Solution of under-voltage fault while running

Fault Name: 

Reporting under-voltage fault while running

Fault Symptom:

The frequency inverter runs normally, but it would report the under-voltage fault with the load after starting.

Causes:

The cause of the scene

Solution: 

Check if the power supply is too low 

Check if the incoming line is loose

Analysis:

Insufficient power supply voltage. This is mainly because the capacity of the power transformer is not large enough. If the load is heavy, it is easy to report the under-voltage fault due to low voltage. According to the national standard, the lower limit of the incoming line voltage is 380×0.9=342V. The voltage is sampled by the internal bus. The DC average voltage at 342V is 342 × 1.35 = 462V. However, the lower limit DC voltage in the actual inverter is usually set at 380V. This is because the device of the main circuit is not damaged when the voltage is too low. Therefore, as long as the current of the motor is within the allowable range and the drag system can operate normally, it won’t trip.

The input terminal of the incoming line is loose. When the terminal of the power supply line is loose, the contact resistance at the terminal increases, the voltage drop also increases, and the voltage actually input to the inverter decreases, which may also cause under-voltage.