Transmission And Distribution

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c    c

1. A preferred relay scheme for transmission line protection consists of: (a) Time-graded over-current relays (b) Current-graded over-current relays (c) Mho-relays (d) Impedance relays

(b) (c) (d)

Ans a 8. The principle reason for using high voltage for power transmission is to: (a) Reduced the transmission line (b) Reduce the transmission loss (c) Make the system more reliable (d) To simplify the transmission of power

Ans d 2. In a transmission system the receiving end voltage can be maintained close to sending-end voltage by using: (a) Synchronous converter (b) Static or synchronous condensers (c) Static converter (d) None of these

Ans b 9. The advantage of D.C system over A.C system is: (a) Improved line regulation (b) No skin effect (c) No charging currents (d) All of above

Ans b 3. Mho relay is normally used for the protection to transmission lines of: (a) Long lengths (b) Medium lengths (c) Short lengths (d) Any lengths

Ans b 10. For high voltage application, th e insulator used are of: (a) Suspension type (b) Pin type (c) Strain type (d) None of these

Ans a 4. Which of the following is not the transmission voltage in india? (a) 66KV (b) 132KV (c) 275KV (d) 400KV

Ans a 11. The top most wire in a distribution line is: (a) Neutral wire (b) Earth wire (c) Phase wire (d) Any one of these

Ans c 5. Which of the following is usually generating voltage in india (a) 11KV (b) 22KV (c) 33KV (d) 66KV

Ans c

Ans d 6. Highest voltage for transmitting electrical power in india (a) 800KV (b) 500KV (c) 765KV (d) 400KV Ans a 7. Over head distribution line earth wire which runs along, is earthed at four equally spaced point during in every (a) 1.6 KM ? ?

2.8KM 5 KM 10KM


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12. In a power transmission line, the sag depends upon: (a) Conductor material alone (b) Tension in conductors alone (c) Height of tower alone (d) All of these Ans d 13. Conductors used in high voltage transmission lines are stranded to: (a) Make it easy to handle (b) Reduced the cost (c) Increase the cost (d) Increase its conductivity (e) Increase its tensile strength

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(a) (b) (c) (d)

Ans a 14. On a transmission line, when ever the conductors are dead ended or there in change in the direction of transmission line, the insulators used are: (a) Suspension type (b) Strain type (c) Pin type (d) None of these

Ans c 21. Temperature increase produce the following effect on a t ransmission line: (a) Tension of the conductor an d its sag (b) Tension of the conductor decreasing its sag increase (c) Tension of the conductor decreasing its sag increase (d) Tension the conductor increasing its sag decreases

Ans b 15. Ground wire is used: (a) To avoid over loading (b) To give good insulation (c) To connect a circuit conductor or other device to an earth plate (d) None of these

Ans c 22. As per india standards, the cross sectional area of the neutral wire in a 3 phase wire system is: (a) Twice that of phase conductor (b) Equal to that of a phase conductor (c) Half that of a phase conductor (d) One fourth that of a phase conductor

Ans c 16. The ground wire should not be smaller than: (a) No 6 copper (b) No 8 copper (c) No 10 copper (d) No 12 copper

Ans d

Ans c

23. As per india standards, the permissible rang of power supply frequency is: (a) 49.5 to 50.5 HZ (b) 49 to 51 HZ (c) 48.5 to 51.5 HZ (d) 48 to 52 HZ

17. Grounding is generally done in transmission line at: (a) The supply end (b) The receiving end (c) Middle of the line (d) None of these

Ans d

Ans a 18. Earthing of transmission line is necessary to provide protection against: (a) Over load (b) Electric shock (c) Voltage fluctuation (d) Temperature rise of conductors Ans b 19. Thermal protection switch is provided power line system to protect against: (a) Over load (b) Temperature rise (c) Short circuit (d) None of these Ans a 20. Earthing switch is generally installed on: ? ?

