At standstill the rms currents in the main and auxiliary windings of a four-pole, capacitor-start induction motor are/main = 20.7 A and Iaux = 11.1 A respectively. The auxiliary-winding current leads the main-winding current by 53°. The effective turns per pole (i.e., the number of turns corrected for the effects of winding distribution) are Nmain = 42 and Naux = 68. The windings are in space quadrature.

a. Determine the peak amplitudes of the forward and backward stator-mmf waves.

b. Suppose it were possible to adjust the magnitude and phase of the auxiliary-winding current. What magnitude and phase would produce a purely forward mmf wave?