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

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. 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

3. Low voltage at motor terminals is due to____________?

   A. inadequate motor wiring
   B. poorely regulated power supply
   C. any one of the above
   D. none of the above

4. The low power factor of induction motor is due to___________?

   A. rotor leakage reactance
   B. stator reactance
   C. the reactive lagging magnetizing current necessary to generate the magnetic flux
   D. all of the above

5. 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

6. 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

7. If an induction motor with certain ratio of rotor to stator slots, runs at 1/7 of the normal speed, the phenomenon will be termed as____________?

   A. humming
   B. hunting
   C. crawling
   D. cogging

8. The speed characteristics of an induction motor closely resemble the speedload characteristics of which of the following machines?

   A. D.C. series motor
   B. D.C. shunt motor
   C. universal motor
   D. none of the above

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