Single Phase Induction Motors Multiple Choice Questions and Answers In English-01

1. 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

2. 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 inductance
Ans: B

3. 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

4. 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

5. 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

6. 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

7. 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

8. A capacitor-start single phase induction motor is switched on to supply with its capacitor replaced by an inductor of equivalent reactance value. It will
(A) start and then stop
(B) start and run slowly
(C) start and run at rated speed
(D) not start at all
Ans: D

9. Which of the following motors is used in mixies ?
(A) Repulsion motor
(B) Reluctance motor
(C) Hysteresis motor
(D) Universal motor
Ans: D

10. Which of the following motors is inherently self starting ?
(A) Split motor
(B) Shaded-pole motor
(C) Reluctance motor
(D) None of these
Ans: B

11. Short-circuit is used in
(A) repulsion induction motor
(B) repulsion motor
(C) repulsion start induction run motor
(D) none of the above
Ans: C

12. 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

13. A single-phase induction motor is
(A) inherently self-starting with high torque
(B) inherently self-starting with low torque
(C) inherently non-self-starting with low torque
(D) inherently non-self-starting with high torque
Ans: C

14. A schrage motor can run on
(A) zero slip
(B) negative slip
(C) positive slip
(D) all of the above
Ans: D

15. A universal motor can run on
(A) A.C. only
(6) D.C. only
(C) either A.C. or D.C.
(D) none of the above
Ans: C

16. 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

17. 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

18. 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

19. Burning out of winding is due to
(A) short circuited capacitor
(B) capacitor value hiving changed
(C) open circuiting of capacitor
(D) none of the above
Ans: A

20. 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