Single Phase Motors 2

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Objectives for Electrician and Wireman: Single Phase Motors 2

Subject: Single Phase Motors 2

Part 2: Objective questions and answers of Single Phase Motors

 

Q1. What is the working principle of split phase motor?

a) Lenz's law

b) Joule's law

c) Faraday's laws of electrolysis

d) Faraday's laws of electromagnetic induction

 

Q2. Which method is adopted to start the single phase induction motor?

a) Split phase method

b) Varying supply voltage method

c) Reversal of input supply terminals

d) Reversal of running coil connection

 

Q3. Which type of AC single phase motor having low starting torque?

a) Induction start induction run motor

b) Capacitor start induction run motor

c) Capacitor start capacitor run motor

d) Resistance start induction run motor

 

Q4. What is the function of centrifugal switch in single phase motors?

a) Maintain constant speed

b) Break the starting winding

c) Break the running winding

d) Protect the motor from over loading

 

Q5. Which single phase motor is fitted with wound rotor?

a) Repulsion motor

b) Shaded pole motor

c) Permanent capacitor motor

d) Capacitor start capacitor run motor

 

Q6. How the direction of rotation of a capacitor start induction run motor is reversed?

a) By changing the supply terminals

b) By changing the capacitor connections

c) By interchanging main winding terminals

d) By interchanging both main and auxiliary winding terminals

 

Q7. Which type of single phase induction motor is used in food mixer?

a) Universal motor

b) Repulsion motor

c) Shaded pole motor

d) Permanent capacitor motor

 

Q8. Why the hysteresis motor is suitable for sound recording instruments?

a) Small in size

b) High efficiency

c) Noiseless operation

d) Less error operation

 

Q9. Which type of motor has relatively small starting torque?

a) Universal motor

b) Capacitor start capacitor run motor

c) Capacitor start induction run motor

d) Resistance start induction run motor

 

Q10. How to produce starting torque in a shaded pole fan motor?

a) Using rings on poles

b) Using capacitor on winding circuits

c) Interchanging cage rotor windings by switch

d) Interchanging the field coil windings by switch

 

Q11. Which motor is having half coil winding?

a) Mixer

b) Grinder

c) Ceiling fan

d) Washing machine

 

Q12. Calculate the slot distance for a ceiling fan having 28 slots, 14 poles, 14 coils in half coil connection?

a) 90 Degree

b) 120 Degree

c) 180 Degree

d) 240 Degree

 

Q13. Which type of single phase motor is used for hard disk drives?

a) Stepper motor

b) Repulsion motor

c) Hysteresis motor

d) Reluctance motor

 

Q14. Which type of single phase motor is having very high starting torque than any other type of single phase motor?

a) Universal motor

b) Reluctance motor

c) Repulsion start induction run motor

d) Capacitor start induction run motor

 

Q15. Which motor is used in table fan?

a) Universal motor

b) Shaded pole motor

c) Eddy current motor

d) Permanent capacitor motor

 

Q16. What is the effect if the centrifugal switch is not disconnected after the motor starts?

a) Motor will run normally

b) Motor will stop immediately

c) Starting winding will burn out

d) Motor will run very slow speed

 

Q17. Why a capacitor is connected across centrifugal switch in the centrifugal switch speed control method?

a) To maintain constant speed

b) To protect from over loading

c) To improve the power factor

d) To reduce the sparks in contacts

 

Q18. How the radio interference can be suppressed in centrifugal switch method of speed control of universal motor?

a) By connecting capacitor across centrifugal switch

b) By connecting capacitor in series with centrifugal switch

c) By adding compensating winding with armature

d) By connecting an inductor in series with centrifugal switch

 

Q19. The rotor of a split-phase motor receives its power from:

a) The line voltage

b) Slip-rings

c) A centrifugal switch

d) Magnetic induction

 

Q20. The direction of rotation of a capacitor-start motor can be reversed by :

a) Interchanging the supply connections

b) Reversing the connections of the auxiliary winding (starting winding) only

c) Reversing the connections of either the running winding or the starting winding

d) Reversing the connections of the running winding only

 

Part 2: Objective questions and answers of Single Phase Motors

 

Q1. Answer a

Q2. Answer a

Q3. Answer d

Q4. Answer b

Q5. Answer a

Q6. Answer c

Q7. Answer a

Q8. Answer c

Q9. Answer d

Q10. Answer a

Q11. Answer c

Q12. Answer a

Q13. Answer a

Q14. Answer a

Q15. Answer d

Q16. Answer c

Q17. Answer d

Q18. Answer a

Q19. Answer d

Q20. Answer c

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