (Si.sub.p B.sub.q P.sub.r C.sub.s).sub.z, wherein x+y+z is 100 atomic % based on all of the elements, y is from 0.001 to 10 atomic %, z is from 21 to 25.5 atomic %, p+q+r+s is atomic % 1, p is from 0.40 to 0.75, r is fro 0.0001 to 0.05, the ratio s/q is from 0.03 to 0.4, and z is z.ltoreq.50p+1, z.ltoreq.10p+19, z.

Abstract: A safety transformer with low coupling factor, which comprises at least one primary winding mounted on a spool and at least one secondary winding mounted on a spool, and a core including a first section cooperating with the primary winding(s) and a second section cooperating with the secondary winding(s). The first and second core sections have facing ends and all facing ends of these core sections are separated by an isolating means.

Abstract: Two fluorescent lamps are lightened by a single inverter circuit which provides switched power current to a single leakage transformer. The leakage transformer has a single primary winding coupled with said inverter circuit and a pair of secondary windings each coupled with a related fluorescent lamp. The core of said leakage transformer has a closed magnetic core with a pair of short legs each of which bridges across said closed magnetic path with a non-magnetic material so that said pair of short legs provides three windows and bypass leakage magnetic paths. The first window is defined by said pair of short legs, and each of the second and the third legs is defined by one of said short legs and said closed magnetic path. The primary winding is mounted in said first window, and each of said pair of secondary windings is mounted in said second or third window.

Abstract: A three-phase choke, includes a five-leg core formed of a central core leg carrying a winding, two outer core legs each carrying a winding and two return legs, the central and outer core legs being formed of stacks of laminations, a lower yoke having ends adjacent the return legs, an upper yoke formed of sections having ends defining gaps between the ends of the sections and gaps between the return legs and the ends of the sections of the upper yoke adjacent thereto, and non-magnetic material filling the gaps, the yokes and return legs having cross sections being smaller than the cross sections of the core legs carrying a winding, each of the return legs and the ends of the yokes adjacent thereto having a first magnetic resistance, the upper yoke having a respective portion thereof disposed between the central core leg and each of the outer core legs each having a second magnetic resistance, and the lower yoke having a respective portion thereof disposed between the central core leg and each of the outer core

Abstract: Electric machine, such as a transformer, a choke or a constant-voltage regulator, having an iron core assemblable from a plurality of individual, substantially rectangular core parts, including legs and intermediate yoke parts, formed of mutually held-together laminate layers, and clamping means such as clamping straps or plates clampable into engagement with a corresponding clamping surface at outer contours of the leg core parts transversely to the laminate layers by clamping elements such as screws or rivets, includes means defining channel or tunnel-shaped recesses extending parallel to all of the mutually parallel laminate layers of all of the assemblable individual core parts and substantially perpendicularly to juxtaposed joint abutments of the respective individual core parts.

Abstract: A stepped iron core formed of sheetmetal laminations for a static or dynamic electric machine, such as a transformer, having yokes and legs and intermediate parts of at least one thereof including stacks of the sheetmetal laminations mutually held together forming individual steps of the yokes and the legs, the yoke stacks and the leg stacks being joinable with one another at respective abutment joint locations formed thereon, and means located at the respective abutment joint locations for achieving a varying magnetic reluctance therebetween so that a longer path of lines of force passes through the respective abutment joint locations in the region thereof of lower magnetic reluctance.

Abstract: A shielded transformer of the type particularly used as an isolation transformer, has a greatly reduced interwinding capacitance. Metallic overlap is provided, completely across a juncture of the metallic shield with faces of the windows in the core, and completely across a juncture of the metallic shield with the metallic case. This metallic overlap is tolerant to misalignments and variations in fit, completely eliminating gaps that cannot be economically made small with the butt joint of present art. The overlap comprises grooves in faces of the window or in the case. In a second embodiment, the overlap comprises grooves in channels on faces of the window and on the case. The shield fits into the grooves.

