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Electrical Engineering Objective Questions { DC Motors }

204.  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
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205.  Which of the following motor has the Poorest speed regulation?
A. Shunt motor
B. Series motor
C. Differential compound motor
D. Cumulative compound motor
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206.  Buses, trains, trolleys, hoists, cranes require high starting torque and therefore make use of
A. D.C. series motor
B. D.C. shunt motor
C. Induction motor
D. All of above motors
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207.  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
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208.  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
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209.  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
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210.  Usually wide and sensitive speed control is desired in case of
A. centrifugal pumps
B. elevators
C. steel rolling mills
D. colliery winders
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