A magnetic amplifier has a rectifier in addition to a saturablecore reactor. Seminar 500 topic 7 magnetic amplifier control texas instruments. There is a point upon the magnetization curve where the saturable core reactor should be operated. A magamp device may look like a transformer but the operating principle is quite different from a transformer essentially the magamp is a saturable reactor. By the 1950s, the magnetic amplifier was not just an experimental dream languishing in some inventors notebook. An inductor wound on such a core is called a saturable reactor, and its inductance will vary according to the extent to. In the magnetic amplifier, the rectifier causes current flow in a uniform direction that. The theory of magnetic amplifiers is dated, but its simplistic design has benefits for modern applications.
Following is a sample of the information contained on this cd. Magnetic amplifiers and their applications bright hub. The original control system supplied a waveform to the saturable core device that was decidedly not dc. In a magnetic amplifier having power input and output circuits and a saturable reactor with a reactance winding connected in series with a halfwave rectifier be tween the input and output circuits for selfsaturation, and with means including a source of alternating cur rent coupled to the reactor for supplying alternating control current to.
Price new from used from hardcover, import please retry. Where the vacuum tube controls a current flowing to a d. Consequently, a thorough understanding of the saturable reactor is a must before one is able to fully understand the magnetic amplifier. In the magnetic amplifier, the variation of a control voltage brings about a change in the inductance of a coil and, hence, its inductive reactance. Now that you have seen the basic operation of a saturable core reactor, there is one other idea to discuss before moving on to the circuitry of a magnetic amplifier. The presence of a magnetic core drastically alters the behavior of the coil by increasing the magnetic flux and confining most of the flux to the core. Magnetic amplifier project gutenberg selfpublishing. Sampieri, aroused renewed interest in a well founded control technique.
Magneticamplifier analysis using a generalized model for. Rugged, dependable, empproof, and capable of handling greater electrical powers than either transistor or tube, the magnetic amplifier is a simple device that can be built by anyone. The magnetic flux density, b, is a function of the applied mmf. The inductive dc current measuring device used in dc transmission applications is generally the zeroflux type, which mainly comprises the saturable reactor, auxiliary ac power supply, rectifier circuit, and burden resistor. Magneticamplifier analysis using a generalized model for the saturable reactor core by herbert horace woodson s. Magnetic properties of cobaltrich amorphous alloys for.
Saturable reactor model a saturable reactor is a magnetic circuit element consisting of a single coil wound around a magnetic core. It regulates the auxiliary outputs of a switching power supply by delaying the rise in voltage of a p wm pulse. Once saturated, the inductance of the saturable reactor drops dramatically. A saturable reactor, illustrating the principle of a magnetic amplifier visually a mag amp device may resemble a transformer, but the operating principle is quite different from a transformer essentially the mag amp is a saturable reactor. The evaluation is, expected to be completed no later than march 22, 2019.
For controlled saturation characteristics, the magnetic amplifier employs core materials that have. Saturable reactor as a diode the saturable reactor will surely achieve waveform manipulations according to its nonlinear characteristsic. This article includes a control circuit diagram for a magnetic amplifier and discusses the working theory of the circuit as well as the drawbacks of magnetic amplifiers. Magnetic amplifier technology involves unique techniques that can be tailored to match the fit, form, and function of your application. A saturable reactor capitalizes on this effect by forcing the core into a state of saturation with a strong magnetic field generated by current through another winding. May 04, 2018 a saturable reactor in electrical engineering is a special form of inductor where the magnetic core can be deliberately saturated by a direct electric current in a control winding. If the square wave generator is powerful enough, the differential amp may not be necessary. The magnetic amplifier is also called the saturable reactor or the transductor. A simple electronic amplifier that works on the principle of magnetic saturation of a transformer core is called a magnetic amplifier.
Magnetic amplifiers for voltage regulation applications. The enclosed report addresses an ongoing evaluation regarding a saturable reactor magnetic amplifier for vickers voltage regulator system, pn 8408218esi. Sec drives the mag amp core out of saturation and resets it by an. A circuit without diodes may have a power gain of just 15 but it is still impressive and can certainly amplify.
