Related Mcqs:

1. 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

2. 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

3. A 3-phase 440 V, 50 Hz induction motor has 4% slip. The frequency of rotor e.m.f. will be____________?

   A. 200 Hz
   B. 50 Hz
   C. 2 Hz
   D. 0.2 Hz

4. The number of slip rings on a squirrel cage induction motor is usually____________?

   A. two
   B. three
   C. four
   D. none

5. 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

6. Slip of an induction motor is negative when_____________?

   A. magnetic field and rotor rotate in opposite direction
   B. rotor speed is less than the synchronous speed of the field and are in the same direction
   C. rotor speed is more than the synchronous speed of the field and are in the same direction
   D. none of the above

7. The shape of the torque/slip curve of induction motor is__________?

   A. parabola
   B. hyperbola
   C. rectangular parabola
   D. straigth line

8. The stating torque of the slip ring induction motor can be increased by adding__________?

   A. external inductance to the rotor
   B. external resistance to the rotor
   C. external capacitance to the rotor
   D. both resistance and inductance to rotor

9. In induction motor, percentage slip depends on__________?

   A. supply frequency
   B. supply voltage
   C. copper losses in motor
   D. none of the above

10. In medium sized induction motors, the slip is generally around___________?

    A. 0.04%
    B. 0.4%
    C. 4%
    D. 14%