Abstract: A device for improving the shielding effectiveness of apertures used for mounting electrical component in an enclosure from Electromagnetic Interference (EMI). The device includes a hollow housing which contains and a disc with an aperture, where the disc is attached to an inner surface of the housing to define a first and second inner space. The device also includes a ferrite core which is fit into the second inner space.

Abstract: A brushless resolver comprising a housing, a rotor rotatably mounted in the housing, a rotary transformer comprising a primary winding carried by the housing and secondary winding on the rotor and operatively associated with the primary winding, a resolver comprising a stator winding carried by the housing and a rotor winding on the rotor and operatively associated with the stator winding, characterized by an electromagnetic flux absorber in the housing between the rotary transformer and the resolver for absorbing leakage electromagnetic flux from the rotary transformer so as to reduce any deviation between the indicated electrical position of the rotor and the actual mechanical position of the rotor during each revolution of the rotor. The flux absorber comprises a copper ring between the rotary transformer primary winding and the resolver stator winding so that the leakage flux creates eddy currents in the ring thereby absorbing or reducing the leakage flux.

Abstract: A three-dimension inductor structure formed in a conventional integrated circuit technology has a direction of magnetic field perpendicular to the normal direction of the substrate of an applied integrated circuit. Due to the direction of the magnetic field, the electromagnetic interference induced by the three-dimension inductor structure affects other components in the same integrated circuit slightly. The three-dimension inductor structure includes an N-turn coil. Each turn coil in the N-turn coil includes a first-level metal line, a second-level metal line and third-level metal line. The three levels of metal lines are separated from one another by isolating layers. Two nearby levels of metal lines are connected through via plugs in the isolating layers between them. The integral coil is accomplished by connecting the second-level metal line of the Nth turn coil to the third-level metal line of the (N+1)th turn coil.

Abstract: A sheet transformer wherein a coil pattern is formed on each of substrates so as to constitute a coil substrate, a plurality of the coil substrates are overlaid in multiple layers to form a primary coil and a secondary coil. The primary coil and the secondary coil are overlaid such that the middle leg cores of EE type, EI type, EER type or EIR type cores are disposed in the center of the coils and both the outside leg cores are disposed outside the coils, thereby obtaining a magnetic coupling between the coils. A higher potential side of the primary coil and a higher potential side of the secondary coil are disposed in an opposed configuration so as to face each other.

Abstract: Electronic ballast system for fluorescent lights. A power oscillator connected to the primary winding of a power transformer for operation at a predetermined frequency in the range of 10 KHz to 5 MHz, and a ballasting network is connected to the secondary winding of the transformer and to one or more fluorescent lamps. The ballasting network is resonant at a frequency within about .+-.10 percent of the predetermined frequency, and in some embodiments, the resonant frequency of the ballasting network remains the same regardless of the number of lamps connected to it.

Abstract: The present invention relates to an arrangement for reduction of magnetic alternating fields for example in a vehicle or similar which comprises at least one electrical system which comprises at least two elements of which at least one comprises one or more components generating and/or consuming electricity, and which are connected through at least one connecting cable in which flows a current having an alternating current component generating a low frequency magnetic field. The arrangement also comprises at least one detecting element which is arranged to detect the alternating current component, and means for generating a compensating current with the use thereof. The compensating current flows adjacent to the connecting cable in such a way that the low frequency magnetic field is reduced or eliminated.

Abstract: An eddy current sensor comprises a generally E-shaped core having three parallel legs joined together by a bridge. Current carrying coils are mounted on each of the outer legs and a signal coil is mounted on the central leg. Identical a.c. currents are caused to flow through the two outer coils for generating two magnetic fields which combine to form a sensing magnetic field extending outwardly from the ends of the legs for sensing purposes but which cancel one another within the central leg. The sensor is disposed within an E-shaped, hollow shield of an eddy current producing, electrically conductive material. The sensor fits within the shield as fingers in a glove with the parallel legs of the sensor magnetically separated from one another by walls of the shield. Only the ends of the sensor legs are exposed through apertures through the shield for emergence of the various magnetic fields. The shield cancels unwanted fringing fields and better guides the magnetic fields in desired directions.

Abstract: A transducer for a stringed instrument comprises a first uppermost coil, and a second lowermost coil with the axes of the coils coincident. At least one permanent magnet pole piece associated with the coils and a shield of magnetically permeable material arranged between the coils with the shield having one or more walls which extend over sides of the coils.

