If any two phases are reversed what will happen?

If any two phases are reversed what will happen?

• A. Rotation will stop
• B. Rotation will change
• C. Rotation will reverse temporarily then resume
• D. No effect

Answer: (B)

In a three-phase machine, the direction of rotation is set by the order of the supply phases. The rotating magnetic field that drives a three-phase motor is created by three windings spaced 120 degrees apart, and the field’s direction follows the phase sequence (for example, ABC). If you swap any two supply lines, the phase sequence becomes reversed (ACB), which flips the rotating magnetic field. The rotor then follows this new field immediately, so the motor starts turning in the opposite direction. There’s no stoppage or temporary reversal—just a direction change that persists as long as the two phases remain swapped.

In a three-phase machine, the direction of rotation is set by the order of the supply phases. The rotating magnetic field that drives a three-phase motor is created by three windings spaced 120 degrees apart, and the field’s direction follows the phase sequence (for example, ABC). If you swap any two supply lines, the phase sequence becomes reversed (ACB), which flips the rotating magnetic field. The rotor then follows this new field immediately, so the motor starts turning in the opposite direction. There’s no stoppage or temporary reversal—just a direction change that persists as long as the two phases remain swapped.