| 1. | Ward-Leonard control is basically a ? | |
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voltage control method
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field divertor method
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field control method
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armature resistance control method
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Report Question| 2. | Speed control by Ward Leonard method gives uniform speed variation ? | |
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in one direction
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in both directions
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below normal speed only
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above normal speed only
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| 3. | Which one of the following is not the function of pole shoes in a D.C. machine ? | |
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To reduce eddy current loss
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To support the field coils
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To spread out flux for better uniformity
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To reduce the reluctance of the magnetic path
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| 4. | Which D.C. motor will be suitable along with flywheel for intermittent light and heavy loads ? | |
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Series motor
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Shunt motor
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Cumulatively compounded motor
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Differentially compounded motor
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| 5. | Starters are used with D.C. motors because ? | |
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these motors have high starting torque
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these motors axe not self starting
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back e.m.f. of these motors is zero initially
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to restrict armature current as there is no back e.m.f. while starting
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| 6. | Which of the following application requires high starting torque ? | |
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Lathe machine
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Centrifugal pump
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Locomotive
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Air blower
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| 7. | The condition for maximum power in case of dc motor is ? | |
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back e.m.f. = 2 x supply voltage
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back e.m.f. = 1/2 x supply voltage
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supply voltage = 1/2 x back e.m.f.
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supply voltage= back e.m.f.
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| 8. | The speed of a motor falls from 1100 r.p.m. at no-load to 1050 r.p.m at rated load. The speed regulation of the motor is ? | |
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2:36 %
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4.76%
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6. 77%
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8.4%
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| 9. | The condition for maximum efficiency for a D.C. generator is ? | |
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eddy current losses= stray losses
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hysteresis losses= eddy current losses
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copper losses = 0
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variable losses = constant losses
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| 10. | Which method of braking is generally used in elevators ? | |
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Plugging
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Regenerative braking
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Rheostatic braking
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Nope of the above
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