What are the consequences of the aluminum shell motor starting when the phase is missing and how to deal with it?

Update:20 Mar 2020
Summary:

  When the aluminum shell motor is stopped, the mo […]

 

When the aluminum shell motor is stopped, the motor is missing when a phase power supply is started. Generally, only a dull buzzing sound will be issued, and the motor will not turn. If the power is not immediately disconnected, the motor winding will be burned. When a normal motor is fed with symmetrical three-phase AC power, a circular rotating magnetic field is generated in the stator core, so that the motor can run normally. However, when the power supply lacks a single phase, a single-phase pulsating magnetic field is generated in the stator core, which cannot cause the motor to generate starting torque. Therefore, the motor cannot start when the power supply lacks one phase. However, during operation, when there is no one-phase power supply, the elliptical rotating magnetic field with higher three-phase harmonic components generated in the air gap of the motor, so the running motor can still operate without a one-phase power supply, but the magnetic field Distortion occurs, the harmful current component increases sharply, and eventually the winding is burned.

Approach:

(1) Regardless of whether the motor is static or dynamic, the direct hazard caused by lack of phase operation is that one or two phase windings of the motor are burned out. Therefore, when the motor is running, it is necessary to strengthen the inspection. Once you find that the speed drops and the temperature increases, you should immediately pull the brake, disconnect the power, and check the motor. After troubleshooting, put it into operation again.

(2) Before the motor is started, it is necessary to strengthen the reliability of the contact points of the power supply lines, control switches, and components, which is conducive to preventing phase loss.

(3) Use of advanced phase-loss protection elements or phase-loss protection circuits