[amp_mcq option1=”smaller brush width” option2=”less number of field turns” option3=”series motor as compared to” option4=”less air gap E. all of the above” correct=”option1″]
Single phase induction motors
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
[amp_mcq option1=”start and then stop” option2=”start and run slowly” option3=”start and run at rated speed” option4=”not start at all” correct=”option4″]
23. Hysteresis motor is particularly useful for high-quality record players and tape-recorders because
[amp_mcq option1=”it revolves synchronously” option2=”it is not subject to any magnetic or mechanical vibrations” option3=”it can be easily manufactured in extremely small sizes of up to 1 W output” option4=”it develops hysteresis torque which is extremely steady both in amplitude and phase” correct=”option4″]
24. Which of the following statements regarding two value capacitor motor is incorrect ?
[amp_mcq option1=”It is a reversing motor” option2=”It is preferred to permanent-split single-value capacitor motor where frequent reversals are required” option3=”It has low starting as well as rushing currents” option4=”It has high starting torque” correct=”option4″]
25. After the starting winding of a single phase induction motor is disconnected from supply, it continues to run only on
[amp_mcq option1=”running winding” option2=”rotor winding” option3=”field winding” option4=”compensating winding” correct=”option1″]
26. Starting winding of a single phase motor of a refrigerator is disconnected from the circuit by means of a
[amp_mcq option1=”Magnetic relay” option2=”Thermal relay” option3=”Centrifugal switch” option4=”None of the above” correct=”option3″]
27. Burning out of winding is due to
[amp_mcq option1=”short circuited capacitor” option2=”capacitor value hiving changed” option3=”open circuiting of capacitor” option4=”none of the above” correct=”option1″]
28. Which of the following single-phase motors has relatively poor starting torque ?
[amp_mcq option1=”Universal motor” option2=”Repulsion motor” option3=”Capacitor motor” option4=”All single phase motors have zero starting torque” correct=”option2″]
Detailed SolutionWhich of the following single-phase motors has relatively poor starting torque ?
29. The rotor of a hysteresis motor is made of
[amp_mcq option1=”aluminium” option2=”cast iron” option3=”chrome steel” option4=”copper” correct=”option1″]
30. If a particular application needs high speed and high starting torque, then which of the following motor will bepreferred ?
[amp_mcq option1=”Universal motor” option2=”Shaded pole type motor” option3=”Capacitor start motor” option4=”Capacitor start and run motor” correct=”option1″]