How does phase sequence affect the rotation direction of a motor, and how can you correct incorrect sequence?

How does phase sequence affect the rotation direction of a motor, and how can you correct incorrect sequence?

• A. The phase sequence has no effect on rotation direction.
• B. The phase sequence determines rotation direction; swap any two supply lines to reverse rotation.
• C. The phase sequence affects only torque but not rotation.
• D. The phase sequence is fixed and cannot be changed.

Answer: (B)

Phase sequence is the order in which the three power lines reach their peak voltages, and in a three‑phase motor that order decides the rotating magnetic field direction. When the sequence is in the normal order, the field rotates one way and the motor turns accordingly. If two supply lines are swapped, the sequence reverses and the motor spins in the opposite direction. To correct an incorrect sequence, interchange any two of the three supply lines at the motor (or at the disconnect). This flips the phase order back to the desired direction. If a drive or VFD is involved, ensure it is configured for the correct line sequence.

Phase sequence is the order in which the three power lines reach their peak voltages, and in a three‑phase motor that order decides the rotating magnetic field direction. When the sequence is in the normal order, the field rotates one way and the motor turns accordingly. If two supply lines are swapped, the sequence reverses and the motor spins in the opposite direction. To correct an incorrect sequence, interchange any two of the three supply lines at the motor (or at the disconnect). This flips the phase order back to the desired direction. If a drive or VFD is involved, ensure it is configured for the correct line sequence.