A magnetic amplifier or saturable reactor, as it is sometimes called is a true amplifier. Why does this system deviate so significantly from the magnetic amplifier theories of operation with which we are familiar. Saturable reactor square permalloy and namglass iii toroid tape core pulse transformers silectron. Dec 14, 2014 a magnetic amplifier differs from a saturable core reactor in one important aspect. Saturable core reactors an overview sciencedirect topics. The preferable properties for saturable cores used in magnetic amplifiers of high frequency switchedmode power supply are 1 a large remanence ratio b r b s, 2 a low core loss and 3 a small longterm change in the magnetic properties. Simplified magnetic amplifier circuitry, summary of. Dc motor speed control using feedback magnetic amplifier v. A simulation model for the saturable reactor, an electromagnetic devices widely used as a protective element for the thyristor circuit, is presented. Scaling amplifier, difference amplifier, circuit for q31. A magnetic amplifier consists of electric and saturable magnetic circuits so interlinked that the reactance of an ac circuit is controlled by an independently applied magnetization. It makes use of magnetic saturation of the core, a nonlinear property of a certain class of transformer cores. Magnetic amplifierbased power flow controller osti.
The saturable reactor is the device from which the magnetic amplifier has been fundamentally developed. Earlier in this article we studied that it is designed based on the design of the saturable reactor, which consists of major parts such as dc source, magnetic core with windings and ac source. What is the difference between an fcma and conventional magnetic amplifier or saturable core reactor. The block diagram symbol for a magnetic amplifier is shown in figure 341. Frequently asked questions about fcma soft starters. Saturable reactor works on the principle by varying the saturation of the core the current flow through a coil wound on a magnetic core can be varied. L1 is the schematic symbol for a saturablecore reactor. New patent cd for magnetic core for saturable reactor.
A magamp device may look like a transformer but the operating principle is quite different from a transformer. The three essential elements of saturable reactor are. A magnetic amplifier has a rectifier in addition to a saturable core reactor. The point of the previous thread which im keeping on about is that it will never convert an ac into a dc current without the help of a real rectifier diode. Pdf battery charger technologies jayvee dime academia. A saturable reactor for power flow control srpfc is a novel application of a concept well known to electronics and power electronics engineers that provides continuous modulation of line reactance by controlling the magnetization in a ferromagnetic core.
A magnetic amplifier or magamp is a post regulation method utilizing a saturable reactor wire wrapped saturable core. Historically magnetic amplifiers were used in many different power supply applications. The reactors power winding is the one carrying the ac load current, and the control winding is one carrying a dc current strong enough to drive the core into. This decreases inductive reactance and allows increased flow of the alternating current ac.
This makes for smaller control equipment and greater flexibility than if the output power were controlled directly. Saturable reactor magnetic amplifier for vickers voltage regulator system, pn 8408218esi dear sir. The double bar between the inductors stands for an iron core, and the symbol that cuts across the two windings is a. In this paper, we discuss the fact that the controlled magnetization curve is preferable for evaluating saturable cores operating in. Magnetic amplifier made from common 12 volt transformers.
Magneticamplifier analysis using a generalized model for the saturable reactor core. A magnetic amplifier is an electromagnetic device that amplifies electrical signals utilizing a transformers core saturation principle, and the core non linear property. The parameters of the saturable reactor are mentioned in table 1 the three phase supply is 380 volts lineline with frequency 50 hz. Visually a mag amp device may resemble a transformer, but the operating principle is quite different from a transformer essentially the mag amp is a saturable reactor. Magnetic amplifier analysis using a generalized model for the saturable reactor core by herbert horace woodson s. The saturable reactor continued principal of magnetic amplifier 1. Here is a brief overview of why saturable reactors are occasionally referred to as magnetic amplifiers. Resonant power conversion through a saturable reactor halinria. The saturable core reactor symbol in the center of the triangle identifies the amplifier as a magnetic amplifier. The triangle is the general symbol for an amplifier. Schematic diagram of a simple saturable core reactor. Second, we still lack an understanding of how the innards of what we affectionately call the brain box accomplish.