Abstract: A laminated core for an ignition coil is made from E shaped and bar shaped laminated members. The E shaped member has equal length outer legs and a shorter center leg with oblique surfaces on the inner free ends of the outer legs. The bar shaped member has oblique surfaces at the ends thereof adapted to engage the oblique surfaces of the first member when the second member is oriented perpendicularly to the center leg of the first member and further to bend the outer legs of the first member outward to generate a restoring spring force as the second member is advanced toward the center leg to reduce the air gap. A coil assembled on the center leg is used to monitor a physical parameter indicative of a desired magnetic or electrical characteristic as the air gap is reduced and the members are fixed together when said characteristic is obtained.

Abstract: A low self-capacitance inductor is described for use as an output inductor in high frequency inverter power supplies. A pair of channel-shaped ferrite core members are assembled with a gap of material approximating the permeability of air. The core members are arranged to provide an axial aperture therebetween. A plurality of conductor segments are disposed in the aperture and are electrically interconnected to plated through holes in a supporting printed circuit board assembly. The conductor turns for the inductor are selected by the pattern of printed circuit interconnections between selected ones of the plated through holes, whereby the same current densities in the inductor are achieved for different conductor turns arrangements.

Abstract: The invention relates to a magnetic circuit for inductance devices, to an induction device incorporating such circuit, as well as a process for producing the above-mentioned circuit. The novel magnetic circuit is constituted by a parallelepipedic bar of magnetic material comprising at least two substantially superimposed grooves. This circuit is substantially H-shaped in a plane perpendicular to said grooves. The lower branches of the H, delimiting the lower groove or grooves, are provided with electrical connection means. Consequently, the induction devices thus obtained may be easily and efficiently fixed onto printed circuits, or directly fixed onto hybrid circuit supports. The induction devices thus produced are particularly adapted to be miniaturized.

Abstract: This induction winding includes a magnetic core formed by a vertical stack of iron disks separated by air gaps. The disks (8) include a plurality of sector-shaped portions (1) each of which is constituted by a succession of magnetic laminations (6), a first part (12,13) of these laminations are all of identical length and a second part (14) are of regularly decreasing length from one lamination to the next. The direction (F.sub.1) in which the laminations are rolled in the mill is perpendicular to the axis (7) of the winding. The increased magnetic loss that this causes is compensated by the improved filling coefficient that can then be readily obtained.

Abstract: A laminated magnetic core characterized by an electromagnetic core having core legs which comprise elongated apertures and edge notches disposed transversely to the longitudinal axis of the legs, such as high reluctance cores with linear magnetization characteristics for high voltage shunt reactors. In one embodiment the apertures include compact bodies of microlaminations for more flexibility and control in adjusting permeability and/or core reluctance.

Abstract: The invention relates to a device for tightening the core and the upper and lower cross pieces of a shunt inductance winding by means of a plurality of tie rods (5, 6, 7) which are preferably seven in number and which pass through the central hole of the core. A cup-shaped part (12) held by nuts (13) is fitted onto the tie rods, the outer wall of this part is threaded, a nut (14) is screwed onto this part (12) and bears against axially elastic washers (15).

Abstract: A pincushion distortion correction saturable reactor is a saturable transformer comprising a core having four legs, controlled and control coils being coupled to the core legs in a perpendicular relation to each other. The core gap for the controlled coil is provided in an unbalanced form, and a parabolic current at the vertical scanning frequency (or at horizontal scanning frequency) containing a superimposed DC component is supplied through the control coil to modulate the inductance of the controlled coil. The inductance of the controlled coil is thus reduced in a region where the magnetomotive force produced by the control coil is greater than that produced by the control coil to preclude deflectional distortion in the neighborhood of the center of the reproduction on the screen and improve the horizontal linearity.

