The magnetic amplifier is also called the saturable reactor or the transductor. Saturable reactor model a saturable reactor is a magnetic circuit element consisting of a single coil wound around a magnetic core. Once saturated, the inductance of the saturable reactor drops dramatically. There is a point upon the magnetization curve where the saturable core reactor should be operated. Dc motor speed control using feedback magnetic amplifier v. The schematic diagram of this circuit is shown in figure 333. 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. The saturable reactor is the device from which the magnetic amplifier has been fundamentally developed. Saturable reactor square permalloy and namglass iii toroid tape core pulse transformers silectron. The triangle is the general symbol for an amplifier. Resonant power conversion through a saturable reactor halinria.
Magnetic amplifiers and their applications bright hub. Magneticamplifier analysis using a generalized model for. The double bar between the inductors stands for an iron core, and the symbol that cuts across the two windings is a. Consequently, a thorough understanding of the saturable reactor is a must before one is able to fully understand the magnetic amplifier. It regulates the auxiliary outputs of a switching power supply by delaying the rise in voltage of a p wm pulse. 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. 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 amplifierbased power flow controller osti. A magnetic amplifier is a circuit that uses changes in core saturation of an inductor to bring about amplification. The control winding is shown with five loops, and the load winding is shown with three loops. 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. A magnetic amplifier or saturable reactor, as it is sometimes called is a true amplifier. L1 is the schematic symbol for a saturablecore reactor. Saturable reactor for power flow control in electric.
Sampieri, aroused renewed interest in a well founded control technique. Following is a sample of the information contained on this cd. Second, we still lack an understanding of how the innards of what we affectionately call the brain box accomplish. 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.
The theory of magnetic amplifiers is dated, but its simplistic design has benefits for modern applications. Price new from used from hardcover, import please retry. 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 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.
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. For controlled saturation characteristics, the magnetic amplifier employs core materials that have. Like a vacuum tube, it uses a small signal to control a large one. The original control system supplied a waveform to the saturable core device that was decidedly not dc. Where the vacuum tube controls a current flowing to a d. 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. Historically magnetic amplifiers were used in many different power supply applications. 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. Special transformers and applications transformers. 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.
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. A magnetic amplifier or magamp is a post regulation method utilizing a saturable reactor wire wrapped saturable core. Schematic diagram of a simple saturable core reactor. Osborne has been involved in a wide variety of saturable reactor design projects over the years. 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 saturablecore reactor symbol in the center of the triangle identifies the amplifier as a magnetic amplifier. The three essential elements of saturable reactor are. Full text of magnetic amplifiers principles and applications. The magnetic amplifier acts as a variable impedance switch where a small amount of dc current can control the output voltage of a circuit. Scaling amplifier, difference amplifier, circuit for q31.
This principle is similar to the functioning of the magnetic amplifier or the. Magneticamplifier analysis using a generalized model for the saturable reactor core. 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. The magnetic amplifier shares with the amplidyne comparative freedom from electrical interference. Seminar 500 topic 7 magnetic amplifier control texas instruments. The parameters of the saturable reactor are mentioned in table 1 the three phase supply is 380 volts lineline with frequency 50 hz. Saturable reactor magnetic amplifier for vickers voltage regulator system, pn 8408218esi dear sir. 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.
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. Saturable reactors are magnetic amplifiers saturable reactors are not common electromagnetic components. Pdf battery charger technologies jayvee dime academia. Magnetic amplifier made from common 12 volt transformers. Control and limitation of high shortcircuit currents. A magnetic amplifier has a rectifier in addition to a saturable core reactor. New patent cd for magnetic core for saturable reactor. Saturable reactor for power flow control in electric transmission. Saturable core reactors an overview sciencedirect topics. Magnetic amplifier engineering hardcover january 1, 1959 by george m. Saturable reactor as a diode the saturable reactor will surely achieve waveform manipulations according to its nonlinear characteristsic. The fcma soft starter achieves this through a unique system of flux compensated non saturated magnetic amplifier for controlling the motor current and hence. 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.
Magnetic amplifier project gutenberg selfpublishing. 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. In the magnetic amplifier, the rectifier causes current flow in a uniform direction that. This makes for smaller control equipment and greater flexibility than if the output power were controlled directly. Here is a brief overview of why saturable reactors are occasionally referred to as magnetic amplifiers. The evaluation is, expected to be completed no later than march 22, 2019. Magnetic amplifiers for voltage regulation applications. Magnetic amplifier technology involves unique techniques that can be tailored to match the fit, form, and function of your application. 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. Saturable reactors and magnetic amplifiers were used as early as 1885, through to roughly the mid 1900s, where their use declined rapidly. 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. Frequently asked questions about fcma soft starters. 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. 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.
If the square wave generator is powerful enough, the differential amp may not be necessary. This decreases inductive reactance and allows increased flow of the alternating current ac. Applications of saturablecore reactors scr in power. It consists of an iron core with two or more coils wound around it. Consider a saturable reactor, with a hysteresis curve as shown in fig.
An904 application note magnetic amplifier with lpr30 controller by f. The block diagram symbol for a magnetic amplifier is shown in figure 341. A magnetic amplifier is an electromagnetic device that amplifies electrical signals utilizing a transformers core saturation principle, and the core non linear property. The saturable core reactor symbol in the center of the triangle identifies the amplifier as a magnetic amplifier. Sometimes referred to as transductors magnetic amplifiers came into use. It makes use of magnetic saturation of the core, a nonlinear property of a certain class of transformer cores. A magamp device may look like a transformer but the operating principle is quite different from a transformer. Dec 14, 2014 a magnetic amplifier differs from a saturable core reactor in one important aspect. In this paper, we discuss the fact that the controlled magnetization curve is preferable for evaluating saturable cores operating in. A magnetic amplifier differs from a saturablecore reactor in one important aspect. The saturable reactor continued principal of magnetic amplifier 1. The magnetic flux density, b, is a function of the applied mmf.
Simplified magnetic amplifier circuitry, summary of. Magnetic properties of cobaltrich amorphous alloys for. Why does this system deviate so significantly from the magnetic amplifier theories of operation with which we are familiar. Saturable reactors are commonly used to transfer a system voltage to a load through a series impedance division circuit. 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. Magnetic amplifier analysis using a generalized model for the saturable reactor core by herbert horace woodson s. A simple electronic amplifier that works on the principle of magnetic saturation of a transformer core is called a magnetic amplifier. 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. 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. Paris author see all formats and editions hide other formats and editions. 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. 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. A circuit without diodes may have a power gain of just 15 but it is still impressive and can certainly amplify.
Weve prepared the illustrations below to share six established saturable reactor element core and. 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. 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. 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. A magnetic amplifier has a rectifier in addition to a saturablecore reactor. Sec drives the mag amp core out of saturation and resets it by an. 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. Since then, the magnetic amplifier has become allbut.
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