Top 150+ Solved DC Motor MCQ Questions Answer
Q. Following motor is used where high starting torque and wide speed range control isrequired.
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 same direction
d. the motor will not work and come to stop
Q. Which of the following motor has the poorest speed regulation ?
a. Shunt motor
b. Series motor
c. Differential compound motor
d. Cumulative compound motor
Q. Buses, trains, trolleys, hoists, cranes require high starting torque and therefore makeuse of
a. D.C. series motor
b. D.C. shunt motor
c. induction motor
d. all of above motors
Q. As -the load is increased the speed of D.C. shunt motor will
a. reduce slightly
b. increase slightly
c. increase proportionately
d. remains unchanged
Q. The armature torque of the D.C. shunt motor is proportional to
a. field flux only
b. armature current only
c. both (a) and (b)
d. none of the above
Q. Which of the following method of speed control of D.C. machine will offer minimum efficiency ?
a. Voltage control method
b. Field control method
c. Armature control method
d. All above methods
Q. Usually wide and sensitive speed control is desired in case of
a. centrifugal pumps
b. elevators
c. steel rolling mills
d. colliery winders
Q. The speed of a motor falls from 1100 r.p.m. at no-load to 1050 r.p.m. at rated load. Thespeed regulation of the motor is
a. 2.36%
b. 4.76%
c. 6.77%
d. 8.84%
Q. 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
Q. As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent a heavy 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 field winding
Q. The speed of a D.C. shunt motor can be increased by
a. increasing the resistance in armature circuit
b. increasing the resistance in field circuit
c. reducing the resistance in the field circuit
d. reducing the resistance in the armature circuit
Q. If I2 be the armature current, then speed of a D.C. shunt motor is
a. independent of Ia
b. proportional to la
c. varies as (Ia)
d. varies as la
Q. In case the back e.m.f. and the speed of a D.C. motor are doubled, the torque developedby the motor will
a. remain unchanged
b. reduce to one-fourth value
c. increase four folds
d. be doubled
Q. At the instant of starting when a D.C. motor is put on supply, it behaves like
a. a highly resistive circuit
b. a low resistance circuit
c. a capacitive circuit
d. none of the above