Cause : I too low comes when the difference smoothed with P159 between excitation current setpoint and actual value (r160 - r156) deviates from zero by more than 25% of the rated magnetizing current.

Check the following things:
- whether the current limitation of the excitation current control is too small,
- whether the dynamic performance of the excitation current injection is too low,
- whether the excitation current injection function is operating,
- whether the wiring of excitation current actual-value P155 is correct,
- whether the wiring of excitation current setpoint r160 is correct,
- whether there is a wire break between MASTERDRIVES and the excitation device,
- whether the voltage limitation is too low for dynamic excitation current control,