Abstract: In an electrodeless discharge lamp of the type including an ionizable medium within a sealed envelope capable of emitting radiant energy when subjected to a radio frequency field, an oscillator for generating an output signal at a given radio frequency, a Class D RF amplifier including first and second transistors responsive to the oscillator output signal, and an induction coil responsive to the output of the amplifier, the coil being positioned in close physical proximity to the medium in the envelope for coupling to the medium an electric field having a magnitude sufficient to initiate ionization of the medium and a magnetic field for maintaining the ionization, there is disclosed an improved transformer for driving the Class D amplifier which results in a significant decrease in power consumption. The oscillator output signal is connected to the primary winding of a transformer which includes a toroidal, magnetic core.

Abstract: A transformer comprising a plurality of conductive screening foils located between the core and the windings and between the primary and secondary windings. In order to prevent eddy current losses in the screening foils, at least the first screening foil is made of a soft-magnetic material.

Abstract: A ferrite core type transformer, such as a flyback transformer used in a television receiver, includes a ferrite core unit and a coil unit mounted on the core unit. The ferrite core unit is constituted by a pair of U-shaped core members which are arranged to assume a figure "O" with a suitable spacer members held between each of the matching ends. A first bonding agent of quick hardening type is applied between the matching ends of the U-shaped core member, and a second bonding agent having resiliency is deposited in a contacting area between the core unit and the coil unit.

Abstract: In a transformer for use in a receiver set, a non-magnetic material arranged in part of a closed magnetic path established by a magnetic core is made of a plastic material such as paper mash or silicon putty. The non-magnetic material is pressurized and deformed so as to set the inductance of a coil mounted on the magnetic core to a predetermined value.

Abstract: An impedance coil core which includes a plurality of core legs and yokes which interconnect the core legs in an assembled condition of the core is provided with aligned recesses in the yokes and in the core legs for accommodating tensioning bolts which extend into the recesses and press the yokes against the core legs in the assembled condition. Each of the core legs includes a plurality of laminated assemblies including sheet metal elements. Those portions of the yokes and at least of the laminated assemblies adjoining the latter are provided with non-magnetic intermediate layers in the central region which is provided with the recesses. The intermediate layers in the core legs are wedge-shaped and diverge toward the adjacent yokes, and the intermediate layers in the yokes are cross-sectionally rectangular.

Abstract: A residual current transformer comprises an annular magnetic core which has not a gap nor sectional part crossing said magnetic core but has one or more narrow sectional area parts.

Abstract: A lamp ballast has a pair of adjacent gapped "O" magnetic cores made of nested, almost complete loops of amorphous metal strip with the gaps in the loops shaped and arranged under the secondary coil to simulate any type of restricted cross section for shaping the lamp current. A long slender reactor has a similar configuration in which the gaps are staggered; a different embodiment has a long central core of compressed amorphous metal flake and a helical overwrap of ribbon. An alloy of iron, boron, and silicon with a high B.sub.r /B.sub.s ratio is preferred for these inductive devices.

Abstract: The ferromagnetic core of a transformer in a switching regulator power supply is configured to improve the efficiency of the supply. Since the switching times and their resultant losses occupy a greater percentage of the energy-storage energy-transfer cycle as the operating frequency increases, efficiency is increased by narrowing the operating frequency range. There is provided a transformer core which allows the inductances in the transformer windings to vary during each energy-storage and energy-transfer half cycle. The initial inductance can be chosen such that a predetermined time interval is added to each half cycle regardless of output load to thereby decrease the operating frequency range.

Abstract: A magnetic circuit for inductive electrical devices, preferably reactors, comprises a frame consisting of yokes and side walls, the frame having a preferably rectangular cross-section and being manufactured from laminated magnetic material. At least one core leg having a preferably circular cross-section and composed of laminated magnetic material is arranged in the frame between the two yokes. Between the ends of the core leg and the yokes are arranged cross-flux plates of laminated magnetic material in order to distribute the flux between the legs and yokes. The laminations in the cross-flux plates are oriented to be perpendicular to the laminations in the yokes. Each cross-flux plate covers at least the full width of the yoke and at least the complete width of the core leg. The width of each plate is suitably as great as the diameter of the winding which is arranged around the core leg. Each plate will thus act as a mechanical support for the ends of the winding.

