| 1. | Which of the following statements is correct regarding a 3-phase motor ? | |
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Its magnetic flux alternates at the supply frequency
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lt is cheap, robust and needs no skilled maintenance
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Stator is externally connected rotor
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Three-phase supply is usually connected to its rotor
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Report Question| 2. | The speed of a three-phase cage-rotor induction motor depends on ? | |
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number of poles only
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input voltage
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frequency of supply only
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number of poles and frequency of the supply
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| 3. | The overheating of an induction motor maybe due to ? | |
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overloading
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loss of ventilation
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low supply voltage
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any of the above
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| 4. | Which of the following statements is correct about an induction motor ? | |
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It is self starting with high torque
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It is self starting with zero torque
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It is self starting with small torque as compared to rated torque
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None of the above
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| 5. | The upper bars in a double squirrel cage induction motor have ? | |
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low resistance and high reactance
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high resistance and high reactance
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high resistance and low reactance
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low resistance and low reactance
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| 6. | The fractional slip of an induction motor is the ratio ? | |
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rotor copper loss/rotor output
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rotor copper loss/rotor input
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rotor copper loss/stator copper loss
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stator copper loss/stator input
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| 7. | The rotor of an induction motor runs at ? | |
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synchronous speed
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below synchronous speed
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above synchronous speed
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any of the above
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| 8. | Blocked rotor test on induction motors is used to find out ? | |
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leakage reactance
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power factor on short circuit
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short-circuit current under rated voltage
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all of the above
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| 9. | The value of transformation ratio of an induction motor can be found by ? | |
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open-circuit test only
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short-circuit test only
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stator resistance test
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none of the above
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| 10. | Star-delta starting of motors is not possible in case of ? | |
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single phase motors
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variable speed motors
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low horse power motors
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high speed motors
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