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0a7991: Siemens Fault

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

This alarm is documented across a wide range of Siemens industrial drives, including:

In more sophisticated drives like the SINAMICS S120, the A7991 alarm appears as part of a structured optimization sequence:

Once the internal mapping registers update successfully, parameter p1900 drops back down to 0 , and the A07991 alarm clears automatically. siemens fault 0a7991

: Visit the Siemens website. They often have support sections where you can search for specific fault codes. Siemens also offers technical support through phone, email, or chat, depending on your region.

The motor may emit a whistling sound for several seconds as it carries out measurements at a standstill .

An engineer or technician may have intentionally activated the routine by setting parameters like P1900 (Motor Data Identification) or P1910 (Static Motor Data Identification). The drive will inject a controlled current into

: The alarm remains continuously active if parameter p1900 (Motor data identification selection) is set to a value other than zero (e.g., p1900 = 1 for stationary measurement).

Restoring the drive to its default settings will also reactivate the motor identification function, causing the alarm to reappear.

Comprehensive Guide to Siemens SINAMICS Alarm Code A07991 (0A7991) : Visit the Siemens website

To resolve the Siemens fault 0A7991, follow these steps:

The drive blocks you from saving its configuration permanently. If a rotating measurement configuration is requested, the software restricts writing data from . The drive must finish its measurement before it unlocks normal data backup and standard production operations. Step-by-Step Solutions to Resolve A07991

If you are testing the machine locally without a network connection, set parameter p2030 = 0 (No Protocol) to tell the drive not to look for an active fieldbus line. Perform a RAM-to-ROM save, cycle the 24V control power, and the secondary communication error will drop out.

Technically categorized as an alarm rather than a permanent hardware fault, this message serves as a system notification: the drive is waiting for an upcoming ON command to measure the electrical characteristics of the connected motor to optimize control performance. Technical Causes of Code A07991