| 1. | In a synchronous motor running with fixed excitation, when the load is increased three times, its torque angle becomes approximately ? | |
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one-third
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twice
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thrice
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six times
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Report Question| 2. | A synchronous motor running with normal excitation adjusts to load increases essentially by increase in ? | |
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back e.m.f.
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armature current
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power factor
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torque angle
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| 3. | The maximum power developed in a synchronous motor occurs at a coupling angle of ? | |
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30º
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60º
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90º
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180º
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| 4. | When the field of a synchronous motor is under-excited, the power factor will be ? | |
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leading
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lagging
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unity
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zero
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| 5. | As the load is applied to a synchronous motor, the motor takes more armature current because ? | |
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the increased load bas to take more current
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the rotor by shifting its phase backward causes motor to take more current
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the back e.m.f. decreases causing an increase in motor current
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the rotor strengthens the rotating field causing more motor current
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| 6. | When the excitation of an unloaded salient pole synchronous motor suddenly gets disconnected ? | |
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The motor stops
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it runs as a reluctance motor at the same speed
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it runs as a reluctance motor at a lower speed
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none of the above
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| 7. | A synchronous motor working at leading power factor can be used as ? | |
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voltage booster
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phase advancer
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noise generator
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mechanical synchronizer
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| 8. | The mechanical displacement of the rotor with respect to the stator. in polyphase multipolar synchronous motors running at full load, is of the order of ? | |
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zero degree
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two degrees
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five degrees
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ten degrees
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| 9. | Due to which of the following reasons a synchronous motor fails to pull into synchronism after applying D.C. field current ? | |
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High field current
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Low short circuit ratio
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High core losses
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Low field current
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| 10. | A 3-phase synchronous motor is running clockwise. If the direction of its field current is reversed ? | |
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the motor will stop
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the motor continue to run in the same direction
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the winding of the motor will burn
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the motor will run in the reverse direction
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