Siemens Fault 0a7991 Best Jun 2026

in Siemens drive systems (such as SINAMICS S120 or G120) refers to a

: Motor data identification not performed. This explicitly warns that the VFD lacks crucial operational physics parameters.

The motor nameplate data entered into the drive does not align with the physical motor connected. siemens fault 0a7991 best

. It typically appears during the initial setup or commissioning of Sinamics drives (such as the G120 or S120) and means the drive is waiting to perform a measurement of the motor's electrical characteristics. Siemens SiePortal How to Resolve Fault A07991

The drive has the "ID" command but is missing the "ON" command or hardware enables (like STO) to actually pulse the motor. in Siemens drive systems (such as SINAMICS S120

The drive receives A and B signals (indicating the motor is spinning), but it fails to detect the "R" pulse (the zero marker) after one full revolution. The drive essentially "loses its place."

The search results for largely point toward technical troubleshooting for Alarm A7991 The drive receives A and B signals (indicating

If this is happening frequently, can you tell me if it’s a or if it started after a power outage ? I can help you figure out if it's a configuration issue or a memory issue.