Single Phase Induction Motors Multiple Choice Questions and Answers In English -03

1. In a two value capacitor motor, the capacitor used for running purposes is
(A) air capacitor
(B) paper spaced oil filled type
(C) ceramic type
(D) a.c. electrolytic type
Ans: B

2. Which of the following motors can be run on AC. as well as D.C. supply ?
(A) Universal motor
(B) Repulsion motor
(C) Synchronous motor
(D) Reluctance motor
Ans: A

3. In A.C. series motor compensating winding is employed to
(A) reduce the effects of armature reaction
(B) increase the torque
(C) reduce sparking at the brushes
(D) none of the above
Ans: C

4. Which of the following single-phase induction motors is generally used in time phonographs ?
(A) Resistance start
(B) Capacitor start capacitor run
(C) Shaded pole
(D) Universal
Ans: C

5. Which of the following motors has highest starting torque ?
(A) Repulsion motor
(B) Shaped pole motor
(C) Capacitor-start motor
(D) Split-phase motor
Ans: C

6. In a single phase motor the centrifugal switch
(A) disconnects auxiliary winding of the motor
(B) disconnects main winding of the motor
(C) reconnects the main winding the motor
(D) reconnects the auxiliary winding of the motor
Ans: A

7. The running winding of a single phase motor on testing with meggar is found to be ground. Most probable location of the ground will be
(A) at the end connections
(B) at the end terminals
(C) anywhere on the winding inside a slot
(D) at the slot edge where coil enters or comes out of the slot
Ans: D

8. 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

9. 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

10. A shaded pole motor can be used for
(A) toys
(B) hair dryers
(C) circulators
(D) any of the above
Ans: D

11. For which of the applications a reluctance motor is preferred ?
(A) Electric shavers
(B) Refrigerators
(C) Signalling and timing devices
(D) Lifts and hoists
Ans: C

12. In a shaded pole single-phase motor, the revolving field is produced by the use of
(A) inductor
(B) capacitor
(C) resistor
(D) shading coils
Ans: D

13. A centrifugal switch is used to dis- connect ‘starting winding when motor has
(A) run for about 1 minute
(B) run for about 5 minutes
(C) picked up about 50 to 70 per cent of rated speed
(D) picked up about 10 to 25 per cent of rated speed
Ans: C

14. If a particular application needs high speed and high starting torque, then which of the following motor will be preferred ?
(A) Universal motor
(B) Shaded pole type motor
(C) Capacitor start motor
(D) Capacitor start and run motor
Ans: A

15. The value of starting capacitor of a fractional horse power motor will be
(A) 100 uF
(6) 200 uF
(C) 300 uF
(D) 400 uF
Ans: C

16. In repulsion motor direction of rotation of motor
(A) is opposite to that of brush shift
(B) is the same as that of brush shift
(C) is independent of brush shift

(D) none of the above
Ans: B

17. The motor used on small lathes is usually
(A) universal motor
(B) D.C. shunt motor
(C) single-phase capacitor run motor
(D) 3-phase synchronous motor
Ans: C

18. Single phase induction motor usually operates on
(A) 0.6 power factor lagging
(B) 0.8 power factor lagging
(C) 0.8 power factor leading
(D) unity power factor
Ans: A

19. In split-phase motor auxiliary winding is of
(A) thick wire placed at the bottom of the slots
(B) thick wire placed at the top of the slots
(C) thin wire placed at the top of the slots
(D) thin wire placed at the bottom of the slots
Ans: C

20. 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