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.Management Sciences
Category: D.C. Motors
If I2 be the armature current, then speed of a D.C. shunt motor is_______________?
A. independent of Ia
B. proportional to la
C. varies as (Ia)
D. varies as la
The direction of rotation of a D.C. series motor can be changed by___________?
A. interchanging supply terminals
B. interchanging field terminals
C. either of A. and B. above
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
The power mentioned on the name plate of an electric motor indicates____________?
A. the power drawn in kW
B. the power drawn in kVA
C. the gross power
D. the output power available at the shaft
A dc series motor should not be started on no load because it would___________?
A. not develop starting torque
B. fail to start without load
C. run at dangerously high speed
D. draw more current without producing sufficient torque
D.C. motor is to a drive a load which is almost nil for certain part of the load cycle and peak value for short duration. We will select this______________?
A. series motor
B. shunt motor
C. compound motor
D. any of the above
With the increase in temperature, the speed of DC series motor______________?
A. decreases
B. increases
C. remain same
D. none of the above
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
If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens__________?
A. nothing will happen to the motor
B. this will make armature to take heavy current, possibly burning it
C. this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses D. motor will run at very slow speed
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