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.Management Sciences
Category: D.C. Generators
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
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
Iron losses in a D.C. machine are independent of variations in______________?
A. speed
B. load
C. voltage
D. speed and voltage
Eddy currents are induced in the pole shoes of a D.C. machine due to______________?
A. oscillating magnetic field
B. pulsating magnetic flux
C. relative rotation between field and armature
D. all above
Which of the following generator will have negligible terminal voltage while running on no-load?
A. Series generator
B. Shunt generator
C. Compound generator
D. Separately excited generator
Which generator would you prefer for feeding long D.C. transmission lines ?
A. Series generator
B. Shunt generator
C. Over compound generator
D. Flat compound generator
The terminal voltage of a D.C. shunt generator drops on load because of all of the following reasons except:_____________?
A. armature reaction
B. armature resistance drop
C. field weakening due to armature reaction and armature
D. commutation
D.C. generators are connected to the busbars or disconnected from them only under the floating condition________________?
A. to avoid sudden loading of the primemover
B. to avoid mechanicaljerk to the shaft
C. to avoid burning of switch contacts
D. all above
In a D.C. machine stray loss is the sum of_____________?
A. total copper loss and mechanical loss
B. armature copper loss and iron loss
C. shunt field copper loss and mechanical loss
D. iron loss and mechanical loss
In lap winding, the number of brushes is always_____________?
A. double the number of poles
B. same as the number of poles
C. half the number of poles
D. two
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