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."
Disclaimer: Always follow safety procedures and the official Siemens documentation for your specific drive model. If you want me to, I can: commissioning steps. List the most critical parameters (P0300 series) to check.
: Disabling this may lead to sub-optimal motor performance or other faults (like
Follow these steps in order to resolve the A7991 fault efficiently. 1. Check Parameter P1900 siemens fault 0a7991 best
When this alarm is triggered, the variable frequency drive (VFD) restricts parameter saving and system operation until the routine completes or is bypassed. Below is a comprehensive guide to understanding, resolving, and optimizing your system when dealing with the A07991 alarm. Core Technical Causes of A07991
Is this a or an existing machine that suddenly failed?
The most reliable method to eliminate code A07991 is allowing the drive to complete its automatic calibration routine. The drive receives A and B signals (indicating
Depending on whether you are on a live site with a motor connected or conducting a Factory Acceptance Test (FAT) without a physical load, select the appropriate method below. Method 1: Execute the Planned Motor ID (Best Practice)
, and the drive is waiting to perform its measurement routine.
I can provide the specific and wiring diagrams for your exact hardware. Share public link List the most critical parameters (P0300 series) to check
: If disabling the motor ID causes an overcurrent fault, the motor data might be incorrectly parameterized, or the control mode ( p1300 ) might be too aggressive for the unmeasured motor. If you tell me the exact drive model (e.g., SINAMICS G120C Go to product viewer dialog for this item.
Parameter p1900 was actively set to 1 (Identification at standstill) or 2 (Rotating measurement).
: The drive will inject current into the motor windings for roughly 10 to 15 seconds. The motor may hum but will not rotate.
system moves from commissioning to full production with minimal downtime. Are you experiencing this alarm on a new installation or a system that was previously working Fault A07991 cannot be cleared on SINAMICS G120C drive
In many applications, especially with G120 drives, A07991 appears alongside (PROFINET No Cyclic Connection). This is a communication alarm indicating that the drive has lost cyclic communication with the PLC [10†L25-L27]. While the fix for A07991 remains the same as described above, addressing A08526 requires a separate approach: