SY-EE-SEN-III-EPT-22419.pdf - Zeal Polytechnic

Zeal Education Society’s

ZEAL POLYTECHNIC, PUNE

NARHE │PUNE -41 │ INDIA

DEPARTMENT OF ELECTRICAL ENGINEERING

SECOND YEAR (SY)

SCHEME: I SEMESTER: IV

NAME OF SUBJECT: Electrical Power Transmission & Distribution

Subject Code: 22419

UNIT WISE MULTIPLE CHOICE

QUESTIONS BANK

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ZEAL EDUCATION SOCIETY’S

ZEAL POLYTECHNIC,PUNE



Question Bank for Multiple Choice Questions

01 – Basics Of Transmission & Distribution Marks:-014

Content of Chapter:- 1.1 SINGLE line diagram with componants of the electrical supply transmission & distribution system. 1.2 Classification of transmission line: Primary & Secondary transmission: Standard voltage used in INDIA. 1.3 Classification of transmission line: based on type of voltage ,voltage level, length & other. 1.4 Characteristics of high voltage for power transmission. 1.5 Method of construction of electric supply transmission system. 1.6 Method of construction of electric supply Distribution system.

Ques 1. By which of the following method electric power may be transmitted from one location to another location?

a) Under Ground System b) Overhead system c) Both a and b d) None of the above

Ans- Both a and b

Ques 2. Which of the following transmission line have more initial cost?

a) Overhead Transmission b) Underground transmission c) Both have almost the same initial cost d) None of the above

Ans-b) Underground transmission

Ques 3. Name the cable or conductor which connects the distributor to the consumer terminals.

a) Service Mains b) Distributor

Program: Diploma in Electrical engineering Program Code:- EE

Scheme:- I Semester:- IV

Course:- Electrical Power Transmission & Distribution

Course Code:- 22419

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c) Feeders d) None of the above

Ans- a) Service Mains

Ques 4. Which of the following materials are not used for the transmission and distribution of electrical power?

a) Copper b) Aluminum c) Tungsten d) Steel

Ans-c) Tungsten

Ques 5. The usual spans with R.C.C. poles are

a) 40—50 metres b) 60—100 metres c) 200 – 300 meters d) 80 – 150 meters

Ans- d) 80 – 150 meters

Ques 6. Which of the following are the constants of the transmission lines?

a) Inductance b) Capacitance c) Resistance d) Conductance e) All of the above

Ans- e) 80 – 150 meters

Ques 7. The phenomenon of rising in voltage at the receiving end of the open-circuited or lightly loaded line is called as

a) Roman Effect b) Skin Effect c) Corona Effect d) Ferranti Effect

Ans- d) Ferranti Effect

Ques 8. Low tension cables are meant for use up to

a) 1 kV b) 5 kV c) 10 kV d) 33 kV

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Ans- a) 1 kV

Ques 9. The operating voltage of high tension cables is up to

a) 1 – 11 kV b) 11 – 20 kV c) 11 – 33 kV d) above 33 kV

Ans- a) 1 – 11 kv.

Ques 10. The operating voltage of super tension cable is

a) 1 – 11 kV b) 11 – 33 kV c) 33 – 66 kV d) bove 66 kV

Ans- 11 – 33 kV

Ques 11. The operating voltage of Extra high tension cable is upto

a) 11 kV b) 33 kV c) 66 kV d) Above 66 kV

Ans-c) 66 kV

Ques 12. Which of the following methods is used for laying of underground cables?

a) Direct laying b) Solid system c) Draw-in-system d) All of the Above

Ques 13. Which of the following is the source of heat generation in the cables?

a) Dielectric losses in cable insulation b) Conductor losses c) Sheath loses d) All of the above

Ques 14. Due to which of the following reasons the cables should not be operated too hot?

a) The oil may lose its viscosity and it may start drawing off from higher levels b) Expansion of the oil may cause the sheath to burst c) Unequal expansion may create voids in the insulation which will lead to ionization d) Unequal expansion may create voids in the insulation which will lead to ionization e) All of the above

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Ques 15. Besides a method of trial and error, which of the following methods is employed for the solution of network problems in an interconnected system?

a) Kirchhoff’s laws b) Superposition of currents c) Thevenin’s theorem d) All of the above

Ques 16. A booster is a

1. Synchronous generator 2. Shunt-wound generator 3. Series wound generator 4. None of the above

Ques 17. Which of the following D.C. distribution system is the simplest and lowest in first cost?

