Power Generator

71. In a practical transformer, copper losses account for how many percent of the total losses?

1. 75%
2. 25%
3. 85%
4. 95%

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72. In a simplex wave winding, the number of parallel paths is equal to

1. number of poles in the machine
2. 2
3. number of pair poles
4. 1

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73. In a vacuum cleaner, ___________ motor is generally used

1. shunt
2. series
3. commutatively compounded
4. differentially compounded

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74. In a very large dc motor with severe heavy duty, armature reaction effects are corrected by

1. using interpole only
2. using compensatory windings in addition to interpoles
3. shifting the brush position
4. fixing the brush position

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75. In a wave winding, the commutator pitch is approximately equal to

1. pole pitch
2. thrice the pole pitch
3. twice the pole pitch
4. half the pole pitch

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76. In an alternator, the effect of armature reaction is minimum at power factor of

1. 0.866 lagging
2. 0.5 lagging
3. 0.866 leading
4. Unity

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77. In an auto transformer, the primary and secondary are ___________ coupled

1. only magnetically
2. magnetically as well as electrically
3. only electrically
4. directly

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78. In case if a 4 pole machine, 1 mechanical degree corresponds to___________ electricaldegree

1. 2
2. 8
3. 4
4. 6

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79. In the short circuit test in a transformer, ___________ winding is generally short circuited

1. high voltage
2. low voltage
3. either low or high voltage
4. neither low nor high voltage

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80. Intermittent sparking at the brushes of dc motor may be caused due to

1. an open armature coil
2. loose coupling
3. intermittent load
4. incorrect voltage

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