InterviewSolution
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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
For a 3 phase synchronous generator of terminal voltage as 1 pu and field excitation of 1 pu. If the resistive drop is 0.2 pv, then what can be concluded for power factor?(a) Leading(b) Lagging(c) Upf(d) ZpfI had been asked this question in final exam.Query is from Power Flow Through an Inductive Impedance in division Efficiency and Regulation of Electrical Machines |
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Answer» CORRECT OPTION is (a) Leading Explanation: Here VT > Ef-Ia*RA. |
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| 2. |
For a 3 phase synchronous generator of terminal voltage as 1 pu and field excitation of 1.2 pu. If the resistive drop is 0.2 pv, then what can be concluded for power factor?(a) upf(b) zpf(c) lagging pf(d) leading pfThe question was asked at a job interview.Question is taken from Power Flow Through an Inductive Impedance in section Efficiency and Regulation of Electrical Machines |
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Answer» RIGHT answer is (a) upf For explanation: The VALUE for Ef-Ia*RA = Vt; Here it is Vt = 0. So it is upf. |
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| 3. |
In a 3-phase cylindrical-rotor alternator, synchronous reactance is sum of _____________(a) mutual and leakage reactance(b) magnetizing and leakage reactance(c) magnetizing and mutual reactance(d) mutual, magnetizing and leakage reactanceI had been asked this question during an internship interview.I would like to ask this question from Efficiency of Synchronous Machines in division Efficiency and Regulation of Electrical Machines |
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Answer» The correct option is (a) MUTUAL and leakage REACTANCE |
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| 4. |
The given variable losses are 5kW fr a 500 KVA, 11 kV, 3-phase star connected alternator having armature resistance of 4 ohms. Calculate the full load armature current per phase.(a) 26.24 A(b) 20.41 A(c) 79 A(d) 40 AThis question was posed to me in an international level competition.Question is from Efficiency of Synchronous Machines topic in section Efficiency and Regulation of Electrical Machines |
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Answer» RIGHT ANSWER is (a) 26.24 A Easiest EXPLANATION: I = P/1.73*V = 5000/1.73*11000 = 26.24 A. |
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| 5. |
The reactive power output of a synchronous generator is limited by _________(a) armature current and field current(b) field current and load angle(c) load angle and excitation(d) armature current onlyThe question was posed to me in an online interview.This intriguing question originated from Efficiency of Synchronous Machines in portion Efficiency and Regulation of Electrical Machines |
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Answer» The correct CHOICE is (a) ARMATURE current and FIELD current |
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| 6. |
The given variable losses are 5kW fr a 500 KVA, 11 kV, 3-phase star connected alternator having armature resistance of 4 ohms. Calculate the current at which maximum efficiency occurs?(a) 20.4A(b) 10.2A(c) 40A(d) 26AThis question was posed to me in an interview for job.I would like to ask this question from Efficiency of Synchronous Machines topic in portion Efficiency and Regulation of Electrical Machines |
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Answer» RIGHT OPTION is (a) 20.4A To EXPLAIN I would say: I^2=5000/3*4 I = 20.4 A. |
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| 7. |
An 3 phase alternator star connected 400 V synchronous motor takes a power input of 5472 watts at rated voltage. Its synchronous reactance is 10** per phase and negligible resistance. If its excitation voltage is adjusted equal to the rated voltage of 400 V, its power factor is _______(a) cos(10°)(b) cos(20°)(c) cos(40°)(d) cos(30°)The question was asked in an interview for internship.Question is taken from Power Flow Through an Inductive Impedance topic in chapter Efficiency and Regulation of Electrical Machines |
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Answer» The correct choice is (a) COS(10°) |
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| 8. |
The short circuit load losses is/are ______________(a) direct load loss and stray load losses(b) direct load loss(c) stray load losses(d) field current lossThe question was asked in semester exam.This is a very interesting question from Efficiency of Synchronous Machines in section Efficiency and Regulation of Electrical Machines |
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Answer» Correct CHOICE is (a) direct LOAD loss and stray load losses |
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| 9. |
An alternator, with synchronous reactance of 0.8 pv is connected to an IBB at rated voltage. With its excitation emf adjusted to 1.3 pv, the alternator delivers an output of 0.5 pv. The load angle is __________(a) 17.92(b) 72.08(c) 34.92(d) 90I had been asked this question in a national level competition.The question is from Power Flow Through an Inductive Impedance topic in chapter Efficiency and Regulation of Electrical Machines |
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Answer» CORRECT ANSWER is (a) 17.92 Easiest EXPLANATION: δ = ATAN(0.5*0.8/1.3) = 17.92°. |
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| 10. |
An ________ synchronous machine delivers reactive power whereas an ________ one absorbs reactive power.(a) over excited, under excited(b) under excited, over excited(c) over excited, over excited(d) under excited, normal excitedThe question was posed to me during a job interview.The question is from Power Flow Through an Inductive Impedance in section Efficiency and Regulation of Electrical Machines |
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Answer» The correct ANSWER is (a) over EXCITED, under excited |
