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.Management Sciences
Category: D.C. Motors
D.C. generators are normally designed for maximum efficiency around_____________?
A. full-load
B. rated r.p.m.
C. rated voltage
D. all of the above
Which of the following motors is most suitable for signalling devices and many kinds of timers ?
A. D.C. shunt motor
B. D.C. series motor
C. Induction motor
D. Reluctance 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
Which of the following motor has the poorest speed regulation ?
A. Shunt motor
B. Series motor
C. Differential compound motor
D. Cumulative compound motor
These days D.C. motors are widely used in____________?
A. pumping sets
B. air compressors
C. electric traction
D. machine shops
Which D.C. motor is preferred for elevators ?
A. Shunt motor
B. Series motor
C. Differential compound motor
D. Cumulative compound motor
The speed of a D.C. series motor is_____________?
A. proportional to the armature current
B. proportional to the square of the armature current
C. proportional to field current
D. inversely proportional to the armature current
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
During rheostat braking of D.C. series motors_____________?
A. motor is run as a generator
B. motor is reversed in direction
C. motor is run at reduced speed
The type of D.C. motor used for shears and punches is_____________?
A. shunt motor
B. series motor
C. differential compoutid D.C. motor
D. cumulative compound D.C. motor
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