A. to reduce the reluctance of the mag¬netic path
B. to spread out the flux to achieve uniform flux density
C. to support the field coil
D. to discharge all the above functions
Related Mcqs:
- In D.C. generators the pole shoes are fastened to the pole core by_____________?
A. rivets
B. counter sunk screws
C. brazing
D. welding - 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 - In case of a 4-pole D.C. generator provided with a two layer lap winding with sixteen coils, the pole pitch will be__________________?
A. 4
B. 8
C. 16
D. 32 - The number of armature parallel paths in a two-pole D.C. generator having duplex lap winding is______________?
A. 2
B. 4
C. 6
D. 8 - In case of D.C. machine winding, number of commutator segments is equal to______________?
A. number of armature coils
B. number of armature coil sides
C. number of armature conductors
D. number of armature turns - In a four-pole D.C. machine____________?
A. all the four poles are north poles
B. alternate poles are north and south
C. all the four poles are south poles
D. two north poles follow two south poles - The e.m.f. generated by a shunt wound D.C. generator isE. Now while pole flux remains constant, if the speed of the generator is doubled, the e.m.f. generated will be_______________?
A. E/2
B. 2E
C. slightly less than E
D. E - In case of D.C. machines, mechanical losses are primary function of____________?
A. current
B. voltage
C. speed
D. none of above - Iron losses in a D.C. machine are independent of variations in______________?
A. speed
B. load
C. voltage
D. speed and voltage - 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
