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

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

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

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

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

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

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

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 uniformity
D. To reduce the reluctance of the magnetic path

If the supply voltage for a D.C. motor is increased, which of the following will decrease ?

A. Starting torque
B. Operating speed
C. Full-load current
D. All of the above

Which of the following motor is preferred for operation in highly explosive atmosphere ?

A. Series motor
B. Shunt motor
C. Air motor
D. Battery operated motor