| 1. | The low power factor of induction motor is due to ? | |
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rotor leakage reactance
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stator reactance
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the reactive lagging magnetizing current necessary to generate the magnetic flux
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all of the above
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Report Question| 2. | Out of the following methods of starting a 3-phase induction motor, which one requires six stator terminals ? | |
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Direct-on-line
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Star-delta
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Auto-transformer
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Rotor rheostat
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| 3. | If single-phasing occurs on the running position in an induction motor, the motor will ? | |
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fail to carry load
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produce peculiar noise
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draw unbalanced and excessive currents
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not start
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| 4. | Which of the following statement about a double squirrel cage induction motor is incorrect ? | |
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It has better speed regulation than squirrel cage motor
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Its upper cage is of low resistance and lower cage of high resistance
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It is particularly useful where frequent starting under heavy loads is required
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It maintains high efficiency during normal operating conditions
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| 5. | When an induction motor is switched on the rotor frequency is ? | |
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zero
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60 Hz
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same as slip frequency
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same as supply frequency
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| 6. | Synchronous wattage of induction motor means ? | |
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stator input in watts
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motor input fan watts
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combined stator and rotor input in watts
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shaft output in watts
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| 7. | The noise and tooth pulsation losses can be minimised by using ? | |
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Large number of narrow slots in stator
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large number of open slots in stator
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small number of narrow slots in stator
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small number of open slots in stator
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| 8. | What is the function of putting resistance in parallel to one phase of 3-phase induction motor ? | |
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To attain a higher starting torque
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To achieve a smooth starting
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To reduce the starting current to a very low value
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To attain a higher maximum torque
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| 9. | In an induction motor if air-gap is increased ? | |
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the power factor will be low
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windage losses will be more
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bearing friction will reduce
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copper loss will reduce
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| 10. | A 3-phase slip ring motor has ? | |
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double cage rotor
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wound rotor
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short-circuited rotor
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any of the above
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