Single phase induction motors

11. Speed control of a universal motor is achieved by

Varying field flux with tapped field windings
Connecting rheostat in series
Applying variable voltage by means of silicon controlled rectifier
All of the above methods

Detailed SolutionSpeed control of a universal motor is achieved by

12. A single-phase induction motor is

inherently self-starting with high torque
inherently self-starting with low torque
inherently non-self-starting with low torque
inherently non-self-starting with high torque

Detailed SolutionA single-phase induction motor is

13. If the capacitor of a single-phase motor is short-circuited

the motor will not start
the motor will run
the motor will run in reverse direction
the motor will run in the same direction at reduced r.p.m.

Detailed SolutionIf the capacitor of a single-phase motor is short-circuited

14. If starting winding of a single-phase induction motor is left in the circuit, it will

run faster
spark at light loads
draw excessive current and overheat
run slower

Detailed SolutionIf starting winding of a single-phase induction motor is left in the circuit, it will

15. Which of the following motor will give relatively high starting torque ?

Capacitor start motor
Capacitor run motor
Split phase motor
Shaded pole motor

Detailed SolutionWhich of the following motor will give relatively high starting torque ?

16. Which of the following motors has highest starting torque ?

Repulsion motor
Shaped pole motor
Capacitor-start motor
Split-phase motor

Detailed SolutionWhich of the following motors has highest starting torque ?

17. The rotor developed by a single-phase motor at starting is

more than rated torque
rated torque
less than the rated torque
zero

Detailed SolutionThe rotor developed by a single-phase motor at starting is

18. Which of the following motor will have relatively higher power factor ?

Capacitor run motor
Shaded pole motor
Capacitor start motor
Split phase motor

Detailed SolutionWhich of the following motor will have relatively higher power factor ?

19. Speed torque characteristic of a repulsion induction motor is similar to that of a D.C.

shunt motor
series motor
A. shunt motor B. series motor C. compound motor
separately excited motor

Detailed SolutionSpeed torque characteristic of a repulsion induction motor is similar to that of a D.C.

20. The direction of rotation of an hysteresis motor is determined by

interchanging the supply leads
position of shaded pole with respect to main pole
retentivity of the rotor material
none of these

Detailed SolutionThe direction of rotation of an hysteresis motor is determined by

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