Practice Test: Question Set - 03
1. A separately excited generator as compared to a self-excited generator
- (A) Is amenable to better voltage control
- (B) Is more stable
- (C) Has exciting current independent of load
current
- (D) Has all above features
2. In D.C. generators, the brushes on commutator remain in contact with conductors which
- (A) Lie under South Pole
- (B) Lie under North Pole
- (C) Lie under interpolar region
- (D) Are farthest from the poles
3. For a D.C. machines laboratory following type of D.C. supply will be suitable
- (A) Rotary converter
- (B) Mercury are rectifier
- (C) Induction motor D.C. generator set
- (D) Synchronous motor D.C. generator set
4. Compensating windings are used in D.C. generators
- (A) Mainly to reduce the eddy currents by providing
local short-circuits
- (B) To provide path for the circulation of cooling air
- (C) To neutralize the cross-magnetizing effect of the
armature reaction
- (D) None of the above
5. Open circuited armature coil of a D.C. machine is
- (A) Identified by the scarring of the commutator
segment to which open circuited coil is connected
- (B) Indicated by a spark completely around the
commutator
- (C) Both (A) and (B)
- (D) None of the above
6. Inter-pole flux should be sufficient to
- (A) Neutralize the commutating self induced e.m.f.
- (B) Neutralize the armature reaction flux
- (C) Neutralize both the armature reaction flux
as well as commutating e.m.f. induced in the coil
- (D) Perform none of the above functions
7. In a D.C. generator the magnetic neutral axis coincides with the geometrical neutral axis, when
- (A) There is no load on the generator
- (B) The generator runs on full load
- (C) The generator runs on overload
- (D) The generator runs on designed speed
8. In a D.C. generator the critical resistance refers to the resistance of
- (A) Brushes
- (B) Field
- (C) Armature
- (D) Load
9. Lap winding is composed of
- (A) Any even number of conductors
- (B) Any odd number of conductors
- (C) That even number which is exact multiple of
poles + 2
- (D) That even number which is exact multiple of poles
10. In a D.C. generator
- (A) External resistance = internal characteristic armature
reaction
- (B) Internal characteristic = magnetization
characteristic ohmic drop
- (C) External characteristic = magnetization
characteristic ohmic drop armature reaction
- (D) Magnetization characteristic = external
characteristic
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