Showing papers on "Magnetic core published in 1971"

A New Method to Eliminate AC Harmonic Currents by Magnetic Flux Compensation-Considerations on Basic Design

Abstract: A new method of eliminating ac harmonic current is proposed, which is based on the principle of the magnetic flux compensation in a transformer core. By means of the new method, abnormal harmonics as well as normal harmonics can effectively be dealt with. Considerations on the basic design of the new method are given.

Integrated magnetic recording heads

Abstract: A new type of integrated magnetic recording head has been developed. The head is made completely from thin films by vacuum deposition through a mask. This technology enables us to make many heads in one vacuum cycle. A special study has been carried out on the geometrical forms and on the anisotropic magnetic material. The demagnetizing fields require that we make magnetostatic coupling layers for each magnetic leg of the head. Also, the results indicate that the heads can be used for writing and reading.

Analysis of the Efficiency of Thin‐Film Magnetic Recording Heads

Abstract: Equations for the flux, magnetic field, and current distributions in a single‐turn planar magnetic recording head are derived making the assumption that the magnetic material has constant permeability. These equations are solved in the frequency domain and an expression is given for the head efficiency in terms of the head dimensions, permeability, and frequency.

Regulating and filtering transformer

Abstract: Transformer for providing a regulated and filtered output voltage. Input voltage is applied to an input winding which is wound around two magnetic cores. One magnetic core saturates for part of each half-cycle of the induced alternating flux during normal operation. The other magnetic core does not saturate during normal operation and includes air gaps in the legs thereof. An output winding is positioned around the non-saturating core and connected in parallel with a capacitor to form an output tank circuit resonant at the operating frequency of the transformer.

Power Transformer Core Behavior Under Transient Conditions

Abstract: The solution of an electric circuit problem is only valid if the circuit elements have been validly modelled. The iron-cored coil is a common nonlinear circuit element, especially in power system circuits, where the iron core is laminated grain-oriented silicon-iron sheet. This paper attempts to show that eddy-current loss modelling in such a core is at least as important as hysteresis loss modelling, and demonstrates the accuracy of linear modelling of the eddy-current effect. If the circuit analyst has confidence in this complete model he can then decide which aspects of the model can be ignored with impunity when studying such circuit phenomena as ferroresonance, subharmonics and inrush current.

Alternating current fault indicating means

Abstract: Fault current flow in an alternating current carrying conductor is shown by operation of a target to fault indicating position from which it is restored in response to the energizing voltage of the conductor. A C-shaped magnetic core embraces the conductor and has a winding thereon the output of which is rectified and, when it reaches a predetermined value, is applied to a trip winding of a fault indicator to operate the target. A reset winding of the fault indicator is energized from a capacitor that is charged from the conductor voltage a source of which may be obtained from a capacitor plate embedded in the insulation of a conductor terminator. In a modification alternating current is applied to the trip winding to demagnetize the magnetic core of the indicator and allows a permanent magnet to bias the target to fault indicating position. Other modifications include energization of the reset circuit from the secondary winding of a distribution transformer, provision for magnetizing the distal ends of a U-shaped yoke embracing a conductor carrying fault current, and application of the yoke to the conductor of a pad mounted switching arrangement for a transformer.

Shorted turn axial driver-sensor

Abstract: A pressure measuring system utilizes an aneroid capsule as the frequency determining mechanical feedback element of an electrical oscillator, the capsule having closely spaced diaphragm walls, each carrying a separate electromagnetic element cooperating with a separate magnetic yoke assembly. Each electromagnetic element is a copper sleeve defining a shorted turn at its free end that is axially movable in an annular gap defined by the magnetic yoke. Each yoke assembly includes a soft iron core section projecting through a cylindrical pole face to define a radial flux field in the annular gap for coupling with the shorted turn.

Magnetic core structure

Abstract: A circular magnetic core structure comprises a plurality of laminations of prestressed oriented silicon steel secured together near their juxtaposed ends which are biased into mutual engagement and are separable to receive an alternating current carrying conductor to induce into the core alternating magnetic flux which induces alternating current into a coil on the core corresponding to the current in the conductor. The core and coil are encapsulated in insulating material. In one embodiment self curing cement is applied to the juxtaposed ends after the core is applied to the conductor to seal them together. In another embodiment the ends are provided with interlocking separable coupling extensions of corrosion resisting magnetic material.

