Abstract: A powder core is obtained by compaction-forming magnetic powder. The magnetic powder is an alloy comprising 1-10 wt % Si, 0.1-1.0 wt % O, and balance Fe. An insulator comprising SiO2 and MgO as main components is interposed between powder particles having a particle size of 150 &mgr;m or less.

Abstract: A magnetic flux guiding apparatus comprises a conduit having a wall that comprises an electrically conducting material. An electrically insulating gap is formed in the wall along an entire length of the conduit. The electrically insulating gap prevents the conduit from having a closed electrical path that links any of the desired magnetic flux paths. For example, the electrically insulating gap can prevent the conduit from having a closed electrical path that surrounds a lengthwise axis of the conduit. The apparatus can also comprise a magnetic-field source that produces a magnetic flux that passes through an interior region bounded by the conduit. Where the conduit comprises a conventional electrically conducting material, the magnetic-field source can be a source of time-varying magnetic flux, such as an electrical coil.

Abstract: A common mode and differential mode inductance assembly including first and second torridial cores wherein first and second windings are wrapped about first and second segments of the first core and the first core forms a first surface and wherein the second core forms a second surface and is positioned adjacent the first core such that the first and second surfaces oppose each other and a gap is formed between the first and second surfaces.

Abstract: In an I-conductor for the high-frequency or microwave systems, two uniform cores are disposed parallel to each other with a gap therebetween and a coil is disposed on each core in such a way that, when energized by an HF current, a magnetic circuit through the two cores is generated by way of the gap at one end of the arrangement. The magnetic field forming windings are uniform. As cores, magnetically anisotropic materials may be used.

Abstract: A reactor in which two first cores 1 made of lamination and I-shaped and two second cores 2 made of lamination and I-shaped are disposed such that the two first cores are parallel to each other, the two second cores are parallel to each other and that the two second cores having respective coils 4 therearound are perpendicular to the two first cores, thereby forming a rectagular shape, wherein there are provided a first spacer 10 and a second spacer 20, which have on their respective outward side faces two protrusions 13, 23 for positioning each first core and two other protrusions 14, 15 for holding longer sides of each first core with one thereof having at its tip end an engaging mechanism to secure each first core, and which have on their respective inward side faces four protrusions 17, 27 for positioning two neighboring corners of the respective second cores and an elevated portions 16, 26 provided between the four protrusions and elevated in a direction perpendicular to the length of the first cores.

Abstract: An electromagnetic apparatus having an adjusting effective core gap includes: (a) an electrical winding; and (b) a ferrous core situated proximal with the electrical winding. The core has a first terminus and a second terminus arranged in spaced relation to establish a gap distance between the termini in a region in substantial register with the termini. The winding and the core cooperate to establish an inductance related with an electrical current applied to the winding. At least one terminus of the termini has a configuration responsive to varying the current by effecting selective local saturation of successive portions of the at least one terminus for successive values of the current. The selective local saturation establishes successive new effective gap distances. Each respective new effective gap distance is appropriate for establishing a successive new optimum inductance for the current value then extant.

Abstract: A conventional braided wire has high direct current resistance and high winding resistance in high-frequency regions, making it impossible to achieve a power conversion transformer having sufficient conversion efficiency. In the present invention, a braided wire is braided from three or more cluster wires, each comprising multiple strands, and is used as winding material for a leakage flux-type power conversion transformer. The braid pitch of the braided wire is set so that the ratio between one-turn winding length and the braid pitch is between 0.5 and 2.5.

Abstract: An inductor with multiple air-gap separations comprises a magnetic core and an enameled wire around the magnetic core. The magnetic core has an air gap with at least a large-gap portion and a small-gap portion. The small-gap portion provides enough inductance in case of low load input to prevent harmonic distortion. The large-gap portion provides enough inductance in case of heavy load output and low input voltage to prevent saturation and temperature rise, thus enhancing power efficiency.

Abstract: A wire wound core has windings which are wound in a single-layer winding fashion around substantially cylindrical body portions of bobbins. A gap is provided between the inner wall of a hole formed in the substantially cylindrical body portion of each bobbin and the outer peripheral surface of a leg portion of a corresponding core member by a rail-shaped rib disposed on the inner wall of the hole. Another gap is provided between the inner surface of an arm portion of the core member and the outer major of a flange portion of the bobbin by a convex spacer disposed on the outer major surface of the core member.

