1. The main reason for the overload of the inverter
(1) Malfunction, the current detection part inside the inverter has a problem, and the detected current signal is too large, resulting in tripping.
(2) The mechanical load is overloaded, and the main feature of the overload is that the motor heats up, and the operating current can be read from the display screen to find.
(3) The three-phase voltage is unbalanced, causing the operating current of a certain phase to be too large, resulting in overload tripping, which is characterized by unbalanced heating of the motor, and the difference can be found when reading the running current from the display screen (because the display screen only shows one phase current).
2. How to check whether the inverter is overloaded
(1) Check whether the three-phase voltage on the motor side is balanced, if the three-phase voltage on the motor side is unbalanced, then check whether the three-phase voltage at the output end of the inverter is balanced, if it is not balanced, the problem is inside the inverter.
If the voltage balance at the output end of the inverter, the problem is on the line from the inverter to the motor, you should check whether the screws at all terminals have been tightened, if there is a contactor or other electrical appliances between the inverter and the motor, you should also check whether the terminals of the relevant electrical appliances have been tightened, and whether the contact condition of the contacts is outstanding.
If the three-phase voltage balance on the motor side, the operating frequency at the time of tripping should be understood: if the operating frequency is low, and there is no vector control (or no vector control), the first thing is to reduce the U/f ratio, if the load can still be driven after the drop, it is clear that the original preset U/f ratio is too high, the peak value of the excitation current is large, and the current can be reduced by decreasing the U/f ratio;
If the load cannot be carried after the drop, the capacity of the inverter should be increased; If the inverter has a vector control function, the vector control mode should be used.
(2) Check whether the motor is heated, if the temperature rise of the motor is not high, the first thing to check is whether the electronic thermal protection function of the inverter is preset reasonably, if the inverter still has a margin, 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 is a normal overload, it is stated that the motor is overloaded. At this time, the first thing should be whether the transmission ratio can be appropriately increased to reduce the load on the motor shaft. If it can be increased, the transmission ratio will be increased. If the transmission ratio cannot be increased, the capacity of the motor should be increased.
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