Induction Motors Objective type Questions - Set 05 - ObjectiveBooks

Induction Motors Objective type Questions - Set 05

Practice Test: Question Set - 05

1. The torque of an induction motor is
    (A) Directly proportional to slip
    (B) Inversely proportional to slip
    (C) Proportional to the square of the slip
    (D) None of the above

2. The shaft of an induction motor is made of
    (A) High speed steel
    (B) Stainless steel
    (C) Carbon steel
    (D) Cast iron

3. The term 'cogging' is associated with
    (A) Three-phase transformers
    (B) Compound generators
    (C) D.C. series motors
    (D) Induction motors

4. Rotor rheostat control method of speed control is used for
    (A) Squirrel-cage induction motors only
    (B) Slip ring induction motors only
    (C) Both (A) and (B)
    (D) None of the above

5. The 'cogging' of an induction motor can be avoided by
    (A) Proper ventilation
    (B) Using DOL starter
    (C) Autotransformer starter
    (D) Having number of rotor slots more or less than the number of stator slots (not equal)

6. Which type of bearing is provided in small induction motors to support the rotor shaft?
    (A) Ball bearings
    (B) Cast iron bearings
    (C) Bush bearings
    (D) None of the above

7. A change of 4% of supply voltage to an induction motor will produce a change of approximately
    (A) 4% in the rotor torque
    (B) 8% in the rotor torque
    (C) 12% in the rotor torque
    (D) 16% in the rotor torque

8. 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

9. 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 per stator phase is 57.7% of the line voltage

10. The frame of an induction motor is usually made of
    (A) Silicon steel
    (B) Cast iron
    (C) Aluminium
    (D) Bronze

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