Operation of Three-Phase Motors

Three-phase motors have the operating principle based on the rotating electric field. This field appears when an alternating power system is applied to the poles of an engine. The speed in three-phase motors is determined by the frequency of the power supply, which ensures excellent conditions for its operation at constant speeds. The speed of rotation that this type of motor works is supplied by the speed of the rotating electric field. This speed is called synchronous speed. It is determined as a function of the number of poles of the motor, being a characteristic constructive and as a function of the frequency that arrives at the entrance of the motor. Then we can conclude that the speed of the three-phase motor is proportional to the motor frequency.


Most of the industrially produced electrical energy is generated in alternating current (AC). Three-phase alternating current motors are less complex than the DC motor, this would justify the widespread use of these motors. In addition, we have the absence of mobile contacts in its structure ensuring its operation for a longer period without the need for maintenance.