Question

Provide the proof of rotating magnetic field.

Answer 1

The three phases of the stator winding (balanced) carry balanced alternating (sinusoidal) currents as shown below

$i_R= I_mcos ωt$

$i_Y= I_m cos (ω t-120°)$

$i_B= I_mcos(ωt+120°)= I_mcos(ωt-120°)$

The phase sequence is R-Y-B. I_m is the maximum value of the phase currents, and, as the phase currents are balanced, the RMS values are equal (|I_R| =|I_Y|=|I_B|).