Induction plasmas at low frequencies

Abstract: The possibility of generating thermal electrodeless plasmas at frequencies below the rf range through the use of magnetic materials has been investigated, both analytically and experimentally. Existing minimum frequency and voltage criteria for the maintenance of quasisteady, tube filling a.c. arcs were combined with the induction law to yield design criteria for a "plasma transformer" which consists of a conventional iron core and primary but has the secondary replaced by a torus-shaped vessel containing a single plasma turn. The idea has been tested, at a frequency of 9600 Hz, on a small model with an iron core of 100 cm cross section. Glow and arc discharges at pressures up to 600 torr have been generated in argon. Applicability to operation at 60 Hz is discussed.

Regulating and filtering transformer having a magnetic core constructed to facilitate adjustment of non-magnetic gaps therein

Abstract: A parametric regulating and filtering transformer including a magnetic core having input, output and saturating regions, input and output windings disposed in inductive relation with the input and output regions, and a capacitor connected to the output winding to provide a tank circuit. Different embodiments of the parametric transformer develop a non-magnetic gap or gaps, in the output region of the magnetic core, required to provide the desired waveform and electrical performance of the transformer, while facilitating the manufacture and assembly of the transformer.

Magnetic core elements for rotating electrical machines

Abstract: Magnetic core elements for rotating electrical machines which are prepared by winding a magnetic steel strip several times while applying a sufficient pressure permanently to deform it into a flattened state so as to obtain a smooth surface on both sides of the resultant coil, spot welding the individual turns at least near the forward and rear ends of the coiled strip rigidly to form them into an integral body and punching a plurality of slots through which to insert the winding of a rotating electrical machine in a prescribed periphery of the coil.

Regulating transformer with non-saturating input and output regions

Abstract: A three-path parametric regulating and filtering transformer having an adjustable output voltage. The regulating transformer includes a magnetic core having input, output and saturable regions, an input winding disposed about the input region, an output winding disposed about the output region, and a capacitor connected to the output winding to provide a tank circuit. In one embodiment, a magnetic element is disposed to influence the magnitude of the voltage across the output winding, with the position of the magnetic element, relative to the output winding, being adjustable. In another embodiment, the output region of the magnetic core is divided into two spaced portions, the output winding is disposed about both portions, and electrical control coils are disposed about each portion and connected in opposition. A unidirectional control current is passed through the control coils, with the magnitude of the unidirectional current controlling the voltage across the output winding.

Electrical insulators for slotted magnetic cores

Abstract: Electrical insulators, for example, slot liners, are produced from an elongated continuous strip of dielectric material in the slots of a magnetic core. Individual pieces of dielectric strip material having different preselected sizes and desired configurations are then produced; and may have laterally extending portions and an intermediate axially extending bight portion at one end thereby permitting shorter coils to be used in the magnetic core while also allowing the coils to take a gradual bend adjacent the core, next to the bight portion, which tends to prevent damage to the coils.

Write-process study on integrated magnetic heads

Abstract: The write field of multilayered integrated heads has been computed avoiding the usual assumptions that the head contour is an equipotential surface, by starting from the effect of the coil field on the magnetization of the layers. The magnetic analysis assumes that the magnetization of each layer curls near the head boundary, and it is shown that this curling significantly affects the write-field distribution. Experimental measurements are in good agreement with these theoretical results, and it is shown that integrated heads produce a write field whose magnitude is comparable to that of classical heads.

Linear motor for guided transport - installation

Abstract: A linear motor for a guided transport installation, notably public transportation systems on rail, which comprises a fixed field member or inductor carried by the track and a armature member carried by the vehicle or vehicles. It is characterized in that the inductor consists of a cylindrical or prismatic magnetic core surrounded by annular coils of same section connected to the phases of a multiphase wiring system in order to yield a sliding field driving the vehicle or vehicles, and that the armature consists of a sleeve having a U-shaped or substantially U-shaped cross-section which surrounds the inductor and comprises throughout its length an aperture permitting the passage of the device fastening the inductor in position, this armature consisting of a flux return yoke of U-shaped or substantially Ushaped cross-section, provided on its inner surface with a conductive layer adapted to become the seat of induced currents, said layer being thicker on the aperture side to enable these currents to close the loop from pole to pole.

