| 1. | Short-circuit test on an induction motor cannot be used to determine ? | |
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windage losses
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copper losses
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transformation ratio
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power scale of circle diagram
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Report Question| 2. | Reduced voltage starter can be used with ? | |
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slip ring motor only but not with squirrel cage induction motor
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squirrel cage induction motor only but not with slip ring motor
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squirrel cage as well as slip ring induction motor
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none of the above
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| 3. | The efficiency of an induction motor is ...... than that of a transformer ? | |
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lower
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higher
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either of the above
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none of the above
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| 4. | Which of the following AC. motors is used for industrial application ? | |
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Commutator motor
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3-phase induction motor
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D.C. series motor
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Synchronous motor
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| 5. | If stator voltage of a squirrel cage induction motor is reduced to one-half its. normal value, its starting current is reduced to ... .. percent of its full voltage value ? | |
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75
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60
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50
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15
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| 6. | Whenever any polyphase induction motor is loaded ? | |
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induced e.m.f. decreases and frequency increases
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induced e.m.f. in the rotor remains constant
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induced e.m.f. in the rotor increases and its frequency also increases
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induced e.m.f. in the rotor increases and its frequency falls
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| 7. | During starting if an induction motor hums, the probable cause could be ? | |
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open circuit
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unequal phase resistance
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inter-turn short circuit on rotor
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any of the above
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| 8. | The probable reason for an induction motor running too hot could be ? | |
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low voltage
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uneven air gap
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clogged ventilating ducts
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any of the above
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| 9. | In the squirrel-cage induction motor the rotor slots are usually given slight skew ? | |
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reduce the magnetic hum and locking tendency of the rotor
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to increase the tensile strength of the rotor bars
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to ensure easy fabrication
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none of the above
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| 10. | In case of 3-phase induction motors, plugging means ? | |
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pulling the motor directly on line without a starter
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tocking of rotor due to harmonic
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starting the motor on load which is more than the rated load
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interchanging two supply phases for quick stopping
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