Applicable Systems
EFC
FEX
FEI
HNC
Symptoms
Power stage damage detected. The drive has identified a fault in the IGBT power module that prevents safe operation. The motor stops immediately.
Possible Causes
- IGBT module failure (short circuit or open circuit)
- Gate driver circuit failure on the power board
- DC bus capacitor failure causing voltage instability
- Thermal damage to power module from prolonged overload
Troubleshooting Steps
- Step 1: Disconnect all power and wait for DC bus discharge (5 minutes minimum)
Verify DC bus voltage below 36V before inspection - Step 2: Inspect IGBT module visually for cracks, burn marks, or thermal damage
Any visible damage confirms power module failure - Step 3: Test IGBT modules with a multimeter diode check function
All IGBT junctions show expected diode characteristics; no short circuits - Step 4: Replace the drive unit if IGBT damage is confirmed
New unit operates motor without F8091
How to Reset
1) Total power disconnect. 2) DC bus discharge. 3) Visual and electrical IGBT inspection. 4) Replace drive if confirmed. Caution: Do not attempt to power on a drive with confirmed IGBT damage.
Common Replacement Parts
- R911319000: IndraDrive complete unit or power module (Field replacement of complete unit recommended for safety)
Frequently Asked Questions
- Q: Can F8091 be caused by external factors?
Yes. Prolonged overload, inadequate cooling, or repeated overcurrent events can thermally damage the IGBT module. Ensure proper sizing and ventilation.
- Q: Is IGBT replacement a field repair?
For most IndraDrive models, the complete unit or power module must be replaced. PCB-level IGBT replacement requires factory service.
Source: Rexroth IndraDrive HCS/HMS Fault Code List, Bosch Rexroth AG
Category: PLC & VFD