1. Radial system 2. Inter-connected system 3. Ring system 4. Any of the above

Answer : a) Radial system

Ques 18. Which of the following faults is most likely to occur in cables?

a) Breakdown of cable insulation b) Cross or short-circuit fault c) Open circuit fault d) All of the above

Answer d. All of the above

Ques 19. The voltage of the single-phase supply to residential consumers is

a) 110 V b) 230 V c) 440 V d) Any of the above

Answer . b. 230 V

Ques 20. The distributors for residential areas are

a) Three-phase four-wire b) Three-phase three-wire c) Single-phase d) None of the above

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Answer -a. Three-phase four-wire

Ques 21. The conductors of the overhead lines are

a) Stranded conductors b) Solid conductors c) Both solid and stranded d) None of the above

Answer- a) Stranded conductors

Ques 22. High voltage transmission lines use

a) Suspension insulators b) Pin insulators c) Any of the above d) None of the above

Answer- a) Suspension insulators

Ques 23. Multicore cables generally use

a) Square conductors b) Rectangular conductors c) Sector-shaped conductors d) Circular conductors

Answer- c ) Sector-shaped conductors

Ques 24. The material commonly used for insulation in high voltage cables is

a) Rubber b) Paper c) Lead d) Any of the above

Answer- b) Paper

Ques 25. Overhead lines generally use

a) A.C.S.R. conductors b) Copper conductors c) Aluminum conductors d) Any of the above

Answer – a) A.C.S.R. conductor

Ques 26. The power factor of industrial loads is generally

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a) Unity b) Lagging c) Leading d) Any of the above

Answer -c) Leading

Ques 27. The material generally used for the armour of high voltage cables is

a) Copper b) Brass c) Aluminum d) Steel

Answer- d) Steel

Ques 28. In transmission lines, the cross-arms are made of

a) Steel b) Wood c) R.C.C d) Either Steel or Wood

Answer- d) Either Steel or Wood

Ques 29. Transmission line insulators are made of

a) Porcelain b) Glass c) Composite Polymer d) Any of the above

Answer- d) Any of the above

Ques 30. The material commonly used for sheaths of underground cables is

a) Lead b) Rubber c) Copper d) Iron

Answer- a) Lead

Prepared By Ms.Sangale P.V

Verified By Mr.Lavate V.J.

Module Coordinator

Re-Verified By Mr.Patil S.S.

Academic Coordinator

Approved By Mr. Mandale R.K.

HoD EE

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02–Transmission Line Parameter & Performance Marks:-014

Content Of Chapter:- 2.1 Line Parameter: Concept Of R,L,C Of Line Parameter. Types Of Line. 2.2 Performance Of Short Line: Efficiency, Regulation And Its Derivation ,Effect Of Power Factor ,Vector Diagram For Different Power Factor. 2.3: Performance Of Medium Line: Nominal T Method, Nominal Tt Method & End Condenser Method. 2.4 Transposition Of Conductor & Its Necessary. 2.5 Skin Effect & Proximate Effect

.

01. Which of the following distribution system is more reliable? A. Radial system B. Tree system C. Ring main system D. All are equally reliable Ans- C. Ring main system 02. Which of the following distribution systems is the most economical? A. A.C. 1-phase system B. A.C. 3-phase 3 wire system C. A.C. 3-phase 4 wire system D. Direct current system Ans- D. Direct current system 03. In a distribution system major cost is that of A. Earthing system B. Distribution transformer C. Conductors D. Metres Ans- C. Conductors

04. Which of the following distribution system is more reliable? A. Radial system B. Tree system




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C. Ring main system D. All are equally reliable Ans- C. Ring main system 05. Which of the following distribution systems is the most economical? A. A.C. 1-phase system B. A.C. 3-phase 3 wire system C. A.C. 3-phase 4 wire system D. Direct current system Answer- D. Direct current system 06. In a distribution system major cost is that of A. Earthing system B. Distribution transformer C. Conductors D. Metres Answer- B. Distribution transformer 07. In the design of a distributor which of the following is the major consideration? A. Voltage drop B. Current carrying capacity C. Frequency D. KVA system Answer- A. Voltage drop 08. The area of cross-section of the neutral in a 3-wire D.C. system is generally .........the area of cross section of main conductor A. Same as B. One fourth C.One half D. Double Answer- C. One half 09. The effect of corona can be detected by A. Presence of zone detected by odour B. Hissing sound C. Faint luminous glow of bluish colour D. All of the above Answer- D. All of the above 10. Corona results in A. Radio interference B. Power factor improvement C. Better regulation

