It is advisable to avoid line starting of induction motor and use starter because____________?

Related Mcqs:

1. It is advisable to avoid line-starting of induction motor and use starter because__________?

   A. motor takes five to seven times its full load current
   B. it will pick-up very high speed and may go out of step
   C. it will run in reverse direction
   D. starting torque is very high

2. In a star-delta starter of an induction motor___________?

   A. resistance is inserted in the stator
   B. reduced voltage is applied to the stator
   C. resistance is inserted in the rotor
   D. applied voltage perl stator phase is 57.7% of the line voltage

3. The starting torque of a squirrel-cage induction motor is___________?

   A. low
   B. negligible
   C. same as full-load torque
   D. slightly more than full-load torque

4. The starting torque of a 3-phase squirrel cage induction motor is____________?

   A. twice the full load torque
   B. 1.5 times the full load torque
   C. equal to full load torque

5. The starting torque of a three phase induction motor can be increased by__________?

   A. increasing slip
   B. increasing current
   C. both A. and (b)
   D. none of the above

6. Slip ring motor is preferred over squirrel cage induction motor where___________?

   A. high starting torque is required
   B. load torque is heavy
   C. heavy pull out torque is required
   D. all of the above

7. DOL starting of induction motors is usually restricted to_____________?

   A. low horsepower motors
   B. variable speed motors
   C. high horsepower motors
   D. high speed motors

8. Reduced voltage starter can be used with_____________?

   A. slip ring motor only but not with squirrel cage induction motor
   B. squirrel cage induction motor only but not with slip ring motor
   C. squirrel cage as well as slip ring induction motor
   D. none of the above

9. Stepless speed control of induction motor is possible by which of the following methods ?

   A. e.m.f. injection in rotor eueuit
   B. Changing the number of poles
   C. Cascade operation
   D. None of the above

10. The torque developed by a 3-phase induction motor least depends on__________?

    A. rotor current
    B. rotor power factor
    C. rotor e.m.f.
    D. shaft diameter