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.Management Sciences
Category: D.C. Generators
Armature reaction of an unsaturated D.C. machine is_____________?
A. crossmagnetising
B. demagnetising
C. magnetising
D. none of above
Welding generator will have____________?
A. lap winding
B. wave winding
C. delta winding
D. duplex wave winding
Wave 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
In a D.C. generator the critical resistance refers to the resistance of_____________?
A. brushes
B. field
C. armature
D. load
To achieve sparkless commutation brushes of a D.C. generator are rockedm ahead so as to bring them?
A. just ahead of magnetic neutral axis
B. in magnetic neutral axis
C. just behind the magnetic neutral axis
D. none
In a commutator_____________?
A. copper is harder than mica
B. mica and copper are equally hard
C. mica is harder than copper
D. none of the above
In any rotating machine that part which houses the conductors and in which e.m.f. induced is to be utilized is called____________?
A. rotor
B. stator
C. field
D. armature
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 neutralise the cross-magnetising effect of the armature reaction
D. none of the above
The series field of a short-shunt D.C. generator is excited by_______________?
A. external current
B. armature current
C. shunt current
D. load current
The main factor which leads to unstable parallel operation of flat and over compounded generators is_____________?
A. their rising voltage characteristics
B. unequal number of turns in their series field windings
C. unequal speed regulation of their primemovers
D. unequal series field resistances
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