Abstract: An electromagnetic apparatus having an adjusting effective core gap includes: (a) an electrical winding; and (b) a ferrous core situated proximal with the electrical winding. The core has a first terminus and a second terminus arranged in spaced relation to establish a gap distance between the termini in a region in substantial register with the termini. The winding and the core cooperate to establish an inductance related with an electrical current applied to the winding. At least one terminus of the termini has a configuration responsive to varying the current by effecting selective local saturation of successive portions of the at least one terminus for successive values of the current. The selective local saturation establishes successive new effective gap distances. Each respective new effective gap distance is appropriate for establishing a successive new optimum inductance for the current value then extant.

Abstract: An inductor with multiple air-gap separations comprises a magnetic core and an enameled wire around the magnetic core. The magnetic core has an air gap with at least a large-gap portion and a small-gap portion. The small-gap portion provides enough inductance in case of low load input to prevent harmonic distortion. The large-gap portion provides enough inductance in case of heavy load output and low input voltage to prevent saturation and temperature rise, thus enhancing power efficiency.

Abstract: A low-power planar transformer for cell phone chargers or the like includes a primary bobbin structure carrying connection pins aligned for mounting the transformer in a through-hole configuration or directly on a circuit board, and a secondary bobbin structure that fits wholly within the primary bobbin structure.

Abstract: “A Hall effect sensor or device may be used in a variety of embodiments, such as measuring current within an associated conductor by helping to measure flux density within a gap of a ferromagnetic power meter core, such as in a power meter. A high linearity interface for a Hall effect device is provided for minimizing offset effects without using complicated electronic circuits. Hall effect device may include a substrate, first and second device inputs, and first and second device outputs. The substrate of the Hall effect device may be connected electrically to an output pin of the Hall device to eliminate any effects caused by asymmetry of the voltage appearing in the channel relative to the substrate. The net effect of the high linearity interface is to eliminate any adverse effects to linearity of the system, especially at low magnetic flux levels where the output voltage of the Hall device would be relatively small compared to the offset voltage levels involved.

Abstract: Disclosed are a gapped magnetic core which may be coated or uncoated with an insulating layer or housed in an insulting box having a physical gap whose dimension is close to that of the gapped magnetic core and automated or semi-automated methods of applying copper wire on the gapped core or the core assembly and filling the gap with a spacer in the core or core assembly. The disclosed processes allow various combinations of core and spacer materials and gap configurations, resulting in a wide variety of core-coil assemblies which are useful as inductive components in electric and electronic circuits. Also disclosed is a core-coil assembly wherein a magnetic core with a gap directed off the conventional radial direction of a toroidally-wound core.

Abstract: An isolation transformer is provided having primary and secondary cores (2, 4) and primary and secondary coils (3, 5) with the primary coil and the secondary coil being disposed with a gap G provided therebetween. Each of the primary coil and the secondary coil is formed of a wire having at least two substantially parallel long sides, and a length of the two long sides in each of the wires is set to be longer than a distance between the two long sides in each of the wires. Each of the wires is wound to have a plurality of turns in a manner such that an outer one of the two long sides of each inner one of the turns is adjacent to an inner one of the two long sides of each respective adjacent outer one of the turns.

Abstract: The present invention relates to a transformer with an additional integrated inductor. To this end it is envisaged that the transformer is provided with a first core (1) which has at least a primary winding (5), a second core (2) which has at least a secondary winding (4), and a third core (3), while each core (1, 2, 3) is a separate component.

Abstract: In order to provide an inductance part having excellent DC superposition characteristic and core-loss, a magnetically biasing magnet, which is disposed in a magnetic gap of a magnetic core, is a bond magnet comprising magnetic powder and plastic resin with the content of the resin being 20% or more on the base of volumetric ratio and which has a specific resistance of 0.1 &OHgr;·cm or more. The magnetic powder used is rare-earth magnetic powder having an intrinsic coercive force of 5 kOe or more, Curie point of 300° C. or more, and an average particle size of 2.0-50 &mgr;m. A magnetically biasing magnet used in an inductance part that is treated by the reflow soldering method has a resin content of 30% or more and the magnetic powder used therein is Sm—Co magnetic powder having an intrinsic coercive force of 10 kOe or more, Curie point of 500° C. or more, and an average particle size of 2.5-50 &mgr;m.

