Do the stator and rotor of a three-phase motor have to be energized? What is the effect of installing it backwards?

Do both the rotor and the stator of a three-phase motor have to be energized?

Both the rotor and the stator of a three-phase motor need to be powered to function properly. Among them, the stator is energized to generate a rotating magnetic field, and the rotor rotates under the action of the rotating magnetic field, thereby driving the load of the motor to work. The way of electrification can be through an external power supply, such as a three-phase AC power supply or a DC power supply, or through a built-in rotor generator. Either way, the rotor and stator must be energized for the motor to function properly.

In a three-phase motor, the power supply is three-phase alternating current, which is input into the stator windings, and a rotating magnetic field is generated. The effect of this rotating magnetic field is to start the rotor spinning. The magnetic poles on the rotor are acted upon by the magnetic field of the stator, which generates torque and turns the mechanical load. If only the stator is energized and the rotor is not energized, then the rotor has no way to feel the effect of the stator's magnetic field and cannot rotate. Therefore, in order for a three-phase motor to work properly, the stator and rotor must be energized at the same time in order to generate a rotating magnetic field and rotate the rotor.

It should be noted that the power received by the rotor and the stator must be of the same frequency and phase. Otherwise, the magnetic field between the rotor and the stator will be out of phase, which can cause the motor to run erratically or not to run.

In addition, there are different working principles for some special types of three-phase motors . For example, the rotor of an induction motor is not directly energized, but the rotating magnetic field of the stator induces the current in the rotor of the motor to generate torque. In the permanent magnet synchronous motor, the magnetic poles of the rotor are composed of permanent magnets, and no external power is required.

In summary, in a three-phase motor, the rotor and stator must be energized at the same time to work properly. This is the basic principle of three-phase motor operation. Mastering this principle can better understand the working principle of three-phase motors, and can also better maintain and manage the operation of three-phase motors.

What is the effect of installing the rotor of a three-phase motor in reverse?

If the rotor of the three-phase motor is reversed, it will have a negative impact on the operation of the motor, mainly in the following aspects:

Difficulty in starting: After the rotor is reversed, the motor will have insufficient torque and difficulty in starting when starting, because the direction of motion of the counter rotor is opposite to the direction of the rotating magnetic field, and the interaction between the two will reduce the torque.

Unstable operation: After the motor starts, there will be fluctuations in speed and unstable operation, because the direction of the rotor and the stator's rotating magnetic field are different after the rotor is reversed, which will cause the operation of the motor to be unstable.

Decreased energy efficiency: After the rotor is reversed, the torque direction of the rotor and the stator is opposite, which will lead to a decrease in the efficiency of the motor and an increase in energy consumption.

Therefore, when installing and using a three-phase motor, it is necessary to ensure that the rotor is installed correctly to avoid reverse installation. If it is found that the counter rotor has been installed, it should be corrected immediately to avoid adverse effects on the normal operation of the motor.