Usually wide and sensitive speed control is desired in case of____________?

Related Mcqs:

1. Following motor is used where high starting torque and wide speed range control is required?

   A. Single phase capacitor start
   B. Induction motor
   C. Synchronous motor
   D. D.C. motor
   E. None of the above

2. The ratio of starting torque to full-load torque is least in case of____________?

   A. series motors
   B. shunt motors
   C. compound motors
   D. none of the above

3. 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

4. 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

5. The speed of a motor falls from 1100 r.p.m. at no-load to 1050 r.p.m. at rated load. The speed regulation of the motor is______________?

   A. 2.36%
   B. 4.76%
   C. 6.77%
   D. 8.84%

6. The speed of a D.C. shunt motor is required to be more than full load speed. This is possible by______________?

   A. reducing the field current
   B. decreasing the armature current
   C. increasing the armature current
   D. increasing the excitation current
   E. none of the above methods

7. 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

8. Which of the following motors is usually used in house-hold refrigerators ?

   A. D.C. shunt motor
   B. D.C. series motor
   C. Single phase induction motor (split phase start or induction run motor)
   D. Reluctance motor
   E. Synchronous motor

9. If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will_________?

   A. increase
   B. decrease
   C. remain same
   D. become zero

10. In variable speed motor___________?

    A. a stronger commutating field is needed at low speed than at high speed
    B. a weaker commutating field is needed at low speed than at high speed
    C. same commutating field is needed at low speed than at high speed
    D. none of the above is correct