Abstract: A circuit breaker assembly having an electronic trip unit used to detect an overcurrent condition in a protected electrical circuit. The electronic trip unit being electrically connected to a current transformer used to sense electrical current and provide operating power to the electronic trip unit. The current transformer comprising a metal core having a top surface and a bottom surface where the difference between the top and bottom surfaces defines a height of the core. The core having a concentrical opening extending through the height so that the distance between an outside point on the concentrical opening and the closest outside point of the core defines a thickness of the core at that point. Passing through the core opening is a primary winding and encircling the thickness of the core is a secondary winding. To optimize usage of the current transformer, a partial air gap is added to the metal core so that the range of operation is maximized while at the same time minimizing the remanence attenuation.

Abstract: An ignition coil assembly is disclosed for a spark plug of the type used in internal combustion engines. The ignition assembly includes a housing, a tubular and cylindrical primary coil, and a tubular and cylindrical secondary coil. The primary and secondary coils are each wound on their individual bobbins and the bobbins are mounted in the housing such that the primary coil is coaxially positioned inside the secondary coil. The ignition coil assembly further includes a magnetic core having a first portion which extends through the interior of both the primary and secondary coil and a second portion which extends exteriorly of the primary and secondary coils. The first portion of the coil is substantially circular in cross sectional shape thus matching the circular interior of the primary bobbin. In order to construct the primary coil and secondary coil subassembly, the primary bobbin is first positioned on a winding machine and the primary wire is wound on the bobbin.

Abstract: In a discharge lamp apparatus for a vehicle, it is determined that a grounded condition is present when a lamp voltage is less than a predetermined voltage and a lamp current is less than a predetermined current. Electric power supply to the lamp is stopped temporarily in response to the determination of the grounded condition, and then the lighting operation is restarted again. If the grounded condition is determined again, the above operation is repeated. If this repetition continues for a predetermined period, the lighting operation is disabled continuously. In controlling the lamp, a voltage of a battery is boosted by a voltage booster transformer, which is turned on and off by a MOS transistor so that electric power supplied to the lamp is duty-controlled. An upper limit is set to the duty ratio, and the upper limit is increased as the lamp current decreases, so that the lighting characteristics of the lamp is improved.

Abstract: Disposed in a magnetic gap of a magnetic core, a magnetically biasing permanent magnet is a bond magnet comprising rare-earth magnetic powder and a binder resin. The rare-earth magnetic powder has an intrinsic coercive force of 5 kOe or more, a Curie temperature of 300° C. or more, and an average particle size of 2.0-50 &mgr;m. The rare-earth magnetic power has a surface coated with a metallic layer containing an oxidation-resistant metal. In order to enable a surface-mount to reflow, the rare-earth magnetic powder may have the intrinsic coercive force of 10 kOe or more, the Curie temperature of 500° C. and the average particle size of 2.5-50 &mgr;m. In addition, to prevent specific resistance from degrading, the metallic layer desirably may be coated with a glass layer consisting of low-melting glass having a softening point less than a melting point of the oxidation-resistant metal.

Abstract: A transformer includes a bobbin with spacers extending inwardly from the bobbin and a barrier extending outwardly from the bobbin. A ferrite core positioned within the bobbin is separated by the spacers to provide a controlled air gap. Primary windings wound around the bobbin are separated into series connected windings by the barrier. The barrier is aligned with spacers so as to prevent any wound portion of the primary windings from overlapping the air gap in the ferrite core.

Abstract: A low-profile magnetic core capable of reducing the thickness of an inductor component is provided. The magnetic core includes at least one gap in a magnetic path, and a permanent magnet is inserted in the gap. The magnetic core has an alternating current magnetic permeability at 20 kHz of 45 or more in a magnetic field of 120 Oe under application of direct current, and has a core loss characteristic of 100 kW/m3 or less under the conditions of 20 kHz and the maximum magnetic flux density of 0.1 T. An inductor component is produced by applying at least one turn of coil to the aforementioned magnetic core.

Abstract: A magnetic core having excellent DC superposition characteristics and core-loss characteristics is provided. The magnetic core comprises a magnetically biasing magnet disposed in a magnetic gap thereof to provide a magnetic bias from opposite ends of the magnetic gap to the core. The said magnetically biasing magnet comprises a bond magnet which comprises rare-earth magnetic powder and a binder resin. The rare-earth magnetic powder has an intrinsic coercive force of 5 kOe or more, a Curie temperature Tc of 300° C. or more, specific resistance of 0.1 &OHgr;·cm or more, residual magnetization Br of 1000 to 4000 G and coercive force bHc of a B-H curve of 0.9 kOe or more.

