MCQ online Practice Test on DC Motors - Set 10 - ObjectiveBooks

# Practice Test: Question Set - 10

1. Which D.C. motor will be suitable along with flywheel for intermittent light and heavy loads?
(A) Series motor
(B) Shunt motor
(C) Cumulatively compounded motor
(D) Differentially compounded motor

2. Which D.C. motor is generally preferred for cranes and hoists?
(A) Series motor
(B) Shunt motor
(C) Cumulatively compounded motor
(D) Differentially compounded motor

3. For a D.C. shunt motor if the excitation is changed
(A) Torque will remain constant
(B) Torque will change but power will remain constant
(C) Torque and power both will change
(D) Torque, power and speed, all will change

4. The hysteresis loss in a D.C. machine least depends on
(A) Frequency of magnetic reversals
(B) Maximum value of flux density
(C) Volume and grade of iron
(D) Rate of flow of ventilating air

5. D.C. motor is to drive a load which has certain minimum value for most of the time and some peak value for short duration. We will select the
(A) Series motor
(B) Shunt motor
(C) Compound motor
(D) Any of the above

6. If the field of a D.C. shunt motor gets opened while motor is running
(A) The speed of motor will be reduced %
(B) The armature current will reduce
(C) The motor will attain dangerously high speed 1
(D) The motor will continue to run at constant speed

7. The ratio of starting torque to full-load torque is least in case of
(A) Series motors
(B) Shunt motors
(C) Compound motors
(D) None of the above

8. For which of the following applications a D.C. motor is preferred over an A.C. motor?
(A) Low speed operation
(B) High speed operation
(C) Variable speed operation
(D) Fixed speed operation

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

10. The condition for maximum efficiency for a D.C. generator is
(A) Eddy current losses = stray losses
(B) Hysteresis losses = eddy current losses
(C) Copper losses = 0
(D) Variable losses = constant losses

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