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Engaged in the maintenance of Siemens inverters for many years, the faults seen are strange, and there are many things. I would like to talk about a problem that I encountered not long ago. I will discuss it with you. If you can bring something to your colleagues, you will be grateful.
Siemens G130 series inverter, 315kw, two parallel outputs, control one 500kw double winding motor, one CU320 control two inverters start at the same time, stop, except the address, the parameters are exactly the same. Customer warranty, showing F30002, over current. After going to the site, back up the parameters, and adjust the inverter parameters, historical fault record, F30002, detect the main parts of the inverter power, intact. Trial run, about a few seconds after startup, the inverter alarms, F00032, No. 1 inverter fault lights. The AOP panel is too late to detect current and has been shut down. Based on this situation, we first empty the test and disconnect the motor. Change the parameters, the no-load operation found that the AC output of the No. 1 inverter is balanced, but when the output terminal measures the DC voltage on the DC bus, it is found that the U-phase output voltage is about 10V lower. The No. 2 inverter is connected to the 3-phase AC output balance, and the DC bus measurement is also balanced. Initially judged that there is a problem with the No. 1 inverter. After pulling it back to the company for further comprehensive testing, it was found that there was no abnormality in the drive circuit. After replacing the fiber-optic signal conversion board, the three-phase output was balanced, with load test, and the parameters were normal. After the installation on site, try again, still a short time after starting, and F30002, over current. Disconnect the motor from no-load operation again. The inverter fault light is no longer on, and the no-load output is normal. I found a small power motor to be loaded on site and work normally.遂 I suspect that the customer's motor is faulty, responding to the customer, the customer replied, the motor has been tested, and there is no abnormality. Because there is no bridge at the scene, the motor can only be tested with a megger. The megohmmeter shows that the motor is indeed abnormal. Therefore, it is suspected that the inverter still has problems, but repeated troubleshooting, no problems found, the motherboard is replaced, the fault is not eliminated, the fiber conversion board is replaced, the fault is not eliminated, the driver board and the IGBT are replaced, and the fault is not eliminated. I was in a stalemate. Finally, the inverter alarm signal is carefully retrieved and found to be a v-phase fault. It is thus thought that the phase sequence will be reversed and the motor coupling will be removed to allow the motor to idle. Start the inverter again, monitor the alarm signal and find that the fault value has changed. It becomes a u-phase overcurrent, and it is judged that the motor has a malfunction. After the customer sends the motor to the motor factory for comprehensive testing, the test result is short circuit between the windings of the motor winding.
After half a month, the motor is repaired and the fault is removed after startup. Therefore, I think that as a maintenance personnel of the inverter, it is necessary to understand the motor and, if conditions permit, a bridge for testing the motor. In other words, at the scene, you must make judgments based on your own professional knowledge, and minimize the interference of customers' attitudes and opinions. This leads to misjudgment.