Abstract: A toroidal current transformer magnetic shield includes, in one form, a cup portion and a cap portion. Both the cup and the cap are C-shaped, and when the cap is placed over the cup, the cup and cap define a toroidal sensor chamber. The cup portion and the cap portion are constructed of magnetically permeable material, such as iron or steel. A toroidal current transformer is positioned within the sensor chamber, so that the cap and cup enclose, and magnetically shield, the toroidal current transformer.

Abstract: A proximity sensor includes a transducer and a circuit having a switch that changes state in response to a presence of an object in spaced relation to the transducer. The transducer includes a magnetic form defining a generally planar surface facing a sensing zone of the sensor. The magnetic form includes a side surface that extends away from the sensing zone and an internal cavity that opens outwardly toward the sensing zone. A sensing coil is positioned within the magnetic form cavity. The transducer additionally includes a sensor housing supporting the sensing coil and the magnetic form in relation to the sensing zone. A non-ferrous metal shield is positioned inside the sensor housing to surround at least a portion of the magnetic form and enhance a sensing range of the proximity sensor. The shield has an edge that faces the sensing zone located substantially co-incident with the generally planar surface of the magnetic form.

Abstract: A transformer that comprises a winding assembly, a first and a second output terminal and a first and a second conductive path. The winding assembly includes a first and a second winding assembly terminal, a winding coupled between the first and second winding assembly terminals, and a resistive load coupled between the first and second winding assembly terminals. The resistive load has a resistance and an intrinsic inductance effectively in series with the resistance. The first conductive path connects the first winding assembly terminal and the first output terminal. The second conductive path connects the second winding assembly terminal and the second output terminal. The first and second conductive paths enclose an area through which magnetic flux can pass so as to provide a pickup loop inductance between the first and second output terminals.

Abstract: A current transformer for monitoring a current in a conductor. The current transformer comprises a winding assembly that includes a resistive load. The transformer further comprises a compensation circuit that has an impedance selected to reduce output signal overshoot across the output terminals of the current transformer caused by the intrinsic inductance of the resistive load. The transformer also comprises a small gauge semi-rigid coaxial cable to reduce a loop pickup area formed by the conductive paths that connect the winding assembly terminals of the winding assembly and the output terminals of the current transformer. This results in output signal overshoot across the output terminals being further reduced. Additionally, the transformer comprises a transformer shield that encloses the winding assembly and has end portions that do not contact each other to define a gap that prevents the transformer shield from acting as a shorted turn.

Abstract: A transformer in which a magnetic medium provides flux paths within the medium, two or more windings enclose the flux paths at separated locations along the paths, and an electrically conductive medium, arranged in the vicinity of the magnetic medium and the windings, defines a boundary within which flux emanation from the magnetic medium and the windings is confined and suppressed. In a transformer constructed in accordance with the present invention, both controlled values of leakage inductance and the benefits of separated windings can be achieved. The conductive medium can be configured to reduce the leakage inductance of a controlled-leakage inductance transformer (e.g. for use in a zero-current switching power converter), having separately located windings, by at least 25%, and can be configured to reduce the leakage inductance of a low-leakage inductance transformer (e.g. for use in a PWM power converter), having separately located windings, by at least 75%.

Abstract: A transducer for a stringed instrument comprises a first uppermost coil and a second lowermost coil with the axes of the coils coincident. Permanent magnet pole pieces are arranged in the first coil and metallic non-magnetized pole pieces are arranged in the second coil. Oppositely directed U-shaped shields each having a web and outwardly directed opposed flanges are arranged back to back and receive the coils to shield the coils from each other both magnetically and inductively.

Abstract: The present invention relates to a measuring transformer which contains a primary conductor which carries current to be measured, and a secondary coil which is magnetically coupled thereto. The primary conductor is shaped helically and forms a body, like a helical spring, which surrounds the secondary coil with at least one turn. The primary conductor is preferably formed by a tube having a spiral groove which passes through its wall. The primary conductor has inherent stability which is very high such that no special holding means are required for the secondary coil. The secondary coil is extremely easy to install in the primary conductor and there are no problems with installation tolerances and the like.

Abstract: The current and voltage transformer (10, 11) is intended for a metal-encapsulated, gas-insulated high-voltage installation. It has an annular supporting body (13) which can be fixed inside the metal encapsulation (7) and is used for holding a current sensor and a voltage sensor. The current sensor, held on the supporting body (13), is constructed as a toroidally wound coil (14) and the voltage sensor, held on the supporting body (13), is constructed as a hollow-cylindrical measurement electrode (15). After fitment in the installation, the coil (14) and measurement electrode (15) concentrically surround a current conductor (5) of the installation. This current and voltage transformer is intended to have small dimensions and is intended to be capable of fitment without problems at any point in the installation.

