Technical Ability - SPLessons
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Power System

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Power System

shape Introduction

What is an Electric Power System? Electric Power System is a network of electrical components primarily instrumental to supply, transfer, and use electric power. Primarily an Electric Power System consists of generation, distribution and transmission system. The power plant, transformer, transmission line, substations, distribution line, and distribution transformer are the six main components of the power system.

shape Quiz

Q1. In a minimum oil circuit breaker the oil is used
    A. to act as circuit breaking medium only B. for circuit breaking and providing insulation C. for providing insulation only D. for none of the above purposes Answer: A

Q2. Series capacitor is used in a transmission line to
    A. compensate the voltage drp B. reduce line loss C. limit short circuit current D. improve load power factor Answer: A

Q3. Corona loss in a transmission line is dependent on
    A. diameter of the conductor B. material of the conductor C. height of the conductor D. none of these Answer: A

Q4. A fault is more severe from the view point of RRRV if it is a
    A. Short length fault B. Medium length line fault C. Long length line fault D. None of these Answer: A

Q5. Skin effect in conductor is proportional to
    A. [latex](diameter of conductor)^{1/2}[/latex] B. diameter of conductor C. [latex](diameter of conductor)^{2}[/latex] D. [latex](diameter of conductor)^{4}[/latex] Answer: C

Q6. For constant voltage transmission, the voltage drop along the line is maintained constant by installing
    A. capacitors B. inductors C. resistors D. synchronous phase modifiers at the receiving end Answer: D

Q7. Neutral earthing is provided for
    A. the safety of personnel from electric shock B. reducing the voltage stress on lines and equipment with respect to earth under various operating and ault conditions C. controlling the earth fault currents for protective relaying D. both (b) and (c) Answer: D

Q8. In which of the following cases are delay fuses used?
    A. For the protection of light circuits B. For the protection of power out-let circuits C. For the protection of fluorescent lamps D. For the protection of motors Answer: D

Q9. Different types of insulators used for transmission lines are
    A. pin type only B. suspension type only C. strain type only D. pin type, suspension type and shackle type Answer: D

Q10. The function of steel wire in an ACSR conductor is to
    A. compensate for skin effect B. take care of surges C. provide additional mechanical strength D. educe inductance Answer: C
Q11. AC network analyser is employed for solving the problems of
    A. load flow B. load flow and stability C. load flow and short-cicuit D. load flow, stability and short-circuit Answer: D

Q12. Which of the following method or techniques can be used for the measurement of high (d)(c) voltages?
    A. Generating voltmeter B. Electrostatic voltmeter C. Peak voltmeter D. Half effect generators Answer: A

Q13. If two synchronous generators connected in parallel loose synchronism, it will lead to
    A. stalling of generators B. wild fluctuations in current C. wild fluctuations in current and voltage D. None of these Answer: C

Q14. The insulation of the modern EHV lines is designed based on
    A. corona B. switching voltage C. lightning voltage D. all of these Answer: A

Q15. In a transformer, the exciting current will be in phase quadrature with the impressed voltage provided?
    A. only the leakage impedance drop is ignored B. only the core loss is ignored C. both the leakage impedance drop and the core loss are ignored D. only the no-load copper loss is ignored Answer: C

Q16. The voltage measurements using uniform spark gap are
    A. affected by dust particles B. affected by polarity of supply C. affected by temperature D. none of these Answer: A

Q17. The change in excitation in an alternator connected to an infinite line provides a corresponding change in
    A. terminal voltage B. speed of rotor C. power generated D. power factor Answer: A

Q18. The function of Lightning arrester is
    A. to limiting the short-circuit fault current B. to provide path to high voltage surge to earth C. to reduce arcing D. none of these Answer: A

Q19. The conductor connecting consumer's terminals to the distributor is called the
    A. feeder B. distributor C. service main D. none of the above Answer: C

Q20. In order to improve the voltage profile of the line, compensation is resorted by providing
    A. capacitors at the receiving end B. reactors at the receiving end C. resistors at the receiving end D. none of these Answer: A
Q21. The ripple voltage in dc output is small if
    A. frequency of supply voltage is small B. the filtering capacitor is small C. load current is small D. none of these Answer: D

Q22. A differential relay responds to
    A. algebraic difference of two or more similar electrical quantities B. vector difference of two or more similar electrical quantities C. algebraic difference between two currents D. algebraic difference between two voltages Answer: B

Q23. In case of Impulse Thermal break down of solid insulating materials, the critical electric field is proportional to
    A. critical absolute temperature B. square of critical absolute temperature C. square of [latex]T_{0}[/latex] D. none of these Answer: C

Q24. A booster is connected in
    A. series with the feeder B. parallel with the feeder C. both (a) and (b) are correct D. none of these Answer: A

