Siemens Fault 0a7991 Site

Follow these steps to resolve the fault. Ensure all power is safely disconnected before checking physical connections.

If the fault is intermittent:

According to Siemens Technical Support documentation (List Manuals), fault code 0A7991 falls under the umbrella of "Motor blocked" or "Vapor lock" . Depending on the application: siemens fault 0a7991

In essence, the drive commands the motor to accelerate to a target speed. The internal speed encoder (or sensorless vector control) reports back the actual speed. If the actual speed remains significantly below the target speed for a defined period (set by parameter p2178), the drive assumes the motor is mechanically blocked and trips.

Sometimes, a logical glitch is all it takes. Follow these steps to resolve the fault

To prevent the CPU from going into STOP on future I/O errors:

When the drive outputs torque > p2175 but speed remains < 5% of setpoint for longer than p2177 or p2178, the system triggers 0A7991. In essence, the drive commands the motor to

Prepare: