As shown in figure "A" of the illustration, what is the primary reason that the propulsion transformers are configured differently so as to produce a 30 degree phase shift in the pulses between the two synchroconverters supplying separate stator windings? Illustration EL-0160

Correct Answer: Option C — to minimize motor shaft vibration

Propulsion transformers are configured with a 30-degree phase shift to cancel out specific harmonic frequencies. This phase displacement between the two synchroconverter outputs effectively reduces torque pulsations, thereby minimizing mechanical stress and shaft vibration in the propulsion motor, consistent with IEEE 45 standards for large rotating machinery.