For three-phase motors, exceeding the rated current during operation should be due to the following reasons.
① lack of power phase
If the motor is not equipped with a comprehensive protector, the motor is still running in the absence of phase, and the three-phase current is seriously unbalanced. At this time, the overheating will occur. If a thermal relay is installed, the thermal relay will protect the thermal relay when it reaches the protection value of the thermal appliance Action, if not, it won't take long to burn out. The solution is to install a comprehensive protector, which will immediately cut off the power in the state of lack of phase. If there is no comprehensive protector, at least a thermal relay must also be installed. If only an open circuit is used to start directly, once a fault occurs during operation, Phase, it is easy to burn out the motor.
② Mechanical failure
The most common is bearing damage. Minor bearing damage. The motor can still run. If you have no experience, you can turn the bearing by hand. Basically, you cannot feel its friction, but the sensitive protector will protect the action. Be careful with this bearing. Another situation is the imbalance of the rotor, which mostly occurs in the repaired motor, which is caused by the carelessness of the maintenance master.
③ overload
Any device has its range, a certain voltage, a certain current, a certain power.
④ Poor heat dissipation
The motor must have sufficient ventilation and heat dissipation. Due to the narrow design space of the equipment, the motor often has poor ventilation and heat dissipation. This situation is often encountered, especially for customized non-standard products.
⑤ Short circuit or open circuit between coil turns
In this case, please ask someone to repair it. The common phenomenon is that the speed of the motor is slow and weak, and the heat is generated quickly, and occasionally a buzzing sound may appear.