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D. None of the above Answer- A. Radio interference 11. Which of the following has least effect of corona? A. Atmospheric temperature B. Number of ions C. Signage and charge per ion D. Mean free path Answer- A. Atmospheric temperature 12. Power loss due to Corona is not directly proportional to A. Spacing between conductors B. Supply voltage frequency C. Phase-neutral voltage D. All of the above Answer- A. Spacing between conductors 13. Corona is likely to occur maximum in A. Transmission lines B. Distribution lines C. Domestic wiring D. All of the above Answer- A. Transmission lines 14. Corona is A. Partial breakdown of air B. Complete breakdown of air C. Sparking between lines D. All of the above Answer- B. Complete breakdown of air 15. Corona is accompanied by A. Violate visible discharge in darkness B. Hissing sound C. Vibration D. All of the above Answer- D. All of the above 16. Corona loss increases with A. Decrease in conductor size and increase in supply frequency B. increase in both conductor size and supply frequency C. Decrease in both conductor size and supply frequency D. Increase in conductor size and decrease in supply frequency Answer- A. Crease in conductor size and increase in supply frequency

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17. Corona loss can be reduced by the use of hollow conductors because A. The current density is reduced B. The eddy current in the conductor is eliminated C. For a given cross-section, the radius of the conductor is increased D. Of better ventilation in the conductor Answer- C. For a given cross-section the radius of the conductor is increased 18. 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 the above Answer- A. Diameter of the conductor 19. Only advantage of corona is that in A. Produces a pleasing luminous glow B. Makes line current sinusoidal C. Works as a safety valve for surges D. Ozone gas is produced Answer- C. Works as a safety valve for surges

20. The chances of occurrence of corona are maximum during A. Humid weather B. Dry weather C. Winter D. Hot summer Answer- A. Humid weather

21. The charging current in a transmission line increases due to corona effect because corona increases A. Line current B. effective line voltage C. Power loss in lines D. Effective conductor diameter Answer- D. Effective contactor diameter

22. The effect of corona A. Increased energy loss B. Increased reactance C. Increased inductance D. All of the above Answer- A. Increased energy loss 23. Corona losses are minimised when A. Conductor size is reduced B. Smooth conductor is used C. Sharp points are provided in the line hardware D. Current density in conductor is reduced

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Answer- B. Smooth contactor is used 24. Corona occurs between two transmission conductors when they A. Have high potential difference B. Are closely spaced C. Carry DC power D. Both A and B Answer- D. Both A and B 25. In humid weathers, corona occurs at a voltage A. Much less then that needed in fair weather B. Much higher than that needed in fair weather C. Equal to that needed in fair weather D. None off the above Answer- A. Much less then that needed in fair weather 26. Compared with a solid conductor of the same radius, corona appears on a stranded conductor at a lower voltage, because stranding A. Assists ionisation B. Make the current flow spirally about the axis of the conductor C. Produces oblique sections to a plane perpendicular to a axis of the conductor D. Produces surfaces of smaller radius Answer- D. Produces surfaces of smaller radius 27. The good effect of corona on overhead lines is to A. Increase the line carrying capacity due to conducting ionised air envelop around the conductor B. Increase the power factor due to corona loss C. Reduce the radio interference from the conductor D. Reduce the steepness of surge fronts Answer- D. Reduce the steepness of surge fronts 28. Corona loss in a DC line A. Less than that in AC line operating at same rms voltage B. More than that in AC line at same rms voltage C. Same as in AC linear equal rms voltage D. None of the above Answer- A. Less than that in AC line operating at same rms voltage 29. The skin effect in a conductor results in A. Increases in its DC resistance B. Decrease in its AC resistance C. Increase in its AC resistance D. None of the above Answer- C. Increase in its AC resistance 30. The skin effect of a conductor reduces with the increase in A. Supply frequency B. Resistivity of the conductor material C.X-section of conductor

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D. Permeability of conductor material Answer- B. Resistivity of the conductor material