Abstract: According to the invention, the ring transformer for resistance butt welders comprises a plurality of sections, each composed of a non-closed magnetic core, a part of the primary winding and a part of the secondary winding. Each section is so arranged with respect to the other sections that the end faces of its non-closed magnetic core are in contact with the end faces of the two adjacent sections, whereby the non-closed magnetic cores of all the sections make up a closed magnetic core of the transformer. The primary winding of each section is connected to those of all the other sections so that they all make up the primary winding of the transformer. The secondary winding of each section is connected to those of the other sections so that they all make up the secondary winding of the transformer.

Abstract: To permit adjustment of the air gap of an inductance unit suitable as a ballast for fluorescent lamps particularly in form of a leakage transformer or as a choke, for multi-voltage connection, an outer, essentially U-shaped core structure (1, 100), and having an integral connecting cross element (1, 101a), and two parallel leg elements (1b, 101b), has at least one longitudinally slidable cross element (2, 2', 2"; 3, 3'), the cross element being formed with a central longitudinal core element (14, 15; 14', 14") extending parallel to the leg elements, and short of the adjacent cross element, and longitudinally slidable within the leg elements so that the air gap between the longitudinal element and the adjacent cross element, and forming a magnetic shunt, can be adjusted after manufacture of the attached laminate to compensate for manufacturing tolerances and provide an inductance element having design impedance regardless of variation in the size of the longitudinal core element.

Abstract: A transformer formed of primary and secondary coils wound concentrically about a bobbin and maintained in spaced relation by a precision spacer. Two symmetric, L-shaped, ferrite core elements are mounted to form a magnetic flux path for flux generated by the coils; these core elements are maintained, at least partially, in spaced relation by flanges of the bobbin, thereby forming two gaps which may be of relatively large dimension. One of the flanges includes wire passageways and spaced holes for providing electrical connection, with strain relief, to the coils of the transformer.

Abstract: A laser beam (23) is directed at a portion of at least one of a pair of opposed sections (12 or 13) which define an air gap (22) in an inductive device (10). That portion is heated to cause the material of the section to flow into the air gap to adjust the device by decreasing the reluctance of the device to increase the inductance thereof.

Abstract: A ferrite toroid has two radially extending gaps. Into each gap there is inserted an insulative shim having a magnetic metal ribbon folded over the shim. When current is applied to a winding on the core, the resultant magnetic flux is steered into the magnetic ribbons and around the gaps. For high frequency excitations eddy current losses in the ribbons are high and the windings have low Q but high inductance. At high winding currents, the magnetic ribbons are saturated, the inductance is reduced and the Q of the winding increases. In a switching voltage regulator, this inductor tends to generate only a small amount of ringing and electromagnetic radiation noise.

Abstract: A stabilized saturated reactor comprising a solid toroidal core of magnetic material. The core has at least one end face provided with plural circumferentially spaced slots. Each slot extends in a substantially radial plane with respect to the central axis of the core. Each slot has a width substantially less than the cross-sectional dimensions of the core. The core may have a second end face which is provided with plural slots staggered circumferentially in relation to the slots in the other end face to simulate a linear reactor. The core, with both end faces slotted, may be combined under a common winding with an unslotted saturated toroidal core spaced therefrom to simulate the stabilized saturated reactor core having only one slotted end face.

Abstract: The rod-shaped core portion carrying the high-voltage secondary winding is separated from the U-shaped core portion carrying the primary winding by an insulating partition integral with an insulating casing that both provides galvanic separation between the primary and secondary parts of the transformer and also defines the so-called air gaps of the core.

Abstract: A shell-type voltage regulating transformer includes a magnetic core comprising a stack of modified EI laminations having a center leg forming two sections. One of the center leg sections defines a low reluctance magnetically saturable path while the other section defines a high reluctance non-saturating path. A primary winding is wound on the center leg for magnetically coupling with both sections and a pair of secondary windings are wound each for magnetically coupling with only one of the sections. The two secondary windings are connected in series opposing relationship to supply a substantially constant voltage to a load.

