Hiried Polyphase Induction Motors Multiple choice Questions and Answers pdf

41.    The power factor of an induction motor under no-load conditions will be closer to
(a) 0.2 lagging   
(b) 0.2 leading
(c) 0.5 leading   
(d) unity
Ans: a

42.    The 'cogging' of an induction motor can be avoided by
(a)     proper ventilation
(b)     using DOL starter
(c)    auto-transformer starter
(d)    having number of rotor slots more or less than the number of stator slots (not equal)
Ans: d

43.    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
Ans: c

44.    Slip of an induction motor is negative when
(a)     magnetic field and rotor rotate in opposite direction
(b)     rotor speed is less than the syn-chronous speed of the field and are in the same direction
(c)    rotor speed is more than the syn-chronous speed of the field and are in the same direction
(d)    none of the above
Ans: c

45.    Size of a high speed motor as compared to low speed motorfor the same H.P. will be
(a) bigger
(b) smaller
(c) same
(d) any of the above
Ans: b

46.    A 3-phase induction motor stator delta connected, is carrying full load and one of its fuses blows out. Then the motor
(a)    will continue running burning its one phase
(b)    will continue running burning its two phases
(c)    will stop and carry heavy current causing permanent damage to its winding
(d)    will continue running without any harm to the winding
Ans: a

47.    A 3-phase induction motor delta connected is carrying too heavy load and one of its fuses blows out. Then the motor
(a)    will continue running burning its one phase
(b)    will continue running burning its two phase
(c)    will stop and carry heavy current causing permanent damage to its winding
(d)    will continue running without any harm to the winding
Ans: c

48.    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
Ans: c

49.    In an induction motor the relationship between stator slots and rotor slots is that
(a)     stator slots are equal to rotor slots
(b)     stator slots are exact multiple of rotor slots
(c)    stator slots are not exact multiple of rotor slots
(d)    none of the above
Ans: c

50.    Slip ring motor is recommended where
(a)     speed control is required
(6)     frequent starting, stopping and reversing is required
(c)    high starting torque is needed
(d)    all above features are required
Ans: d

Read More Questions:
Polyphase Induction Motors MCQs Part1
Polyphase Induction Motors MCQs Part2
Polyphase Induction Motors MCQs Part3
Polyphase Induction Motors MCQs Part4
Polyphase Induction Motors MCQs Part5
Polyphase Induction Motors MCQs Part6
Polyphase Induction Motors MCQs Part7
Polyphase Induction Motors MCQs Part8
Polyphase Induction Motors MCQs Part9
Polyphase Induction Motors MCQs Part10