Showing papers on "Magnetic core published in 1982"

Magnetic performance of step-lap joints in distribution transformer cores

Abstract: The magnetic characteristis of cores with step-lap joints are analyzed by using the finite element method taking into account eddy current and magnetic saturation. The effects of the following factors on the magnetic characteristics such as flux and eddy current distributions and magnetizing current are clarified quantitatively. 1)step-lap length 2)length of air gap at the joint 3)number of laminations per one stagger layer 4)flux density (magnetic saturation) Obtained results give useful suggestions improving the design of the joints of transformer cores.

Magnetic shielding to multi-gigawatt magnetic switches ten years of amorphous magnetic applications

Abstract: The applications of ferromagnetic amorphous alloys provide an excellent example of the unpredictable nature of the benefits from research and from the development of a technology This paper traces a brief history of applications of amorphous alloys as soft magnetic materials Specific applications are then discussed in which amorphous alloys are currently being used due to their unique properties Applications which offer promise for significant future uses are also discussed

Method for the measurement of rotational power loss and related properties in electrical steel sheets

Abstract: An apparatus is described which is used to measure the magnetic field vectors in electrical steel sheets in rotating magnetic fields. To avoid complicated eddy current effects we produce a rotating B-vector with constant modulus and angular velocity. Considerable variations of the modulus of the magnetic field strength and of the angle between \vec{B} and \vec{H} during one period of rotation are observed in a sample of non-oriented silicon iron. The results concerning the rotational losses are in good agreement with these measured with a different technique.

Influence of transformer core design on power losses

Abstract: The results of an experimental investigation on reduced models of the influence of core design on core losses are presented. The characteristics of single-phase and three-phase three-limbed cores are compared, and the influence of the core proportions on the core building factor is determined. Four types of T-joint design for a three-phase core have been investigated. It has been found that the widely applied V-45° T-joint does not have the best magnetic properties, as usually assumed. The influence of the corner joint overlap length, the number of laminations per stagger layer, and the yoke cross-section form on the core building factor have been determined.

A magnetic core in the Sun? The solar rotator

Abstract: The previously found solar distortion rotating rigidly and wave-like on the surface with a ∼ 12 day period is interpreted as the shape of the gravitational potential induced by the solar core distorted by an internal magnetic field and rotating rigidly with this period. The distortion does not have a symmetry axis and the necessary magnetic field is not compatible with the axial symmetry required of a quasi-static field locked in the rotating core. It is concluded that if the solar distortion is due to such a process the core is oscillating with a very long period, a toroidal oscillation with a period of the order of years.

Magnetic core selection for transformers and inductors : a user's guide to practice and specification

Abstract: Magnetic-core power-handling ability transformer output circuits transformer and inductor design examples magnetic-core material trade-off conversion data for magnet wire cased toroids MPP and iron powder cores ferrite cores laminations C cores caseless toroids E cores PC board mounts/headers and transformer mounting brackets.

Transducer free of any magnetic core for contactless current measurement

Abstract: A transducer free of any magnetic core for contactless measurement of a current includes an electrically conducting strip adapted to carry the current in a predetermined direction. The current thus generates a first primary magnetic field which has a direction at right angles to the predetermined direction near one side of the strip, and a second primary magnetic field near the other side of the strip, which has a direction opposite to the predetermined direction. A first magnetic field sensor near one side measures the first primary magnetic field and provides a first output signal, and a second magnetic field sensor near the other side of the strip measures the second primary magnetic field, and provides a second output signal. A circuit connected to the first and second magnetic field sensor processes the first and second output signals, and generates an output signal proportional to the measured current. This construction minimizes the influence of any stray magnetic field on the measurement of the current.

Electric motor having helical stator

Abstract: An electric motor comprises a stator provided with a helical magnetic core within whose grooves is laid an armature winding, and a rotor disposed within a stator boring. The rotor is provided with salients for forming a main magnetic field, disposed therearound along a helical line, the length of the salients being equal to αδτ, and the distance therebetween being (2-αδ)τ, where αδ is a coefficient of a rated pole arc, and τ is a pole pitch of the motor. According to the invention, in the magnetic core is provided an additional groove wherein is laid an excitation winding, the portions of each turn of the magnetic core whereon the armature winding and the excitation winding are disposed have such a length which ensures axial alignment of the grooves for placing the armature winding within all the turns of the magnetic core.

