The fault code "F7900" on Siemens drives indicates a "Motor Blocked" condition. This fault occurs when the drive detects that the motor is unable to rotate freely due to a mechanical obstruction or binding.

A Siemens Sinamics drive error code F7900 indicates a "Motor Blocked" condition. This means the drive detects that the motor connected to it is unable to rotate freely. Here's a breakdown of the issue and some troubleshooting steps:

Possible Causes of F7900 Error:

• Mechanical Obstruction: The most common cause is a mechanical obstruction that prevents the motor shaft from turning. This could be due to debris, seized bearings, misaligned components, or excessive load on the motor.
• Brake Not Releasing: If the motor has an integrated brake, it might not be releasing fully, causing the motor to drag.
• Internal Motor Issue: In rare cases, an internal problem within the motor itself, such as a mechanical failure, could prevent rotation.
• Drive Settings: Incorrect settings on the Sinamics drive, such as overly aggressive torque limits, could contribute to the motor stalling under normal operating conditions.

Troubleshooting Steps:

1. Physical Inspection: Turn off the power supply to the Sinamics drive completely. Then, visually inspect the motor and surrounding machinery for any mechanical obstructions, binding components, or misalignment.
2. Check Brake Operation: If the motor has a brake, ensure it's releasing properly. Refer to the motor's manual for instructions on how to verify brake operation.
3. Review Drive Settings: Consult the Sinamics drive manual and verify settings related to motor torque limits, acceleration/deceleration times, and overload protection. Make sure these settings are appropriate for the application and not causing the motor to stall under normal load.
4. Reset Drive Fault: Once you've addressed the potential cause, you might need to reset the F7900 fault on the Sinamics drive. Refer to the drive's manual for specific instructions on how to reset the fault code (it might involve a button press or a function within the drive's user interface).