Top 150+ Solved DC Motor MCQ Questions Answer
Q. If the terminals of armature of D.C. motor are interchanged, this action will offerfollowing kind of braking
a. regenerative
b. plugging
c. dynamic braking
d. none of the above
Q. Which of the following motors one will choose to drive the rotary compressor ?
a. D.C. shunt motor
b. D.C. series motor
c. Universal motor
d. Synchronous motor
Q. If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will
a. increase
b. decrease
c. remain same
d. become zero
Q. Why are the D.C. motors preferred for traction applications ?
a. Torque and speed are inversely proportional to armature current
b. Torque is proportional to armature current
c. Torque is proportional to square root of armature current
d. The speed is inversely proportional to the torque and the torque is proportional to square of armature current
Q. Which of the following motors is usually used in house-hold 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
Q. Which of the following motors is most suitable for signalling devices and many kindsof timers ?
a. D.C. shunt motor
b. D.C. series motor
c. Induction motor
d. Reluctance motor
Q. Which motor should not be started on no-load ?
a. Series motor
b. Shunt motor
c. Cumulatively compounded motor
d. Differentially compounded motor.
Q. Ward-Leonard control is basically a
a. voltage control method
b. field divertor method
c. field control method
d. armature resistance control method
Q. For constant torque drive which speed control method is preferred ?
a. Field control
b. Armature voltage control
c. Shunt armature control
d. Mechanical loading system
Q. In Ward-Leonard control the lower limit of speed is imposed by
a. residual magnetism of the generator
b. core losses of motor
c. mechanical losses of motor and gen¬erator together
d. all of the above
Q. The main disadvantage of the Ward-Leonard control method is
a. high initial cost
b. high maintenance cost
c. low efficiency at Hght loads
d. all of the above
Q. Regenerative method of braking is based on that
a. back e.m.f. is less than the applied voltage
b. back e.m.f. is equal to the applied voltage
c. back e.m.f. of rotor is more than the applied voltage
d. none of the above
Q. 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
Q. 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
Q. The losses occurring in a D.C. generator are given below. Which loss is likely to havehighest proportion at rated load of the generator ?
a. hysteresis loss
b. field copper loss
c. armature copper loss
d. eddy current loss