Magnetic modulating system

Abstract: CONSISTING OF TWO RESONANT CIRCUITS COMPOSED OF THE NONLINEAR INDUCTOR AND A CONDENSER. THE OUTPUT SIGNAL OF THE DIFFERENTIAL OUTPUT CIRCUIT CAN BE CONTROLLED ACCORDING TO THE INPUT SIGNAL SO ASD TO MODULATE THE OUTPUT SIGNAL WITH HIGH SENSITIVITY BY MEANS OF A VERY SMALL INPUT SIGNAL. A MAGNETIC MODULATING SYSTEM HAS A MAGNETIC CORE AND TWO RESONANT CIRCUITS WHICH ARE SUPPLIED WITH AN ALTERNATING EXCITING CURRENT AND AN INPUT SIGNAL. AN ALTERNATING DRIVING MAGNETIC FIELD IS APPLIED TO THE MAGNETIC CORE AND AN ALTERNATING BIAS CURRENT IS APPLIED TO A NONLINEAR INDUCTANCE ELEMENT OF A DIFFERENTIAL OUTPUT CIRCUIT

Transducer system for detecting and measuring mechanical loads or stresses

Abstract: An apparatus and a transducer system for detecting and measuring mechanical stress applied on the transducer composed of at least one magnetic core of laminated silicon steel sheet construction, a plurality of coils wound on the magnetic core, a constant voltage a.c. source connected to these coils, pick-up means for picking up any variation caused in the current flowing through the coils due to the application of a load or stress on the magnetic core, a rectifying means for rectifying the thus picked-up variation in the current, a compensating means for compensating the zero point of the response characteristic of the transducer, a prestress applying means for improving the linearity of the response curve of the characteristics, whereby the magnitude of the load applied on the magnetic core is determined from the reading on a voltmeter or ammeter also included in the transducer system.

Pressure ring for transformer windings

Abstract: Pressure ring apparatus for securing the windings of power transformers. The pressure ring includes a body portion with magnetic radial members positioned therein to direct the leakage flux from the winding structure back into the magnetic core. The radial members are constructed from a plurality of metallic laminations which are stacked with their edges perpendicular to the leakage flux. Other magnetic members may be positioned in the body portion to help direct the leakage flux into the radial members. In one embodiment of this invention, one side of the pressure ring is stepped to conform to the shape of the yoke portion of the magnetic core.

Apparatus and method for forming shaped insulators and for developing coils and for inserting insulators and coils into a magnetic core

Abstract: Method and apparatus for forming shaped insulators and for developing coil turns into coil groups and inserting the insulators and coils into preselected slots of a magnetic core. The insulators are automatically formed at an insulator-forming station by an assembly including control mechanism for providing a series of insulators corresponding to predetermined slots of the core. Coil turns for the coil groups are generated about a coil turn-forming assembly of a winding head mechanism at a turn-forming station. Insulator and coil insertion tooling is movable between the insulator-forming station, to receive formed insulators; the turn-forming station, to receive coil turns; and an insertion station, at which insulators and coil turns are inserted from the insertion tooling into the magnetic core.

Process for manufacture of a magnetic transducer using a pre-existing unitary foil

Abstract: Magnetic transducing heads capable of reading and writing magnetic information in the form of a pattern of magnetization on a magnetic recording medium are provided utilizing a unitary structure of magnetic sheet metal foil and conductive, nonmagnetic metal foil and thin film deposition techniques. In the preferred embodiment, the transducing heads consist of a monolithic sandwich of thin metallic magnetic foil forming a magnetic core enclosing a conductive non-magnetic metal foil exciting winding. The transducer is prepared from a prefabricated unitary laminate of magnetic metal foil and conductive metal foil which laminate is shaped into a magnetic head by, for example, photolithographic and deposition techniques.

Magnetic head having a combination core formed from a pretreated magnetic layer

Abstract: A magnetic head for use in a magnetic disc of a computer, a magnetic drum or a video tape recorder manufactured through by a thin film technique. A first portion of the magnetic core thereof is a pretreated rolled permalloy which reduces the magnetic reluctance of the core to almost one-half of that of the conventional cores. This first portion taken with a second portion form a somewhat U-shaped core. Between the open ends is disposed a conductive layer surrounded by one or more dielectric layers. A supporting insulating layer may be provided over the second portion of the core.

