The gear reducer can rotate, but the running 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 exceeding range is not large, and usually does not produce a large impulse current. If the gear reducer motor is overloaded, we need to find out the cause of its overload, and then use the correct way to solve the overload problem of the gear reducer.
Specific cause analysis of gear reducer overload:
1. The specific feature of heavy mechanical load is that the motor heats up and can be found by reading the running current from the display screen.
2. The three-phase voltage is unbalanced, resulting in excessive operating current of a phase and overload tripping. Its feature is that the heating of the gear reducer is unbalanced, which may not be found when reading the operating current from the display screen (because the display screen only shows one phase current).
3. In case of malfunction, the current detection part inside the frequency converter fails, and the detected current signal is too large, causing tripping.
Inspection method of gear reducer overload:
1. Check whether the gear reduction motor is heated. If the temperature rise of the motor is not high, first check whether the electronic thermal protection function of the frequency converter is reasonable. If the frequency converter has margin, loosen the preset value of the electronic thermal protection function.
If the temperature rise of the motor is too high, and the overload occurred belongs to normal overload, it indicates that the load of the motor is heavy. At this time, first of all, whether the transmission ratio can be moderately increased to reduce the load on the shaft of the gear reduction motor. If it can be increased, 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 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 lies in the inside of the frequency converter.
If the voltage at the output end of the frequency converter is balanced, the problem lies in the line from the frequency converter to the motor. Check whether the screws at all terminals have been tightened. If there are contactors or other electrical appliances between the frequency converter and the motor, check whether the terminals of relevant electrical appliances have been tightened, and whether the contact conditions of their contacts are good, etc.
3. If the three-phase voltage on the motor side is balanced, you should know the working frequency when tripping
If the working frequency of the gear reducer is low and vector control is not used (or there is no vector control), first reduce the u/f ratio. If the load can still be driven after reduction, it indicates that the original u/f ratio is too high, and the peak value of the excitation current is too large. You can reduce the current by reducing the u/f ratio; If there is no live load after reduction, consider increasing the capacity of the frequency converter; If the frequency converter has vector control function, the vector control method should be used.
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