Siemens Fault 0.a7991 -
Unlike a critical hardware failure, A7991 is an informative alarm. It signifies that the drive is prepared to perform a "Motor ID" run—a calibration process where the drive measures the electrical characteristics of the connected motor (such as resistance and inductance) to ensure precise control.
If the actual telegram from the drive (visible in Start‑Up tool > Drive parameters > r2050, r2060) does not match these MDs, alarm 0.A7991 is triggered. siemens fault 0.a7991