Related Mcqs:

1. In Ns is the synchronous speed and s the slip, then actual running speed of an induction motor will be___________?

   A. Ns
   B. s.N,
   C. (l-s)Ns
   D. (Ns-l)s

2. Size of a high speed motor as compared to low speed motor for the same H.P. will be__________?

   A. bigger
   B. smaller
   C. same
   D. any of the above

3. Which of the following methods is easily applicable to control the speed of the squirrel-cage induction motor _____________?

   A. By changing the number of stator poles
   B. Rotor rheostat control
   C. By operating two motors in cascade
   D. By injecting e.m.f. in the rotor circuit

4. 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

5. The speed of a squirrel-cage induction motor can be controlled by all of the following except_____________?

   A. changing supply frequency
   B. changing number of poles
   C. changing winding resistance
   D. reducing supply voltage

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. An induction motor with 1000 r.p.m. speed will have____________?

   A. 8 poles
   B. 6 poles
   C. 4 poles
   D. 2 poles

8. A 500 kW, 3-phase, 440 volts, 50 Hz, A.C. induction motor has a speed of 960 r.p.m. on full load. The machine has 6 poles. The slip of the machine will be__________?

   A. 0.01
   B. 0.02
   C. 0.03
   D. 0.04

9. What will happen if the relative speed between the rotating flux of stator and rotor of the induction motor is zero ?

   A. The slip of the motor will be 5%
   B. The rotor will not run
   C. The rotor will run at very high speed
   D. The torque produced will be very large

10. An induction motor can run at synchronous speed when____________?

    A. it is run on load
    B. it is run in reverse direction
    C. it is run on voltage higher than the rated voltage
    D. e.m.f. is injected in the rotor circuit