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
0.04375
0.126388889
0.085416667
0.125694444
0.125694444
The voltage drop for which of the following types of brush can be expected to be least ?
Graphite brushes
Carbon brushes
Metal graphite brushes
None of the above
Metal graphite brushes
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
2E
E
slightly less than E
E/2
2E
The material for commutator brushes is generally
carbon
copper
mica
cast iron
carbon
In a D.C. generator the ripples in the direct e.m.f. generated are reduced by
using equalizer rings
using carbon brushes of superior quality
using conductor of annealed copper
using commutator with large number of segments
using carbon brushes of superior quality
The insulating material used between the commutator segments is normally
mica
graphite
paper
insulating varnish
mica
In D.C. generators the brushes on commutator remain in contact with conductors which
are farthest from the poles
lie under north pole
lie under south pole
lie under interpolar region
lie under interpolar region
If brushes of a D.C. generator are moved in order to bring these brushes in magnetic neutral axis there will be
demagnetisation only
cross magnetisation as well as magnetisation
cross magnetisation as well as demagnetising
cross magnetisation only
cross magnetisation as well as demagnetising
Armature reaction of an unsaturated D.C. machine is
cross magnetising
none of above
magnetising
demagnetising
cross magnetising
In a D.C. generator the ripples in the direct e.m.f. generated are reduced by
using carbon brushes of superior quality
using commutator with large number of segments
using conductor of annealed copper
using equalizer rings
using carbon brushes of superior quality
पोस्ट अच्छी लगी हो तो प्लीज नीचे दिए गए लिंक पर क्लिक कर शेयर जरुर करें
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