Магнитный усилитель — это такой статический electrical apparatus, which is designed to control the value of the value of alternating current using DC The principle of operation of such a device is based on the nonlinear characteristics of a magnetized magnetic circuit. Magnetic amplifier is often used in the field of automatic regulation of electric motors (both synchronous and asynchronous), which operate on alternating current.

The device of such a device is quite simple.A magnetic amplifier consists of a working winding, which is located on its extreme rods. It is made of two coils connected in series. The control winding with a large number of turns is placed on the middle rod. If no current is 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 applied alternating voltage due to the small number of turns. In this case, all the voltage will fall on the resistance of the working winding (it will in this case be reactive). In this case, low power will be released on the load.

The magnetic circuit of an instrument such as magneticthe 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 this 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 quite small signals on the control winding, large powers can be controlled.
In the simplest case, a device such asA magnetic amplifier is an inductance that is controlled by a direct current. For proper control, the inductance must be connected in series to the load in the AC circuit.

For large inductance values of currentin series and load is small. With a small inductance in a series circuit, the current will be high. On the load, respectively, its value will also increase in proportion to the decrease in inductance. There are numerous developments in which a device such as a magnetic amplifier is used as, for example, a contactless relay (for carrying out contactless current switching), for doubling the frequency value, for stabilizing the voltage in a circuit, for modulating high-frequency signals with low-frequency signals, as such a device , as a current amplifier, for regulating the supply voltage and so on.
Although recently magnetic amplifiers have been insome areas of its application are pressed by semiconductor devices, in such areas as control of electric drives in construction equipment, lighting control of concert halls and cinemas, in control of diesel locomotives the magnetic amplifier has no competitors to this day.