Main board Isolator frame Circuit breaker frame None of these

24. Rise of temperature of transmission line (a) Increases the stress and decrease the length (b) Decreases the stress and increase the length (c) Increase the stress and increase the length (d) Decrease the stress and decrease the length Ans b 25. Lightning arrestier should be located: (a) Away from the circuit breaker (b) Near the circuit breaker (c) Away from the transformer (d) Near the transformer Ans d

26. Guy is attached to a transmission line ?
?? ?

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c    c

(a) (b) (c) (d)

pole to: Reduce the sag Hold the telephone line Strength the pole None of these

(a) (b) (c) (d)

Ans

Ans c

27. Overloading is mostly cause of fault is (a) Overload line equipment (b) Transmission equipment (c) Alternator equipment (d) None of these

33. High voltage transmission line is used (a) To improve power factor (b) To reduce the capacity of generators (c) To minimize transmission losses (d) To avoid pilferage of power

Ans b

Ans c

28. Between the power house and consumer, these are usually a number of transformation and switching station. These are called (a) Station transformer (b) Intermediate station (c) Substations (d) Switch fears

34. In the transmission line, the wire above all the other wire is: (a) Red phase wire (b) Yellow phase wire (c) Blue phase wire (d) Earth wire Ans d 35. In erection of 11 kv lines we provide earth wire which is made of: (a) Bare copper (b) All aluminium (c) G.S.S (d) A.C.S.R

Ans c 29. From the consideration of cost and safety, the outdoor substation are installed for voltage exceeding: (a) 6.6KV (b) 11KV (c) 33KV (d) 66KV Ans c 30. ACSR is used for transmission of power in preference to copper conductors because: (a) It is lighter (b) It is more economical (c) It has higher current carrying capacity (d) It can stand higher surge voltage Ans b 31. Typical gap length of rod type surge diverter used for 132 KV line is: (a) 10 cm (b) 20 cm (c) 35 cm (d) 65 cm Ans d 32. Batteries at a power sub -station are used ? ?

for operating: Circuit breaker Relays Trip circuit All of these


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36. A distribution transmission sub -station is located at a plane (a) Near to P.S.E.B office (b) Near to grid sub-station of P.S.E.B (c) Load center of the loads to be connected (d) Near the farthest load

37. A.C.S.R conductor is used for transmission of power, rather than copper conductor because: (a) It is lighter to transport (b) It is more economical (c) It can with stand surge voltage b etter (d) It has high current carrying capacity

38. Shackle/bobbin insulators are used in erection of: (a) L.T line ? ?

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c    c

(b) (c) (d)

11 Kv lines Telephone lines Extra high volateg line

(d)

Ans d

Ans a 39. The advantage of transmission power at high voltage is: (a) It reduces generating cost (b) It increase the efficiency of the power station (c) It reduces the size of the conductor (d) Insulator cost is less

45. If a transmission line sag is kept too low, then : (a) The highest of the towers will be more (b) Tension will be more on overhead conductor (c) The height of the towers will be less (d) More conductor material is needed Ans b 46. If a transmission line voltage is increased in times, the size of the conductor would be (a) Increased n2 times (b) Reduced 1/n times (c) Reduced 1/n2 times (d) Increased n times

Ans c 40. The primary function of a fuse is to (a) Protect the appliance (b) Open the circuit (c) Prevent excessive currents (d) Protect the line Ans c

Ans c

41. The best material for a fuse wire (a) Silver (b) Aluminium (c) Copper (d) Zinc

47. Earthing is necessary to give protection against: (a) Overloading (b) Voltage fluctuation (c) High temperature of the conductor (d) Danger of electric shock

Ans

Ans d

42. For 66 KV overhead transmission line. The clearance along any street above ground shall not be less than: (a) 5.791 m (19 feet) (b) 5.486 m (18 feet) (c) 5.182 m (17 feet) (d) 6.096 m (20 feet)

48. In an overloading transmission line, the tension on the conductor during summer season is: (a) More (b) Equal to winter summer (c) Less (d) None of the above

Ans d

Ans

43. In the case of a neutral wire: (a) Its potential is zero at all points (b) It acts as a return conductor (c) It may carry current only in case of earth fault (d) It is connected to earth at an intermediate point

49. Conductor used in high tension transmission lines, are stranded b ecause : (a) It is easy to handle (b) It is cheap (c) It increases tensile strength (d) It increases conductivity

Ans b 44. The device which connects a conduct or to the earth to dischange the charge on the conductor to the earth is called: (a) H.R.C fuse (b) Circuit breaker (c) Insulator ? ?

