Common problems of AC motors
The shaft of the motor --- the bearing base -- the current in the base circuit is called the shaft current. The reasons of shaft current generated: (1) magnetic field asymmetry; (2) harmonic current in power supply; (3) manufacturing, installation is not good, because the rotor eccentricity caused by uneven air gap; (4) the removable stator core has a gap between two half; (5) a stack of fan stator core the patch number of inappropriate choice.
Hazard: cause the surface of motor bearing or ball to be eroded, the shape of micro hole is changed, the performance of bearing is deteriorated, and the friction loss and heating increase
Prevention: (1) eliminating the pulsating flux and power harmonics (such as in the inverter output side with AC reactor); (2) motor design, the bearing seat and a base bearing insulation insulation cover, the outer ring of the rolling bearing and the end. 2, why can't the General Motors be used in the plateau area? The altitude has adverse effects on motor temperature rise, motor corona (high voltage motor) and commutation of DC motor. We should pay attention to the following three aspects: (1) the high altitude, the motor temperature rise, the output power is small. But when the temperature drops with the elevation, it is enough to compensate the influence of elevation on the temperature riseWhen the rated output power of the motor can be changed; (2) high voltage motor to take anti corona measures in the plateau; (3) altitude against commutation, be sure to use carbon materials. 3, why should not the motor run light load? When the motor is in light load, it will cause (1) the motor power factor is low; (2) the motor efficiency is low. Will cause waste of equipment and uneconomical operation. (1) the load is too large; (2) lack of phase; (3) the air duct is blocked; (4) the low speed running time is too long; (5) the power supply harmonic is too big.
