Applicable Systems
EFC
FEX
FEI
HNC
Symptoms
The drive trips. The error display shows E-1002, indicating a DC bus overvoltage. The DC link voltage has exceeded the safe maximum limit.
Possible Causes
- Deceleration time too short causing regenerative overvoltage
- Braking resistor not installed or disconnected
- Supply voltage too high
- Load inertia too high for the braking capacity
Troubleshooting Steps
- Step 1: Check the deceleration time parameter
Deceleration time is sufficient for the load inertia - Step 2: Verify a braking resistor is installed and connected
Braking resistor is present and properly connected - Step 3: Measure the braking resistor resistance
Resistance value matches the drive manual specification - Step 4: Measure the input supply voltage
Supply voltage is within the drive rated range
How to Reset
To reset: 1) Fix the overvoltage cause (increase deceleration time, install/fix braking resistor). 2) Clear the fault. Caution: DC bus overvoltage damages capacitors and IGBTs. Always fix the root cause before restarting.
Frequently Asked Questions
- Q: How do I size a braking resistor for a Rexroth drive?
Calculate the regenerative braking power from the load inertia, speed, and deceleration time. Select a resistor with the resistance value specified in the drive manual and adequate power dissipation capacity.
- Q: What is the DC bus overvoltage trip threshold?
For 400V class Rexroth drives, the DC bus overvoltage trip typically occurs at approximately 800V DC. For 230V class drives, the threshold is around 400V DC. Check the specific model manual for exact values.
Source: Bosch Rexroth EFC Drive Manual, 2023
Category: PLC & VFD