Have problem with diesel genset 50 kw 3 ph 400v 50hz
AVR good
But no output power
Tip... Rotor slip ring reads 6 ohms

 

Check for Reversed Residual Magnetism (RRM)
Disconnect the Field Coil.
Check the output Voltage.
Re Connect the field coil.
Voltage Drop → RRM
How to correct: Flash the Field coil from a 12 volt car Battery a few times. Make sure to use the correct polarity.
RRM will be corrected.

 

Verify the integrity of the rotating field coil circuit. The symptom is no rotating field. It could be a stuck brush. Verifying that the current is correct is a logical diagnostic step.