253. 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

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254. In a D.C. generator the ripples in the direct e.m.f. generated are reduced by
A. using conductor of annealed copper
B. using commutator with large number of segments
C. using carbon brushes of superios quality
D. using equiliser rings

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255. In D.C. generators, lap winding is used for
A. high voltage, high current
B. low voltage, high current
C. high voltage, low current
D. low voltage, low current

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256. 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

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257. D.C. generator varies significantly with the load current?
A. Field copper loss
B. Windage loss
C. Armature copper loss
D. None of the above

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258. The match between the control method needed and the speed/torque regime is as follows P Field Control, Q Armature Control1. Below base speed2. Above base speed3. Above base torque4. Below base torque
A. P-1; Q-3
B. P-2; Q-1
C. P-2; Q-3
D. P-1; Q-4

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259. motor draws 1.5 A from a supply voltage of 25 V and runs at 1500 rpm. The efficiency of the motor while it is operating on load at 1500 rpm drawing a current of 3.5 A from the motor may result in same source
A.48.00%
B. 57,1%
C.59.20%
D.88.80%

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