Top 80+ Solved 3 Phase Induction Motors MCQ Questions Answer
Q. Which of the following component is usually fabricated out of silicon steel ?
a. Bearings
b. Shaft
c. Statorcore
d. None of the above
Q. The frame of an induction motor is usually made of
a. silicon steel
b. cast iron
c. aluminium
d. bronze
Q. The shaft of an induction motor is made of
a. high speed steel
b. stainless steel
c. carbon steel
d. cast iron
Q. In squirrel cage induction motors, the rotor slots are usually given slight skew in orderto
a. reduce windage losses
b. reduce eddy currents
c. reduce accumulation of dirt and dust
d. reduce magnetic hum
Q. In case the air gap in an induction motor is increased
a. the magnetising current of the rotor will decrease
b. the power factor will decrease
c. speed of motor will increase
d. the windage losses will increase
Q. A 3-phase 440 V, 50 Hz induction motor has 4% slip. The frequency of rotor e.m.f. willbe
a. 200 Hz
b. 50 Hz
c. 2 Hz
d. 0.2 Hz
Q. In Ns is the synchronous speed and s the slip, then actual running speed of aninduction motor will be
a. Ns
b. s.N,
c. (l-s)Ns
d. (Ns-l)s
Q. The efficiency of an induction motor can be expected to be nearly
a. 60 to 90%
b. 80 to 90%
c. 95 to 98%
d. 99%
Q. The number of slip rings on a squirrel cage induction motor is usually
a. two
b. three
c. four
d. none
Q. The starting torque of a squirrel-cage induction motor is
a. low
b. negligible
c. same as full-load torque
d. slightly more than full-load torque
Q. A double squirrel-cage induction motor has
a. two rotors moving in oppsite direction
b. two parallel windings in stator
c. two parallel windings in rotor
d. two series windings in stator