Cause : UCE upper switch/UCE Phase L3 comes when there was an UCE shutdown in phase L3. This fault signifies an issue with the inverter's ability to control the voltage or current on that specific phase during operation.

The fault F027 in a Siemens Masterdrive indicates a problem with the output phase. The specific phase will be denoted after the fault code, for example, F027-L3 signifies an issue with phase L3. This fault essentially means there's a problem with the power delivered to the motor on a specific phase.

1. Phase L3 for short-circuit or ground fault.
2. Check the converter outputs for earth fault.
3. Check the CU is correctly inserted.