Applicable Systems
FRENIC
Symptoms
The FRENIC reports a DC bus overvoltage fault at constant speed detected. The drive trips to protect the capacitor bank and switching devices.
Possible Causes
- Regenerative energy from the motor exceeded the braking resistor capacity
- Deceleration time too short causing excessive regenerative voltage
- Input power supply voltage at the upper limit of the drive range
Troubleshooting Steps
- Step 1: Increase the deceleration time to reduce regenerative energy
DC bus voltage stays below the trip threshold - Step 2: Check if a braking resistor is installed and correctly rated
Braking resistor absorbs regenerative energy adequately - Step 3: Measure the input supply voltage and verify it is within range
Input voltage is within the drive rated range
How to Reset
To reset: Reduce the DC bus voltage below the threshold, then reset the fault.
Source: Fuji FRENIC-Ace Inverter Manual, Fuji Electric Co.
Category: PLC & VFD