TO THE CHOICE OF THE MATERIALS FOR MAGNETIC CIRCUITS OF THE TRACTION TRANSFORMER OF RAISED FREQUENCY

In conditions the limited space of the body of tractive electric rolling stock an increasing the work frequencies is a perspective way to increase the specific power of the traction electric equipment, but such approach requires to use a special materials during its production. For the production of magnetic circuit of powerful traction transformer of the raised frequency (up to 3 кHz) it is reasonable to use the electrotechnical steel such types as 3422, 3423, 3424, 3425, which ensure the implementation of necessary power. They are characterized by processability and the relative stability of its parameters under influence of destabilizing factors. The best value to magnetic induction is defined from condition of the mini-mum losses in transformer’s magnetic circuit. In work is considered a rational border of the increasing the frequency, which provides the minimum overall dimensions and the maximum of the coefficient of efficiency. The maximum frequency, which corresponding to the upper border of increase the frequency ? it’s a "critical" frequency. The value of magnetic induction, the specific losses and critical frequency for transformer within the range of powers from 1000 up to 16000 кVA are investigated in the work. Based on the requirement to provision the minimum level of specific losses in material, for magnetic circuit of traction transformer of the raised frequency it is reasonable to use steel of the 3424 type with the thicknesses of the tape 0,08 mm. Presented results of the researches are allow to confirm that with the power increasing of the transformer of the raised frequency it is follows to reduce the work frequency for the reason to reduce the power losses in magnetic circuit. This will reduce the advantage in volume of magnetic circuit, but will provide the conservation of the power losses value in magnetic circuit on low level. The investigation of practicability of the introduction the three-phase traction transformer raised frequency is presented by separate question. Besides it is determined an analytical dependency for the change the volume of magnetic circuit of the three-phase transformer of raised frequency in comparison with a transformer of the industrial frequency under conditions of increasing of their power. Usage the three-phase traction transformer of the raised frequency will allow to reduce the power losses in magnetic circuit approximately in three times, in contrast with the power losses in magnetic circuit of the three-phase transformer of industrial frequency.