D.C. Motors

91. Ward-Leonard control is basically a

1. voltage control method
2. field divertor method
3. field control method
4. armature resistance control method

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92. What will happen if the back e.m.f. of a D.C. motor vanishes suddenly?

1. The motor will stop
2. The motor will continue to run
3. The armature may burn
4. The motor will run noisy

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93. When the armature of a D.C. motor rotates, e.m.f. induced is

1. self-induced e.m.f.
2. mutually induced e.m.f.
3. back e.m.f.
4. none of the above

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94. When two D.C. series motors are connected in parallel, the resultant speed is

1. more than the normal speed
2. loss than the normal speed
3. normal speed
4. zero

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95. Where D.C. motor of H.P. 12 or more requires frequent starting, stopping, reversing and speed control

1. drum type controller is used
2. three point starter is used
3. four point starter is used
4. all above can be used

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96. Which D.C. motor has got maximum self loading property?

1. Series motor
2. Shunt motor
3. Cumulatively compounded ‘motor
4. Differentially compounded motor

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97. Which D.C. motor has got maximum self relieving property?

1. Series motor
2. Shunt motor
3. Cumulatively compounded motor
4. Differentially compounded motor

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98. Which D.C. motor is generally preferred for cranes and hoists?

1. Series motor
2. Shunt motor
3. Cumulatively compounded motor
4. Differentially compounded motor

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99. Which D.C. motor is preferred for elevators?

1. Shunt motor
2. Series motor
3. Differential compound motor
4. Cumulative compound motor

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100. Which D.C. motor will be preferred for machine tools?

1. Series motor
2. Shunt motor
3. Cumulative compound motor
4. Differential compound motor

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