A. demagnetisation only
B. cross magnetisation as well as mag¬netisation
C. crossmagnetisation as well as demagnetising
D. cross magnetisation only
Related Mcqs:
- 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 - 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 - 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 a D.C. generator in order to reduce sparking at brushes, the self-induced e.m.f. in the coil is neutralised by all of the following except______________?
A. interpoles
B. dummy coils
C. compensating winding
D. shifting of axis of brushes - 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 - 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 - 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 - 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 - The material for commutator brushes is generally_______________?
A. mica
B. copper
C. cast iron
D. carbon - The rapid wear of brushes takes place due to____________?
A. abrasion from dust
B. excessive spring pressure
C. rough commutator bars
D. high mica insulation between com-mutation bars
E. all of the above factors
