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EEE :: Single Phase Induction Motors

  1. A universal motor can run on

  2. A.

     D.C. only

    B.

     D.C. only

    C.

     either A.C. or D.C.

    D.

     none of the above


  3. Locked rotor current of a shaded pole motor is

  4. A.

     equal to full load current

    B.

     less than full load current

    C.

     slightly more than full load current

    D.

     several times the full load current


  5. The rotor of a hysteresis motor is made of

  6. A.

     aluminium

    B.

     cast iron

    C.

     chrome steel

    D.

     copper


  7. In case of a reluctance motor, when the load is increased so that it cannot maintain synchronous speed the motor will

  8. A.

     Become unstable

    B.

     Draw excessive armature current and may burn out

    C.

     Fall out of synchronism and come to stand still

    D.

     Run as induction motor


  9. Which of the following motor will give the highest starting torque ?

  10. A.

     D.C. shunt motor

    B.

     Schrage motor

    C.

     Repulsion start and induction run motor

    D.

     Universal motor


  11. Which of the following motors has highest starting torque ?

  12. A.

     Repulsion motor

    B.

     Shaped pole motor

    C.

     Capacitor-start motor

    D.

     Split-phase motor


  13. A capacitor-start single phase induction motor is switched on to supply with its capa-citor replaced by an inductor of equivalent reactance value. It will

  14. A.

     start and then stop

    B.

     start and run slowly

    C.

     start and run at rated speed

    D.

     not start at all


  15. If starting winding of a single-phase induction motor is left in the circuit, it will

  16. A.

     run faster

    B.

     spark at light loads

    C.

     draw excessive current and overheat

    D.

     run slower


  17. The rotor slots, in an induction motor, are usually not quite parallel to the shaft because it

  18. A.

     improves the efficiency

    B.

     helps the rotor teeth to remain under the stator teeth

    C.

     helps in reducing the tendency of the rotor teeth to remain under the stator teeth

    D.

     improves the power factor


  19. In case of a shaded pole motor the direction of rotation of the motor is

  20. A.

     from main pole to shaded pole

    B.

     from shaded pole to main pole

    C.

     either of the above depending on voltage

    D.

     either of the above depending on power factor