Ans: Limitations of Arno converter:
1. Unbalanced current in the 3-phase of stator winding
2. Undue heat produced in the winding.
3. Voltage fluctuation and voltage unbalance. Output voltage obtained from Arno converter fluctuates from 290 V to 460 V.
4. When output voltage of Arno converter raises to 460 V, because of excessive magnetizing current, p.f. is poor
5. Stator winding carries single phase motoring current and 3 phase generating current.
6. Motoring phases carry both motoring and generating currents, resultant current is small where as generating phase carries only generating current, its magnitude is higher than motoring phases.
7. Negative sequence torque has pronounced effect on starting torque.
8. Problem in starting