Single phase induction motors

21.

smaller brush width
less number of field turns
series motor as compared to
less air gap E. all of the above

Detailed Solution

22. A capacitor-start single phase induction motor is switched on to supply with its capa-citor replaced by an inductor of equivalent reactance value. It will

start and then stop
start and run slowly
start and run at rated speed
not start at all

Detailed SolutionA capacitor-start single phase induction motor is switched on to supply with its capa-citor replaced by an inductor of equivalent reactance value. It will

23. Hysteresis motor is particularly useful for high-quality record players and tape-recorders because

it revolves synchronously
it is not subject to any magnetic or mechanical vibrations
it can be easily manufactured in extremely small sizes of up to 1 W output
it develops hysteresis torque which is extremely steady both in amplitude and phase

Detailed SolutionHysteresis motor is particularly useful for high-quality record players and tape-recorders because

24. Which of the following statements regarding two value capacitor motor is incorrect ?

It is a reversing motor
It is preferred to permanent-split single-value capacitor motor where frequent reversals are required
It has low starting as well as rushing currents
It has high starting torque

Detailed SolutionWhich of the following statements regarding two value capacitor motor is incorrect ?

25. After the starting winding of a single phase induction motor is disconnected from supply, it continues to run only on

running winding
rotor winding
field winding
compensating winding

Detailed SolutionAfter the starting winding of a single phase induction motor is disconnected from supply, it continues to run only on

26. Starting winding of a single phase motor of a refrigerator is disconnected from the circuit by means of a

Magnetic relay
Thermal relay
Centrifugal switch
None of the above

Detailed SolutionStarting winding of a single phase motor of a refrigerator is disconnected from the circuit by means of a

27. Burning out of winding is due to

short circuited capacitor
capacitor value hiving changed
open circuiting of capacitor
none of the above

Detailed SolutionBurning out of winding is due to

28. Which of the following single-phase motors has relatively poor starting torque ?

Universal motor
Repulsion motor
Capacitor motor
All single phase motors have zero starting torque

Detailed SolutionWhich of the following single-phase motors has relatively poor starting torque ?

29. The rotor of a hysteresis motor is made of

aluminium
cast iron
chrome steel
copper

Detailed SolutionThe rotor of a hysteresis motor is made of

30. If a particular application needs high speed and high starting torque, then which of the following motor will bepreferred ?

Universal motor
Shaded pole type motor
Capacitor start motor
Capacitor start and run motor

Detailed SolutionIf a particular application needs high speed and high starting torque, then which of the following motor will bepreferred ?

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