701. If a D.C. motor is connected across the A.C. supply it will_______________?
A. run at normal speed
B. not run
C. run at lower speed
D. burn due to heat produced in the field winding by .eddy currents
702. To get the speed of D.C, motor below the normal without wastage of electrical energy is used?
A. Ward Leonard control
B. rheostatic control
C. any of the above method
D. none of the above method
703. When two D.C. series motors are connected in parallel, the resultant speed is____________?
A. more than the normal speed
B. loss than the normal speed
C. normal speed
D. zero
704. The speed of a D.C. shunt motor more than its full-load speed can be obtained by_____________?
A. decreasing the field current
B. increasing the field current
C. decreasing the armature current
D. increasing the armature current
705. In a D.C. shunt motor, speed is______________?
A. independent of armature current
B. directly proportional to the armature current
C. proportional to the square of the current
D. inversely proportional to the armature current
706. A direct on line starter is used: for starting motors___________?
A. up to 5 H.P
B. up to 10 H.P
C. up to 15 H.P
D. up to 20 H.P
707. What will happen if the back e.m.f. of a D.C. motor vanishes suddenly?
A. The motor will stop
B. The motor will continue to run
C. The armature may burn
D. The motor will run noisy
708. In case of D.C. shunt motors the speed is dependent on back e.m.f. only because____________?
A. back e.m.f. is equal to armature drop
B. armature drop is negligible
C. flux is proportional to armature current
D. flux is practically constant in D:C. shunt motors
709. In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be_____________?
A. almost negligible
B. rated full-load current
C. less than full-load current
D. more than full-load current
710. These days D.C. motors are widely used in____________?
A. pumping sets
B. air compressors
C. electric traction
D. machine shops
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