Which statement correctly describes reversing the direction of a three-phase squirrel-cage motor?

Prepare for the NCCER Electrical Level 2 Control Systems and Fundamental Concepts exam. Utilize flashcards and multiple choice questions with hints and explanations. Ensure success on your exam!

Multiple Choice

Which statement correctly describes reversing the direction of a three-phase squirrel-cage motor?

Explanation:
The key idea is that the rotation of a three-phase motor is set by the order of the three phase voltages applied to the windings. If you interchange two of the supply lines, you change the phase sequence (for example from A-B-C to A-C-B), which flips the direction of the rotating magnetic field and thus reverses the motor’s rotation. You don’t need to swap a specific predetermined pair—any two of the three lines will produce reversal. Swapping all three lines leaves the sequence effectively unchanged, so it won’t reverse direction. Reversing a three-phase squirrel-cage motor is indeed possible by changing the phase sequence.

The key idea is that the rotation of a three-phase motor is set by the order of the three phase voltages applied to the windings. If you interchange two of the supply lines, you change the phase sequence (for example from A-B-C to A-C-B), which flips the direction of the rotating magnetic field and thus reverses the motor’s rotation. You don’t need to swap a specific predetermined pair—any two of the three lines will produce reversal. Swapping all three lines leaves the sequence effectively unchanged, so it won’t reverse direction. Reversing a three-phase squirrel-cage motor is indeed possible by changing the phase sequence.

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