For constant torque drive which speed control method is preferred ?

Related Mcqs:

1. 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

2. Which of the following load normally needs starting torque more than the rated torque?

   A. Blowers
   B. Conveyors
   C. Air compressors
   D. Centrifugal pumps

3. 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

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 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

6. 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%

7. 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

8. Which of the following application requires high starting torque ?

   A. Lathe machine
   B. Centrifugal pump
   C. Locomotive
   D. Air blower

9. 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

10. Torque developed by a D.C. motor depends upon_____________?

    A. magnetic field
    B. active length of the conductor
    C. current flow through the conductors
    D. number of conductors
    E. radius of armature
    F. all above factors