Module Coordinator




HoD EE

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03– Extra High Voltage Transmission Marks:-014

Content of Chapter:- 3.1 Extra High Voltage Transmission Line : Necessity, High Volatage Substation Componants Advantages ,Limitation, Application And Lines In India. Ferranti And Corona Effect. 3.2 Hvdc Transmission Line : Components, Advantages, Limitation, Applications. Layout Of Monopolar, Bipolar, Homopolar Transmission Lines In India. 3.3 Featured Of Ehvac & Hvdc Transmission Lines. 3.4 Flexible Ac Transmission Lines: Features , D Type Fact Controller. 3.5 New Trends In Wirelss Transmission Of Electrical Power

Ques 1. By which of the following method electric power may be transmitted from one location to another location?

a) UnderGround System b) Overhead system c) Both 1 and 2 d) None of the above

Answer- c. Both 1 & 2 Ques 2. Which of the following transmission line have more initial cost?

a) Overhead Transmission b) Underground transmission c) Both have almost the same initial cost d) None of the above e)

Answer- b. Underground Transmission line Ques 3. Name the cable or conductor which connects the distributor to the consumer terminals.

a) Service Mains b) Distributor c) Feeders




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d) None of the above Answer- a . Service Mains Ques 4. Which of the following materials are not used for the transmission and distribution of electrical power?

a) Copper b) Aluminum c) Tungsten d) Steel Answer- c. Tungsten Ques 5. The usual spans with R.C.C. poles are

a) 40—50 metres b) 60—100 metres c) 200 – 300 meters d) 80 – 150 meters

Answer -d. 80 – 150 meters Ques 6. Which of the following are the constants of the transmission lines?

a) Inductance b) Capacitance c) Resistance d) Conductance e) All of the above

Answer- e. All of the Above Ques 7. The phenomenon of rising in voltage at the receiving end of the open-ciruited or lightly loaded line is called as

a) Roman Effect b) Skin Effect c) Corona Effect d) Ferranti Effect

Answer d. Ferranti Effect Ques 8. Low tension cables are meant for use up to

a) 1.1 kV b) 5 kV c) 10 kV d) 33 kV

Answer- a1. 1 kV

Ques 9. The operating voltage of high tension cables is up to

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a) 1.1 – 11 kV b) 11 – 20 kV c) 11 – 33 kV d) above 33 kV

Answer- a.1. 1 – 11 kV Ques 10. The operating voltage of super tension cable is

a) 1 – 11 kV b) 11 – 33 kV c) 33 – 66 kV d) Above 66 kV

Answer- d. Above 66 kV Ques 11. The operating voltage of Extra high tension cable is upto

a) 11 kV b) 33 kV c) 66 kV d) Above 66 kV

Answer 3. 66 kV Ques 12. Which of the following methods is used for laying of underground cables?

a) Direct laying b) Solid system c) Draw-in-system 1. All of the Above

Answer 4. All of the Above Ques 13. Which of the following is the source of heat generation in the cables?

a) Dielectric losses in cable insulation b) Conductor losses c) Sheath loses d) All of the above

Answer d. All of the above Explanation: Ques 14. Due to which of the following reasons the cables should not be operated too hot?

a) The oil may lose its viscosity and it may start drawing off from higher levels b) Expansion of the oil may cause the sheath to burst c) Unequal expansion may create voids in the insulation which will lead to ionization d) Unequal expansion may create voids in the insulation which will lead to ionization e) All of the above

Answer e. All of the above Ques 15. Besides a method of trial and error, which of the following methods is employed for the solution of network problems in an interconnected system?

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a) Kirchhoff’s laws b) Superposition of currents c) Thevenin’s theorem d) All of the above

Answer- d. All of the above Ques 16. A booster is a

a) Synchronous generator b) Shunt-wound generator c) Series wound generator d) None of the above

Answer- c. Series wound generator Ques 17. Which of the following D.C. distribution system is the simplest and lowest in first cost?

a) Radial system b) Inter-connected system c) Ring system d) Any of the above

Answer- a. Radial system Ques 18. Which of the following faults is most likely to occur in cables?

a) Breakdown of cable insulation b) Cross or short-circuit fault c) Open circuit fault d) All of the above e)

Answer d. All of the above Ques -19. The voltage of the single-phase supply to residential consumers is

a) 110 V b) 230 V c) 440 V d) Any of the above e)

