Top 150+ Solved DC Motor MCQ Questions Answer
Q. Which of the following law/rule can he used to determine the direction of rotationofD.C. motor ?
a. Lenz's law
b. Faraday's law
c. Coloumb'slaw
d. Fleming's left-hand rule
Q. Which of the following load normally needs starting torque more than theratedtorque?
a. Blowers
b. Conveyors
c. Air compressors
d. Centrifugal pumps
Q. In a D.C. series motor, if the armature current is reduced by 50%, the torque of themotor will be equal to
a. 100% of the previous value
b. 50% of the previous value
c. 25% of the previous value
d. 10% of the previous value
Q. Which D.C. motor will be suitable alongwith flywheel for intermittent light andheavyloads?
a. Series motor
b. Shunt motor
c. Cumulatively compounded motor
d. Differentially compounded motor
Q. In case of conductively compensated D.C. series motors, the compensating winding is provided
a. as separately wound unit
b. in parallel with armature winding
c. in series with armature winding
d. in parallel with field winding
Q. If the supply voltage for a D.C. motor is increased, which of the following willdecrease?
a. Starting torque
b. Operating speed
c. Full-load current
d. All of the above
Q. 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
Q. In D.C. machines the residual magnetism is of the order of
a. 2 to 3 per cent
b. 10 to 15 per cent
c. 20 to 25 per cent
d. 50 to 75 per cent
Q. In D.C. machines the residual magnetism is of the order of
a. 2 to 3 per cent
b. 10 to 15 per cent
c. 20 to 25 per cent
d. 50 to 75 per cent
Q. 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
Q. Three point starter can be used for
a. series motor only
b. shunt motor only
c. compound motor only
d. both shunt and compound motor
Q. Sparking, is discouraged in a D.C. motor because
a. it increases the input power con-sumption
b. commutator gets damaged
c. both (a) and (b)
d. none of the above
Q. Speed control by Ward Leonard method gives uniform speed variation
a. in one direction
b. in both directions
c. below normal speed only
d. above normal speed only.
Q. Flywheel is used with D.C. compound motor to reduce the peak demand by the motor,compound motor will have to be
a. level compounded
b. under compounded
c. cumulatively compounded
d. differentially compounded