| 1. | In a 3-phase synchronous motor, the negative phase sequence exists when the motor is ? | |
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supplied with unbalanced voltage
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under-loaded
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over-loaded
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none of the above
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Report Question| 2. | ln which of the following motors the stator and rotor fields rotate simultaneously ? | |
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D.C. motor
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Reluctance motor
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Universal motor
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Synchronous motor
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| 3. | The power factor of a synchronous motor is better than that of induction motor because ? | |
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stator supply is relieved of responsibility of producing magnetic field
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mechanical load on the motor can be adjusted
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synchronous motor runs at synchronous speed
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synchronous motor has large air gap
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| 4. | Synchronous motors are ? | |
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not self starting
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self-starting
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essentially self-starting
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none of the above
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| 5. | Armature of a synchronous machine is kept fixed because ? | |
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of reducing number of slip rings on the rotor
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armature is associated with large power as compared to the field circuits
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of difficulty of providing high voltage insulation on rotor
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all of the above reasons
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| 6. | Stability of a synchronous machine ? | |
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decreases with increase in its excitation
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increases with increase in its excitation
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remains unaffected with increase in excitation
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any of the above
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| 7. | A rotory converter can also be run as a ? | |
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d.c. shunt motor
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d.c. series motor
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d.c. compound motor
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synchronous motor
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| 8. | The effect of increasing the load on a synchronous motor running with normal excitation is to ? | |
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decrease both armature current and power factor
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decrease armature current but increase power factor
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increase armature current but decrease power factor
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increase both its armature current and power factor
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| 9. | If the field of a synchronous motor is under-excited, the power factor will be ? | |
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zero
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unity
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lagging
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leading
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| 10. | The back e.m.f. in the stator of a synchronous motor depends on ? | |
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number of poles
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flux density
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rotor speed
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rotor excitation
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