Theory Practice Test on DC Motors - Set 06

Practice Test: Question Set - 06


1. The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is
    (A) 4.0
    (B) 2.0
    (C) 1.0
    (D) 0.5

2. Which of the following motor has the poorest speed regulation?
    (A) Shunt motor
    (B) Series motor
    (C) Differential compound motor
    (D) Cumulative compound motor

3. The speed of a D.C. motor can be varied by varying
    (A) Field current
    (B) Applied voltage
    (C) Resistance in series with armature
    (D) Any of the above

4. Which of the following motors is usually used in household refrigerators?
    (A) D.C. shunt motor
    (B) D.C. series motor
    (C) Single phase induction motor (split phase start or induction run motor)
    (D) Reluctance motor

5. Which of the following loss in a D.C. generator varies significantly with the load current?
    (A) Field copper loss
    (B) Windage loss
    (C) Armature copper loss
    (D) None of the above

6. Hopkinson's test on D.C. machines is conducted at
    (A) No load
    (B) Part load
    (C) Full load
    (D) Overload

7. The speed of a D.C. shunt motor is required to be more than full load speed. This is possible by
    (A) Reducing the field current
    (B) Decreasing the armature current
    (C) Increasing the armature current
    (D) Increasing the excitation current

8. The speed of a D.C. shunt motor more than its full-load speed can be obtained by
    (A) Decreasing the field current
    (B) Increasing the field current
    (C) Decreasing the armature current
    (D) Increasing the armature current

9. In D.C. motor which of the following can sustain the maximum temperature rise?
    (A) Slip rings
    (B) Commutator
    (C) Field winding
    (D) Armature winding

10. D.C. series motors are used
    (A) Where load is constant
    (B) Where load changes frequently
    (C) Where constant operating speed is needed
    (D) In none of the above situations

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Item Reviewed: Theory Practice Test on DC Motors - Set 06 Rating: 5 Reviewed By: Pranab Debnath
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