Single Phase Induction Motors Multiple Choice Questions and Answers Preparation for Competition exams pdf

1. In a split phase motor, the running winding should have
(a)    high resistance and low inductance
(b)    low resistance and high inductance
(c)    high resistance as well as high inductance
(d)    low resistance as well as low inductiance
Ans: b

2.    If the capacitor of a single-phase motor is short-circuited
(a)    the motor will not start
(b)    the motor will run
(c)    the motor will run in reverse direction
(d)    the motor will run in the same direction at reduced r.p.m.
Ans: a

3.    In capacitor start single-phase motors
(a)    current in the starting winding leads the voltage
(b)    current in the starting winding lags the voltage
(c)    current in the starting winding is in phase with voltage in running winding
(d)    none of the above
 Ans: a

4.    In a capacitor start and run motors the function of the running capacitor in series with the auxiliary winding is to
(a)    improve power factor
(b)    increase overload capacity
(c)    reduce fluctuations in torque
(d)    to improve torque
Ans: a

5.    In a capacitor start motor, the phase displacement between starting and running winding can be nearly
(a)  10°   
(b) 30°
(c) 60°   
(d) 90°
Ans: d

6.    In a split phase motor
(a)    the starting winding is connected through a centrifugal switch
(b)    the running winding is connected through a centrifugal switch
(c)    both starting and running windings are connected through a centrifugal switch
(d)     centrifugal switch is used to control supply voltage
Ans: a

7.    The rotor developed by a single-phase motor at starting is
(a)     more than i.he rated torque
(b)     rated torque
(c)    less than the rated torque
(d)    zero
Ans: d

8.    Which of the following motor will give relatively high starting torque ?
(a) Capacitor start motor
(b) Capacitor run motor
(c) Split phase motor
(d) Shaded pole motor
Ans: a

9.    Which of the following motor will have relatively higher power factor ?
(a)    Capacitor run motor
(b)    Shaded pole motor
(c)    Capacitor start motor
(d)    Split phase motor
Ans: a

10.    In a shaded pole motor, the shading coil usually consist of
(a) a single turn of heavy wire which is in parallel with running winding
(b) a single turn of heavy copper wire which is short-circuited and carries only induced current
(c) a multilayer fine gauge copper wire in parallel with running winding
(d) none of the above
Ans: b

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