Top 150+ Solved DC Motor MCQ Questions Answer
Q. 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
Q. 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.
Q. 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
Q. Which motor has the poorest speed control?
a. Differentially compounded motor
b. Cumulatively compounded motor
c. Shunt motor
d. Series motor
Q. 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
Q. In a differentially compounded D.C. motor, if shunt field suddenly opens
a. the motor will first stop and then run in opposite direction as series motor
b. the motor will work as series motor and run at slow speed in the same direction
c. the motor will work as series motor and run at high speed in the samedirection
d. the motor will not work and come to stop
Q. Buses, trains, trolleys, hoists, cranes require high starting torque and therefore make useof
a. D.C. series motor
b. D.C. shunt motor
c. induction motor
d. all of above motors
Q. Which of the following method of speed control of D.C. machine will offer minimumefficiency ?
a. Voltage control method
b. Field control method
c. Armature control method
d. All above methods
Q. The speed of a motor falls from 1100 r.p.m. at no-load to 1050 r.p.m. at rated load.The speed regulation of the motor is
a. 2.36%
b. 4.76%
c. 6.77%
d. 8.84%
Q. As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent aheavy current from flowing though the armature circuit
a. a resistance is connected in series with armature
b. a resistance is connected parallel to the armature
c. armature is temporarily open circuited
d. a high value resistor is connected across the fieldwinding
Q. At the instant of starting when a D.C. motor is put on supply, it behaveslike
a. a highly resistive circuit
b. a low resistance circuit
c. a capacitive circuit
d. none of the above
Q. Which motor has the poorest speed control?
a. Differentially compounded motor
b. Cumulatively compoundedmotor
c. Shunt motor
d. Series motor
Q. The plugging gives the
a. zero torque braking
b. smallest torque braking
c. highest torque braking
d. none of the above
Q. The plugging gives the
a. zero torque braking
b. smallest torque braking
c. highest torque braking
d. none of the above
Q. 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