Earthing switch


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Ans a 50. The main reason is using high voltage for long distance power is to: (a) Reduce the travel of transmission (b) Reduce the transmission losses (c) None of the above ? ?

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c    c

(d)

(d)

Make the system reliable

Ans b

Ans b

57. In a L.T distribution overload lines without street light, number of wires provided is: (a) 3 (b) 4 (c) 5 (d) 6

51. Overhead distribution system has the following, advantage over underground system: (a) Initial cost is low (b) Maintenance cost is minimum (c) Chances of accidents are minimum (d) No interference with communication circuits

Ans c

Ans a 52. The horizontal clearance between the nearest conductor and any part of a building for a 11KV distribution line shall, on the basis of maximum deflection due to wind pressure be not less than: (a) 1.829 m (6 feet) (b) 1.219 m (4 feet) (c) 2.439 m (8 feet) (d) 0.61 m (2 feet) Ans b 53. In a 3 star connected system, line current is equal to: (a) Phase current (b) 3Xphase current (c) 53Xphase current (d) 1/53Xphase current Ans a 54. For 11 kv underground system.it is possible to wotk upon a length of: (a) 100 miles (b) 300 miles (c) 1000 miles (d) None of the above

58. In direct laying method of 11 kv underground cables, thickness of sand bed made under the cable is about: (a) 5 cm (b) 12 cm (c) 20 cm (d) 30 cm Ans a 59. The depth to be normally embedded in the ground while erecting a RCC pole, is equal to: (a) ¼ th. Of pole length (b) 1/5 th. Of pole length (c) 1/6 th. Of pole length (d) 1/7 th. Of pole length Ans c 60. Platform for supporting a 11 kv /0.4 kv transformer is a pole mounted sub station is usually made of: (a) 6 nos channel froms (b) 6 nos is equal forms (c) 2 nos angle irons and 4 nos channel irons (d) 4 nos angle irons and2 nos channel irons Ans a

Ans a

61. No. of L.T bushings on a 11/0.4 KV distribution transformer are: (a) 3 (b) 4 (c) 5 (d) 6

55. In direct lazing method of 1 kv underground cables, normal size of trench due is: (a) 1 m wide and 1m deep (b) ½ m wide and ½ m deep (c) ½ m wide and 1 m deep (d) ½ m wide and ¾ m deep

Ans b

Ans c

62. A sub-station is earthed at minimum of (a) 3 places (b) 2 places (c) 1 places

56. 11 kv armoured underground cable has: (a) 2 cores (b) 3 cores (c) Four cores ? ?

Three and a half cores


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(d)

4 places

(b) (c) (d)

Ans a 63. Gang operating switched called G.O switch is used for switching on and off the: (a) 33 KV (b) 11 KV (c) LT KV (d) EHV line Ans b

Surge absorbers Horn gap All of the above

Ans d 69. Transmission efficiency increases as (a) Voltage and P.F both increase (b) Voltage and P.F both decrease (c) Voltage increases but P.F decrease (d) Voltage decrease but P.F increase Ans a

64. In our house we have normally 230V, AC 70. Wooden poles for supporting 50 HZ supply and there are two wire transmission lines are used on voltage up connected to supply system these wire to are: (a) 400 V (a) One neutral and one earth (b) 11 KV (b) One neutral and one phase (c) 22 KV (c) One phase and one wire connected to (d) 66 KV earth (d) Two phase of A.C distribution system Ans c 71. The expected life of wooden poles is (a) Six months (b) One years (c) 5 years (d) 15 years

Ans b 65. Number of lighting arrestors to be installed on a pole mounted distribution sub-station is: (a) 2 (b) 3 (c) 4 (d) None of the above

Ans d 72. Maximum permissible span wooden pole is (a) 15 meters (b) 35 meters (c) 60 meters (d) 250 meters

Ans b 66. Where the lightening arrestors installed on a pole mounted distribution sub station (a) On the top of h pole (b) Near the HT fuse unit (c) Away from the transformer (d) None of the above

Ans c 73. In which of the following type pole structured distribution transformer installed (a) I type (b) J type (c) H type (d) A type

Ans b 67. Power factor of a factory can be improved by the factory by installing: (a) Transformer near his factory (b) Installing power factor meter (c) Shunt capacitors near load (d) By generating more KVAR at the power house

Ans c 74. The disadvantage of transmission lines as compared to cables is (a) Exposure to lightening (b) Exposure to atmospheric hazards like smoke, ice etc (c) Inductive interference between power and communication circuits

Ans c 68. Which of the following is the protective device against lightning over voltage? (a) Rod gap ? ?


