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ELECTRICAL LICENSING BOARD, ODISHA, BHUBANESWAR

SCC (HT) EXAMINATION-2017

PAPER-I

Time – 2 Hrs Full Marks - 100

Pass Marks – 50

(Without aid of Books, Notes or External assistance)

Put tick (√) mark on the option provided on bracket against a, b, c or d for right answer

(All questions carry equal marks)

1. The inductance of power transmission line increases with

a) Decrease in line length

b) Increase in diameter of conductor

c) Increase in spacing between phase conductors

d) Increase in load current carried by conductors

2. Stringing chart is useful for

a) Design of tower b) design of insulator ring

c) Finding the sag in conductor d) Finding distance between towers

3. Which of the following protects a cable against external injury?

a) Armoring b) Sheath

c) Bedding d) None of the above

4. The switch that cannot be operated in load condition is

a) AB switch b) OCB

c) AB circuit breaker d) Isolator

5. Which type of connection is employed for current transformer (CT) for the

protection of star-delta connected 3 phase transformer

a) delta-delta b) star-star

c) star-delta d) delta-star

6. Which type of distance relay is preferred for protection of long transmission line

a) Ohm relay b) Reactance relay

c) Mho relay d) all of the above

7. In the protection of transformers, harmonic restraint coil is used to guard against

a) Unbalanced operation b) Lightening

c) Magnetic Inrush Current d) Switching Over voltage

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8. Which of the following is true about transformer?

a) Constant frequency device b) Constant power device

c) Constant flux device d) All of the above

9. The nature of induced emf in transformer is

a) Dynamically induced emf b) statically induced emf

c) Both a & b d) none of the above

10. In two watt meter method of 3 ph power measurement, the load is resistive. The

readings of watt meter are W1 and W2, then

a) W1=W2 b) W1 is less than W2

c) W1 is greater than W2 d) none of the above

11. A 200/400V, 10 kva, 50 hertz single phase transformer has, at full load ,a copper

loss of 120W.If it has an efficiency of 98% at full load, the iron loss is

a) 92 W b) 84W

c) 117W d) 106W

12. A transformer can have zero voltage regulation at

a) zero power factor b) leading power factor

c) Lagging power factor d) unity power factor

13. Skew is used in induction machines in order to reduce torque due to

a) Time harmonics b) space harmonics

c) Slot harmonics d) none of the above

14. The crawling of an induction motor is caused by

a) Improper design b) low voltage supply

c) High loads d) harmonics developed by motor

15. The type of alternators preferred for alternators driven by steam turbine is

a) Cylindrical rotor b) Slip ring rotor

c) Salient pole d) Squirrel cage

16. A generator produces 100 kw of power at a potential difference of 10 KV. The

power is transmitted through cables of total resistance 5 ohm. What is power loss

in cables?

a) 1000W b) 250W

c) 50W d) 500WS

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17. In metropolitan areas most commonly employed distribution scheme is

a) Ring scheme b) Radial scheme

c) Interconnected system d) none

18. What is the resistance of a coil which draws10A and dissipates 1520W

a) 152 ohm b) 15.2 ohm

c) 1.52 ohm d) none of the above

19. The earth wire should not be thinner than

a) 20 SWG wire b) 16 SWG wire

c) 10 SWG wire d) 8 SWG wire

20. Power transmission lines are transposed to reduce

a) Skin effect b) Ferranti effect

c) Transmission loss d) Interference with neighboring communication line

21. Long distance railways use

a) 200 Volt DC b) 25 KV single phase AC

c) 25 KV three phase AC d) none

22. In Fleming’s left hand rule, fore finger always represents

a) Voltage b) current

c) Magnetic field d) direction of force on conductor

23. How many earth connections are required for motor frame as per IE rule 61?

a) One b) two separate & distinct

c) Three separate & distinct d) none

24. The monitor and control of energy management is done by using

a) MATLAB b) SCADA

c) Auto CAD d) none

25. Danger notice is affixed as per which Indian standard?

a) IS-15652 b) IS-2551

c) None of the above

26. A rectifier is used for

a) Measurement of high current b) converting DC to AC

c) Converting AC to DC d) none

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27. Three meters A,B,C require 5 mA, 10 mA & 15 mA respectively for full scale

deflection. This implies

a) A is least sensitive b)B is least sensitive

c) C is least sensitive d) All three are equally sensitive

28. A factory draws an apparent power of 300 kva at a p.f.of 0.65 lagging. What is the

reactive power drawn at a p.f. of 0.85 lagging?

a)195 kvar b)110kvar

c)121kvar d)150kvar

29. Which of the following acts as a protection against high voltage surges due to

lightening & switching?

a) Horn gaps b) Breather

c) Conservator d) Thermal overload relay

30. Which of the following transformers has the largest size?

a) 100 KVA, 25 Hz b) 100 KVA, 50 Hz

c) 100 KVA, 75 Hz d) 100 KVA, 100 Hz

31. All day efficiency is related to

a) Generator b) Distribution Transformer

c) Motor d) Power Transformer

32. A workshop measures 10m X 25m, illuminated by 24 lamps of 200 watts each,

lumen efficiency is 15 lumen/ watt.

