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ABB ACS880 drives are increasingly used on servo press retrofits and new installations. The 7081 and 7082 fault codes relate to motor thermal protection.
## Fault 7081: Motor Overtemperature (Estimated)
The ACS880 uses a thermal model to estimate motor temperature. Fault 7081 triggers when the estimated temperature exceeds the motor thermal limit.
This is a model-based fault - the drive does not have a direct temperature measurement, it calculates temperature based on current history and the motor thermal time constant (parameter 35.50).
Common causes in press applications:
- Running above rated continuous SPM for extended periods
- Thermal time constant (35.50) set incorrectly for the actual motor
- Ambient temperature higher than the 40C design point
- Motor cooling fan failed or blocked
Fix:
1. Check parameter 35.50 (motor thermal time constant): should match the motor datasheet value
2. Check parameter 35.51 (motor load curve): verify the curve matches the motor nameplate
3. If the motor has a PTC thermistor, connect it to the drive and use direct temperature measurement instead of the model
4. Reduce SPM or add a duty cycle (run 45 minutes, rest 15 minutes)
## Fault 7082: Motor Overtemperature (Measured)
This fault uses a direct temperature measurement from a PTC thermistor or PT100 sensor in the motor winding.
If you get 7082, the motor is actually hot - do not reset and continue.
Diagnosis:
1. Let the motor cool for 30 minutes
2. Check motor cooling: is the fan running? Are the fins clean?
3. Check the duty cycle: what is the actual SPM and forming load?
4. Check the thermistor connection: a broken thermistor wire reads as maximum resistance, which the drive interprets as overtemperature
## ACS880 Data Logger for Press Diagnostics
The ACS880 has a built-in data logger accessible via ABB Drive Composer software. For press fault diagnosis, configure the logger to capture:
- Motor current (01.06)
- Motor torque (01.10)
- Motor temperature (35.01)
- DC bus voltage (01.11)
Log at 1ms intervals for 10 seconds triggered on the fault. This gives you the complete picture of what happened before the fault.
## ACS880 Parameter Backup Before Maintenance
Always back up parameters before any maintenance that might reset the drive:
1. Connect Drive Composer
2. File > Backup > Save to PC
3. Store the backup file with the press serial number and date
Restoring a parameter backup after a drive replacement takes 10 minutes and avoids re-commissioning from scratch.