Abstract: A high frequency drive circuit operating as a push-pull, Class C oscillator for driving a high-intensity, gaseous discharge lamp and avoiding the use of a relatively large ballast coil. A highly stable power supply for operating in conjunction with such circuit is also provided.

Abstract: A current limiter to protect circuit elements from excessive current caused by transient load impedance or power supply surges. A multiple branch element magnetic circuit includes at least one saturable branch element inductively coupled by a coil connected in series with the load of an external electric circuit. The magnetic circuit further includes lower permeance bias branch element which biases the saturable branch element in a low permeance, saturated state when current through the coil is below a predetermined threshold value, and which biases at least one saturable branch element in its high permeance, non-saturated state when current through the coil is in a predetermined range above and extending from the threshold value. A relatively high permeance shunt branch element provides a shunt path for magnetic flux.

Abstract: An ignition coil for an internal combustion engine comprises a magnetic c having a plurality of arms lying at an angle to each other, a primary inductive winding on one of said arms and a secondary high voltage winding on another of said arms.The primary and secondary windings are on adjacent arms and have intersecting axes, with a plane through one end of one of said windings perpendicular to the axis of said one winding intersecting both ends of the other winding.

Abstract: A device for controlling an A.C. motor having an electromagnetic field ining coil wound around a conductive element having at least one inwardly directed opening bound by surface areas thereof and having a gap a between the surface areas defined by the formula a .gtoreq. .delta., wherein .delta. is the wave penetrating depth of an instantaneous operating frequency of the induced electromagnetic energy, the coil being wound so as to surround the open space and the element.

Abstract: A transformer assembly comprising a core structure having an open space, primary and secondary coil units mounted either in parallel or in concentric relationship on the core structure, and a unitary insulating envelope of heat-resistant dielectric material such as silicon rubber, the insulating envelope a portion encapsulating the windings of the primary and secondary coil units and a portion occupying that area of the above mentioned open space which is subject to production of a corona discharge due to the high voltage to be developed in the secondary coil unit. The insulating envelope is formed by injecting the dielectric material of fluid state into a mould to which the subassembly of the core structure and coil units is fitted in part of in its entirety except for terminal elements. A partial vacuum is established in the mould so that the insulating envelope produced is void-free.

Abstract: A coil of insulated wire surrounds a low reluctance core. A combination of low reluctance and high reluctance materials positioned adjacent said coil: (1) control the spatial extent of the magnetic flux and, (2) concentrate the total reluctance of the magnetic circuit of the exciting coil into a volume of controlled size and shape within the material being tested. The magnetic flux is controlled, and the reluctance is concentrated, in such a manner as to optimize the sensitivity of the eddy-current generator to variations in the material being tested; at the same time, the coil impedance is maintained at a value which is optimum for the performance of any selected precision electrical impedance measuring device.

Abstract: A constant voltage transformer or other ferromagnetic device in which operating characteristics depend on the effective length of the air gap in a shunt forming part of the magnetic core structure. Different effective air gaps are obtained, using identically the same core lamination sets (which may be in a low-scrap pattern) by (a) forming shunt laminations of a length to provide a maximum air gap length and with a longitudinally offset rivet hole, offset by slightly less than half the maximum air gap length, (b) stacking the shunt laminations on a rivet in a stacking pattern in which the long ends of some laminations are oriented inward and the long ends of others oriented outward so as to produce a shunt stack with the laminations in a staggered relationship, and (c) varying the stacking pattern to thereby vary the proportion of outward to inward-oriented laminations. The stacking pattern, e.g., 1 out .times. 1 in; 1 out .times. 2 in; 2 out .times. 5 in; 1 out .times. 3 in; 1 out .times. 4 in; etc.