Answer-. b. 230 V Ques 20. The distributors for residential areas are

a) Three-phase four-wire b) Three-phase three-wire c) Single-phase d) None of the above

Answer -a. Three-phase four-wire

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Ques 21. The conductors of the overhead lines are

a) Stranded conductors b) Solid conductors c) Both solid and stranded d) None of the above

Answer .1. Stranded conductors Ques 22. High voltage transmission lines use

a) Suspension insulators b) Pin insulators c) Any of the above d) None of the above

Answer -a. Suspension Insulator Ques 23. Multicore cables generally use

a) Square conductors b) Rectangular conductors c) Sector-shaped conductors d) Circular conductors

Answer-c. Sector-shaped conductors

Ques 24. The material commonly used for insulation in high voltage cables is

a) Rubber b) Paper c) Lead d) Any of the above

Answer –b. Paper Ques 25. Overhead lines generally use

a) A.C.S.R. conductors b) Copper conductors c) Aluminum conductors d) Any of the above

Answer -a. A.C.S.R. conductors Ques 26. The power factor of industrial loads is generally

a) Unity b) Lagging c) Leading d) Any of the above

Answer - b. Lagging

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Ques 27. The material generally used for the armour of high voltage cables is

a) Copper b) Brass c) Aluminum d) Steel

Answer -d. Steel Ques 28. In transmission lines, the cross-arms are made of

a) Steel b) Wood c) R.C.C d) Either Steel or Wood

Answer -d. Either Steel or Wood Ques 29. Transmission line insulators are made of

a) Porcelain b) Glass c) Composite Polymer d) Any of the above

Answer-d. Any of the above Ques 30. The spacing between phase conductors of a 220 kV line is approximately equal to

a) 2 m b) 3 m c) 6 m d) 10 m

Answer -c. 6 m



Module Coordinator




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04– AC DISTRIBUTION SYSTEM Marks:-016

Content Of Chapter:- 4.1 Ac Distribution: Components ,Classification ,Requirement Of Ideal Distribution System. 4.2 Feeder & Distributor: Factor To Be Consider Design Of Feeder & Distributors. 4.3 Types of different distribution scheme 4.4 Voltage Drop: Sending End Voltage & Receiving End Voltage. 4.5 Distribution Substation : Classification, Advantages, Disadvantages, Application. 4.6 Single Line Diagram

.

01. Which of the following distribution system is more reliable? A. Radial system B. Tree system C. Ring main system D. All are equally reliable Ans- C. Ring main system 02. Which of the following distribution systems is the most economical? A. A.C. 1-phase system B. A.C. 3-phase 3 wire system C. A.C. 3-phase 4 wire system D. Direct current system Ans- D. Direct current system 03. In a distribution system major cost is that of A. Earthing system B. Distribution transformer C. Conductors D. Metres Ans- C. Conductors

04. Which of the following distribution system is more reliable? A. Radial system B. Tree system




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C. Ring main system D. All are equally reliable Ans- C. Ring main system 05. Which of the following distribution systems is the most economical? A. A.C. 1-phase system B. A.C. 3-phase 3 wire system C. A.C. 3-phase 4 wire system D. Direct current system Answer- D. Direct current system 06. In a distribution system major cost is that of A. Earthing system B. Distribution transformer C. Conductors D. Metres Answer- B. Distribution transformer 07. In the design of a distributor which of the following is the major consideration? A. Voltage drop B. Current carrying capacity C. Frequency D. KVA system Answer- A. Voltage drop 08. The area of cross-section of the neutral in a 3-wire D.C. system is generally .........the area of cross section of main conductor A. Same as B. One fourth C.One half D. Double Answer- C. One half 09. The effect of corona can be detected by A. Presence of zone detected by odour B. Hissing sound C. Faint luminous glow of bluish colour D. All of the above Answer- D. All of the above 10. Corona results in A. Radio interference B. Power factor improvement C. Better regulation

