Question

Reversing (changing the rotation of) a three-phase, 60-cycle induction motor should be done by

A) switching any two leads to the rotor.
B) reversing the field connections.
C) reversing the connecting to the starting winding.
D) interchanging two of the power leads.

Answer 1

To reverse the direction of a three-phase induction motor, one should interchange any two of the three power leads supplying the motor, not by modifying the rotor, the field connections, or the starting winding. This changes the sequence of the phases and thus the motor's direction.

Step-by-step explanation:

To reverse the direction of a three-phase, 60-cycle induction motor, the correct method is to interchange any two of the three power leads supplying the motor. This effectively changes the sequence of the phases, thus reversing the rotation direction of the motor's magnetic field and, consequently, the rotor itself. It is important to ensure that the motor is powered off before interchanging any leads.

Contrary to options A, B, and C, switching any two leads to the rotor, reversing the field connections, or reversing the connection to the starting winding are not appropriate methods for three-phase induction motors, as these could lead to damage or improper functioning of the motor. The action that achieves the desired reverse rotation without causing the issues mentioned is option D, interchanging two of the power leads.