Abstract: Thin-film transformer suitable for use in a thin-film magnetic head has two magnetically permeable thin layers 3 and 5 primary turn constituted by an electrically conducting which form a magnetic yoke. A layer 13 and a secondary turn constituted by an electrically conducting layer 15 are located in the yoke. A layer 21 of a superconducting material is provided between the layer 3 and the turns, or the turns are closely fitted together and made of a superconducting material themselves.

Abstract: A magnetic field sensor coil wherein the coil is formed into a shape comprising two generally C-shaped limbs (2, 3) one within the other, one of these limbs being covered by a magnetic screening material (4). In operation an e.m.f. is induced in each turn of the unscreened part of the coil (3) while no e.m.f. is induced in the screened part (4) and so the total e.m.f. induced is approximately equal to the e.m.f. that would be induced in a simple concentrically wound coil of the same number of turns and of the same dimensions as the unscreened portion of the coil. The coil according to the invention is especially suitable for use with a system for monitoring an electric motor where the coil may be placed adjacent the motor end plate concentrically around the motor shaft without having to uncouple the motor from its load.

Abstract: A meter for sheet conductance measurements does not touch the conductive surface of a sample. A probe having a resonant tank coil is positioned against a parallel supporting surface of the sample, which may be flat or curved and of unrestricted area. An oscillator incorporating the tank coil is controlled to stabilize oscillator amplitude in response to eddy current loading by the sample. An electrostatic shield in a finger configuration prevents capacitive coupling between the tank coil and the sample without hindering magnetic coupling. A readout of sheet conductance is driven by the oscillator control. Direct current can be coupled to the tank coil for temperature control preventing undesired resistance changes in the tank coil. The oscillator can be controlled by an optically coupled variable gain element. Measurements can be made with the tank coil up to at least 0.75 inch from the conductive surface of the sample.

Abstract: A coil is made having a plurality of layers of adjacent metal conductor windings subject to voltage stress, where the windings have insulation therebetween containing a small number of minute disposed throughout its cross-section, where the voids are voids filled with SF.sub.6 gas to substitute for air or other gaseous materials in from about 60% to about 95% of the cross-sectional void volume in the insulation, thus incorporating an amount of SF.sub.6 gas in the cross-section of the insulation effective to substantially increase corona inception voltages.

Abstract: A method for improving the electrical insulation of an electrode in a power transformer included in a converter plant of a high voltage direct current (HVDC) transmission system. The method involves winding around the electrode, layers of tape of woven or non-woven fibrous structure of non-conducting cellulose material, inorganic plastics material, or inorganic insulating material. This means that ions approaching the electrode, which are migrating under the influence of a high d.c. field outside the electrodes, do not sense the porous tape insulation as any noticeable obstacle, while at the same time the insulating layer is sufficiently dense to increase the breakdown value in the case of electrical surges.

Abstract: An electric resonator includes first and second pluralities of conductors which are disposed in side-by-side relationship to form a first layer of alternating first and second conductors. Additional layers of alternating first and second conductors are disposed atop the first layer such that each conductor of one of the pluralities is horizontally and/or vertically adjacent to conductors of the other plurality. The resulting resonator reduces undesirable capacitance between various conductors thereby increasing the quality factor, or Q, of the resonator.

Abstract: Non-magnetic sensor having a ring-shaped core (10), through which a primary conductor (12) runs and which supports a secondary winding (14). A magnetic shield (18) encloses the core (10), whereas a non-magnetic conducting shield (22) is inserted between the conductor (12) and the core (10) with the winding (14). The sensor is applicable to medium and high voltage installations.

Abstract: This invention relates to a molded transformer whose windings are cast-insulated with a cast resin, and consists in disposing an electrically conductive layer within the resin insulation of the winding and grounding the conductive layer, thereby to enhance a withstand voltage with the dimensions of the air gap between the windings reduced and with a winding supporting spacer omitted.

Abstract: The disclosed invention is suited for use in conjunction with a borehole logging device wherein transmitting and receiving antenna coils are wound on insulating media around the axis of a support means that includes an elongated electrically conductive pipe. In accordance with the invention there is provided a shield for shielding each coil of the device, the shield being adapted to reduce spurious electromagnetic field components (especially transverse magnetic components) while not substantially interfering with the desirable transverse electric components. The shield for each coil comprises a hollow closed-end cylinder mounted on the pipe and surrounding the coil, the cylinder being formed of an electrically conductive material and having a series of equally spaced slots therein. Each slot extends radially outward from the support means along a plane which passes substantially through the axis of the pipe so as to pass through the ends and sides of the cylinder.

