The gear reduction motor is able to rotate, but the operating current exceeds the rated value, which is called overload.

The basic reflection of motor overload is that although the current exceeds the rated value, the excess amplitude is not significant and generally does not form a significant impact current. Once the gear reducer motor experiences overload, we should investigate the cause of the overload and adopt the correct method to solve the overload problem of the gear reducer motor.

Analysis of the main causes of overload in gear reduction motors

1. The mechanical load is too heavy, and the main characteristic of excessive load is the motor heating, which can be detected by reading the operating current on the display screen.

2. The unbalanced three-phase voltage causes the running current of a phase to be too large, which leads to overload tripping. Its characteristic is that the gear reducer motor is unbalanced in heating, which may not be found when reading the running current from the display screen (because the display screen only shows one phase current).

3. Misoperation caused a malfunction in the current detection part inside the frequency converter, resulting in a large detected current signal and tripping.

Inspection method for overload of gear reduction motor

1. Check whether the gear reducer motor is heating up. If the temperature rise of the motor is not high, first check whether the electronic thermal protection function of the frequency converter is preset reasonably. If there is still room for the frequency converter, the preset value of the electronic thermal protection function should be relaxed.

If the temperature rise of the motor is too high, and the overload that occurs belongs to normal overload, it indicates that the motor is overloaded. At this point, the first thing to consider is whether it is possible to increase the transmission ratio appropriately to reduce the load on the gear reducer motor shaft. If possible, increase the transmission ratio. If the transmission ratio cannot be increased, the capacity of the motor should be increased.

2. Check whether the three-phase voltage at the motor side is balanced. If the three-phase voltage at the gear reducer motor side is unbalanced, check whether the three-phase voltage at the output end of the frequency converter is balanced. If it is also unbalanced, the problem is inside the frequency converter.

If the voltage at the output end of the frequency converter is balanced, the problem lies in the wiring from the frequency converter to the motor. All terminal screws should be checked to ensure they are tightened. If there are contactors or other electrical appliances between the frequency converter and the motor, the terminals of the relevant electrical appliances should also be checked to ensure they are tightened and the contact conditions of the contacts are in good condition.

3. If the three-phase voltage at the motor side is balanced, the operating frequency at the time of tripping shall be known

If the working frequency of the gear reduction motor is low and vector control (or no vector control) is not used, the U/f ratio should be reduced first. If the reduced U/f ratio can still drive the load, it indicates that the originally preset U/f ratio is too high and the peak excitation current is too high. The current can be reduced by reducing the U/f ratio; If the load cannot be carried after reduction, it should be considered to increase the capacity of the frequency converter; If the frequency converter has vector control function, vector control should be adopted.