Power Generator

111. The demand for a large increase in torque of a dc shunt motor is met by a

1. large decreased in speed
2. large increased in current
3. large increased in speed
4. small increased in current

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112. The disadvantage of a short pitched coil is that

1. harmonics are introduced
2. waveform becomes non-sinusoidal
3. voltage round the coil is reduced
4. voltage round coil is increases

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113. The distribution of load between two alternators operating in parallel can be changed by changing

1. phase sequence
2. field excitation of alternators
3. driving torques of prime movers
4. current direction

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114. The effect of armature reaction is to

1. decreased the total flux
2. make the air gap flux uniform
3. increase the total flux
4. make the flux constant

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115. The effect of leakage flux in a transformer is to

1. increase copper losses
2. decrease copper losses
3. cause voltage drop in the windings
4. reduce eddy current losses

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116. The efficiency of a transformer will be at maximum when

1. leakage reactance of the two windings are equal
2. resistance of the two windings are equal
3. copper loss is equal to constant loss
4. copper loss is zero

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117. The efficiency of the turbo-alternator ___________ with increase in speed

1. decreases
2. remains the same
3. increases
4. becomes 100%

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118. The field structure of a dc machine uses

1. Salient pole arrangement
2. Non salient pole arrangement
3. Silicon steel
4. Cast steel

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119. The field winding of a dc shunt machine usually carries ___________ of the rated current of the machine

1. 2% to 5%
2. more than 20%
3. 15% to 20%
4. less than 0.5%

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120. The field winding of an armature is ___________ excited

1. dc
2. ac
3. both ac and dc
4. battery

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