(a) 288 lux (b) 290 lux

(c) 360 (d) 420

33. Which is not true in fluorescent tube installation

(a) P.F. is improved by providing capacitor.

(b) Choke is connected in series with capacitor

(c) Choke acts as a ballast in running condition

(d) Choke provides high voltage impulse during starting

34. For laying a single HT cable, the minimum width of the trench should be

(a) 60cm (b) 35cm

(c) 25cm (d) 15cm

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35. The minimum depth of the trench for laying HT cable should be

(a) 30cm (b) 50cm

(c) 80cm (d) 120cm

36. Which test is recommended to be essential after jointing of HT cable

(a) IR test (b) DC HV test

(c) Hot set test (d) Annealing test

37. Which is not a requirement in insulator

(a) Mechanically strong (b) High dielectric strength

(c) Should be porous (d) Not affected by change of

temperature

38. The ‘KN’ marked on the insulator stands to indicate

(a) Isolated neutral (b) Mechanical failing Load

(c) Trademark of manufacturer (d) none of the above

39. Transformer oil in transformer acts as a

(a) coolant (b) Arc extinguishing medium

(c) Insulator (d) All of the above

40. Maximum allowable water content in a new barrel of transformer oil as per IS335

- (1993)

(a) 20ppm (b) 50ppm

(c) 75ppm (d) 100ppm

41. Which is not a part of stay

(a) Anchor rod (b) Turn buckle

(c) Thimble (d) Clamp

42. For a 25HP, 3Phase,50 Hz motor pump set 3 core cable recommended is

(a) 2.5 sqmm (b) 6 sqmm

(c) 10 sqmm (d) 25sqmm

43. For a 1KW load fuse wire recommended in the cut out is

(a) 16SWG (b) 20SWG

(c) 24SWG (d) 35SWG

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44. Main drawback of underground system over overhead system is

(a) Exposure to lightning

(b) Heavy initial cost

(c)Exposure to atmospheric hazard

(d) Inductive interface with adjacent power & communication circuit

45. If 5MW power is to be transmitted over a distance of 30KM, desirable transmission

voltage

(a) 11KV (b) 33KV

(c) 66KV (d) 3.3KV

46. ACSR conductors have

(a) All conductors made of aluminum

(b) Outer conductors made of aluminum

(c)Inner conductor made of aluminum

(d) No conductor made of aluminum

47. Guy wire is employed for

(a) Providing protection against surge (b) Providing emergency earth route

(c) Supporting pole (d) All of the above

48. Strain type insulators are used

(a) At dead ends (b) at intermediate anchor tower

(c) On straight run (d) any of (a) or (b)

49. In a suspension type insulator potential drop is maximum

(a) across the lower disc (b) Uniform across all disc

(c) across the top most disc (d) at the middle disc.

50. The use of guard ring

(a) equalizes the voltage division across the insulators

(b) is an unnecessary complication to the system

(c) decreases string efficiency

(d) all of the above

51. dielectric strength of air is

(a) 100KVp/cm (b) 21.1 KVp/cm

(c) 30KVp/cm (d) 200KVp/cm

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52. Bundled conductor reduce

(a) Surface electric stress of conductor (b) Increase the line reactance

(c) Decrease the line capacitance (d) none of the above

53. Paper as an insulating material has the following draw back

(a) is hygroscopic (b) has poor dielectric

(c) has low insulation resistivity (d) has high capacitance

54. The advantage of hydroelectric Power plant

(a) Low operating cost

(b) They can be used as base load as well as peak load

(c) They can be started and loaded quickly

(d) all of the above

55. Location of surge tank, in an hydroelectric power station is near to the

(a) Turbine (b) tailrace

(c) Reservoir (d) Dam

56. As per Grid standard ,maximum permissible value of voltage unbalance in 33KV

system voltage

(a) 1% (b) 2%

(c) 3% (d) 4%

57. The Degree of protection of all motors in a thermal power plant shall be

a) IP55 (b) IP 66

(c) IP 54 (d) IP 65

58. For an electrical equipment which is correct

(a) Power frequency withstand voltage is more than impulse withstand voltage.

(b) Power frequency withstand voltage is less than impulse withstand voltage.

(c) Power frequency withstand voltage is equal to impulse withstand voltage.

(d) Can be any of the above.

