Applicable Systems
PLC
Symptoms
The PLC reports a DC bus overvoltage fault 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.
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Source: B&R Automation System Manual, B&R Industrial Automation
Category: PLC & VFD
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