Abstract: A planar magnetic device with vertically oriented coil windings having a cross-section of a core with a torroidally-shaped winding structure taken transverse to the plane of the winding structure having two adjacent “winding windows” where the coils are present. One or more gaps in the core materials surrounding the windings store most of the energy generated by the inductor. The gap of height of at least one half the height of the winding structure is confined to the area between the winding cross-sections. Furthermore, in another aspect of the invention the gap is filled with a multi-layer structure of an alternating mono-layer of equally sized ferrite particles and a layer of synthetic resin.

Abstract: A method and apparatus for transmitting a signal through a power magnetic structure. A power magnetic core has one or more windings for transmitting power, and two windings for transmitting a signal or auxiliary power. The signal or auxiliary power windings are looped around features of the core so as to cancel the effect of magnetic flux circulating in the core as a result of currents flowing through the one or more power windings.

Abstract: A variable inductance transformer includes a core defining a gap between opposing first and second ends. A primary winding and at least one secondary winding are coupled to the core. The secondary winding is provided for stepping up the voltage across the primary winding. A carriage assembly includes a magnetic shunt movable against the core and variably across the gap. The magnetic shunt has a width at least as wide as the gap for moving the shunt to a predetermined position along the core in a range from an uncovered position not overhanging the gap, throught intermediate positions overhanging the gap, to a covered position where the shunt bridges the gap. A control circuit controllably energized a motor to move the carrriage assembly and position the magnetic shunt against the core for adjustably varying the inductance of the secondary winding a to maintain a high output voltage of the transformer for a given resistive supply current.

Abstract: A Hall effect sensor or device may be used in a variety of embodiments, such as measuring current within an associated conductor by helping to measure flux density within a gap of a ferromagnetic power meter core, such as in a power meter. A high linearity interface for a Hall effect device is provided for minimizing offset effects without using complicated electronic circuits. First and second levels of modulation relative to line frequency are used to synchronize Hall effect device input switching circuits and feedback loops for improved elimination of offset signals or noise from the ultimate system output. The substrate of the Hall effect device may be connected electrically to an output pin of the Hall device or to a separate virtual ground to eliminate any effects caused by asymmetry of the voltage appearing in the channel relative to the substrate.

Abstract: An inductance component comprises a magnetic core having at least one magnetic gap, means for generating a direct-current biased magnetic field produced by mounting a permanent magnet in the vicinity of a generally closed magnetic circuit which passes through the magnetic gap in the magnetic core or on the outside thereof, and a coil wound around the magnetic core, wherein the permanent magnet is mounted near the magnetic gap at one or more legs of the magnetic core which sandwich the magnetic gap.

Abstract: An inductance device according to the present invention, which is for use in power supply units, is constructed in such a manner that a slit 3 is provided in one side of a polygonal cylindrical ferrite core 1 in the same direction to a hollow portion 2 to form an open magnetic path, and a belt-like conductor 4 is inserted through the hollow portion 2, so as to minimize the dimensions, have an inductance value not more than 1 &mgr;H, and hold DC overlapping characteristic flat even if high current flows.

Abstract: In a transformer wound on a core having three or more legs (N legs), N−1 of the legs can have a flux distribution winding on them comprising flux distribution coils on each of the N−1 legs. The flux distribution coils are all connected together, usually in phase, so all of the coils see the same voltage. If the several coils have different numbers of turns, then the volt per turn will differ inversely, and so too will the flux in the N−1 legs. The flux in the Nth leg is the algebraic sum of the flux in the N−1 legs, and is usually the “Main” flux path. A winding around one of the legs would have a terminal voltage proportional to the number of turns and the flux in the leg. A winding may make several turns around the main leg of the transformer, then make one or more turns around a side leg having a different flux, usually some fraction of the flux in the main leg. The extra turns, having a fractional flux, are the equivalent of a fractional turn.

Abstract: The invention relates to a current transformer for three-phase systems and it used to detect currents, for example with three-phase current meters or electronic devices which trigger low voltage protection breakers. The invention aims at developing a current transformer that can be produced and fixed in a simple and low cost fashion and permitting to measure total current. Therefore, four mutually spaced apart, parallel, identical cylindrical conversion coils (4-7) are provided. In each case, a three-phase current lead (1, 2, 3) runs between two conversion coils (4-5, 5-6, 6-7) arranged adjacent and substantially normal to their longitudinal axes (10). Conversion coils (4-7) are held headwise through two low coercivity yokes (8, 9) extending in their longitudinal axes plane.

