Siemens Fault — 0a7991

The notification triggers whenever the of the motor's electrical characteristics (such as stator resistance and leakage inductance). This calibration is essential for high-performance control modes, safety protections, and energy-efficient motor management.

If you encounter this status on a test bench during a Factory Acceptance Test (FAT) where no physical motor is wired to the VFD terminals: How can resolve the alarm Code 7991 and 8526 - SiePortal

Power down the 400V and 24V inputs completely, wait 30 seconds, and reboot to confirm the configuration holds. 4. Bypassing Without a Connected Motor (FAT Setup) siemens fault 0a7991

: Check p1910 and ensure it is set to 0 to halt active standstill measurements. 3. Perform a RAM-to-ROM Copy

Once the identification run is successfully completed, the alarm should disappear automatically, and the drive transitions into its normal operating state. Siemens SiePortal Troubleshooting and Resolution Strategies The notification triggers whenever the of the motor's

[A07991 Alarm Active] ──> Apply ON/Start Command ──> Drive Executes Tuning ──> Auto-Clears Alarm How can resolve the alarm Code 7991 and 8526 - SiePortal

: When setting p1960 for advanced speed controller tuning, which automatically hooks into motor data verification. How A07991 Impacts Drive Behavior Perform a RAM-to-ROM Copy Once the identification run

The drive will inject a controlled current into the stator windings. The system will run silent stationary measurements for roughly 10 to 30 seconds.

It is very common for A07991 to appear alongside the fieldbus interface alarm . This happens because an incomplete commissioning file prevents the VFD from organizing its active cyclic process words with the upstream master controller.

: If parameter data is not permanently stored from volatile memory (RAM) to non-volatile memory (ROM), the drive reverts to an uncommissioned state after power-cycles. Step-by-Step Fixes for Alarm A07991 1. Complete the Standard Motor Identification Run