Saturable reactors are magnetic amplifiers saturable reactors are not common electromagnetic components. Background of the invention the present invention relates to a magnetic core for use in a saturable reactor, a multioutput switching regulator controlling the output voltage by a magnetic amplifier, and a computer equipped with such a multioutput switching regulator. Magnetic amplifier regulation of switch mode power supplies basic design of saturable reactors a magnetic amplifier or magamp is a post regulation method utilizing a saturable reactor wire wrapped saturable core. This principle is similar to the functioning of the magnetic amplifier or the. The magnetic amplifier acts as a variable impedance switch where a small amount of dc current can control the output voltage of a circuit. Control and limitation of high shortcircuit currents. Paris author see all formats and editions hide other formats and editions. Simulation results as seen from fig 2 the main winding of the saturable reactor is connected in series with the three phase ac supply and the diode. It consists of an iron core with two or more coils wound around it. The control winding is shown with five loops, and the load winding is shown with three loops. Osborne has been involved in a wide variety of saturable reactor design projects over the years. Saturable reactor for power flow control in electric. Several years ago, a magnetic amplifier based power flow controller mapfc was introduced 2, based on the concept of a saturable core reactor scr 3, 4, 5.
The magnetic amplifier was most prominent in power control and low the saturable reactor the saturable reactor is the device from which the magnetic amplifier has been fundamentally developed. One of the widest applications of the saturable reactor is that of a magnetic amplifier, by means of which large amounts of electric power can be controlled, with rapid response, by making use of much smaller amounts of control power. Saturable reactors are considered magnetic amplifiers because they can use a relatively small amount of dc voltamps to control the transfer of a significant amount of ac. Since then, the magnetic amplifier has become allbut. Saturable reactors are commonly used to transfer a system voltage to a load through a series impedance division circuit. A small amount of dc current change from the 9 volt battery and a 1k pot can cause a large amount of ac current change through a car headlight. Consider a saturable reactor, with a hysteresis curve as shown in fig. Applications of saturablecore reactors scr in power. The concept of utilizing the saturablecore reactor for circuit control dates as early as 1920s 1 and it has been well developed for electronic circuit applications. In all three cases, the control power required to effect the change is less than the power controlled, so that the devices are classed as amplifiers. Like a vacuum tube, it uses a small signal to control a large one. A saturable reactor in electrical engineering is a special form of inductor where the magnetic core can be deliberately saturated by a direct electric current in a control winding.
Sometimes referred to as transductors magnetic amplifiers came into use. Saturable reactors and magnetic amplifiers were used as early as 1885, through to roughly the mid 1900s, where their use declined rapidly. The schematic diagram of this circuit is shown in figure 333. User case study on starting of pumps with fcma soft starters on captive power in sponge iron plant with a view to save capital cost and maintenance cost. The magnetic amplifier shares with the amplidyne comparative freedom from electrical interference. Some mag amp articles convey a stuff shirt attitude that a circuit must have diodes in order to be called a magnetic amplifier and that a circuit without diodes is called a saturable reactor. Saturable reactor for power flow control in electric transmission. Weve prepared the illustrations below to share six established saturable reactor element core and. Different types of amplifiers are used for electronic amplification. Magnetic amplifier engineering hardcover january 1, 1959 by george m.
Patent search on cd containing over 50 related patents in high resolution pdf format cd of information on magnetic core for saturable reactor, magnetic amplifier type multioutput includes drawings, schematics, diagrams and other illustrations of patented technology excellent for researchers, hobbyists, students, teachers, librarians. A magnetic amplifier is a circuit that uses changes in core saturation of an inductor to bring about amplification. Jun 14, 2012 saturable reactors and magnetic amplifiers were used as early as 1885, through to roughly the mid 1900s, where their use declined rapidly. The saturablecore reactor symbol in the center of the triangle identifies the amplifier as a magnetic amplifier. Special transformers and applications transformers. Several years ago, a magnetic amplifierbased power flow controller mapfc was introduced 2, based on the concept of a saturablecore reactor scr 3, 4, 5. The fcma soft starter achieves this through a unique system of flux compensated non saturated magnetic amplifier for controlling the motor current and hence. For normal operation the voltage on the bias winding 28 of the magnetic amplifier 21 is such that it tends to saturate the core of the magnetic amplifier and give a desired current in the control winding 14 of the saturable core reactor. Full text of magnetic amplifiers principles and applications. A magnetic amplifier differs from a saturablecore reactor in one important aspect. An904 application note magnetic amplifier with lpr30 controller by f.
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