1. What are the different types of ac generators in use? Explain their constructional features and essential differences in their construction. [15]
2.a) Calculate the distribution factor for a 36-slot, 4-pole single layer 3-phase winding.[7]
b) Derive the emf equation of synchronous generator from the fundamental principles. [8]
3.a) Explain the effect of load power factor on the armature reaction of alternator.[8]
b) Explain briefly load characteristics of alternator. [7]
4. A 3-phase, 1500 kvA, star-connected, 50-Hz, 2300v alternator has a resistance of 0.12Ω. A field current of 70A produces a short – circuit current equal to fuel load current of 376A in each line. The same field current produces an emf of 700V on open circuit. Determine the synchronous reactance of the machine and its full load regulation at 0.8 lagging power factor. [15]
5. What do you mean by synchronization of alternator? Describe any one method of synchronizing? [15]
6. A 3-phase, 11000v, star – connected synchronous motor takes a load current of 100A. The effective reactance and resistance per phase are 30Ω and 0.8Ω respectively. Find power supplied to the motor and induced e.m.f for
a) 0.8 power factor lagging b) 0.8 p.f leading. [15]
7.a) Explain why synchronous motor is not a self starting motor.[7]
b) Briefly explain different starting methods of synchronous motor. [8]
8.a) Discuss the double revolving field theory of single phase induction motor.[7]
b) Explain principle of operation of single phase induction motor. [8]
2.a) Calculate the distribution factor for a 36-slot, 4-pole single layer 3-phase winding.[7]
b) Derive the emf equation of synchronous generator from the fundamental principles. [8]
3.a) Explain the effect of load power factor on the armature reaction of alternator.[8]
b) Explain briefly load characteristics of alternator. [7]
4. A 3-phase, 1500 kvA, star-connected, 50-Hz, 2300v alternator has a resistance of 0.12Ω. A field current of 70A produces a short – circuit current equal to fuel load current of 376A in each line. The same field current produces an emf of 700V on open circuit. Determine the synchronous reactance of the machine and its full load regulation at 0.8 lagging power factor. [15]
5. What do you mean by synchronization of alternator? Describe any one method of synchronizing? [15]
6. A 3-phase, 11000v, star – connected synchronous motor takes a load current of 100A. The effective reactance and resistance per phase are 30Ω and 0.8Ω respectively. Find power supplied to the motor and induced e.m.f for
a) 0.8 power factor lagging b) 0.8 p.f leading. [15]
7.a) Explain why synchronous motor is not a self starting motor.[7]
b) Briefly explain different starting methods of synchronous motor. [8]
8.a) Discuss the double revolving field theory of single phase induction motor.[7]
b) Explain principle of operation of single phase induction motor. [8]
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