Regularly lubricate bearings and check conveyor/gearbox alignments to minimize parasitic friction.
the fault occurs (e.g., instantly at startup, during acceleration, or randomly during runtime)
The key to resolving 7902 lies in systematic isolation. Always check the mechanical load first, verify the encoder signal integrity second, and fine-tune the stall detection parameters (, p1744 , p1745 ) third. By understanding the relationship between the drive's internal "motor model" and the physical reality of the rotating shaft, engineers can quickly differentiate between a genuine mechanical jam and a software sensitivity issue, ensuring maximum uptime for industrial equipment.
The drive continuously monitors several internal metrics to calculate a stall condition: siemens drive fault code 7902
: Limits for stall detection (such as speed or current thresholds) may be set too strictly for the specific application. Acceleration/Deceleration Rates
If the stall is temporary and expected for the application, you can increase the (delay time) or the (fault tolerance) to prevent nuisance tripping. Siemens SiePortal 3. Comparison with Related Fault Codes Key Difference Motor Blocked
A classic mistake occurs when a motor is wired for a Delta ( Δcap delta Siemens SiePortal 3
Acceleration times that are too short cause the drive to hit torque limits prematurely. 3. Electrical and Feedback Issues
The fluorescent lights of the MagnaDrive factory floor hummed in a low, monotonous key, a sound usually drowned out by the rhythmic thwump-hiss-thwump of the heavy-duty stamping presses. But tonight, the factory was holding its breath.
Incorrect nameplate data (kW, Amps, RPM) entered during commissioning. incorrect electrical parameters
Ensure that the upper/lower torque limits (p1520/p1521) are not set too low. Step 4: Tune the Speed Controller
A stalled motor fault rarely stems from a single isolated issue. It is typically triggered by a combination of mechanical resistance, incorrect electrical parameters, or hardware degradation. The root causes generally fall into four categories: 1. Mechanical Blockages and Overload
Increase the acceleration time to give the motor more time to reach speed without hitting the stall threshold. If you are using a SINAMICS G120XA
It is important to differentiate this from . While similar, F07902 generally occurs when the motor enters a current limit situation above a specific speed threshold. Common Symptoms