Abstract: A ferro-resonant, voltage-regulating transformer. The transformer has a primary winding formed about a portion of each leg in each of two spaced, juxtaposed cores. A regulated output voltage is produced at a resonant circuit formed by a capacitor and a secondary winding around another leg of the first core. The flux variations in the two cores are continuously out of phase with each other. As the primary voltage changes the magnitude of the total flux in the system, the flux in the second core can vary in magnitude and phase thereby to maintain the flux in the first core at a constant level. Thus, the output voltage at the resonant circuit is substantially constant.

Abstract: A shell-core current transformer comprising a tubular main insulator, a measuring core arranged at least substantially coaxially with the main insulator and comprising a primary winding and a secondary winding, and a protecting core, likewise arranged at least substantially coaxially with the main insulator and comprising a primary winding and a secondary winding. The measuring core and the protecting core have a common primary winding, arranged outside the main insulator, and a common outer core part functioning as magnetic return circuit. The inner part of the measuring core, with the exception of the inner yoke portions, and the secondary winding of the measuring core are within the main insulator placed inside the inner part of the protecting core and inside the secondary winding of the protecting core, and the measuring core and the protecting core have common inner yoke portions.

Abstract: A reactor winding in the form of a high current, multi-turn, multi-layer insulated coil stack embracing an inner member of a magnetizable core assembly of a reactor is resiliently supported by the outer member of the core assembly by inserting a plurality of ripple spring sheets of non-magnetic material between the outer member and selected adjacent surfaces of the outer periphery of the windings. The inner core member is resiliently supported within the coil stack by an additional plurality of ripple spring sheets disposed between adjacent surfaces of the coil stack and inner core member. Ripple spring sheets are also positioned between adjacent surfaces of the inner and outer core members. The ripple spring sheets are preferably disposed between flat side sheets to provide uniform distribution of the spring forces.

Abstract: The present invention refers to a magnetic core comprising flat magnetic plates superimposed and joined in order to constitute the toroidal form of the core, creating an internal space for the winding and a lateral air gap groove. There being assembled in the open space of the core or air gap, annulling it, an open hoop made of magnetic material having suitable dimensions, whose outer edge penetrates into the interior space of the winding in order thus to create a new internal air gap because the external diameter of the hoop is smaller than the internal diameter of the space available for the inductance coils. In this way a magnetic shunt is situated between the inductance coils in order to regulate their mutual inductance.

Abstract: A ferrite magnetic core includes a one-piece rectangular outer member with aligned circular apertures in which the ends of a cylindrical center member are retained to thus establish a radial air gap. Radial magnetic forces acting on the core members are summed to zero to theoretically eliminate movement and result in low acoustic noise in high operating frequency power inductors and transformers. A magnetic bridge is added to reduce air gap fringing flux outside the core. Other modifications and a "C" core configuration are described.

Abstract: A current transformer comprising a tubular main insulator, a number of first windings arranged around the main insulator, and a number of second windings arranged inside the main insulator. The second windings are arranged opposite their corresponding first windings so that the pairs of windings formed in this way are, in the direction of the axis of the main insulator, at a distance from each other. The primary windings are connected in series. A magnetic circuit related to each pair of windings consists of a first core portion that surrounds each first winding from the outside and has yoke portions, and of a second core portion covering each second winding and the main insulator from the inside and has likewise yoke portions. The subsequent cores, or core portions, have common intermediate yoke portions and the primary windings are arranged so as to magnetize both cores in the same direction.

Abstract: A current limiter to protect circuit elements from excessive current caused by transient load impedance or power supply surges. A multiple branch element magnetic circuit includes at least one saturable branch element inductively coupled by a coil connected in series with the load of an external electric circuit. The magnetic circuit further includes low permeance bias branch element which biases the saturable branch element in a low permeance, saturated state when current through the coil is below a predetermined threshold value, and which biases at least one saturable branch element in its high permeance, non-saturated state when current through the coil is in a predetermined range above and extending from the threshold value. A relatively high permeance shunt branch element provides a shunt path for magnetic flux.