Toroidal core electromagnetic device

Abstract: An electromagnetic apparatus is provided with a magnetic core and a segmented electrical winding. The core has an enclosed trunk defining a central opening. At least three coil sections of the electrical winding encircle the trunk and are circumferentially spaced about the periphery of the core.

Wound iron core

Abstract: PURPOSE:To obtain a kind of wound iron core for controlling, to be normally formed by winding a strip of thin alloy plate of high permeability, which is excellent in excitation characteristic by the use of a Fe family amorphous alloy thin plate of which saturated magnetic flux density is more than 3KG and less than 9KG as an alloy thin plate. CONSTITUTION:A wound iron core is formed by winding a thin alloy plate of high permeability into a roll. As a thin alloy plate, such an amorphous alloy that is represented by the formula of FedTeSifBg (in the formula, T is one or more than 2 of Be, Mg, Ca, Sr, Ba, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Ru, Co, Ni, Pd, Cu, Zn, Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb or Dy, and d+e+f+g=100), especially such the amorphous alloy that satisfies the conditions of 3<=e<=40, 7< f<25, 7<=g<=10, 15<=f+g<=35 and of which saturated magnetic flux density is more than 3KG and less than 9KG is selected, and it is annealed in the magnetic field of more than 5 oersted at temperature 250-550 deg.C and then cooled off at a speed of 50-500 deg.C per hour and used.

Fuel injection valve

Abstract: PURPOSE:To control open-close operation of a fuel injection valve at high speed CONSTITUTION:An iron core 1 and valve head 2 in a solenoid fuel injection valve are formed by a ferrite core Since the ferrite core can be used also in an extremely high frequency, an eddy current is hardly generated even for a very sharp rise-up of current in a solenoid core Accordingly, delay of the magnetic flux is not caused for change of a current, and the sharper the current is changed the sharper the magnetic force is caused, then the valve can be open- close controlled at high speed

Magnetic fluid damper

Abstract: PURPOSE:To optionally change the spring constant of a damper and more finely control its absorption of vibration, by such constitution that a magnetic fluid is sealed in the damper part simultaneously a flow of this fluid is electrically controlled. CONSTITUTION:In case of constitution as an engine mount 2, a rubber member 7 is deformed by vibration in a state when an electromagnet 8 is not electrically conducted, then a magnetic fluid in chambers 4, 14 moves through a small hole 6, located in a gap part 13 in both end parts of an iron core 9, by deforming a rubber plate 5. At this time, the small hole 6 being fixed in its size can not finely control absorption of vibration. On the contrary, if the electromagnet 8 is electrically conducted, magnetic flux is concentrated to a part of the small hole 6, and a virtual viscosity value of the magnetic fluid in this small hole part 6 is changed in accordance with a level of electric current. Accordingly, circulative resistance of the small hole 6 can be optionally changed to more finely control absorption of vibration.

Iron core for a stationary induction apparatus

Abstract: An iron core for a stationary induction apparatus, such as a transformer or reactor, comprising an alternate laminate of thin amorphous magnetic strips (21a to 21d) and silicon steel sheets (11a to 11d). It is low in electrical loss, and high in workability.

Transformer for low distortion rectifier system

Abstract: A coil for a 12-pulse transformer-rectifier apparatus assembled on a three-leg magnetic core comprising a half primary winding sandwiched between two half secondary windings of substantially the same height as the half primary winding. A pair of coils associated with one leg of a three-leg magnetic core in a 12-pulse transformer-rectifier, are oriented in opposition to one another, and have all their terminal conductors extending parallel to one another with transversal connectors in closely-related parallel planes.

Transformer with windings completely embedded in cast resin

Abstract: Transformer, including an iron core, high voltage and low voltage windings, at least one cast resin body completely embedding, holding and insulating the windings, the cast resin body having cooling channels formed therein and having additional channels formed therein being separated from the cooling channels, and insulating gas filling the additional channels.

