| 1. | The 'crawling' in an induction motor is caused by ? | |
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high loads
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low voltage supply
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improper design of machine
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harmonics developed in the motor
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Report Question| 2. | An induction motor is ? | |
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self-starting with zero torque
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self-starting with high torque
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self-starting with low torque
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non-self starting
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| 3. | lt is advisable to avoid line-starting of induction motor and use starter because ? | |
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motor takes five to seven times its full load current
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it will pick-up very high speed and may go out of step
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it will run in reverse direction
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starting torque is very high
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| 4. | The injected e.m.f. in the rotor of induction motor must have ? | |
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zero frequency
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the same frequency as the slip frequency
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the same phase as the rotor e.m.f.
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high value for the satisfactory speed control
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| 5. | Which of the following component is usually fabricated out of silicon steel ? | |
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Bearings
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Shaft
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Stator core
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None of the above
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| 6. | In three-phase squirrel-cage induction motors ? | |
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rotor conductor ends are short circuited through slip rings
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rotor conductors are short-circuited through end rings
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rotor conductors are kept open
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rotor conductors are connected to insulation
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| 7. | DOL starting of induction motors is usually restricted to ? | |
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low horse power motors
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variable speed motors
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high horsepower motors
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high speed motors
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| 8. | A pump induction motor is switched on to a supply 30% lower than its rated voltage. The pump runs. What will eventually happen ? It will ? | |
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stall after sometime
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stall immediately
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continue to run at lower speed without damage
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get heated and subsequently get damaged
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| 9. | In a three-phase induction motor ? | |
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iron losses in stator will be negligible as compared to that in rotor
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iron losses in motor will be negligible as compared to that in rotor
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iron losses in stator will be less than that in rotor
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iron losses in stator will be more than that in rotor
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| 10. | A 500 kW, 3-phase, 440 volts, 50 Hz, A C. induction motor has a speed of 960 r.p.m. on full load. The machine has 6 poles. The slip of the machine will be ? | |
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0.01
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0.02
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0.03
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0.04
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