| 1. | The direction of rotation of a 3-phase induction motor can be reversed by ? | |
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interchanging any two phases
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supplying low voltage
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reducing load
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reducing frequency
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Report Question| 2. | If stator voltage of a squirrel cage induction motor is reduced to 50 percent of its rated value, torque developed is reduced by percent of its full load value. ? | |
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90
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50
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75
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25
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| 3. | The stator of 5 H.P. induction motor is provided with ? | |
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open slots with tapered teeth
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closed slots with parallel teeth
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semi closed slots with parallel teeth
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open slots with parallel teeth
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| 4. | Rotor rheostat control method of speed control is used for ? | |
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squirrel-cage induction motors only
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slip ring induction motors only
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both (a) and (b)
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none of the above
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| 5. | Speed variations of a squirrel cage induction motor are essentially similar to those of ? | |
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D.C. shunt motor
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D.C. series motor
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synchronous motor
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differential compound motor
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| 6. | The stator frame in an induction motor is used ? | |
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to protect the whole machine
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to ventilate the armature
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as a return path for the flux
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to hold the armature stampings stator
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| 7. | In moist surroundings which frame of motor will be preferred ? | |
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Open type
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Totally enclosed fan cooled
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Drip proof
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Splash proof
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| 8. | In case single phasing occurs in delta connected motor ? | |
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one phase will be seriously overloaded and two others will be slightly overloaded
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two phases will be seriously overloaded and there will be no current in the third phase
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there will be no current in one phase
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there will be no current in two phases
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| 9. | In an induction motor the pulsation losses and noise can be reduced by using ? | |
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large number of semi-open slots
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large number of narrow slots
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less number of narrow slots
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all of the above
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| 10. | What is the advantage of the double squirrel-cage rotor as compared to the round bar cage rotor ? | |
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The slip of the motor is larger
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The efficiency of the motor is higher
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The starting current of the motor is lower
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The power factor of the motor is higher
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