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Quiz On Three Phase Induction Motor
01. The silicon steel is fabricated by which of the following components?
- (a) Bearings
- (b) Shaft
- (c) Stator core
- (d) None of the above
02. In the induction motor, the frame is usually made of
- (a) silicon steel
- (b) cast iron
- (c) aluminum
- (d) bronze
03. In the induction motor, the shaft is made of
- (a) stiff
- (b) flexible
- (c) hollow
- (d) any of the above
04. The material used to make the shaft of an induction motor?
- (a) high-speed steel
- (b) stainless steel
- (c) carbon steel
- (d) cast iron
05. At no-load, the slip in an induction motor is generally?
- (a) less than 1%
- (b) 1.5%
- (c) 2%
- (d) 4%
06. The slip in a medium-sized induction motor is generally around?
- (a) 0.04%
- (b) 0.4%
- (c) 4%
- (d) 14%
07. The rotor slots in a squirrel-cage induction motor are usually given a slight skew in order to?
- (a) reduce windage losses
- (b) reduce eddy currents
- (c) reduce the accumulation of dust and dirt
- (d) reduce magnetic hum
08. If the air gap in an induction motor is increased?
- (a) the rotor magnetizing current will decrease
- (b) the power factor will decrease
- (c) speed of the motor will increase
- (d) the windage losses will increase
09. The material used to make Slip rings?
- (a) copper
- (b) carbon
- (c) phosphor bronze
- (d) aluminum
10. Find the frequency of the rotor e.m.f, if the frequency of the three-phase induction motor is 50 Hz and slip is of 4%?
- (a) 200 Hz
- (b) 50 Hz
- (c) 2 Hz
- (d) 0.2 Hz
11. The s is the slip and Ns is the synchronous speed, then the actual running speed of the motor will be
- (a) Ns
- (b) s.N,
- (c) (l-s)Ns
- (d) (Ns-l)s
12. The efficiency of the induction motor is?
- (a) 60 to 90%
- (b) 80 to 90%
- (c) 95 to 98%
- (d) 99%
13. In the squirrel-cage induction motor, the number of slip rings is usually?
- (a) two
- (b) three
- (c) four
- (d) none
14. In a squirrel-cage induction motor, the starting torque is usually?
- (a) low
- (b) negligible
- (c) same as full-load torque
- (d) slightly more than full-load torque
15. The double squirrel-cage induction motor has two?
- (a) rotors moving in the opposite direction
- (b) parallel windings in the stator
- (c) parallel windings in the rotor
- (d) series windings in the stator
16. The Star-delta starting of motors is not usually applicable in case of?
- (a) single-phase motors
- (b) variable speed motors
- (c) low horsepower motors
- (d) high-speed motors
17. The term ‘cogging’ is associated with
- (a) three-phase transformers
- (b) compound generators
- (c) D.C. series motors
- (d) induction motors
18. The torque in the induction motor is?
- (a) inversely proportional to (Islip)
- (b) directly proportional to (slip)2
- (c) inversely proportional to slip
- (d) directly proportional to slip
19. An induction motor with a speed of 1000 r.p.m. will have how many numbers of poles?
- (a) 8 poles
- (b) 6 poles
- (c) 4 poles
- (d) 2 poles
20. In the induction motor, the good power factor can be achieved if the average flux density in the air gap is?
- (a) absent
- (b) small
- (c) large
- (d) infinity
21. An induction motor is also called as?
- (a) D.C. compound motor
- (b) D.C. series motor
- (c) synchronous motor
- (d) asynchronous motor
22. In an induction motor, the injected emf must-have?
- (a) zero frequency
- (b) the same frequency as the slip frequency
- (c) the same phase as the rotor e.m.f.
- (d) high value for the satisfactory speed control
23. To control the speed of the squirrel-cage induction motor which of the following method can easily applicable?
- (a) By changing the number of stator poles
- (b) Rotor rheostat control
- (c) By operating two motors in cascade
- (d) By injecting e.m.f. in the rotor circuit
24. In the induction motor, the crawling is caused by
- (a) low voltage supply
- (b) high loads
- (c) harmonics developed in the motor
- (d) improper design of the machine
- (e) none of the above
25. To start the cage induction motor, the auto-starter can be used for which of the following type?
- (a) star connected only
- (b) delta connected only
- (c) (a) and (b) both
- (d) none of the above
I hope this article “quiz on three phase induction motor” may help you all a lot. Thank you for reading. If you have any doubts related to quiz on three phase induction motor, then comment below.