Question 29Electricity & Electronics - 1st Asst/Chief

The correct answer is B) reversing the direction of current flow in the motor field windings. Reversing the direction of current flow in the motor field windings is the fundamental way to reverse the direction of a DC propulsion motor. By changing the polarity of the field windings, the direction of the magnetic field is reversed, which in turn reverses the direction of rotation of the motor. The other options are incorrect because: A) a 12 pulse converter is used for speed control, not reversal; C) a shunt field regulator is used to control motor speed, not reversal; and D) reversing the phase sequence applies to AC motors, not DC motors.