Most Synchronous Motors

1. A 3-phase synchronous motor is running clockwise. If the direction of its field current is reversed

1. the motor will stop
2. the motor continue to run in the same direction
3. the winding of the motor will burn
4. the motor will run in the reverse direction

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2. A pony motor is basically a

1. small induction motor
2. D.C. series motor
3. D.C. shunt motor
4. double winding A.C./D.C. motor

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3. A rotory converter can also be run as a

1. d.c. shunt motor
2. d.c. series motor
3. d.c. compound motor
4. induction motor
5. synchronous motor

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4. A synchronous machine with large air gap has

1. a higher value of stability limit
2. a small value of inherent regulation
3. a higher synchronizing power which makes the machine less sensitive to load variations
4. all of the above

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5. A synchronous machine with low value of short-circuit ratio has

1. lower stability limit
2. high stability limit
3. good speed regulation
4. good voltage regulation

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6. A synchronous motor can be made self starting by providing

1. damper winding on rotor poles
2. damper winding on stator
3. damper winding on stator as well as rotor poles
4. none of the above

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7. A synchronous motor can be started by

1. pony motor
2. D.C. compound motor
3. providing damper winding
4. any of the above

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8. A synchronous motor can be used as a synchronous capacitor when it is

1. under-loaded
2. over-loaded
3. under-excited
4. over-excited

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9. A synchronous motor can develop synchronous torque

1. when under loaded
2. while over-excited
3. only at synchronous speed
4. below or above synchronous speed

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10. A synchronous motor can operate at

1. lagging power factor only
2. leading power factor only
3. unity power factor only
4. lagging, leading and unity power factors

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