F07900Fault · DriveUsually repairable
SINAMICS S120 F07900: Drive Motor Blocked/Speed Controller At Its Limit
Also shown as: Can be set as N, A
What F07900 means
The speed controller stayed at its torque limit while the motor speed stayed near zero, so the drive decided the motor is blocked.
Symptoms
The axis does not move when commanded, then trips after a short delay.
Is it repairable?
Yes: brake coil replacement and encoder alignment are common repairs.
Common causes
- Holding brake not releasing (failed brake or missing 24 V)
- Mechanical jam
- Encoder fault or wrong commutation
- One motor phase missing
Safe checks
- 1Listen for the brake releasing on enable
- 2Check the 24 V brake supply
- 3With power off, check the axis turns freely
- 4Check all motor phases are connected
Drives hold dangerous voltage after power-off. Checks should only be done by qualified personnel, with power isolated and the DC link discharged.
Reviewed by AutomIQ repair technicians. Code and name from the SINAMICS S120/S150 List Manual.
Related SINAMICS S120 faults
- F07011Motor overtemperature
- F30001Overcurrent
- F30002DC link voltage overvoltage
- F30003DC link voltage undervoltage
- F30004Overtemperature heat sink AC inverter
- F30005Overload I2t