DC Motors Objective Questions and Answers - Set 01 - ObjectiveBooks

DC Motors Objective Questions and Answers - Set 01

Practice Test: Question Set - 01

1. A three point starter is considered suitable for
    (A) Shunt motors
    (B) Shunt as well as compound motors
    (C) Shunt, compound and series motors
    (D) All D.C. motors

2. Which D.C. motor has got maximum self loading property?
    (A) Series motor
    (B) Shunt motor
    (C) Cumulatively compounded motor
    (D) Differentially compounded motor

3. Sparking at the commutator of a D.C. motor may result in
    (A) Damage to commutator segments
    (B) Damage to commutator insulation
    (C) Increased power consumption
    (D) All of the above

4. Following motor is used where high starting torque and wide speed range control is required.
    (A) Single phase capacitor start
    (B) Induction motor
    (C) Synchronous motor
    (D) D.C. motor

5. The armature voltage control of D.C. motor provides
    (A) Constant torque drive
    (B) Constant voltage drive
    (C) Constant current drive
    (D) None of the above

6. Which one of the following is not necessarily the advantage of D.C. motors over A.C. motors?
    (A) Low cost
    (B) Wide speed range
    (C) Stability
    (D) High starting torque

7. If a D.C. motor designed for 40°C ambient temperature is to be used for 50°C ambient temperature, then the motor
    (A) Of lower H.P. should be selected
    (B) Of higher H.P. should be selected
    (C) Can be used for 50°C ambient temperature also
    (D) Is to be de-rated by a factor recommended by manufacturer and select the next higher H.P. motor

8. Which motor should not be started on no-load?
    (A) Series motor
    (B) Shunt motor
    (C) Cumulatively compounded motor
    (D) Differentially compounded motor

9. The losses occurring in a D.C. generator are given below. Which loss is likely to have highest proportion at rated load of the generator?
    (A) Hysteresis loss
    (B) Field copper loss
    (C) Armature copper loss
    (D) Eddy current loss

10. Which of the following losses are significantly reduced by laminating the core of a D.C. generator?
    (A) Hysteresis losses
    (B) Eddy current losses
    (C) Copper losses
    (D) Windage losses

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