The is a common notification that appears on Siemens variable frequency drives (VFDs), most notably within the SINAMICS G120, G120C , and S120 drive series .
If the issue persists after mechanical and parameter checks, provide:
: While this alarm is active鈥攅specially if a rotating measurement is selected鈥攜ou may be unable to save parameter assignments to the ROM until the process finishes. Common Troubleshooting Steps
: A food processing plant using a SINAMICS G120 to drive a dough mixer reports recurring fault 0A7991 every morning at first start, but runs fine rest of the day.
Depending on the identified root cause, here are the appropriate solutions. siemens fault 0a7991
Let the motor hum or turn slightly for roughly 10 to 15 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.
You can resolve this alarm using one of two primary methods through the Siemens SiePortal Complete the Identification Process
The VFD will not execute standard speed or torque profiles upon receiving a standard "Run" command. Instead, it will attempt to inject test currents into the motor to perform the measurement. Step-by-Step Resolution Strategies The is a common notification that appears on
If the drive is functioning normally but the alarm persists despite being configured, the data is likely only stored in the drive's temporary memory (RAM). The drive is looking for a setting that hasn't been saved permanently.
To resolve the Siemens fault 0A7991, follow these steps:
High-inertia loads take time to accelerate. The default p2178 (typically 1鈥�2 seconds) is too short.
Before attempting a reset, understanding the logic behind the fault is crucial. Depending on the identified root cause, here are
Users often see together with A8526 ("Drive: PLC signal not valid"). This typically means the PROFIdrive telegram from the PLC is not sending the correct status word, or the motor ID run failed, causing the PLC to stop sending commands. Solution for A8526/A07991 Combo: Address A07991 by performing the ID run.
When you encounter F07991 on a Siemens SINAMICS panel or Starter/TIA Portal, follow this structured diagnosis.
: This turns off the motor data identification and rotation test.
The Siemens fault code 0A7991 is a specific error code that indicates a problem with a Siemens device or system. This report aims to provide a detailed overview of the fault, its possible causes, symptoms, and recommended actions for troubleshooting and resolution.