What determines the direction of rotation in a 3-phase motor?

The direction of rotation in a 3-phase motor is primarily determined by the configuration of the power supply connections. In a 3-phase motor, the three phases of the electrical supply are arranged in a specific sequence. When the phases are connected in a certain order, they create a rotating magnetic field that causes the motor rotor to turn in a particular direction.

If the order of the phases is reversed, the direction of the rotating magnetic field also reverses, leading to a change in the direction of the rotor’s rotation. This phenomenon is fundamental to the operation of 3-phase motors and is a key aspect that technicians consider when wiring or troubleshooting motor systems.

The other factors listed, such as the magnitude of the load, size of the motor, and phase resistance, do not determine the rotation direction. While they may affect the performance or efficiency of the motor, they do not influence the inherent directionality created by the phase sequence of the power supply. Hence, the configuration of the power supply connections is crucial for establishing the correct rotational direction of a 3-phase motor.