The alarm means that the drive's automatic motor data identification routine is currently active or is scheduled to run upon the next power-on command. During this process, the SINAMICS drive tries to measure electrical parameters (such as stator resistance, leakage inductance, etc.) of the connected motor to optimize control performance. Key Characteristics:
If the alarm cannot be cleared through standard parameter changes, performing a factory reset and reconfiguring basic settings may be necessary to clear the drive's internal state. Siemens SiePortal Operational Impact The most significant impact of A07991 is that it typically prevents the drive from starting
: When configuring a new drive via tools like TIA Portal, Startdrive, or a Basic Operator Panel (BOP-2), the wizard flags the system to perform a motor identification routine.
: If the alarm returns even after you thought it was finished, it likely wasn't saved to permanent memory. Ensure you perform the RAM to ROM save procedure . How can resolve the alarm Code 7991 and 8526 - SiePortal siemens fault 0a7991
: Once the drive records the internal resistance and inductance values, it updates its motor model and automatically dismisses the A07991 code .
It typically appears when motor data has been entered, but the drive has not yet identified the motor's electrical characteristics (resistance, inductance, etc.). Common Scenarios: Initial commissioning. After changing motor parameters (e.g., p0300 - p0311).
Ensure the motor is safe to run. It should ideally be disconnected from the mechanical load (de-coupled) for the best results, though stationary measurement can be done coupled. The alarm means that the drive's automatic motor
If you've activated the Motor ID routine by mistake or need to bypass it for urgent testing (while understanding that drive performance may be suboptimal), you can disable it.
Perform rotating tests (p1900=1) only when it is safe to have the motor spin, ensuring the transport system or load is not damaged, as highlighted in some troubleshooting scenarios.
Method 1: Allow the Identification Routine to Run (Recommended) How can resolve the alarm Code 7991 and
: If parameter data is not permanently stored from volatile memory (RAM) to non-volatile memory (ROM), the drive reverts to an uncommissioned state after power-cycles. Step-by-Step Fixes for Alarm A07991 1. Complete the Standard Motor Identification Run
In many real-world cases, A07991 appears simultaneously with , which indicates a communication configuration issue (e.g., invalid telegram configuration or missing cyclic connection). To resolve both:
: Different Siemens families (G120, S120, Simodrive) use slightly different numbering. Error