| 1. | ln a synchronous motor which loss varies with load ? | |
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Windage loss
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Bearing friction loss
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Copper loss
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Core loss
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Report Question| 2. | A synchronous motor will always stop when ? | |
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supply voltage fluctuates
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load in motor varies
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excitation winding gets disconnected
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supply voltage frequency changes
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| 3. | When the stator windings are connected in such a fashion that the number of poles are made half, the speed of the rotor of a synchronous motor ? | |
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remains same as the original value
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decreases to half the original value
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tends to becomes zero
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increases to two times the original value
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| 4. | When the voltage applied to a synchronous motor is increased, which of the following will reduce ? | |
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Stator flux
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Pull in torque
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Both (a) and (b)
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None of the above
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| 5. | While starting a synchronous motor by induction motor action, field winding is usually ? | |
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connected to D.C. supply
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short-circuited by low resistance
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kept open-circuited
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none of the above
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| 6. | A synchronous motor is running with normal excitation. When the load is increased, the armature current drawn by it increases because ? | |
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speed of the motor is reduced
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power factor is decreased
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Eb (back e.m.f.) becomes less than V (applied voltage)
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Er (net resultant voltage) in armature is increased
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| 7. | If one-phase of a 3-phase synchronous motor is short-circuited, motor ? | |
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will refuse to start
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will overheat in spots
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will not come up to speed
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will fail to pull into step
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| 8. | If the field winding of an unloaded salient pole synchronous motor is open circuited, the motor will ? | |
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stop
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run as induction motor
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function as static condenser
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burn with dense smoke
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| 9. | Exciters of synchronous machines are ? | |
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d.c. shunt machines
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d.c. series machines
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d.c. compound machines
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any of the above
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| 10. | In a synchronous motor, V-curves represent relation between ? | |
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armature current and field current
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power factor and speed
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field current and speed
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field current and power factor
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