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| 11. |
If the synchronous motor connected to the infinite bus bar delivers positive reactive power to it, then it must be operating at __________(a) leading pf(b) lagging pf(c) zero pf(d) unity pfThe question was asked in class test.This key question is from Power Flow Through an Inductive Impedance topic in chapter Efficiency and Regulation of Electrical Machines |
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Answer» RIGHT ANSWER is (a) leading pf Best explanation: An over excited synchronous MOTOR will ACT as a source of the reactive power and it will operate at leading pf. |
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| 12. |
If the synchronous motor connected to the infinite bus bar absorbs reactive power to it, then it must be operating at __________(a) leading pf(b) lagging pf(c) zero pf(d) unity pfThis question was addressed to me by my college director while I was bunking the class.This intriguing question comes from Power Flow Through an Inductive Impedance topic in section Efficiency and Regulation of Electrical Machines |
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Answer» Correct answer is (B) lagging PF |
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| 13. |
Under the conditions of maximum values of active or reactive power, a synchronous machine always absorbs reactive power.(a) True(b) FalseThe question was asked in quiz.The origin of the question is Power Flow Through an Inductive Impedance topic in section Efficiency and Regulation of Electrical Machines |
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Answer» Right answer is (a) True |
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| 14. |
For an underexcited 3 phase synchronous motor, connected to IBB is __________(a) absorbing reactive power from IBB(b) delivering reactive power to IBB(c) absorbing zero reactive power from IBB(d) delivering zero reactive power to IBBI have been asked this question by my college director while I was bunking the class.My query is from Power Flow Through an Inductive Impedance in chapter Efficiency and Regulation of Electrical Machines |
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Answer» Correct answer is (a) ABSORBING reactive power from IBB |
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| 15. |
What is Synchronous motor?(a) absorbs reactive power for maximum input real power(b) absorbs reactive power for maximum input reactive power(c) delivers reactive power for maximum input real power(d) delivers reactive power for maximum input reactive powerThe question was posed to me in a national level competition.This question is from Power Flow Through an Inductive Impedance in portion Efficiency and Regulation of Electrical Machines |
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Answer» The correct answer is (a) absorbs reactive power for MAXIMUM input real power |
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| 16. |
For an overexcited 3 phase synchronous motor, connected to infinite bus is __________(a) motor is delivering reactive power to IBB(b) motor is absorbing reactive power to IBB(c) motor is delivering zero reactive power to IBB(d) none of the mentionedThe question was asked by my school principal while I was bunking the class.The above asked question is from Power Flow Through an Inductive Impedance topic in section Efficiency and Regulation of Electrical Machines |
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Answer» Correct CHOICE is (a) motor is delivering reactive POWER to IBB |
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| 17. |
Under the condition for 3 phase alternator, maximum active power output, the delivered reactive power output is ________ while under maximum reactive power output, the delivered reactive power is ________(a) negative, negative(b) positive, negative(c) negative, positive(d) positive, positiveThe question was posed to me during an internship interview.I want to ask this question from Power Flow Through an Inductive Impedance in chapter Efficiency and Regulation of Electrical Machines |
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Answer» Right CHOICE is (a) negative, negative |
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| 18. |
Under the condition of maximum power delivered, reactive power is __________(a) negative(b) positive(c) zero(d) same as previous conditionI have been asked this question by my college professor while I was bunking the class.The question is from Power Flow Through an Inductive Impedance topic in division Efficiency and Regulation of Electrical Machines |
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Answer» RIGHT choice is (a) negative The EXPLANATION: The alternator will always absorb the REACTIVE power to meet its flux requirements to GENERATE the REAL power. |
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| 19. |
Under the conditions of maximum reactive power output, the reactive power flowing out of an alternator is __________(a) positive(b) negative(c) zero(d) equal to powerI got this question in an interview.This intriguing question comes from Power Flow Through an Inductive Impedance topic in division Efficiency and Regulation of Electrical Machines |
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Answer» The correct answer is (b) negative |
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| 20. |
When terminal voltage exceeds the excitation, then operating power factor is?(a) leading(b) lagging(c) uPF(d) zpfI got this question at a job interview.This question is from Power Flow Through an Inductive Impedance topic in chapter Efficiency and Regulation of Electrical Machines |
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Answer» Right CHOICE is (a) leading |
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| 21. |