Amorphous alloy for magnetic core material

Abstract: There is disclosed an amorphous alloy for a magnetic core material represented by the formula (Co.sub.1-x.sbsb.1.sub.-x.sbsb.2 Fe.sub.x.sbsb.1 M x .sbsb.2) x .sbsb.3 B x .sbsb.4 Si 100-x .sbsb.3 -x .sbsb.4 wherein M is at least one element selected from the group consisting of Ti, V, Cr, Mn, Ni, Zr, Nb, Mo, Ru, Hf, Ta, W and Re, and x 1 , x 2 , x 3 and x 4 are numbers which satisfy relations of 0≦x 1 ≦0.10, 0≦x 2 ≦0.10, 70≦x 3 ≦79 and 5≦x 4 ≦9, respectively. According to the present invention, it could be provided an amorphous alloy suitable for a magnetic core material of a magnetic amplifier in which its coercive force is as low as 0.4 oersted or less at a high frequency of 20 KHz or more, particularly even at 50 KHz, and its rectangular ratio is as much as 85% or more.

Electrodeless gas discharge lamp having heat conductor disposed within magnetic core

Abstract: Electrodeless gas discharge lamp having a lamp vessel which is closed in a vacuum-tight manner, the lamp comprising a rod-shaped core of a magnetic material, a member of a heat-conducting material (for example copper) extending at or near the axis of the core, heat generated in the core during operation of the lamp being discharged to the environment of the lamp by the member.

Soft magnetic ferrites and applications in telecommunication and power converters

Abstract: Ferrite cores are mainly used in filters and broad-band transformers for telecommunication and increasingly in power converters. The requirements for the material properties are different for different applications and accordingly different compositions of the ferrite materials are used. Commercially available ferrites have been steadily improved in quality, though some outstanding properties which have been reported from laboratories a long time ago, are not yet available because of economical aspects. In many cases compromises have to be made, as the best properties cannot be combined in one material at the same time. The development of new core types and of coil formers which enable an automatic handling is of great importance for the application of ferrites. For power converters there exists a great variety of core types while the variation of the material properties is rather limited.

Production of magnetic recording medium

Abstract: PURPOSE:To improve the quality of magnetic recording medium by calendering with an increase in applied pressure by using an elastic roll for calendering produced by forming an under layer harder than a surface layer consisting of a hard elastic material under the surface layer CONSTITUTION:An under layer 11b with 5-15mm thickness consisting of an elastic material having 85-98 deg Shore D hardness and an upper layer 11c with 03- 50mm thickness consisting of an elastic material having 70-90 shore D hardness which is lower than the layer 11b are formed on the outside circumference of an iron core 11a, thereby forming an elastic roll 11 for calendering A magnetic recording medium 4 is guided between such rolls 11 and metallic rolls 2 and is calendered under the conditions of 80-120 degC surface temp of the magnetic layer of the recording medium, 250-350kg/cm linear pressure and 100-300m/min feed speed of the recording medium The packing density of the magnetic powder in the magnetic layer is thus increased and the magnetic flux density is improved

Electric apparatus and its magnetic core of (100)[011] silicon-iron sheet made by rapid quenching method

Abstract: High-silicon steel sheets or ribbons having the crystal texture described by (100)[011] are used for the fabrication of magnetic cores of electrical machinery in such a way that the easy axes of magnetization coincide with the directions of magnetic circuits or lines of magnetic flux. Magnetic cores of, for instance, electric motors or transformers can be remarkably improved in efficiency.

High sensitivity differential protection device for the detection of earthed phase or neutral fault currents

Abstract: 1. Differential protection device (10) for the detection of earthed fault currents in an electrical equipment energized by an alternating current network comprising : a differential transformer comprising a magnetic core with a single core (12) crossed by the phase conductors (L) and neutral conductors (N) of the network constituting the primary windings of the transformer, a first secondary winding (L1 ) wound on the core (12) and cooperating with a measuring and processing circuit (14) able to deliver, after exceeding a predetermined threshold, a tripping order to a control coil (16) of a switch device (18) on appearance of an earthed fault current, an auxiliary supply circuit (20) of the measuring and processing circuit (14), an a. c. voltage generator (G) comprising a pulse oscillator with a stationary frequency, higher the that of the network, cooperating with the differential transformer, and a comparator (24) integrated into said measuring and processing circuit (14) in order to compare the amplitude of the voltage (U1 ) at the terminals of the first secondary winding (L1 ) with a reference voltage, characterized by the fact that the generator (G) is connected electrically with the first secondary winding (L1 ) by means of a connection circuit comprising a resistance (22) the value of which is choosen in such a manner to induce a pilot current of quite constant voltage, and that the output voltage (U2 ) of the generator (G) constitutes the reference voltage for the comparator (24).