Abstract: A permanent magnet type step motor comprising a rotor wherein a disc-like permanent magnet having a magnetic pole in an axial direction and a pair of rotor yokes holding the permanent magnet therebetween are integrally and coaxially mounted on a rotational shaft, and a stator having a stator core opposed to an outer circumference of the rotor yokes. The front and rear brackets are formed of a non-magnetic material in which a thin shield sheet of magnetic material is inserted therein, and the magnetic resistance between the rotor yokes and the ends of the brackets opposed thereto is increased to reduce the leaky magnetic flux from the motor.

Abstract: A pulse transformer is used in a radar transmitter to transform a high current pulse at relatively low voltage into a very high voltage pulse which can be used to directly drive a magnetron oscillator. The potential of the output pulse can be of the order of 30 kV and since the transformer is required to operate at very high peak powers of the order of two megawatts, it must be very carefully designed to avoid excessive electrical losses and voltage breakdown. The core material of the transformer consists of a closely wound reel of magnetic material in the form of an elongate tape, which is mechanically fragile. The magnetic core is loosely mounted within a sealed container so that the primary and secondary windings surround it. A conductive shield is placed around the magnetic material so as to protect it from the very large electric fields generated within the transformer. This prevents the ionization of gases which could lead to the rapid deterioration of the magnetic core material.

Abstract: An inductor having an air gap in its magnetic core is provided with a magnetic shield which surrounds the inductor air gap to not only reverse bias the inductor magnetic circuit so as to increase the amount of current required to achieve inductor saturation but also to return any stray flux radiating from the inductor back into the inductor magnetic circuit to reduce the radiated electromagnetic interference.

Abstract: An electrical shunt reactor coil comprises a rectangular magnetic frame in the form of two vertical members (1,2) interconnected at their ends by two horizontal yoke members (3,4). The frame members are constituted by respective stacks of magnetic laminations. A central core (7) extends across the middle of the frame parallel to the vertical members, and an electrical winding (6) is situated around the core. The horizontal yoke members are of width L which is less than the diameter of the winding and which is close or equal to the diameter of the central core. Magnetic shunts (20 to 23) are placed across the outside of the horizontal yoke members. The shunts are longer than the width L of the yoke members so that they overhang both sides thereof. The magnetic shunts are constituted by respective stacks of laminations extending parallel to the axis of the central core and at right angles to the laminations of the yoke members.

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 current transformer having at least one ring-shaped core with a secondary winding mounted thereon, and a primary conductor, located within its casing. An inner tube is provided between the ring-shaped core and the primary conductor, one end of the tube being electrically connected to the casing and its other parts electrically insulated therefrom. A cylindrical, electrically conductive screening shield at least partially overlaps the inner tube and is electrically connected to the casing on the side of the ring-shaped core which is distal from the electrical connection between the casing and the inner tube, while the other parts of the shield are electrically insulated from the casing. This overlap forms a short-circuit loop for any steep progressing wave which is generated when switching on a potential-free part of the circuitry, or when due to an interruption, a small capacitive current breaks off.

Abstract: A transformer including a lamination core of band iron and a magnetic screen which consists of a wound iron band arranged around the lamination core (5) and which is secured to the core by means of expansion wedges provided in the space between the core and the screen 13. The expansion wedges (7) extend transversely of or at an angle with respect to the winding direction of the wound iron band.

Abstract: A toroidal transformer is provided with an inner winding electrostatic shield formed by bringing together two conductive annular cups having a generally U-shaped radial cross section. The widths and radii of the sidewalls of these cups are dimensioned such that one of the sidewalls of the first cup forms a conductive interference fit with the corresponding sidewall of the second cup, while the other sidewall of the first cup is separated from the corresponding sidewall of the second cup by a gap, which prevents the shield from becoming a shorted turn. The shield formed by these two cups is placed around a wound core and a second winding is wound over the shield to form a transformer.

Abstract: In a high power density transformer composed of a core and a coil assembly unit (or two such units), with the coil assembly unit including a primary winding, a secondary winding, a coil carrier supporting the windings, an insulating system, and a metal shield between the primary and secondary windings which is in electrically and thermally conductive connection with a metal grounding structure so that the metal grounding structure constitutes a support for the coil assembly, the metal shield serves as the coil carrier which is disposed directly on the metal grounding structure.

