With the development of social science and technology, inverters are also developing.Nowadays, the functions of inverter are more and more abundant, and the types of inverter are more and more.In the process of using frequency converter, occasionally overload will lead to equipment failure, so how to check the overload of general frequency converter?
(1) check whether the motor has fever
Motor temperature rise is not high, should check the load size, add delay hour, operating cycle hour configuration can be appropriate, and correct V/F characteristics, check the frequency converter electronic heat protection function preset can be appropriate, if the frequency converter and margin, should relax the electronic heat protection function preset value;Such as frequency converter approval current has no margin, can not be relaxed, and production process, the line overload is a normal overload, then affirm the frequency converter to take improper, should increase the frequency converter capacity, change the frequency converter.This is, the motor drag to modify the load or intermittent load, temperature rise is not pre-emptive rating, is the first time (a few minutes, or even dozens of minutes) overload, and the inverter is not willing to.If the temperature rise of the motor is too high and the overload of the train is normal overload, it is declared that the motor is overloaded.At this point, it should be considered whether it is suitable to increase the transmission ratio to reduce the load on the motor shaft.If possible, the transmission ratio is increased;If the transmission ratio cannot be improved, the motor capacity should be improved.
(2) check whether the three-phase voltage at the motor side can be balanced
If the three-phase voltage at the motor side is not balanced, check whether the three-phase voltage at the transmission end of the inverter can be balanced. If the voltage is not balanced or abnormal, check the inverter inverter module and its drive circuit.If the inverter transmission terminal voltage balance, abnormal line from the frequency converter to the motor, should check whether all wiring terminal screws have been tightened, between the frequency converter and the motor has a converter or other electrical appliances, should also check whether the relevant electrical terminal can be tightened, and contact contact conditions can be good.
If the employment frequency is low and no vector control is used (or no vector control is used), then the U/f ratio will be reduced. If the load can be driven after the decrease, the original preset U/f ratio will be declared to be too high and the peak value of excitation current is poor, so the U/f ratio can be reduced to reduce the current.After the drop with no dynamic load, should be considered to increase the frequency converter capacity;If frequency converter has vector control function, vector control method should be adopted.
(3) check for possible misconduct
If the above check does not find the cause, the check should be an error.The discriminating step is that the ammeter is used to measure the output current of the inverter under the condition of light load or no load, and the running current value is displayed on the display screen.Displays a current reading that is worse than the actual measured current, and declares the measured current in the inverter.Departmental mistakes are bad, and "overloaded" travel can be a mistake.