Abstract: Heat emitting electrical components are encased in a refrigerated package within a housing which may be under vacuum. Power for the components is supplied through a transformer within the vacuum housing, the secondary of which is in thermal contact with the package and has heat transmitting electrical connections to the components. To reduce conduction or convection of heat from the primary of the transformer to the refrigerated package, a small gap of about 1 mil is provided. For pot core transformers the core may be split, with the gap between the split portions. For toroidal transformers, the secondary is spaced from the primary as well as from the core by such gap.

Abstract: An output choke for a D.C. arc welder comprising a high permeability core with an inductance controlling air gap defined by first and second pole pieces terminating in first and second surfaces facing each other and each having two spaced edges with an intermediate area, said surfaces converging from said intermediate area toward each of said edges to generate a specific cross sectional shape for said gap wherein said choke is large enough to carry at least about 100 amperes of weld current.

Abstract: An output choke for a D.C. arc welder comprising a high permeability core with an inductance controlling air gap defined by first and second pole pieces terminating in first and second surfaces facing each other and each having two spaced edges with an intermediate area, said surfaces converging from said intermediate area toward each of said edges to generate a specific cross sectional shape for said gap wherein said choke is large enough to carry at least about 100 amperes of weld current.

Abstract: An inductor, such as for electromagnetic interference (EMI) suppression, comprises a plurality of ferrite layers arranged in stacked relation and joined together to define a ferrite body, and a first electrical conductor extending between a first pair of adjacent ferrite layers. The inductor includes first respective opposing portions of the first pair of adjacent ferrite layers being sintered together, and second respective opposing portions of the first pair of adjacent ferrite layers being in spaced apart relation to define at least one first gap therebetween. Moreover, the device includes a sintering blocking material associated with the at least one first gap. The sintering blocking material causes the gap to form in the ferrite body to selectively block the magnetic path to thereby retain a higher inductance than would otherwise be possible at relatively high currents. In a surface mounting embodiment of the inductor, the ferrite body has a generally rectangular shape.

Abstract: The gap-providing ferrite core half is produced by grinding an abutting surface of a ferrite core half by a rotating grinder with a rotation shaft inclined by 0.

Abstract: The present invention provides a coil device including magnetic cores having gaps at positions of at least opposing to each other in a magnetic path to be formed and a coil wound to include at least one of said gaps and its improvement consists in the fact that a shape of at least one of the opposing magnetic cores forming; the gaps around which said coil is wound is made as a curve of logarithmic function from its base end to its extreme end and its most extreme end is provided with a gap adjusting flat surface. With such an arrangement as above, the present invention provides a coil device capable of reducing a leakage magnetic flux generated around the gaps, preventing an abnormal generation of heat of the coil and further preventing a bad influence of noise against a peripheral apparatus.

Abstract: A waterproof current transformer for supplying current to electrical cable monitoring devices includes a core assembly for attaching a remote circuit module to a monitored conductor and provides a concentrated magnetic flux indicative of the current level in the conductor. To facilitate installation and removal of the current transformer from the conductor, the core assembly is formed by a plurality of laminations served together and arranged in a generally rectangular configuration and joined with a magnetically conductive interlocking connecting means. A means for resisting moisture is disposed about the transformer to enable an indefinite submersion time span.

Abstract: To drastically increase output energy generated by means of an electromagnetic function in a small-sized ignition coil apparatus having a plurality of magnetic circuits arranged around and coaxially with a hole for passing therethrough a shaft.

Abstract: A current transformer includes transformer units combined into a bundle, each of the transformer units including an annular iron core surrounding a bus conductor and a secondary winding wound around the iron core for measuring an electric current flowing through the bus conductor, and a shield winding wound around the bundle of the transformer units. The secondary winding may be provided with an air gap in which no secondary winding is present, located at a portion of the current transformer in a direction of a resultant vector, perpendicular to a line connecting bus conductors neighboring the bus conductor to be measured and passing through the bus conductor to be measured. A second air gap may be provided at the position opposite the air gap of the transformer, relative to the bus conductor to be measured, and the shield winding may be divided into two parts at the air gap and opposite the air gap relative to the bus conductor to be measured.

