ONLINE Multiple Choice Questions EE- Synchronous Generator PAR 3


31. The
armature reaction of an alternator influences
(A) windage losses
(B)
operting speed
(C) generated voltage per phase
(D)
waveform
of voltage generated.

Get Answer

32. For
the same power rating, a lower voltage alternator will be
(A)
more
efficient
(B) larger in size
(C) operating at high rpm
(D)
more
costly.

Get Answer

33. An
alternator is supplying 10A to an inductive load at 220 V, while running at
1000 rpm. Now if the speed of the alternator is reduced to 750 rpm but the
field current remains unchanged, the load current will become
(A)
18 A
(B) 13.3 A
(C)
10 A
(D) 7.5 A.

Get Answer

34. Dampers
in a large generator
(A)
increase
stability
(B)
reduce
voltage fluctuations
(C)
reduce
frequency fluctuations.

Get Answer

35. An
alternator is rated for 75 kW at 0.8 power factor. It means that
(A)
alternator
has 4 poles
(B)
alternator
can supply 75 kW at 0.8 power factor
(C)
alternator
can supply power only to loads having power factor 0.8 only
(D)
the
peak efficiency of alternator occurs only at 75 kW load having 0.8 lagging
power factor.

Get Answer

36. The
regulation of an alternator is
(A)
the
reduction in terminal voltage when alternator is loaded
(B)
the
variation of terminal voltage under the conditions of maximum and minimum
excitation
(C)
the
increase in terminal voltage when load is thrown off
(D)
the
change in terminal voltage from lagging power factor to leading power factor.

Get Answer

37. A
magnetisation curve represents the relationship between
(A) reactive and non-reactive components of
voltage
(B) exciting currents and terminal voltage
(C) power factor and terminal voltage
(D) magnetic flux and armature current.

Get Answer

38. In
an alternator if the armature reaction produces demagnetisation of the main
field, the power factor should be
(A) Zero, lagging load
(B) Zero, leading load
(C) Unity.

Get Answer

39. In
an alternator if the armature reaction produces magnetisation of the main field
the power factor should be
(A) Zero, leading load
(B)  Zero, lagging load
(C) Unity.

Get Answer

40. When
an alternator is supplying unity power factor load, the armature reaction will
produce
(A) magnetisation of the main field
(B) demagnetisation of the main field
(C) distortion of the main field.

Get Answer

41. An
alternator has full load regulation of 4% when the power factor of the load is
0.8 lagging while alternator runs at 1500 rpm. The full load regulation of 1400
rpm for 0.8 pf lagging load will be
(A)
15/14 x 4
percent
(B)
14/15 x 4 percent
(C) 4
percent
(D)
Depends
on other factors also.

Get Answer

42. The
Potier’s triangle separates the
(A) iron losses and copper losses
(B) field mmf and armature mmf
(C) stator voltage and rotor voltage
(D) armature leakage reactance and armature
reaction mmf.

Get Answer

43. In
the Potier’s triangle, the Potier reactance drop per phase is 22 volts per
phase at 88
amperes
per phase. The Potier’s reactance per phase is
(A) 0.22
(B)
0.25
(C) 0.30
(D)
0.44.

Get Answer

44. Two
alternators are running in parallel. The excitation of one of the alternator
is increased. The result will be
(A) machine with excess excitation will burn
(B) both machines will start vibrating
(C) power output will decrease
(D) wattless component will change.

Get Answer

45. The
power output of an alternators is 100 kW. In order that the tangent of pf angle
may be 0.8 lagging, the KVAR rating must be
(A) 80 cosφ KVAR
(B) 80 sin φ KVAR
(C) 80 KVAR
(D) -80 KVAR.

Get Answer

ONLINE Multiple Choice Questions EE- Synchronous Generator PAR 4
ONLINE Multiple Choice Questions EE- Synchronous Generator PAR 2

Leave a Reply