Electrical Machine 11

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Electrical Engineering MCQ Question Papers: Campus Placement

Subject: Electrical Machine 11

Part 5: List for questions and answers of Electrical Machine II

 

Q1. If the frequencies of the two alternators in lamp dark method for synchronization of alternators are unequal, then the two lamps will ?

a) Glow together

b) Become alternately bright and dark

c) Not glow at all

d) None of the above

 

Q2.What happens if a stationary alternator is connected to live bus bar? ?

a) It can result in short circuit

b) A large emf will be induced by alternator

c) Both (a) and (b)

d) None of these

 

Q3.The direct method for finding the voltage regulation of an alternator is/are ?

a) E.M.F method

b) M.M.F. method

c) Z.P.F method

d) None of these

 

Q4.The synchronous generator is loaded for obtaining zero power characteristics by using ?

a) D.C. motor

b) Lamp load

c) Synchronous motor

d) All of these

 

Q5.In Potier’s triangle method, to determine armature leakage reactance and armature reaction mmf separately, the tests performed are ?

a) Open circuit test and short circuit test

b) Open circuit test and zero power factor test

c) Short circuit test and zero power factor test

d) Open circuit test, short circuit test and zero power factor test 

 

Q6.If the value of SCR in an alternator is low then the air gap and voltage drop across synchronous reactance will be?

a) Low, high

b) High, low

c) Low, low

d) High, high

 

Q7.Low value of SCR in an alternator indicates ?

a) High stability limit

b) Low stability limit

c) None of these

d) both a and b

 

Q8.For finding voltage regulation of an alternator, the method which gives most accurate result is?

a) E.M.F method

b) M.M.F. method

c) Z.P.F method

d) ASA modification of M.M.F. method

 

Q9.For high capacity alternators, which method is not suitable for finding percentage regulation??

a) Direct loading method

b) Synchronous impedance method

c) Ampere-turns method

d) Potier triangle method

 

Q10.Which method for finding percentage regulation in synchronous machines is called pessimistic method??

a) E.M.F. method

b) M.M.F. method

c) Z.P.F. method

d) Direct loading method

 

Q11.On unity power factor, the terminal voltage of an alternator is ?

a) Always less than induced emf

b) Always greater than induced emf

c) Same as induced emf

d) None of these 

 

Q12.In an alternator, the voltage regulation will be positive when the power factor of the load is?

a) Leading

b) Unity

c) Lagging

d) Both ( b ) and ( c )

 

Q13.Consider a purely inductive load connected to the alternator having zero lagging power factor. In this case the effect of armature reaction will be ?

a) Demagnetizing effect

b) Cross magnetizing effect

c) Both (a) and (b)

d) None of these

 

Q14.The synchronous reactance of an alternator is equal to ?

a) Leakage reactance of armature

b) Armature reaction reactance

c) Sum of leakage reactance and armature reaction reactance

d) Difference of leakage reactance and armature reaction reactance

 

Q15.If the load connected to the alternator are having zero leading power factor and zero lagging power factor, then the nature of load in each case will be ?

a) Inductive, capacitive

b) Inductive, inductive

c) Capacitive, capacitive

d) Capacitive, inductive

 

Q16.Out of two alternators which are sharing an inductive load equally, if excitation of one alternator is increased then ?

a) Other alternator will deliver less current

b) Other alternator will deliver more current

c) Both will deliver equal current

d) None of these

 

Q17.The leakage flux in the armature of alternator makes the armature winding?

a) Inductive in nature

b) Capacitive in nature

c) Resistive in nature

d) All of these 

 

Q18.The effect of armature flux in an alternator depends on ?

a) Magnitude of current flowing through the armature winding

b) Nature of power factor of the load connected to the alternator

c) Both (a) and (b)

d) None of these

 

Q19.Salient pole alternators are best suitable for the application of ?

a) Hydro electric power plant

b) Thermal power plant

c) Tidal power plant

d) Nuclear power plant

 

Q20.Generally the effective resistance of alternator under a.c. condition is taken as ?

a) Less than 1.25 times the d.c. resistance

b) 1.25 to 1.75 times the d.c. resistance

c) Greater than 1.75 times the d.c. resistance

d) None of these 

 

Part 5: List for questions and answers of Electrical Machine II

 

Q1. Answer: b

 

Q2. Answer: a

 

Q3. Answer: d

 

Q4. Answer: c

 

Q5. Answer: b

 

Q6. Answer: a

 

Q7. Answer: b

 

Q8. Answer: c

 

Q9. Answer: a

 

Q10. Answer: a

 

Q11. Answer: a

 

Q12. Answer: d

 

Q13. Answer: a

 

Q14. Answer: c

 

Q15. Answer: d

 

Q16. Answer: a

 

Q17. Answer: a

 

Q18. Answer: c

 

Q19. Answer: a

 

Q20. Answer: b