Fault Code 7902 | Siemens Drive

If a motor encoder is used and the fault persists after a motor ID, a physical check of the encoder is required. Verify the following:

The fault is most relevant in , where the drive requires precise motor modeling. In V/f control (a simpler method), the drive does not typically monitor for this condition, which is why switching to V/f mode can sometimes mask the issue.

: A faulty or incorrectly configured speed sensor/encoder can provide the wrong feedback to the speed controller. Current Limits : The set current limits ( p0640p 0640 siemens drive fault code 7902

Indicates a problem during the stationary measurement of the stator resistance or leakage inductance. This strongly points toward wrong nameplate data or an open circuit/contactor problem on the specific output phases.

This defines the speed below which the motor is considered stalled. Default is often 20 RPM. If a motor encoder is used and the

He checked the DC link voltage. The capacitors in the line module were humming, charged and ready. But the second motor

) is too short, or the torque limits are set too low to overcome initial friction. Phase Failure: : A faulty or incorrectly configured speed sensor/encoder

Check for mechanical obstructions (brake locked, jammed load). Check motor cable connectivity.

If the parameters are flawless, the issue is likely a physical barrier preventing the identification current from flowing evenly across all three phases.

This article is based on Siemens SINAMICS documentation and field experience. Always refer to the official List Manual for your exact drive series and firmware version before changing parameters.