The plugging gives the____________?

Related Mcqs:

1. 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

2. Kingdom Protoctista includes_______________?

   A. Prokaryotic organisms
   B. Unicellular organisms
   C. Fungi
   D. Eu-cariotiquic organisms

3. If a D.C. motor is to be selected for conveyors, which rriotor would be preferred ?

   A. Series motor
   B. Shunt motor
   C. Differentially compound motor
   D. Cumulative compound motor

4. 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

5. In a D.C. series motor, if the armature current is reduced by 50%, the torque of the motor will be equal to

   A. 100% of the previous value
   B. 50% of the previous value
   C. 25% of the previous value
   D. 10% of the previous value
   E. none of the above

6. 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

7. As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent a heavy current from flowing though the armature circuit____________________?

   A. a resistance is connected in series with armature
   B. a resistance is connected parallel to the armature
   C. armature is temporarily open circuited
   D. a high value resistor is connected across the field winding

8. 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

9. 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

10. If a D.C. shunt motor is working at full load and if shunt field circuit suddenly opens____________?

    A. this will make armature to take heavy current, possibly burning it
    B. this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses
    C. nothing will happen to motor
    D. motor will come to stop