1. Under no load condition, the power factor of a transformer is
Answer : Less than 0.5 lagging
Explain:-
2. A 40 kVa transformer has iron loss of 450 W and full load copper loss of 850 W. If the power factor of the load is 0.8 lagging, the full load efficiency of the transformer is
Answer : 96.1%
Explain:-
3. In a ∆-∆ connection, if one transformer becomes disabled, the capacity will reduce to
Answer : 57.74%
Explain:-
4. For successful parallel operation of two single phase transformers, the most essential condition is that their
Answer : Polarities are properly connected
Explain:-
5. In salient pole field structure, the pole shoes cover about ______ of pole pitch
Answer : two-third
Explain:-
6. A 3-phase, 16 pole alternator has a star connected winding with 144 slots and 10 conductors per slot. The flux per pole is 30 m Wb sinusoidally distributed and the speed is 375 rpm. The frequency of the generated emf is
Answer : 50Hz
Explain:-
7. An under excited alternator supplies
Answer : No active power
Explain:-
8. Pull-out torque of a practical synchronous motor will occur when the torque angle is about
Answer : 75°
Explain:-
9. A synchronous motor is operating with normal excitation. With the increase in load the armature current drawn from the supply mains increases due to
Answer : Increase in resultant voltage across the armature
Explain:-
10. A synchronous motor is connected to a constant voltage and constant supply frequency. The motor is initially operated at lagging power factor. When the field current is increased
Answer : The armature current decreases upto a certain limit and then increases
Explain:-
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