A: In such cases, you must set P1900=0 to disable the identification function. For situations requiring a rotating measurement despite physical constraints, contact Siemens support for custom handling guidance.
| Product Series | Model Examples | Applicable Manual Reference | |:---|:---|:---| | | G120, G120C, G120X, G120XA | Siemens G120 manual (A07991) | | SINAMICS V90 | V90 Servo Drive | SINAMICS V90 Operating Instructions | | SINAMICS S120 | S120 Servo Drive | SINAMICS S120 Commissioning Manual | | Other SINAMICS | G110M, G120P, G115D | Various SINAMICS documentation |
Some users have reported seeing both A7991 and A8526 alarms simultaneously. In these cases, the drive's BF (Bus Fault) LED is also often illuminated. While A7991 is a status notification about Motor Data Identification, A8526 is a more serious alarm indicating that no cyclic connection exists between the drive and the controlling PLC.
While the exact wording may vary slightly depending on the CPU family (S7-300, S7-400, S7-1200, S7-1500), the fault typically translates to: siemens fault 0a7991
When active, the drive will not run the motor normally on the next Start command. Instead, it will begin injecting current into the motor to measure its electrical characteristics such as resistance, inductance, and time constants. This data is crucial for the drive to build an accurate mathematical model of the motor, ensuring better efficiency, higher torque accuracy, and improved motor protection.
The notification commonly surfaces under the following scenarios:
When dealing with the A07991 notification, keep these best practices in mind: A: In such cases, you must set P1900=0
Alarm A07991 appears in the same manner across all these platforms, though specific parameters may vary slightly by model.
Are you currently or did this alarm appear on a system that was already running ? How can resolve the alarm Code 7991 and 8526 - SiePortal
For any permanent or recurring issue, official Siemens Technical Support remains the most reliable resource. Many discussions about this alarm can also be found in the portal, where a thriving community of engineers and Siemens experts share field-tested solutions. In these cases, the drive's BF (Bus Fault)
Are you currently performing an , or did this alarm appear suddenly on a drive that was already running ? How can resolve the alarm Code 7991 and 8526 - SiePortal
This article provides a comprehensive guide to understanding why this fault occurs, its risks, and how to troubleshoot it effectively in industrial environments. What is Siemens Fault Code A07991?
A technician or automated PLC block has changed the parameter p1900 from 0 (Inhibited) to either 1 (Identification at standstill) or 2 (Rotating measurement).
By following these recommendations, users can reduce the likelihood of encountering this fault code and ensure optimal performance of their Siemens equipment or systems.