The generator(3 phase alternator) absorbs reactive power from the infinite bus at leading power factor.(a) True(b) FalseThe question was posed to me in an internship interview.Asked question is from Power Flow Through an Inductive Impedance topic in portion Efficiency and Regulation of Electrical Machines |
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Answer» Right ANSWER is (a) True |
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| 22. |
The reactive power flow is outward from an alternator, then it is ____________(a) over excited(b) under excited(c) critically excited(d) none of the mentionedThis question was addressed to me in examination.This intriguing question originated from Power Flow Through an Inductive Impedance in section Efficiency and Regulation of Electrical Machines |
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| 23. |
The reactive power flow is outward from an alternator, then the alternator works at ____________(a) lagging power factor(b) leading power factor(c) zero power factor(d) normal power factorThe question was asked in an interview.I'm obligated to ask this question of Power Flow Through an Inductive Impedance in section Efficiency and Regulation of Electrical Machines |
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| 24. |
When excitation given to a 3-phase alternator is equal to terminal voltage then ____________(a) the absorbed reactive power is zero(b) the absorbed real power is zero(c) the delivered real power is zero(d) any of the mentionedI have been asked this question in an interview for job.My enquiry is from Power Flow Through an Inductive Impedance in chapter Efficiency and Regulation of Electrical Machines |
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Answer» CORRECT choice is (a) the absorbed reactive POWER is zero The explanation is: When EXCITATION is EQUAL to the terminal voltage there will not be any net flow of energy across the system. |
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| 25. |
For a 3 phase synchronous generator of terminal voltage as 1 pu and field excitation of 1.5 pu. If the resistive drop is 0.2 pv, then what can be concluded for power factor?(a) Leading(b) Lagging(c) Upf(d) ZpfI got this question by my college director while I was bunking the class.This key question is from Power Flow Through an Inductive Impedance topic in division Efficiency and Regulation of Electrical Machines |
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Answer» The correct choice is (B) Lagging |
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| 26. |
Reactive power is a matter of interest at ____________(a) output terminals of generator(b) input terminal of motor(c) output terminals of generator and input terminal of motor(d) none of the mentionedThis question was posed to me in unit test.I need to ask this question from Power Flow Through an Inductive Impedance in chapter Efficiency and Regulation of Electrical Machines |
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Answer» The correct option is (a) output TERMINALS of generator |
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| 27. |
for a 3 phase 315V alternator having impedance angle of 60 degree, the required load angle for the maximum power input to the generator is _______(a) 120°(b) 60°(c) 150°(d) 30°This question was posed to me in an online interview.My question comes from Power Flow Through an Inductive Impedance topic in division Efficiency and Regulation of Electrical Machines |
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Answer» RIGHT OPTION is (a) 120° Easiest EXPLANATION: δ = 90+α = 2α+θ=180-θ Soδ = 180-60=120°. |
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| 28. |
With constant E,V,Z, the maximum input power can be obtained at load angle of value _______(a) 180-θ(b) 90+θ(c) θ(d) 180The question was posed to me in examination.My enquiry is from Power Flow Through an Inductive Impedance in portion Efficiency and Regulation of Electrical Machines |
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Answer» RIGHT OPTION is (a) 180-θ For EXPLANATION: dPi/dδ = EVcos(δ-α) = 0 δ = 90+α = 2α+θ=180-θ. |
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| 29. |
For an alternator, the specified load angle should be _________ for an impedance angle of ‘θ’.(a) δ=θ(b) δ=90-θ(c) δ=90+θ(d) δ=-θThe question was posed to me during an interview for a job.Question is taken from Power Flow Through an Inductive Impedance topic in division Efficiency and Regulation of Electrical Machines |
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Answer» RIGHT OPTION is (a) δ=θ To EXPLAIN I WOULD SAY: dP/dδ = EVcos(δ+α) = 0 δ = 90-α=θ. |
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| 30. |
For a 3 phase synchronous motor, the load angle should be equal to impedance angle.(a) True(b) FalseI had been asked this question in a job interview.My doubt is from Power Flow Through an Inductive Impedance in portion Efficiency and Regulation of Electrical Machines |
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Answer» The CORRECT ANSWER is (a) True |
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| 31. |
The condition for maximum power output for an alternator having its load impedance as (2+j) ohms is?(a) 26.56°(b) 63.43°(c) 90°(d) 116.56°I have been asked this question in quiz.The doubt is from Power Flow Through an Inductive Impedance in chapter Efficiency and Regulation of Electrical Machines |
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Answer» CORRECT CHOICE is (a) 26.56° The explanation is: MAXIMUM POWER output is arctan(1/2)= 26.56°. |
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| 32. |
Which is the correct relation below?(a) Pim = -Pog(b) Pim = (Pog)*(c) Pim = Pog(d) Pim = -(Pog)*The question was posed to me in an interview.The above asked question is from Power Flow Through an Inductive Impedance in division Efficiency and Regulation of Electrical Machines |
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Answer» Correct option is (a) PIM = -Pog |
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