Siemens SINAMICS Fault F07900 — Motor Stall / Locked Rotor

What This Fault Means

F07900 triggers when the drive detects the motor is stalled (rotor not turning despite current flowing). This protects the motor from thermal damage due to locked-rotor current.

Common Causes

• Mechanical blockage preventing motor rotation
• Coupling or gearbox failure locking the shaft
• Bearing seizure
• Overload exceeding the motor's breakdown torque
• Incorrect motor data in the drive causing false detection

Recommended Fix

1. Disconnect the motor from the load and try to start it unloaded.
2. Rotate the motor shaft by hand — it should turn freely.
3. Inspect the coupling, gearbox, and driven equipment for binding.
4. Verify motor nameplate data matches drive parameters (P0304 voltage, P0305 current, P0307 power, P0310 frequency).
5. If the motor runs freely but faults when coupled, the mechanical load is too high.