How does a reversing starter change the direction of a three-phase motor?

A reversing starter changes the direction of a three-phase motor by interchanging two of the line leads connected to the motor. In a three-phase system, the motor's rotation direction is determined by the sequence in which the phases are energized. Each phase has a specific timing in relation to the others, and this timing produces a rotating magnetic field that interacts with the rotor. By swapping any two of the three line leads, the phase sequence is altered, resulting in a reversal of the magnetic field direction. This, in turn, causes the motor to rotate in the opposite direction.

Understanding this principle is essential for troubleshooting and controlling three-phase motors in various applications. The other methods mentioned do not effectively change the motor's direction, as simply altering voltage or changing phase sequences with more than two leads does not have the same direct effect on the motor's operation.