A: This usually means you forgot to save the parameters (P0971=1). The drive resets to the previous configuration when power is cycled.
Sometimes the PLC constantly sends a command to initiate ID run. Ensure the control word from the PLC is not triggering p1900 upon every power-up. Associated Fault: A8526
To break this loop, check out user strategies documented on the Siemens SiePortal Support Forum : siemens fault 0a7991
fault No 7900: motor locked/ at high speed limit reached - SiePortal
A: Typically a few seconds. During the rotating measurement, the motor runs for approximately 10 seconds while the drive measures electrical characteristics. A: This usually means you forgot to save
This is generally an alarm (A) , not a fatal fault (F). It warns you that the motor parameters must be identified before the drive can operate optimally.
Because it prevents standard operation until the drive successfully profiles the motor or the function is disabled, engineers and technicians must address it during commissioning or system restarts. Root Causes of Alarm A07991 Ensure the control word from the PLC is
: Go to parameter p0971 and set it to 1 to copy the newly learned data from RAM to non-volatile ROM. Share public link
: Triggered when a user alters parameter p1900 or p1910 to initialize measurement.
| Step | Action | |------|--------| | 1 | Clear mechanical obstruction. | | 2 | Increase torque limit (temporarily for testing). | | 3 | Check brake control logic & power supply. | | 4 | Perform encoder test (p2500, p2504). | | 5 | Recalculate motor parameters (p304, p305, p311). | | 6 | Disable "stall detection" temporarily (p2178) for diagnosis only. |