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(d)

All of the above Ans d

75. In transmission lines, the feeder feeds power to (a) Service main (b) Generating stations (c) Distributors (d) All of the above Ans c 76. The chance of corona effect are maximum during (a) Summer heat (b) Winter (c) Dry weather (d) Humid weather Ans d 77. Alternating current power is transmitted at high voltage (a) To safeguard against pilferage (b) To minimum transmission losses (c) To reduce cost of generation (d) To make the system reliable Ans b 78. The function of steel wire in ACSR conductors is (a) To take care of surges (b) To prevent corona (c) To reduce inductance and hence improve power factor (d) To provide additional mechanical strength Ans d 79. In high voltage transmission lines the topmost conductor is (a) R-phase conductor (b) Y-phase conductor (c) B-phase conductor (d) Earth conductor Ans d 80. Permissible variation of frequency is (a) +- 0.1 % (b) +- 1 % (c) +- 5 % (d) +- 10 % Ans b ? ?

81. The main advantage of ac transmission system over dc transmission systems is (a) Easy transformation (b) Less losses in transmission over long distances (c) Less insulation problems (d) Less problem if instability Ans b 82. Which of the following equipments will not find application in D.C transmission system? (a) Circuit breakers (b) Transmission towers (c) Capacitor bank (d) Relay Ans c 83. Isolators are used to disconnect a circuit when (a) Line is on full load (b) Line is energized (c) Circuit breaker not open (d) There is no current in the line Ans d 84. Which device automatically interrupts the supply in the event of surge ? (a) Earthing switch (b) Series reactor (c) Isolator (d) Circuit breaker Ans d 85. Current rating is not necessary in case of (a) Isolators (b) Circuit breakers (c) Load breaker switches (d) All of the above Ans a 86. Which of the following equipment is not installed in a sub-station? (a) Shunt reactions (b) Exciters (c) Voltage transformers (d) Series capacitors Ans b 87. Transmission lines link (a) Generating station to receiving end station (b) Service points to consumer premises ?
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(c) (d)

Distribution transformer to consumer premises Receiving end station to distribution transformer

Ans d 94. In a distribution system major cost is that of (a) Earthing system (b) Conductors (c) Meters (d) Distribution transformer

Ans a 88. Floating neutral in 3 -phase supply, is undersirable because it cause (a) Low voltage across the load (b) High voltage across the load (c) Unequal line voltage across the load (d) None of above

Ans d 95. Transmission voltage of 11 KV is normally used for distance upto (a) 20 ± 25 km (b) 45 to 60 km (c) 70 ± 80 km (d) 100 to 120 km

Ans c 89. Due to which of the following reasons aluminum is being favoured as bus bar material? (a) Low density (b) Low cost (c) Ease of fabrication (d) All of the above

Ans a 96. The steel used in steel cored conductors is usually (a) Stainless steel (b) Alloy steel (c) Mild steel (d) Silicon steel

Ans b 90. The effect of wind pressure is more predomination on (a) Supporting towers (b) Neutral wires (c) Transmission lines (d) Insulators

Ans a 97. Which of the following is not a constituent for making porcelain insulators? (a) Duarts (b) Kaolin (c) Feldspar (d) Silica

Ans a 91. Which of the following can be used for bus-bar? (a) Tubes (b) Rods (c) Bars (d) Any of the above

Ans d 98. Transmission line insulator are made of (a) Glass (b) Porce lain (c) Iron (d) PVC

Ans 92. Power system stability is least affected by (a) Reactance of generating (b) Reactance of transmission line (c) Input torque (d) Losses Ans d 93. The material used for the manufacture of grounding wires is (a) Cast iron (b) Aluminium (c) Stain loss steel (d) Galvanized steel ? ?


