How to deal with undervoltage faults during inverter maintenance

In inverter maintenance, we often hear about overvoltage faults, but undervoltage faults are also common problems in inverter use. The cause is the protection action caused by the main circuit voltage being lower than the lower limit, or damage to a certain part of the rectifier bridge, or instantaneous power outage of the power grid, input lack of equalization, etc.



Inverter after-sales personnel summarized the methods of undervoltage alarm detection voltage in the process of inverter undervoltage fault handling, as follows:

1. Comparator detection

The voltage at one end of the comparator is fixed by a voltage regulator tube, and the detected voltage is sampled and compared with it, and the result is output through the comparator.

2. ADC detection (analog/digital converter)

After the detected voltage is sampled by a resistor, it falls within the detectable range of the ADC, and the voltage alarm range can be set by the program.

The energy storage capacitor in the main circuit has a great influence on the overvoltage and undervoltage of the inverter during operation. The various components of the inverter circuit have a certain service life, so once the inverter components reach their service life, they will cause failures. Causes such as the energy storage capacitor or other components in the main circuit may affect the main circuit, causing the entire inverter to malfunction. Usually, if the inverter is out of service for too long, reaching more than one year, a comprehensive physical examination of the energy storage capacitor should be performed.

How to avoid this phenomenon for inverters that have not been used for a long time?

According to the requirements, the inverter that has been out of service should be powered on once every two or three months, each time for 10 to 30 minutes. For electrolytic containers that have not been used for a long time, when powered on, add about 50% of the rated voltage first. As long as the pressure is applied for more than half an hour, its leakage current will drop, and it can be used normally.

In addition, for inverters with a long service life (more than five years), the capacity of the energy storage capacitor must also be tested. Frequent undervoltage faults during operation are mostly caused by insufficient capacity, capacity reduction or loss of capacity of the capacitor in the DC circuit.