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.Management Sciences
Category: D.C. Generators
In a D.C. generator the magnetic neutral axis coincides with the geometrical neutral axis, when_______________?
A. there is no load on|he generator
B. the generator runs on full load
C. the generator runs on overload
D. the generator runs on designed speed
For the parallel operation of two or more D.C. compound generators, we should ensure that_______________?
A. voltage of the incoming generator should be same as that of bus bar
B. polarity of incoming generator should be same as that of bus bar
C. all the series fields should be run in parallel by means of equilizer connection
D. series fields of all generators should be either on positive side or negative side of the armature
E. all conditions mentioned above should be satisfied
The armature core of a D.C. generator is usually made of__________________?
A. silicon steel
B. copper
C. non-ferrous material
D. cast-iron
If residual magnetism is present in a D.C. generator, the induced e.m.f. at zero speed will be____________?
A. zero
B. small
C. the same as rated voltage
D. high
In a separately excited generator supplying rated load the armature reaction.
A. is always present
B. is always absent
C. may be sometimes present
D. none of the above
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
Which of the following could be lamina-proximately the thickness of laminations of a D.C. machine ?
A. 0.005 mm
B. 0.05 mm
C. 0.5 m
D. 5 m
If a self excited D.C. generator after being installed, fails to build up on its first trial run, the first thing to do is to______________?
A. reverse the field connections
B. increase the field resistance
C. increase the speed of primemover
D. check armature insulation resistance
A cumulatively compounded long shunt generator when operating as a motor would be____________?
A. cumulatively compounded long shunt
B. deferentially compounded long shunt
C. cumulatively compounded short shunt
D. differentially compounded short shunt
Which of the following components of a D.C, generator plays vital role for providing direct current of a D.C. generator ?
A. Dummy coils
B. Commutator
C. Eye bolt
D. Equilizer rings
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