Top 350+ Solved Electrical Machine 1 MCQ Questions Answer
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. Sparking at the commutator of a D.C. motor may result in
a. damage to commutator segments
b. damage to commutator insulation
c. increased power consumption
d. all of the above
Q. Which of the following motor is preferred for operation in highly explosiveatmosphere ?
a. Series motor
b. Shunt motor
c. Air motor
d. Battery operated motor
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. Which one of the following is not the function of pole shoes in a D.C. machine ?
a. To reduce eddy current loss
b. To support the field coils
c. To spread out flux for better unifor-mity
d. To reduce the reluctance of the mag-netic path
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. 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
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