Siemens MM4 series inverter displays F231 fault alarm and maintenance measures.
The F231 output current measurement is unbalanced
When the inverter is connected to the power supply, the operating panel shows that the output current measurement is unbalanced. First, the voltage value of the three 7800A related pins was detected, and no abnormality was found, and the input voltages of the three operational amplifiers of TL084 on the side were normal, and when the output voltages of the three operational amplifiers were measured, it was found that the output voltage of the two op amps was the same, and the output voltage of the other I op amps was obviously high. The input resistance and feedback resistance were also checked, and no change in their values was found. This op amp circuit is damaged. After replacing the TL084, the output voltage of the 3-channel op amp circuit is detected to be normal, and the F231 display is eliminated.
Replace the operational amplifier TL084, and the inverter will return to normal.
Because one of the two 084 op amps in the current detection protection circuit is damaged, and there are 3 input signals with the same and 3 output signals are different, so the operation panel displays the output current detection value unbalanced fault, and the fault is eliminated after replacing the op amp.
Siemens inverter repair example.
Siemens MM440 inverter maintenance.
F231 (unbalanced output current detection value) is displayed
This kind of fault is indicated when the inverter is connected to the power supply, usually the fault of the drive circuit and the current detection protection circuit. The relevant parameters of the input and output of the 7800A can be detected first to preliminarily determine whether the fault is in the driving circuit, the light disaster isolation amplifier circuit, or the signal amplifier circuit. When checking the 7800A, it was found that there was a 7800A signal output pin and a damaged open circuit, and the driving circuit was not abnormal. Replace 7800A, troubleshooting.
Due to the aging and damage of the light accident isolator 7800A, the output signals of the 3 current detection protection circuits are different, and the output current detection value displayed by the inverter is unbalanced.