| 1. | The operating speed of a synchronous motor can be changed to new fixed value by ? | |
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changing the load
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changing the supply voltage
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changing frequency
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using brakes
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Report Question| 2. | The shaft of synchronous motor is made of ? | |
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mild steel
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chrome steel
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alnico
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stainless steel
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| 3. | In case one phase of a· three-phase synchronous motor is short-circuited the motor will ? | |
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not start
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run at 2/3 of synchronous speed
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run with excessive vibrations
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take less than the rated load
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| 4. | A three-phase synchronous motor will have ? | |
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no slip-rings
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one slip-ring
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two slip-rings
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three slip-rings
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| 5. | A pony motor is basically a ? | |
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small induction motor
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D.C. series motor
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D.C. shunt motor
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double winding AC./D.C. motor
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| 6. | A synchronous motor can be started by ? | |
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pony motor
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D.C. compound motor
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providing damper winding
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any of the above
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| 7. | The power developed by a synchronous motor will be maximum when the load angle is ? | |
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zero
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45º
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90°
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120º
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| 8. | The synchronous motor is not inherently self-starting because ? | |
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The force required to accelerate the rotor to the synchronous speed in an instant is absent
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the starting device to accelerate the rotor to near synchronous speed is absent
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a rotating magnetic field does not have enough poles
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the rotating magnetic field is produced by only 60 Hz frequency currents
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| 9. | The minimum armature current of the synchronous motor corresponds to operation at ? | |
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zero power factor leading
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unity power factor
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0.707 power factor lagging
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0.707 power factor leading
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| 10. | The back e.m.f of a synchronous motor depends on ? | |
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speed
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load
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load angle
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all of the above
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