Realtime Single Phase Induction Motors Multiple choice Questions and Answers pdf

21.    The direction of rotation of an hysteresis motor is determined by
(a) interchanging the supply leads
(b) position of shaded pole with respect to main pole
(c) retentivity of the rotor material
(d) none of these
Ans: b

22.    Burning out of windings is due to
(a)     short circuited capacitor
(b)     capacitor value hiving changed
(c)    open circuiting of capacitor
(d)    none of the above
Ans: a

23.    Direction of rotation of a split phase motor can be reversed by reversing the connection of
(a) running winding only
(b) starting winding only
(c) either (a) or (b)
(d) both (a) and (b)
Ans: c

24.    Short-circuiter is used in
(a)    repulsion induction motor
(b)    repulsion motor
(c)    repulsion start induction run motor
(d)    none of the above
Ans: c

25.    The range of efficiency for shaded pole motors is
(a) 95% to 99%     
(b) 80% to 90%
(c) 50% to 75%     
(d) 5% to 35%
Ans: d

26.    In a capacitor start single-phase motor, when capacitor is replaced by a resistance
(a)    torque will increase
(b)    the motor will consume less power
(c)    motor will run in reverse direction
(d)    motor will continue to run in same direction
Ans: d

27.    The power factor of a single-phase induction motor is usually
(a)     lagging  
(b)     always leading
(c)    unity
(d)    unity to 0.8 leading
Ans: a

28.    A shaded pole motor can be used for
(a) toys  
(b) hair dryers
(c) circulators  
(d) any of the above
Ans: d

29.    A hysteresis motor works on the principle of
(a)     hysteresis loss
(b)     magnetisation of rotor
(c)    eddy current loss
(d)    electromagnetic induction
Ans: a

30.    Which of the following motor will give the highest starting torque ?
(a)     D.C. shunt motor
(b)     Schrage motor
(c)    Repulsion start and induction run motor
(d)    Universal motor
Ans: b