DC Motors Electrical Engineering MCQ - Set 09 - ObjectiveBooks
DC Motors Electrical Engineering MCQ - Set 09

DC Motors Electrical Engineering MCQ - Set 09

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Practice Test: Question Set - 09

1. If the terminals of armature of D.C. motor are interchanged, this action will offer following kind of braking
    (A) Regenerative
    (B) Plugging
    (C) Dynamic braking
    (D) None of the above
2. D.C. shunt motors are used for driving
    (A) Trains
    (B) Cranes
    (C) Hoists
    (D) Machine tools
3. During rheostat braking of D.C. series motors
    (A) Motor is run as a generator
    (B) Motor is reversed in direction
    (C) Motor is run at reduced speed
    (D) None of these
4. Which D.C. motor is preferred for elevators?
    (A) Shunt motor
    (B) Series motor
    (C) Differential compound motor
    (D) Cumulative compound motor
5. In case of D.C. shunt motors the speed is dependent on back e.m.f. only because
    (A) Back e.m.f. is equal to armature drop
    (B) Armature drop is negligible
    (C) Flux is proportional to armature current
    (D) Flux is practically constant in D.C. shunt motors
6. The current drawn by the armature of D.C. motor is directly proportional to
    (A) The torque required
    (B) The speed of the motor
    (C) The voltage across the terminals
    (D) None of the above
7. Sparking, is discouraged in a D.C. motor because
    (A) It increases the input power consumption
    (B) Commutator gets damaged
    (C) Both (A) and (B)
    (D) None of the above
8. Which motor has the poorest speed control?
    (A) Differentially compounded motor
    (B) Cumulatively compounded motor
    (C) Shunt motor
    (D) Series motor
9. In a D.C. generator all of the following could be the effects of iron losses except
    (A) Loss of efficiency
    (B) Excessive heating of core
    (C) Increase in terminal voltage
    (D) Rise in temperature of ventilating air
10. By looking at which part of the motor, it can be easily confirmed that a particular motor is D.C. motor?
    (A) Frame
    (B) Shaft
    (C) Commutator
    (D) Stator
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