| 1. | In a D.C. generator all of the following could be the effects of iron losses except ? | |
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Loss of efficiency
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Excessive heating of core
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Increase in terminal voltage
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Rise in temperature of ventilating air
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Report Question| 2. | Regenerative braking on, shunt motors is used when ? | |
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the load is variable
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the load is constantly decreasing
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the load acts as a braking force
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the load bas overhauling characteristics
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| 3. | For constant torque drive which speed control method is preferred ? | |
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Field control
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Armature voltage control
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Shunt armature control
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Mechanical loading system
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| 4. | These days D.C. motors are widely used in ? | |
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pumping sets
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air compressors
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electric traction
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machine shops
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| 5. | Ward-Leonard system of speed control is not recommended for ? | |
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very low speeds
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frequent motor reversals
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wide speed range
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constant speed operation
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| 6. | Which of the following can be used to control the speed of a D.C. motor ? | |
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Thermistor
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Thyristor
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Thyratron
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Transistor
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| 7. | Which of the following motor is used in the locomotives motor drives ? | |
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D.C. series motor
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A.C. series motor
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Synchronous motor
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Induction motor
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| 8. | Which of the following motors is most suitable for signalling devices and many kinds of timers ? | |
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D.C. shunt motor
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D.C. series motor
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Induction motor
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Reluctance motor
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| 9. | Field winding of a D.C. series motor is usually provided with thick wire ? | |
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to provide large flux
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to reduce the use of insulating materials
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as it carries large load current
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in order to reduce eddy current
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| 10. | Which of the following steps is likely to result in reduction of hysteresis loss in a D.C. generator ? | |
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Providing laminations in armature core
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Providing laminations in stator
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Using non-magnetic material for frame
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Using material of low hysteresis coefficient for armature core material
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