Q25. Which of the following techniques is used for the measurements of (a)(c) high frequency voltages?
    A. Peak voltmeter B. Series resistance mircro-ammeter C. Resistance potential divider D. All of these Answer: A

Q26. The power transmitted will be maximum when
    A. line reactance is high B. corona losses are minimum C. sending end voltage is more D. receiving end voltage is more Answer: C

Q27. Surge impedance of a transmission line is
    A. independent of its length B. dependent of its length C. independent on its temperature D. none of the above Answer: A

Q28. Which fault gives rise to symmetrical fault currents?
    A. Single line to ground fault B. line to line fault C. Double line to ground fault D. Three phase fault Answer: D

Q29. High voltage Schring bridge is used to measure
    A. large capacitance without additional element B. small capacitance without additional element C. midium value capacitance D. one of these Answer: B

Q30. Protective resistance to be connected between the sphere gap and the test equipment is required while measuring
    A. power frequency and higher frequency (a)(c) voltage B. power frequency and impulse voltage C. all kinds of voltages D. none of these Answer: A
Q31. The passive element that is used as interconnecting element for the stable operation of interconnected system is
    A. reactor B. resistor C. capacitor D. resistor and capacitor Answer: A

Q32. The sage of a transmission line is least affected owing to
    A. weight of the conductor B. current through the conductor C. atmospheric temperature D. ice deposited on the conductor Answer: B

Q33. The conductor carries more current on the surface in comparison to its core. This phenomenon is called the
    A. Skin effect B. Corona C. Ferranti effect D. Lenz's effect Answer: A

Q34. Draw-in-system of laying underground cables has the drawback(s) of
    A. higer cost B. reduced current carrying capacity of the cables C. requirments of much deeper and wider trenches D. All of the above Answer: D

Q35. By transmitting power at high voltage
    A. it will give poor voltage regulation B. it will give better voltage regulation C. it will not effect voltage regulation D. None of these Answer: B

Q36. Use of additional shunt capacitor can be made for increasing the capability of line as it
    A. reduces surge impedance [latex]Z^{0}[/latex] B. increases phase shift C. increase in D. all of the above Answer: A

Q37. Fuses have got advantages of
    A. cheapest type of protection B. inverse time-current characteristic C. maintenance D. current limiting effect under short-circuit conditons E. all of the above Answer: E

Q38. The connected load of a consumer is 2 kW and his maximum demand is 1.5 kW. The load factor of the consumer is
    A. 0.75 B. 0.375 C. 1.33 D. None of these Answer: D

Q39. Which statement about the daily load curve is valid?
    A. The area under the curve gives the average demand. B. The ratio of the area under the curves to the total area of rectangle in which it is contained gives the load factor for the day. C. The peak of the curve gives the installed capacity of the plant D. The area of the curves divided by the number of hours gives load factor. Answer: D

Q40. Resistance witching is normally resorted in case of
    A. Air blast CB B. Bulk oil CB C. Minimum oil CB D. All types of CBs. Answer: A
Q41. What is the main disadvantage of phase advancers?
    A. Cannot be used for motors below 200 H.P B. Produces noise C. Can be used where synchronous motor is un admissible D. None of these Answer: A

Q42. What is the advantage of the static capacitors?
    A. Low losses B. Easy installation C. Lower maintenance D. All of the above Answer: D

Q43. Power factor can be improved by connecting which among these?
    A. Static capacitors. B. Resistors. C. Synchronous condensers. D. Both (a) and (c). Answer: D

Q44. Lower power factor is usually not due to ______ .
    A. Discharge lamp B. Arc lamps C. Incandescent lamps D. Induction furnace. Answer: C

Q45. What is maximum value of power factor?
    A. 0.5 B. 1 C. 1.5 D. 0.95 Answer: D

Q46. What is the power factor tariff?
    A. It considers only maximum demand. B. It considers only semi fixed charges and the power factor. C. It considers only power factor. D. It considers the load factor. Answer: C

Q47. Which tariff is most ideal tariff for the consumer?
    A. Two part tariff B. Three part tariff C. Both (a) and (b) D. None of the above Answer: B

Q48. What is tariff?
    A. The rate at which electrical energy is produced in the plant. B. The rate at which electrical energy is supplied to the consumers. C. Both (a) and (b). D. None of these. Answer: B

Q49. What are fixed charges?
    A. Cost of investment irrespective of energy generated. B. Operating cost of the fuel along with cost of investment plant. C. Operating cost only. D. None of the above Answer: A

Q50. Annual operating cost of a generating plant consists of
    A. Fixed charges B. Semi fixed charges C. Operating or running charges D. All of these Answer: D
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