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D. None of the above Answer- A. Radio interference 11. Which of the following has least effect of corona? A. Atmospheric temperature B. Number of ions C. Signage and charge per ion D. Mean free path Answer- A. Atmospheric temperature 12. Power loss due to Corona is not directly proportional to A. Spacing between conductors B. Supply voltage frequency C. Phase-neutral voltage D. All of the above Answer- A. Spacing between conductors 13. Corona is likely to occur maximum in A. Transmission lines B. Distribution lines C. Domestic wiring D. All of the above Answer- A. Transmission lines 14. Corona is A. Partial breakdown of air B. Complete breakdown of air C. Sparking between lines D. All of the above Answer- B. Complete breakdown of air 15. Corona is accompanied by A. Violate visible discharge in darkness B. Hissing sound C. Vibration D. All of the above Answer- D. All of the above 16. Corona loss increases with A. Decrease in conductor size and increase in supply frequency B. increase in both conductor size and supply frequency C. Decrease in both conductor size and supply frequency D. Increase in conductor size and decrease in supply frequency Answer- A. Crease in conductor size and increase in supply frequency

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17. Corona loss can be reduced by the use of hollow conductors because A. The current density is reduced B. The eddy current in the conductor is eliminated C. For a given cross-section, the radius of the conductor is increased D. Of better ventilation in the conductor Answer- C. For a given cross-section the radius of the conductor is increased 18. 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 the above Answer- A. Diameter of the conductor 19. Only advantage of corona is that in A. Produces a pleasing luminous glow B. Makes line current sinusoidal C. Works as a safety valve for surges D. Ozone gas is produced Answer- C. Works as a safety valve for surges 20. The chances of occurrence of corona are maximum during A. Humid weather B. Dry weather C. Winter D. Hot summer Answer- A. Humid weather 21. The charging current in a transmission line increases due to corona effect because corona increases A. Line current B. effective line voltage C. Power loss in lines D. Effective conductor diameter Answer- D. Effective contactor diameter 22. The effect of corona A. Increased energy loss B. Increased reactance C. Increased inductance D. All of the above Answer- A. Increased energy loss 23. Corona losses are minimised when

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A. Conductor size is reduced B. Smooth conductor is used C. Sharp points are provided in the line hardware D. Current density in conductor is reduced Answer- B. Smooth contactor is used 24. Corona occurs between two transmission conductors when they A. Have high potential difference B. Are closely spaced C. Carry DC power D. Both A and B Answer- D. Both A and B 25. In humid weathers, corona occurs at a voltage A. Much less then that needed in fair weather B. Much higher than that needed in fair weather C. Equal to that needed in fair weather D. None off the above Answer- A. Much less then that needed in fair weather 26. Compared with a solid conductor of the same radius, corona appears on a stranded conductor at a lower voltage, because stranding A. Assists ionisation B. Make the current flow spirally about the axis of the conductor C. Produces oblique sections to a plane perpendicular to a axis of the conductor D. Produces surfaces of smaller radius Answer- D. Produces surfaces of smaller radius 27. The good effect of corona on overhead lines is to A. Increase the line carrying capacity due to conducting ionised air envelop around the conductor B. Increase the power factor due to corona loss C. Reduce the radio interference from the conductor D. Reduce the steepness of surge fronts Answer- D. Reduce the steepness of surge fronts 28. Corona loss in a DC line A. Less than that in AC line operating at same rms voltage B. More than that in AC line at same rms voltage C. Same as in AC linear equal rms voltage D. None of the above Answer- A. Less than that in AC line operating at same rms voltage 29. The skin effect in a conductor results in A. Increases in its DC resistance B. Decrease in its AC resistance

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C. Increase in its AC resistance D. None of the above Answer- C. Increase in its AC resistance 30. The skin effect of a conductor reduces with the increase in A. Supply frequency B. Resistivity of the conductor material C.X-section of conductor D. Permeability of conductor material Answer- B. Resistivity of the conductor material



Module Coordinator




HoD EE

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05–Components Of Transmission & Distribution Lines

Marks:-014

Content of Chapter:- 5.1 Overhead Conductor: Properties Of Material ,Types Of Conductor With Trade Name. 5.2 Line Support : Requirement ,Types Of Line Structure, Method Of Errection. 5.3 Line Insulator: Properties Of Insulating Material ,Selection Of Insulating Material ,Types Of Insulator, Causes Of Insulator Failure. 5.4 Underground Cable : Requirement ,Classification ,Construction ,Comparison With Overhead Lines, Cable Laying & Cable Joining

1. Most of the high-voltage transmission lines are A. Underground B. Overhead C. Either of the above D. None of the above Answer- B. Overhead 2. High-voltage transmission lines use A. Suspension insulators B. Pin insulators C. Both A and B D. None of the above Answer- A. Suspension insulators. 3. The load on distributors systems are generally A. Balanced B. Unbalanced C. Either of the above D. None of the above Answer- B. Unbalanced 4. In transmission lines the cross arms are made of A. Copper




