The necessity of the primary transformers rapidly increases due to the fast development of the microprocessing automated control systems and operation of the railway transport power supply devices, transferring to the flexible automated output. These transformers, besides high metrology characteristics, have to be highly reliable, have a wide range of change, stability, little dimensions.

The article is devoted to the development of methods for calculating magnetic circuits of current converters taking into account the nonlinearity of magnetic characteristics. At the same time, magnetic systems of current converters are of great interest, which, according to the principle of their operation, are magnetized simultaneously by constant and alternating magnetic fields (magnetomodulation converters). Analytical expressions of the magnetization curves of magnetic materials are proposed, experimental schemes are presented, and the feasibility of using a combination of oscillographic and wattmeter methods, the convergence of the calculated and experimental data are shown.

electrified railway transport receives power from the power system and operates on a single-phase current, which leads to uneven loading of networks of the traction power supply system. There is a danger of overload and additional losses of active power and electrical energy of three-phase electric motors by reverse sequence currents, therefore, any information obtained about the values (phase currents and voltages) allows carrying out corrective actions for the level of asymmetry. In this paper, discuss the design of the device for detecting the asymmetry of phase currents in three-phase lines is proposed. It is shown that the device can convert the DC current difference and measure three linear currents in a three-wire three-phase circuit.

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