The Siemens drive fault code (often displayed as 7902 ) indicates a "Motor Stalled" condition. This fault occurs when the drive identifies that the motor has remained in a stalled state for a duration longer than the time set in the delay parameter.
If using an encoder, look at r0061 (encoder speed) and compare with sensorless speed estimate. If they differ wildly, the encoder is suspect. siemens drive fault 7902
If you work with Siemens Sinamics drives (G120, S120, G130, etc.), you’ve likely encountered a sudden machine shutdown accompanied by alarm code . Few things stop production faster than a drive fault, but understanding what “7902” means is the first step to getting back up and running. The Siemens drive fault code (often displayed as
More specifically, the drive’s internal logic has detected that the motor’s actual speed has not followed the speed setpoint within a defined window for a defined period of time. The drive interprets this as a blocked rotor, a stalled motor, or a mechanical jam. If they differ wildly, the encoder is suspect
The drive monitors the deviation between the calculated motor speed (based on its internal model) and the actual speed measured by an encoder or estimated through current feedback. If this deviation exceeds a specific threshold window for longer than the set delay time (parameter ), the drive triggers the F07902 fault to prevent damage.
The machine grinds to a halt. Output drops. Deadlines loom.
Faulty wiring, inverted encoder signals, or a damaged encoder can feed the drive incorrect speed data.