| 1. | If the synchronous motor, properly synchronised to the supply is running on no load and is having negligible loss then ? | |
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the stator current will be zero
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the stator current will be very small
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the stator current will be very high
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the back e.m.f. will be more than the supply voltage
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Report Question| 2. | The armature current of the synchronous motor ? | |
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has large values for low excitation only
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has large values for high excitation only
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has large values for low and high excitation
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any of the above
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| 3. | A synchronous motor can operate at ? | |
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lagging power factor only
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leading power factor only
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unity power factor only
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lagging, leading and unity power factors
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| 4. | Higher the applied voltage ..... will be the stator flux and will be the pull in torque ? | |
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lower, lower
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lower, greater
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greater, lower
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greater, greater
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| 5. | ln a synchronous motor at the back e.m.f. generated in the armature at no load is approximately equal to the applied voltage, then ? | |
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the motor is said to be fully loaded
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the torque generated is maximum
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the excitation is said to be zero percent
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the excitation is said to be hundred per cent
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| 6. | If excitation 9f a synchronous motor running with a constant load is decreased from its normal value, ignoring effects of armature reaction, it leads to ? | |
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increase in both armature current and power factor angle
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increase in back e.m.f. but decrease in armature current
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increase fu both armature current and power factor which is lagging
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increase in torque angle but decrease in back e.m.f.
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| 7. | Slip rings are usually made of ? | |
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carbon or graphite
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brass or steel
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silver or gold
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copper or aluminium
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| 8. | The standard full-load power factor ratings for synchronous motors are ? | |
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zero or 0.8 leading
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unity or 0.8 lagging
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unity or 0.8 leading
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unity or zero
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| 9. | The oscillations in a synchronous motor can be damped out by ? | |
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maintaining constant excitation
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running the motor on leading power factors
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providing damper bars in the rotor pole faces
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oscillations cannot be damped
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| 10. | An over-excited synchronous motor takes ? | |
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leading current
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lagging current
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both (a) and (b)
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none of the above
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