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Ans b 99. In transmission lines the cross arms are made of (a) Copper (b) Wood (c) R.C.C (d) Steel Ans d 100. Distribution lines in india generally use (a) Wooden poles (b) R.C.C poles ? ?

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c    c

(c) (d)

Steel towers None of these

Ans b 107. If the phase to neutral voltage is a three phase system is 230 volts, the phase to phase voltage is approximately (a) 480 V (b) 415 V (c) 600 V (d) 120 V

Ans b 101. The voltage of the single phase supply to residential consumers in (a) 230 KV (b) 200 V (c) 230 V (d) 400 V

Ans b

Ans c

108. The minimum clearance required for service ± drop conductor above commercial areas subject to truck traffic is: (a) M(12 feet) (b) M(15 feet) (c) 5.486 M (18 feet) (d) 6.096 M (20 feet)

102. The usual span with R.C.C poles are (a) 40 ± 50 meters (b) 60 ± 70 meters (c) 80 ± 100 meters (d) 200 ± 300 meters Ans c

Ans

103. Galvanized steel wire is generally used as (a) Stay wire (b) Erath wire (c) Structural component (d) All of the above Ans d 104. Which of the following materials is not used for transmission and distribution of electrical power? (a) Copper (b) Steel (c) Aluminium (d) Nicrome Ans d 105. As per indian electricity rules, the insulation resistance between conductor and earth should not be less than (a) 30 mega-ohms/no.of out lets (b) 50 mega-ohms/no.of outlets (c) 80 mega-ohms/no. of out lets (d) None of the above Ans b 106. A man holds both the terminals of a 500 V meggar, but still safe due to: (a) High voltage (b) Very low current (c) High resistance of the body (d) Low resistance of the body ? ?

109. While earthing the line through erathing rod, the earthing rod is connected: (a) First with line and then with earth (b) First with earth and then with line (c) Both with line and earth simultaneously (d) With none of the above Ans b 110. Permit to work (P.T.W) is printed in many colours for working an electric apparatus in grid substation which colous of P.T.W form used: (a) Red (b) Green (c) Brown (d) White Ans d 111. In a 132 KV substation having 2X40 mva transformers, the supply voltage for protection system is: (a) 24 volt D.C (b) 220 volts D.C (c) 220 volts A.C (d) 440 volts A.C Ans b

112. Capacitors at the substation are used to: (a) Improve voltage only (b) To reduce current only ?
? ? ?

c
         

c    c

(c) (d)

To improve power factor only To achieve all these objectives

(a) (b) (c) (d)

Ans c 113. The current carrying capacity of a conductor: (a) Decreases with rise in temperature (b) Increases with rise in temperature (c) It is not affected Ans a 114. in: (a) (b) (c) (d)

Copper conductor is always tinned V.I.R cables P.V.C cables Paper insulated cables None of the above

Ans c 119. 200 KVA distribution transformer installed for supply a city. Transformer takes how much current in ampereses at 11 KV HT side and 0.4 KV (a) 5.25 A/139.1 A (b) 10.50 A/278.2 A (c) 15.75 A/417.4 A (d) 26.25 A/695.6 A Ans b 120. (a) (b) (c) (d)

Ans a 115. As per Indian electricity rules the maximum difference between declared voltage and actual voltage at consumer permises should be: (a) +-6% (b) +-5% (c) +-8% (d) +-10%

Load shedding is possible through Switching off the loads Frequency reduction Voltage reduction Any of the above Ans d

Ans a 116. The commonly used phase sequence is: (a) RYB (b) BRY (c) YBR (d) Any of the these Ans d

117. 25 KVA distribution transformer installed for supply a village. Transformer takes how much current in ampereses at 11 KV (a) 1.31 A/34.8 A (b) 2.62 A/69.6 A (c) 3.30 A/88.0 A (d) 5.25 A/139.1 A Ans a 118. 63 KVA distribution transformer installed for supply a village. transformer takes how much current in ampereses at 11 Kv side and 0.4 KV LT side ? ?

1.31 A/34.8 A 2.62 A/69.6 A 3.30 A/88.0 A 5.25 A/139.1 A


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