In the frequency converter maintenance we often hear the over-voltage fault, but under-voltage fault is often encountered in the use of frequency converter problems. The reason is that the main circuit voltage is lower than the lower limit caused by the protection action or rectifier bridge a road damage or power grid instantaneous blackout, input lack of phase, etc. .

In the process of dealing with undervoltage fault of frequency converter, we summarize the general methods of undervoltage alarm and voltage detection, as follows:

1.Comparator detection

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

2.ADC detection (analog/digital converter)

After the detected voltage is sampled through the resistance step-down, it falls within the detectable range of the ADC, and the alarm range of the voltage 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 frequency converter in operation. And the various components of the inverter circuit and a certain life, so once the inverter components to reach the life will bring fault. Such as the main circuit of the energy storage capacitor or other components of the main circuit may be affected by the reasons, so that the whole frequency converter failure. Usually the downtime of the inverter is too long, reaching more than one year, then the energy storage capacitor should be done a comprehensive physical examination.

For a long time do not use the inverter, how to avoid this phenomenon?

According to the requirements, the frequency converter should be stopped every two or three months power-once, each time 20-30 minutes. For a long time to ask not to use the electrolytic storage container, when electrified, first increase about 50% of the rated voltage, as long as the pressurization time in more than half an hour, its leakage current will be reduced, it can be used normally.

In addition, the use of a longer period of time (more than five years) of the inverter, but also must be energy storage capacitor capacity detection. The capacitor capacity of DC circuit is insufficient, and the capacitor capacity is decreased or discapacitated.

Source: internet (for study only, intrusion and deletion)