Siemens Drive Fault Code 7902 [better] ★ Extended

Elias shook his head. "It’s an S120 multi-drive system, Marcus. Look at the cabinet. One line supply module, but two motor modules. There’s a main drive for the flywheel, and a secondary servo for the feeder that pushes the metal sheets in. They talk to each other via a telegram to synchronize the speed. If the feeder drive doesn't report its position to the main drive, the main drive locks out to prevent crushing the tooling."

G120XA solution to warning F7902 motor out of step - Siemens

Parameters governing the maximum current limit (p0640) or torque limits (p1520/p1521) might be set too low, preventing the motor from drawing enough power to overcome normal starting inertia. siemens drive fault code 7902

The motor fails to restart after an OFF/ON cycle without p1200 (flying restart) enabled. 3. Step-by-Step Troubleshooting and Solutions

In industrial automation, unexpected drive downtime cuts directly into production profitability. If your Siemens SINAMICS drive system—such as the widely used G120, S120, or G120C series—suddenly trips and displays , the drive has triggered a "Motor stalled" protective action. Elias shook his head

The most straightforward reason is a heavy mechanical load that exceeds the torque capacity of the motor or drive combination. If a mechanical brake does not release properly, or if downstream equipment (such as conveyors, pumps, or mixers) is jammed, the motor will lag behind its frequency command. 2. Missing or Incomplete Motor Commissioning

This is the timeout period for the stall detection. If a stall condition is present, the drive will wait for the duration set in P2178 (in seconds) before tripping the F7902 fault. Impact: If your system experiences brief, acceptable mechanical "binds" (e.g., in a crusher or mixer), a low value (like the default 0.05s to 0.1s) can cause nuisance trips. Increasing this to 0.15s or higher provides the motor time to break free. One line supply module, but two motor modules

Siemens Drive Fault Code F7902: Causes, Troubleshooting, and Fixes

If the problem is not mechanical, the most common solution is to perform a proper motor ID. A standard quick commissioning is often insufficient.

If the system uses closed-loop vector control, a malfunctioning encoder, loose coupling, or damaged feedback cable can report an incorrect speed of "0 RPM" to the drive, tricking it into triggering a stall fault.