Abstract: A transformer, comprising: a closed ferrite magnetic circuit having an air gap; a rigid component filling a portion of the air gap; and, a flexible material filling the remainder of the air gap to substantially absorb vibrations of the ferrite. In the case of air gaps greater than approximately 1 mm, the flexible material fills approximately 1 mm of the air gap and the rigid component fills the remainder of the air gap. The rigid component may be of non magnetic, synthetic resin material. The flexible material may be a one component mastic, for example polysulfur, polysulfate polysulphide or polyurethane. The flexible material may also be a silicone type mastic, for example a neutral silicone.

Abstract: The storage coil has a core and windings which are arranged as conductor tracks on base layers. The base layers each contain only one winding, whose start and end are each passed out on one or more projections on the outer edge of the base layer. In consequence, the projections project out of an opening in a core, for example an E/I core, on which projections the windings of the base layers make contact with one another and with connections. With suitable dimensioning, losses resulting from the skin effect and eddy current losses can be kept very low.

Abstract: An electric noise absorber comprising at least two ferrite pieces having abutting planes, at least two case members containing the ferrite pieces respectively and being closed by means of engagement members, and a spring member provided in at least one of the case members for pressing the ferrite pieces against each other when the case members are closed. Since the case members for keeping the ferrite pieces in appropriate positions and the spring member for pushing up the ferrite pieces for close contact are separately molded, the case members are bestowed with strength and the spring member with elasticity, both suitable for their own purposes. The case members requires no apertures for biasing members and therefore outside magnetic substance is prevented from contacting with the ferrite pieces contained in the case members.

Abstract: An electrical choke comprises a magnetic amorphous metal core having, in combination, a distributed gap and a discrete gap. The amorphous metal is an iron based, rapidly solidified alloy. The distributed gap configuration is achieved by subjecting the magnetic core to a heat treatment, causing partial crystallization of the amorphous alloy. Such partial volume crystallization reduces the permeability of the magnetic core from several thousands to a value ranging from 200 to 800. The discrete gap is introduced by cutting the core and inserting a spacer. Depending on the width of the gap and the value of the annealed permeability, effective permeabilities in the range of 200 to 40 can be achieved. Advantageously, the reduced permeability magnetic core maintains its initial permeability under DC bias field excitation and exhibits low core loss, making it especially suited for use in power factor correction applications.

Abstract: An article comprising a micro-machined, passively self-assembling inductor is disclosed. The inductor is fabricated using MEMS technology and advantageously utilizes materials compatible with CMOS such that inductor is monolithically integrable with a CMOS chip. The inductor includes passive self-assembly means by which the inductor loop is moved away from an underlying substrate, typically silicon, in the final steps of inductor assembly. Such passive self-assembly does not require separate actuation or monitoring steps.

Abstract: A planar-type magnetic structure in which two coils, on two poles of the same core, are separated by an open space which is wide enough and low enough that the air return flux, through the open space, completes the flux circuit for each coil. Thus the coupling coefficient between the two coils is very small, even though they are both mounted on a single continuous core of high-permeability material.

Abstract: Plane sheets which have the same shape as the magnetic circuit and are relatively movable along their contact surface are arranged in a stack. The stack is grasped and part of the circuit is bent out of alignment with the plane of the sheets to enable a coil to be placed on a portion of the circuit which is next to the air gap, whereafter said part is bent back into alignment with said sheets.

Abstract: A ballast stabilizer includes a stack of annular silicon steel plates defining a center through hole, a perforated bottom-open casing mounted within the center through hole of the stack of annular silicon steel plates, a winding holder mounted within the casing, the winding holder having a center open chamber, a peripheral wire groove, and a winding mounted in the peripheral wire groove around the winding holder, a stack of I-shaped silicon steel plates received in the open chamber of the winding holder, and a varnish coating covered over the stack of annular silicon steel plates and filled up the gaps in the casing, the winding holder and the stack of I-shaped silicon steel plates.

Abstract: A choke coil for preventing harmonic distortions having a plurality of laminated iron core sheets formed into a core. A first coil is wound around a first limb of a first core, and a second coil is wound around a first limb of a second core. A third coil is wound around the second limb of both the first core and the second core, and the second core is disposed within the magnetic circuit of the first magnetic core. The iron core sheets have embossments formed on a front and back side for fitting the iron core sheets together. The embossments have longitudinal sides formed orthogonally to the direction of magnetic fluxes in the core, and may be inwardly inclined to face each other.