Vibration monitoring system

Abstract: A vibration monitoring system particularly suited for use in isolating and measuring vibration of varying magnitudes simultaneously imparted to a plurality of mutually spaced locations defined on a moving vehicle. The system is characterized by a plurality of coiled electrical conductors, each being associated with a reciprocable soft iron core, about which exists a magnetic field, and coupled with a current measuring device through a manually operable selector switch, whereby current separately generated in the conductors, as the cores are reciprocated in response to imposed vibratory motion, is measurable for thus providing intelligence indicative of the magnitude of the vibration imposed at any one of the spaced locations.

Magnetic actuator mechanism

Abstract: A magnetic actuator comprising a stationary magnetic core structure having two distinct magnetic flux paths, with a movable armature included in both the flux paths and movable between a rest position and an actuated position. A permanent magnet or winding provides reset or restore flux, and a first winding includes the armature and opposes the restore flux. A second winding provides the major armature attractive force.

Selection matrix including a diode test circuit

Abstract: A test circuit routinely tests buffer diodes of a selection matrix for shorts. Drive lines that are connected to operating conductors of the selection matrix pass through a toroidal magnetic core to induce into a output winding of the core a voltage proportional to change in current in a selected operating conductor. Switching circuits for applying current to selected conductors are arranged to reverse the polarity of voltage applied to the conductors so that when an operating conductor with a shorted diode is selected, approximately twice the normal current change is detected by the test circuit.

Computation of Eddy Currents, Shielding and Transient Forces in Power System Equipment by the Method of Images

Abstract: The magnetic effects of induced eddy currents in thin conducting sheets are analyzed by means of moving current images and by an electrical circuit analogy. The methods are applied to practical power system equipment problems such as shielding and the calculation of conductor short circuit forces.

Line feed and isolation transformer with integral loop supervision

Abstract: Apparatus is disclosed for providing all of the functions of battery-feed, isolation, and supervision for a line circuit in a communication switching system. The apparatus comprises a primary and a secondary winding coupled inductively via a magnetic core which includes an air gap. A reed contact pair is positioned across the air gap to operate and give indication of the presence of magnetic flux across the air gap resulting from current flow in the primary winding.

Method and apparatus for testing ferromagnetic material

Abstract: 1385198 Testing ferromagnetic material BRITISH IRON & STEEL RESEARCH ASSOCIATION 14 July 1972 [16 July 1971] 33552/71 Heading G1N The metallurgical phase, and/or temperature of a ferromagnetic material is detected by passing an alternating magnetic flux through the material and measuring the flux as modified by the material indicative of the magnetic properties of the material. The testing apparatus 8 is disposed below a steel strip 5 from a hot strip mill and includes an H-shaped magnetic core 10 mounted in a chamber 12 through which cooling water flows. A field winding 18 energized from A.C. source 30 produces an alternating flux passing through strip 5 via feet 38. The flux is modified by the magnetic properties of the metal strip 5 and causes a voltage VI to be generated across coils 22, 24 wound so that equal fluxes passing through the parts of the upright 26 from cross bar 20 produce a zero voltage across terminals 29. V 1 is integrated in box 40 to produce a signal representative of the magnetic induction B and a signal V 2 represented of the field H produced by coil 18 is developed across resistor 34. B, H, Hc, Br, Bm and A are obtained from the computer 40 and the hysteresis loops calculated, they may be displayed on an oscilloscope. Various graphs of Bm, Br, dBm/dt dBr/dt versus temperature, H, B versus time and phase diagrams for various cooling rates are described Figs. 4-8 (not shown) from which phase transformation and temperature of the strip 5 can be deduced and signals obtained to control the cooling of the strip to produce a particular phase of the material of the metal strip.

Electromagnetic device having a metal oxide varistor core

Abstract: Electromagnetic devices such as inductors and autotransformers having improved suppression to sparking or high voltage peaks at the terminals and between coil windings are provided using certain sintered metal oxide insulators having varistor characteristics. The metal oxide can be employed in conjunction with magnetic core material, as a composite core in such electromagnetic devices.

Sensing and control device for electric motor-starting circuits

Abstract: A versatile sensing transformer for actuating a semiconductor gate in the starting circuit of an electric motor, comprising a U-shaped magnetic base, inductive coupled primary and secondary windings mounted on the base in coaxial relation to each other and electrically connected to the motor and the semiconductor gate, an adjustable and removable magnetic core threaded into the base and projecting axially of the cores, and a magnetic cap bridging the open end of the base to form a complete magnetic shell, the cap being adjustable toward and away from the coils and core to vary the overall reluctance of the magnetic circuit.