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
Related Mcqs:
- For both lap and wave windings, there are as many commutator bars as the number of_____________?
A. slots
B. armature conductors
C. winding elements
D. poles - In D.C. generators the pole shoes are fastened to the pole core by_____________?
A. rivets
B. counter sunk screws
C. brazing
D. welding - If a D.C. generator fails to build up the probable cause could not be_____________?
A. imperfect brush contact
B. field resistance less than the critical resistance
C. no residual magnetism in the generator
D. faulty shunt connections tending to reduce the residual magnetism - 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 - In a D.C. generator the critical resistance refers to the resistance of_____________?
A. brushes
B. field
C. armature
D. load - Magnetic field in a D.C. generator is produced by_______________?
A. electromagnets
B. permanent magnets
C. both A. and B.
D. none of the above - Two generators A and B have 6-poles each. Generator A has wave wound armature while generator B has lap wound armature. The ratio of the induced e.m.f. is generator A and B will be_______________?
A. 2 : 3
B. 3 : 1
C. 3 : 2
D. 1 : 3 - In over compounded generator, full load terminal voltage is______________?
A. almost zero
B. less than no load terminal voltage
C. more than no load terminal voltage
D. equal to no-load terminal voltage - 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 - In a D.C. generator the critical resistance can be increased by_____________?
A. increasing its field resistance
B. decreasing its field resistance
C. increasing its speed
D. decreasing its speed
