Cause : Stator resistance measurement failure comes when the drive attempts to identify the connected motor by measuring its stator resistance if the measurement fails, then drive show this F0041 fault code.

The F0041 fault code on a Siemens Micromaster 420 (MM420) indicates a stator resistance measurement failure. This fault occurs when the drive is unable to correctly measure the stator resistance of the connected motor. This can be due to several factors such as incorrect motor parameters, wiring issues, or drive hardware problems.

Here are steps to diagnose and resolve this issue:

1. Check Motor Parameters:

   • Verify that the motor parameters in the drive are set correctly. Key parameters to check include:
     • Motor rated current
     • Motor rated frequency
     • Motor rated voltage
     • Motor power
     • Motor stator resistance
   • Ensure these parameters match the motor's nameplate data.

2. Inspect Wiring and Connections:

   • Ensure that all electrical connections between the drive and the motor are secure and correctly sized.
   • Check for any signs of damage, wear, or loose connections in the wiring.

3. Measure Motor Resistance:

   • Manually measure the stator resistance of the motor using a multimeter. Compare the measured value with the motor’s specified resistance.
   • If there is a significant discrepancy, the motor may have an internal fault.

4. Check Drive and Motor Compatibility:

   • Ensure that the drive is compatible with the motor in terms of voltage, current, and power ratings.

5. Drive Self-Tuning:

   • Perform the drive’s motor identification routine to automatically set the motor parameters, including the stator resistance. This is typically done by setting the appropriate drive parameter for automatic motor identification.

6. Review Drive Settings:

   • Verify that the drive’s settings for motor control mode are appropriate for the application. Incorrect settings can affect the accuracy of the stator resistance measurement.