| 1. | If the field circuit of a loaded shunt motor is suddenly opened ? | |
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torque developed by the motor would be reduced to zero
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it would race to almost infinite speed
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it would draw abnormally high armature current
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the fuse or circuit breaker will open the circuit before too much damage is done to the motor
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Report Question| 2. | The purpose of retardation test on D.C. shunt machines is to find out ? | |
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stray losses
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eddy current losses
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field copper losses
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windage losses
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| 3. | A 230 V D.C. shunt motor takes 32 A at full load. The back e.m.f. on full load, if the resistance of motor armature and shunt field windings are 0.2 ? and 115 ? respectively, will be ? | |
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210 V
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215 V
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220 V
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224 V
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| 4. | What will happen if supply terminals of D.C. shunt motor are interchanged ? | |
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The direction of rotation will reverse
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Motor will stop
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Motor will run at speed lower than the normal speed in the same direction
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Motor will run at its normal speed in the same direction as it was running
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| 5. | In a motor, energy conversion would not have been possible but for the ? | |
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production of opposing back e.m.f. Eb in the armature
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input energy from supply
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use of commutator
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application of Fleming's left-hand rule
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| 6. | In a D.C. motor constant torque is produced due to ? | |
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rotor laminations
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end-plates
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pole shoes
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commutator
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| 7. | If conditions for maximum power for a D.C. motor are established, the efficiency of the motor will be ? | |
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less than 50%
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60 to 70%
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80 to 90%
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100%
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| 8. | Which of the following loss of D.C. motor decreases with increase in load ? | |
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Friction and windage loss
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Core Loss
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Brush contact loss
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none of the above
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| 9. | Speed control by the variation of flux, in a D.C. shunt motor, will give ? | |
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constant torque drive
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variable torque drive
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constant power drive
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variable power drive
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| 10. | In variable speed motor ? | |
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a stronger commutating field is needed at low speed than at high speed
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a weaker commutating field is needed at low speed than at high speed
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same commutating field is needed at low speed than at high speed
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none of the above is correct
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