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B. Wood C. R.C.C. D. Steel Answer- A. Copper 5. Transmission line insulators are made of A. Glass B.Porcelain C. Iron D. P.V.C. Answer- B. Porcelain 6. A feeder in a transmission system feeds power to A. Distributors B. Generating stations C. Service mains D. All of the above Answer- A. Distributors 7. Which of the following material is used for overhead transmission lines? A. Still cored aluminium B. Galvanised steel C. Cadmium copper D. Any of the above Answer- D. Any of the above 8. The power transmitted will be maximum when A. Corona losses are minimum B. Reactance is high C. Sending end voltage is more D. Receiving end voltage is more Answer- C. Sending end voltage is more 9. Which of the following D.C. distribution system is the simplest and the lowest in first cost? A. Radial system B. Ring system C. Interconnected system D. None of the above Answer- A. Radio system 10. The phenomena of rise in voltage at the receiving end of the open circuited or slightly loaded line is called the A. Seeback effect B. Ferranti effect C. Raman effect D. None of the above Answer- B. Ferranti effect 11. Which of the following materials is not used for transmission and distribution of electrical power?

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A. Copper B. Aluminium C. Steel D. Tungsten Answer- D. Tungsten 12. Which of the following are the constants of the transmission lines? A. Resistance B. Inductance C. Capacitance D. All of the above Answer- D. All of the above 13. The distributors for residential areas are A. Single phase B. Three phase three wire C. Three phase four wire D. None of the above Answer- C. Three phase four wire 14. The contactors of the overhead lines are A. Solid B. Stranded C. Both solid and stranded D. None of the above Answer- C. Both solid and stranded 15. Which of the following relays is used on long transmission lines? A. Impedance relay B. Mho's relay C. Reactance relay D. None of the above Answer- B. Mho's relay 16. Which of the following characteristics should the line supports for transmission line possess ? A. Low-cost B. High mechanical strength C. longer life D. all of the above Answer- D. All of the above 17. By which of the following methods string efficiency can be improved? A. Using a guard ring B. Grading the insulator C. Using long cross arm D. Any of the above Answer- D. Any of the above

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18. The voltage drop, for constant voltage transmission is compensated by installing A. Inductors B. Capacitors C. Synchronous motor D. All of the above Answer- C. Synchronous motor 19. For transmission of power over a distance of 200 km, the transmission voltage should be A.132 KV B. 66 KV C. 33 KV D.11 KV Answer- A. 132 KV 20. For transmission of power over a distance of 500 km, the transmission voltage should be in the range of A. 150 to 220 KV B. 100 to 120 KV C. 60 to 100 KV D. 20 to 50 KV Answer- A. 150 to 220 KV 21. The top-most conductor in a high transmission line is A. Earth conductor B. R-phase conductor C. Y-phase conductor D. B-phase conductor Answer- A. Earth conductor 22. By which of the following methods voltage of transmission can be regulated? A. Use of series capacitors of neutralise the effect of series reactance B. Switching in shunt capacitors at the receiving end during heavy loads C. Use of tap changing transformers D. Any of the above methods Answer- D. Any of the above methods 23. Which of the following is the main advantage of AC transmission system over DC transmission system ? A. Less instability problem B. Less installation problems C. Easy transformation D. Less losses in transmission over long distances Answer- D. Less losses in transmission over long distances 24. The effect of ice on transmission line conductors is to increase the A. Transmission losses B. Weight of the conductor C. Tendency for corona D. Resistance to flow of current Answer- B. Weight of the conductor

