Generally speaking, when you get a faulty inverter, you should first check the rectifier bridge and IGBT module with a multimeter before powering on, and there is no obvious burning damage on the circuit board.
The specific method is: using a multimeter (preferably using an analog meter) resistor 1K file, the black watch rod is connected to the DC terminal (-) pole of the inverter, and the three-phase input terminal and the three-phase output of the inverter are respectively measured by a red meter bar. The resistance of the terminal should be between 5K and 10K. The resistance of the three-phase should be the same. The resistance of the output is slightly smaller than that of the input, and there is no charge or discharge. Then, in turn, connect the red meter rod to the DC terminal (+) pole of the inverter, and the black meter rod measures the resistance of the three-phase input terminal and the three-phase output terminal of the inverter respectively. The resistance value should be between 5K-10K, three-phase. The resistance value is the same, the resistance at the output is slightly smaller than the input, and there is no charge or discharge. Otherwise, the module is damaged. At this time, you cannot blindly power on, especially if the rectifier bridge is damaged or there is obvious burning damage on the circuit board, especially the power-on is prohibited, so as to avoid further loss.
If the above measurement results show that the module is basically no problem, you can check it on power.
(1) After power-on, the panel displays [F231] or [F002] (MM3 inverter). There are two possibilities for this type of fault. It is common that there is a problem with the power supply board, and a small part is caused by the main control board. You can try another main control board first, otherwise the problem must be in the power supply board.
(2) There is no display on the panel after power-on (MM4 inverter), the indicator light under the panel [green light does not light, yellow light flashes quickly], this phenomenon indicates that the rectifier and switching power supply work basically normal, the problem lies in the switching power supply All the way is not normal (rectifier diode breakdown or open circuit, you can use a multimeter to measure several rectifier diodes of the switching power supply, it is easy to find the problem. The problem of replacing a corresponding rectifier diode is solved. This problem is generally low diode withstand voltage , caused by power supply pulsation.
(3) Sometimes [F0022, F0001, A0501] is indeterminate (MM4). It is normal to hit the case or move the panel and the motherboard. Generally, it is a problem with the connector. Check the connectors of each part. It has also been found that individual machines are caused by quality problems of the RC components on the circuit board or poor soldering.
(4) [-----] (MM4) is displayed after power-on, which is usually the main control board problem. In most cases, the problem of replacing a main control board is solved. Generally, some components of the main control board (such as chip capacitors, resistors, etc.) are damaged due to strong electrical interference on the peripheral control circuit. I analyze the heat dissipation of the main control board. Bad and have a certain relationship. But there are also some problems on the power board.
For example, a MM440-200kW inverter used in a rotary kiln drive in a cement plant in Chongqing, because of the large load inertia, the starting torque is large, the frequency of the equipment can only rise to about 5Hz when it starts, and it can no longer go up, and alarm [ F0001]. The customer requested to go to the on-site service. I thought at the time that there was no problem as the inverter itself. The problem was that the customer parameters were not properly set. The vector control method was used, and then the parameters/models of the motor were correctly set to solve the problem. After another two days, the customer called me to tell me that the inverter has broken. The fault phenomenon is the power-on display [-----]. After on-site inspection and analysis, this kind of fault is caused by the problem of the main control board, because the user did not strictly follow the EMC specification during the installation process, the strong and weak electricity did not have separate wiring, the grounding was bad, and the shielding line was not used, resulting in the main control board. The I/O port was burned. Later, I applied for repair service, SFAE engineers went to the site for repair, and replaced a main control board to solve the problem.
(5) It shows normal after power-on, and it shows over-current when it is running. [F0001](MM4)[F002](MM3) Even if there is no load, this phenomenon generally indicates that the IGBT module is damaged or there is a problem with the drive board. It is necessary to replace the IGBT module and carefully check the drive part before powering up again. Otherwise, it may be because The problem with the drive board caused the IGBT module to be damaged again! This kind of problem arises because the inverter is overloaded several times or the power supply voltage fluctuates greatly (especially low), so that the pulsation current of the inverter is too large, and the CPU of the main control board cannot reflect and take protective measures.
There are also some special faults (uncommon but there are some general meanings, you can give the opposite effect, hope to achieve the effect of throwing bricks and jade), for example:
(6) There is a frequency converter (MM3-30KW), which often stops “no reason†during the use. It may be normal to turn it on again. After the machine got me here, I didn't find the problem at the beginning. After a long period of observation, it was found that the main contactor was not properly connected after power-on - sometimes it would lose power and jump. Check the cause of the fault. The result is that the voltage is low due to the leakage of the filter capacitor from the switching power supply to the power supply of the contactor. At this time, if the power supply voltage is too high, the problem is not serious. If the power supply voltage is low, the contact will be caused. Abnormal suction is caused by unintentional shutdown.
(7) There is also a frequency converter (MM4-22KW), the power-on display is normal, and [P----] or [-----] appears when the operation signal is given. After careful observation, it is found that the fan speed is somewhat If it is not normal, the fan will be unplugged and [F0030] will be displayed. During the maintenance process, the alarm may be disordered, and [F0021\F0001\A0501] will appear. When I first gave the running signal and then connected the fan, [P----] does not appear. However, when a fan is connected, the fan speed is normal, the output three-phase is normal, and the second fan is When the fan is connected, the speed of the fan is obviously abnormal. So I analyzed the problem on the power board. The result is caused by leakage of a power supply filter capacitor from the switching power supply, and the same capacitor problem is solved.
(8) There is a 75kW MM440 inverter in a steel plant. It runs normally after installation. After half an hour, the motor stops, but the running signal of the inverter is not lost but is still maintained. Panel display [A0922 ] Alarm information (the inverter has no load), measure the voltage output of the three-phase output of the inverter. Stop the inverter manually and resume normal operation again. The output current displayed on the normal panel is 40A-60A. After more than 20 minutes, the same fault phenomenon appeared, and the output current displayed on the panel was only about 0.6A. After analysis, it is judged that there is a problem with the current detecting unit on the driving board, and the problem is solved after replacing the driving board.
To sum up, the proportion of large original devices such as IGBT power modules is not much, as I said in the characteristics of Siemens general-purpose inverters, because of some low-end simple original device problems and assembly problems caused by the proportion of failures. More, if there are drawings and parts, these problems are not difficult to solve and the cost is not high, otherwise it is not easy to solve these problems. The easiest way is to change the entire board!
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