Four Common Faults of Mitsubishi Frequency Converter and Their Solutions

Common faults of Mitsubishi frequency converter 1 - OC1 and OC3 faultsOC (overcurrent fault) of Mitsubishi frequency converter is often caused by the following reasons (now take A500 series frequency converter as an example).(1) It is caused by improper parameter setting, such as too short time setting;

(2) Caused by external factors, such as motor winding short circuit, including phase to phase short circuit, short circuit to ground, etc;(3) Inverter hardware failure, such as Hall sensor damage, IGBT module damage, etc.

In the current maintenance of Mitsubishi frequency converter, we sometimes can't solve the problem by eliminating the above reasons. The OC fault still exists. Of course, replacing the control board is not the way to solve the problem. At this time, we can consider whether there is a problem in the driving circuit. The detection circuit of Mitsubishi A500 frequency converter is very powerful. As long as there is a problem at any of the above detection points, it may alarm and fail to operate normally. In addition to the driving power supply, driving optocoupler isolation, driving signal amplification circuit included in the general driving circuit, it also includes output signal feedback circuit, etc. When the detection methods we introduced before can not solve the problem, we should pay special attention to whether the driving circuit is normal. The detection direction mainly includes several components of Mitsubishi driving circuit just introduced.

Common faults of Mitsubishi frequency converter 2 - UVT fault

UVT is an undervoltage fault. I believe many customers will still encounter such problems in use. Our common undervoltage detection points are the voltage on the DC bus side. After voltage division by high resistance resistance, a low voltage value is sampled, and the voltage normal signal, overvoltage signal or undervoltage signal are output after comparison with the standard voltage value. The sampling value of voltage signal of Mitsubishi A500 series frequency converter is obtained from the switching power supply side and isolated by optocoupler. During our maintenance, it is found that the damage of optocoupler accounts for a large proportion of the causes of undervoltage fault. This phenomenon is still rare in previous frequency converter maintenance.

E6, E7 fault

E6 and E7 faults must be familiar to the majority of users. This is a common typical fault of Mitsubishi frequency converter maintenance. Of course, there are many reasons for the damage. (1) The integrated circuit 1302h02 is damaged. This is an IC integrated circuit integrating driving waveform conversion and multi-channel detection signals, and multi-channel signals are associated with the CPU board. In many cases, any signal of this integrated circuit may cause E6 and E7 alarms; (2) The signal isolation optocoupler is damaged. There are multiple strong and weak signals between IC integrated circuit 1302h02 and CPU board that need to be isolated. The damage of isolation optocoupler is still relatively high in the damage proportion of components, so whether it is caused by such factors should also be considered when E6 and E7 alarms occur; (3) Damaged connector or poor connector contact. As the connecting cable between the CPU board and the power board is easy to break and solder after several bends, it is also easy to bend and break the pins on the plug side if it is not used properly. The above reasons may also cause E6 and E7 faults.

Common fault 3 of Mitsubishi frequency converter - damage of switching power supply

The damage of switching power supply is also a common fault of A500 series frequency converter. In addition to the damage of pulse transformer, switching FET, starting resistance and rectifier diode, which we often mentioned before, the common damaged device is a m51996 waveform generator chip with on-off time adjustment and output voltage adjustment, Voltage feedback regulation and other protection in one control chip. The main problems in the maintenance of Mitsubishi frequency converter are the power supply of 14 pins of the chip, 7 pins for adjusting the voltage reference value, 5 pins for feedback detection, and 2 pins for waveform output.

Common fault 4 of Mitsubishi frequency converter - power module damage