Abstract: In a high frequency coil device including a drum core having a lower flange and a shield casing to be securely attached thereto, lugs are provided at the lower ends of a pair of opposing side walls of the shield casing; grooves are formed in a pair of opposing side walls of the lower flange; and the lower ends of those side walls of the shield casing which are provided with the lugs are located at a higher level than the lower ends of the remaining side walls of the shield casing which are provided with no lugs. The lugs are disposed in engagement with the aforementioned grooves and bent into contact with the lower flange. The lower ends of the side walls provided with the lugs are disposed in abutment with the upper surface of the lower flange, and inner surface portions, adjacent to the lower ends, of the side walls provided with no lugs are disposed in engagement with the other opposing side walls of the lower flange.

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: An apparatus for shielding a time dependent magnetic field comprises a magnetic metallic glass element in which a magnetic biasing field is generated having higher frequency components than the major components of the time dependent magnetic field.

Abstract: A directional detector of changes in a local electrostatic field comprising two parallel flat coils of copper wire, separated by an electrically grounded plane rectangular conductor that is coated on both sides with an insulator, and associated signal conditioning electronics has been constructed. The combination of coils and plane rectangular conductors forms two independent wideband antennas which, when placed in an unobstructed electromagnetic radiation field, have induced in them electric currents of equal peak-to-peak values. When the combination was brought near an ungrounded body, such as a person standing on an insulator to earth, a coupling of high frequency potentials of the ungrounded body and the nearest coil occurred, while the coil farthest away from the body, due to the presence of the electrically grounded plane rectangular conductor, was unaffected.

Abstract: Disclosed are improved constructions for power transformers and reactors having windings of tape-formed conductor material which tend to reduce additional losses in the windings. In the improved construction for a power transformer or reactor comprising a core containing magnetic material and having legs and a yoke and comprising windings including a tape-formed conductor material arranged concentrically around the core legs, the innermost of the windings has a first portion located nearest the core leg which has an axial length greater than the length of the portion of the winding located radially outside said first portion. The first portion thereby forms a cylindrical shield for controlling the magnetic leakage flux appearing outside the ends of the winding.

Abstract: A coaxial transformer is employed to provide impedance matching for the input of a bipolar transistor operated in the VHF frequency range. The coaxial transformer comprises a first winding wound around a ferrite toroidal core. The second winding has a single turn and consists of a metal enclosure substantially surrounding the first winding. One end of the first winding is connected to the base of the transistor and the other end of the first winding is connected to ground. One end of the second winding is connected to the emitter of the transistor and the other end of the second winding is connected to ground.

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: The invention is an arrangement of inductive voltage transformers for installation in a completely insulated high-voltage switching installation comprising a metal encapsulation and several high-voltage conductors. In accord with the invention each of the inductive voltage transformers includes an insulating body carrying a respective high-potential winding, and each further includes a bushing laterally joined to its respective insulating body. More particularly, in further accord with the invention the bushings are arranged so as to be continuations of the high voltage conductors of the switching installation when the transformers are disposed therein.

Abstract: A distribution type delay line particularly adapted for use in a color television receiver and for mass production is disclosed. A bobbin with several axially spaced flanges defining several winding or coil slots therebetween is combined with a circuit of series-connected grounding electrode windings or coils each wound in each slot and each consisting of a predetermined number of turns of insulated wire and/or a circuit of series-connected shield windings each wound in each slot and each consisting of a predetermined number of turns of insulated wire, and a circuit of series-connected signal windings each wound in each slot outwardly and/or inwardly of the grounding electrode and/or shield windings and each consisting of a predetermined number of turns of insulated wire, the grounding electrode and shield windings being wound in the opposite directions so that the magnetic fluxes induced thereacross may be cancelled by each other.

Abstract: An electrical winding for electrical inductive apparatus such as a transformer or electrical reactor having at least one winding formed of non-magnetic, electrically conductive sheet, strip or foil, such as copper or aluminum. Magnetically conductive material is disposed between at least certain of the turns of the electrically conductive sheet material to create a low reluctance path for magnetic leakage flux parallel to the winding axis to reduce the magnitude of the radial component of the leakage flux.

Abstract: The disclosed invention is suited for use in conjunction with a borehole logging device wherein transmitting and receiving antenna coils are wound on insulating media around the axis of a support means that includes an elongated electrically conductive pipe. In accordance with the invention there is provided a shield for shielding each coil of the device, the shield being adapted to reduce spurious electromagnetic field components (especially transverse magnetic components) while not substantially interfering with the desirable transverse electric components. The shield for each coil comprises a hollow closed-end cylinder mounted on the pipe and surrounding the coil, the cylinder being formed of an electrically conductive material and having a series of equally spaced slots therein. Each slot extends radially outward from the support means along a plane which passes substantially through the axis of the pipe so as to pass through the ends and sides of the cylinder.