Alternator MCQ | Synchronous Generator MCQ

31. For successful parallel operation of two alternators it is desirable that both have

1. low reactance in comparison to resistance
2. same resistance
3. same reactance
4. high reactance in comparison to resistance

32. Armature reaction in alternator primarily affects

1. terminal voltage per phase
2. frequency of armature current
3. generated voltage per phase
4. rotor speed

33. Two identical alternators are running in parallel and carry equal loads. If the excitation of one alternator increases without changing the steam supply then

1. KVAR supplied by it would decrease
2. power factor will increase
3. it will keep supplying the same load
4. KVAR supplied by it will decrease

34. Drop in alternator frequency is corrected by

1. Damper winding
2. Increased prime mover output
3. Automatic voltage regulator
4. None of these

35. If the excitation of an alternator operating in parallel with other alternators decreased, its

1. Power factor becomes more leading
2. Output KW will change
3. Power factor becomes more lagging
4. Power factor becomes unity

36. Two mechanically coupled alternators deliver power at 50 Hz and 60 Hz respectively. The highest speed of alternators is

1. 600 rpm
2. 500 rpm
3. 3600 rpm
4. 3000 rpm

37. The power factor of an alternator is determined by its

1. prime mover
2. speed
3. excitation
4. load

38. When the speed of an alternator is changed from 3600 rpm to 1800 rpm, the generated emf will be

1. one-half
2. twice
3. one-fourth
4. four times

39. The most common type of prime mover used for low-speed alternators is

1. Steam turbine
2. Petrol engine
3. Hydraulic turbine
4. Diesel engine

40. Which one of the following methods gives voltage regulation higher than the actual value in an alternator?

1. ZPF method
2. mmf method
3. emf method
4. ASA method