Magnetic head having a controllable high-permeability tunnel within a low-permeability sleeve

Abstract: A magnetic record and/or reproduce head, comprised of electrically conductive magnetic core material, has an electrically conductive transducer gap having a magnetic gap length of less than about 15 microinches. The head is selectively actuable by passing a current through the core material via the gap.

Clamp-on ammeter

Abstract: A clamp-on ammeter for measuring current flows in a conductor is described. The ammeter is of a type comprising a magnetic core which can be located about a conductor and an indicator which responds to the magnetic flux consequently generated in the magnetic core to produce a signal indicative of the magnitude of the conductor current. Means are provided for restoring the magnetic core to a predetermined magnetic state for each measurement. The resetting means include a coil wound about the core and a coil energizing circuit which can be activated to produce in the core a residual magnetic flux substantially identical to that produced in the core when unmagnetized by a DC conductor current of predetermined magnitude, which represents the maximum value of any DC current which can be measured by the ammeter. The ammeter includes another coil and energizing circuitry which then produce in the core an offsetting magnetic flux equal in magnitude but opposite in direction to the residual magnetic flux, thereby eliminating any offset which would otherwise be generated by the indicator in response to the residual magnetic flux. To adapt the ammeter for AC measurements, another coil is wound on the core and is electrically shorted when the magnetic flux cutting the windings of the coil changes direction from that of the residual magnetic flux. The shorting of the coil tends to reduce the magnitude of the magnetic flux in the core to substantially zero. By emplying an indicator responsive to a time average magnitude of the core magnetic flux a signal indicative of the magnitude of an alternating current carried by a conductor is produced.

Soft magnetic core including a semiconductor element to sense the magnetic field for measuring alternating and direct currents

Abstract: 1. A magnetic core (1) made of soft magnetic material for a current sensor, which surrounds an electrical conductor (4) and in which there is provided a notch (2) having a magnetic field-dependent semiconductor element (3) arranged therein, characterised in that the magnetic core (1) consists of a soft magnetic powder, which is consolidated together with insulating material, and has an essentially U-shaped core member (8), the open side of which can be covered by an end piece (11) after the insertion of the electrical conductor (4) ; and that at the interior, the U-shaped core member (8) has V-shaped stop faces (9, 10), against which the electrical conductor (4) rests.

Roll magnetically compensated and/or controlled of its deflection

Abstract: A roller used as a press or calender roller in a paper machine is compensated for deflection and end-loaded. The roller has a stationary axle with spaced opposite ends at which the roller is loaded and a cylindrical shell rotatably mounted on the axle. The axle has a magnetic core portion within the shell having pole shoes spaced from the shell by air gaps and magnetizing coils of electrical conductors thereon at corresponding ones of the pole shoes. The coils produce a magnetomotive force and are positioned in a manner whereby magnetic flux passing through the air gaps between the pole shoes and the shell creates a compensating force field between the shell and the magnetic core. The roller has an inner part of the shell consisting of a stack of sheets of magnetically well-conductive material separated from each other by electrical insulation thereby reducing eddy current losses.

Regulation and drive system for high rep-rate magnetic-pulse compressors

Abstract: The essentially unlimited rep-rate capability of non-linear magnetic systems has imposed strict requirements on the drive system which initiates the pulse compression. An order of magnitude increase in the rep-rates achieved by the Advanced Test Accelerator (ATA) gas blown system is not difficult to achieve in the magnetic compressor. The added requirement of having a high degree of regulation at the higher rep-rates places strict requirements on the triggerable switch for charging and de-Queing. A novel feedback technique which applies the proper bias to a magnetic core by comparing a reference voltage to the charging voltage eases considerably the regulation required to achieve low jitter in magnetic compression. The performance of the high rep-rate charging and regulation systems will be described in the following pages.

Bipolar magnetic sensors

Abstract: Lateral bipolar magnetic sensors have been developed whose output signal is measured as a differential voltage between two collectors. Devices can be designed either to respond to magnetic fields applied perpendicular to the surface or to parallel fields. The experiments have resulted in an understanding of the basic operating principles and have led to the design of optimum magnetic sensors. Whereas previous investigations of dual-collector lateral bipolar transistor structures have attributed the unequal collector currents (resulting from the application of a magnetic field) to "carrier deflection" in the base, our experiments clearly demonstrate that it is due to nonuniform injection from the emitter. The applied magnetic field leads to a voltage variation along the emitter-base junction and this, in turn, results in nonuniform carrier injection into the base and subsequent unequal currents to the two collectors.