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25. if the height of transmission tower is increased A. The line capacitance will decrease but line inductance will remain unchanged B. The line capacitance and inductance will not change C. The line capacitance will increase but line inductance will decrease D. The line capacitance will decrease but line inductance will increase Answer- A. The line cap will decrease but line inductance will remain unchanged 26. Which of the following distribution system is more reliable? A. Radial system B. Tree system C. Ring main system D. All are equally reliable Answer- C. Ring main system 27. Which of the following distribution systems is the most economical? A. A.C. 1-phase system B. A.C. 3-phase 3 wire system C. A.C. 3-phase 4 wire system D. Direct current system Answer- D. Direct current system 28. In a distribution system major cost is that of A. Earthing system B. Distribution transformer C. Conductors D. Metres Answer- B. Distribution transformer 29. In the design of a distributor which of the following is the major consideration? A. Voltage drop B. Current carrying capacity C. Frequency D. KVA system Answer- A. Voltage drop 30. The area of cross-section of the neutral in a 3-wire D.C. system is generally .........the area of cross section of main conductor A. Same as B. One fourth C.One half D. Double Answer- C.One half 31. The effect of corona can be detected by A. Presence of zone detected by odour B. Hissing sound C. Faint luminous glow of bluish colour D. All of the above Answer- D. All of the above

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32. Corona results in A. Radio interference B. Power factor improvement C. Better regulation D. None of the above Answer- A. Radio interference 33. Which of the following has least effect of corona? A. Atmospheric temperature B. Number of ions C. Signage and charge per ion D. Mean free path Answer- A. Atmospheric temperature 34. Power loss due to Corona is not directly proportional to A. Spacing between conductors B. Supply voltage frequency C. Phase-neutral voltage D. All of the above Answer- A. Spacing between conductors 35. Corona is likely to occur maximum in A. Transmission lines B. Distribution lines C. Domestic wiring D. All of the above Answer- A. Transmission lines 36. Corona is A. Partial breakdown of air B. Complete breakdown of air C. Sparking between lines D. All of the above Answer- B. Complete breakdown of air 37. Corona is accompanied by A. Violate visible discharge in darkness B. Hissing sound C. Vibration D. All of the above Answer- D. All of the above 38. Corona loss increases with A. Decrease in conductor size and increase in supply frequency B. increase in both conductor size and supply frequency C. Decrease in both conductor size and supply frequency D. Increase in conductor size and decrease in supply frequency

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Answer- A. Crease in conductor size and increase in supply frequency 39. Corona loss can be reduced by the use of hollow conductors because A. The current density is reduced B. The eddy current in the conductor is eliminated C. For a given cross-section, the radius of the conductor is increased D. Of better ventilation in the conductor Answer- C. For a given cross-section the radius of the conductor is increased 40. 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 the above Answer- A. Diameter of the conductor 41. Only advantage of corona is that it A. Produces a pleasing luminous glow B. Makes line current sinusoidal C. Works as a safety valve for surges D. Ozone gas is produced Answer- C. Works as a safety valve for surges 42. The chances of occurrence of corona are maximum during A. Humid weather B. Dry weather C. Winter D. Hot summer Answer- A. Humid weather 43. The charging current in a transmission line increases due to corona effect because corona increases A. Line current B. effective line voltage C. Power loss in lines D. Effective conductor diameter Answer- D. Effective contactor diameter 44. The effect of corona is A. Increased energy loss B. Increased reactance C. Increased inductance D. All of the above Answer- A. Increased energy loss 45. Corona losses are minimised when A. Conductor size is reduced B. Smooth conductor is used C. Sharp points are provided in the line hardware

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D. Current density in conductor is reduced Answer- B. Smooth contactor is used 46. Corona occurs between two transmission conductors when they A. Have high potential difference B. Are closely spaced C. Carry DC power D. Both A and B Answer- D. Both A and B 47. In humid weathers, corona occurs at a voltage A. Much less then that needed in fair weather B. Much higher than that needed in fair weather C. Equal to that needed in fair weather D. None off the above Answer- A. Much less then that needed in fair weather 48. Compared with a solid conductor of the same radius, corona appears on a stranded conductor at a lower voltage, because stranding A. Assists ionisation B. Make the current flow spirally about the axis of the conductor C. Produces oblique sections to a plane perpendicular to a axis of the conductor D. Produces surfaces of smaller radius Answer- D. Produces surfaces of smaller radius 49. The good effect of corona on overhead lines is to A. Increase the line carrying capacity due to conducting ionised air envelop around the conductor B. Increase the power factor due to corona loss C. Reduce the radio interference from the conductor D. Reduce the steepness of surge fronts Answer- D. Reduce the steepness of surge fronts 50. Corona loss in a DC line A. Less than that in AC line operating at same rms voltage B. More than that in AC line at same rms voltage C. Same as in AC linear equal rms voltage D. None of the above Answer- A. Less than that in AC line operating at same rms voltage



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