A magnetic amplifier is a static electrical device that is designed to control the value of an alternating current with a constant. The principle of operation of such a device is based on the nonlinear characteristics of a magnetized magnetic circuit. The magnetic amplifier is often used in the field of automatic control of electric motors (both synchronous and asynchronous) that operate on alternating current.
The device of such a device is quite simple. The magnetic amplifier consists of a working winding, which is located on its extreme rods. It is made up of two coils connected in series. The control winding with a large number of turns is placed on the middle rod. If current is not supplied to it, but passes through the working winding, which is connected in series with the load, then the magnetic circuit will not be saturated with the supplied alternating voltage due to the smallnumber of turns. In this case, all the voltage will fall on the resistance of the working winding (in this case it will be reactive). In this case, low power will be allocated to the load.
The magnetic circuit of such a device as a magnetic amplifier is saturated due to the fact that the current passes through the control winding. Due to the large number of turns on it, even a small current value is sufficient. As a result of such a process, the reactive component of the resistance of the working winding will sharply decrease, and the value of the current in the control circuit will rapidly increase. Thus, with rather small signals on the control winding, large powers can be controlled.
In the simplest case, a device such as a magnetic amplifier is an inductance that is controlled by direct current. For proper control, the inductor must be connected in series with the load in the AC circuit.
For large values of inductance, the value of the current in the series circuit and the load is small. With a small inductance in a series circuit, the current will be large. On the load, respectively, its value will also increase in proportion to the decrease in inductance. There are numerous developments in which such a device as a magnetic amplifier is used as, for example, a non-contact relay (for non-contact current switching), for doubling the frequency value, for stabilizing the voltage in the circuit, for modulating high-frequencylow-frequency signals, as a device such as a current amplifier, for regulating the supply voltage, and so on.
Although recently magnetic amplifiers have been supplanted by semiconductor devices in some areas of their application, in such areas as controlling electric drives in construction equipment, controlling the lighting of concert halls and cinemas, and in controlling diesel locomotives, the magnetic amplifier has no competitors to this day. day.