59. Which one is not a diagnostic equipment

(a) Dissolve gas analyzer

(b) FRA for transformer

(c) Winding resistance measuring instrument

(d) None of the above

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60. Which is not a type of jointing or lamination kit

(a) Heat-shrink (b) Cold-Shrink

(c) Tapex and resin cast (d) XLPE straight through

61. For a 5MVA, 33/0.415KV transformer which option should be considered

(a) A link switch with fuse in primary (b) A circuit breaker in primary

(c) Both a & b (d) either a or b

62. Minimum ground clearance of a 33KV line crossing a street

(a) 5.5m (b) 5.8m

(c) 6.1m (d) 6.4m

63. Minimum ground clearance of a 11KV insulated overhead line

(a) 4.0m (b) 4.6m

(c) 4.2m (d) 5.2m

64. Minimum horizontal clearance between nearest conductor part of a 11KV line &

building shall be

(a) 0.75M (b) 1.2M

(c) 2M (d) 1.5M

65. More vertical clearance between 33KV line & highest part & building, where

overhead line passes over a building

(a) 3m (b) 3.7m

(c) 2.5m (d) 4.2m

66. The earth wire in HT overhead line

(a) Decreases capacitance (b) Increases capacitance

(c) Increases inductance

67. Which type of lightening stroke is most dangerous for transmission lines?

(a) Direct stroke on tower top (b) Direct stroke on line conductor

(c) Direct stroke on ground wire

68. Differential relay used to protect the equipment against

(a) Internal fault. (b) reverse current fault

(c) through fault (d) all of the above

69. To reduce the earth resistance, the method generally employed is to

(a) Increase length of electrode (b) Increase diameter of electrode

(c) Increase both length & diameter of electrode

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70. Minimum vertical clearance between 33KV line & LT line crossing each other

should be

(a) 2.44m (b) 3.05m

(c) 4.00M (d) 1M

71. In AC arc welding, once the arc is struck, the voltage required to

(a) 200-220V (b) 100-120V

(c) 20-30V

72. Transformer having vector group of Dyn11 means

(a) Delta primary leads wye secondary by angle 30o

(b) Delta primary lags wye secondary by angle 30o

(c) wye primary leads wyeDeltasecondary by angle 30o

(d) None of the above

73. Which code is not used as a standard nomenclature for conductor

(a) Squirrel (b) Rabbit

(c) Cat (d) Zebra

74. Step voltage is difference in potential of two points on earth surface that are

(a) 1m apart (b) 1ft apart

(c) 3m apart (d) none

75. Stringing chart is useful for

(a) Stringing the conductor (b) In design of tower

(c) In design of insulator string (d) finding distance between lower

76. As per CEA regulation-2010 for every switchboard exceeding 250V, what is the

minimum clear space to be provided in from of switch board?

(a) 75cm (b) 180cm

(c) 100cm (d) 1.25m

77. As per CEA regulation-2010, transformer of which capacity and above shall be

protected against incipient fault by differential protection

(a) 100KVA (b) 1MVA

(c) 10MVA (d) 20MVA

78. Energy shall not be transmitted into a mines at voltage exceeding

(a) 11KV (b) 6.6KV

(c) 3.3KV

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79. The magnetizing inrush current in a transformer is rich in

(a) 3rd harmonic (b) 5th harmonic

(c) 7th harmonic (d) 2nd harmonic

80. The current which can be drawn for 10hrs., from a battery of 15AH

(a) 0.15amps. (b) 0.75amp.

(c) 1.5amps

81. Flemings left hand rule is applied to find the

(a) Direction of force on a current carrying conductor in a magnetic field

(b) Direction of magnetic field due to current carrying conductor

(c) Direction of force in a solenoid

(d) None of the above.

82. The no load current of a power transformer in terms of full load current

(a) 1 to 3% (b) 3 to 5%

(c) 5 to 7% (d) 10 to 20%

83. The full load copper loss and iron loss of a transformer are 7200 and 5000 watts

respectively. At half load copper loss and iron losses will be

(a) 3600& 2500 watts (b) 1800 & 5000 watts

(c) 7200 & 2500 watts (d) none of the above

84. A transformer having 1000 primary turns is connected to a 250 volt AC supply. If

the secondary voltage is 440 volt, the number of turns in the secondary is

(a) 1250 (b) 1600

(c) 625 (d) 1760

85. Differential relays are used to protect the equipment against

(a) Over current (b) reverse current

(c) Internal fault

86. In balanced condition, how much current will flow in the neutral of a 33/0.4KV

distribution transformer

(a) 1 to 5% of phase current (b) 1.5 to 2% of phase current

(c) zero current (d) all the above

87. A distribution transformer of 90% efficiency is loaded with 270KW on the

secondary side. What should be the input in the primary

(a) 285KW (b) 300KW

(c) 415KW (d) 243KW

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88. A consumer’s supply tariff is Rs.100/-per KVA / month for a maximum demand of

170KW at 0.85pf. The self generation cost is Rs.150/- per kva. Which one will be

cheaper?

(a) Supply tariff (b) Self generation

(c) Both are same

89. A domestic house wiring costs Rs.40/- per point and Rs.25/- per half point or a

consolidated amount of Rs.1900/- for all points. If there are 35 points and 20 half

points, which shall be cheaper

(a) Per point wiring (b) Consolidated amount

(c) Both will be same (d) data insufficient

90. A thermal power station generates 6.4 million units per day from ten tones of coal.

The cost of coal is Rs.4800/- per ton and the proportionate cost of interest,

depreciation, operation & maintenance and other consumable per day are Rs1.6

lakhs. The cost per units is

(a) 307 paise (b) 32paise

(c) 23 paise (d) 48paise

91. The meter constant of a single phase energy meter is 4800 revolutions per kwh.

If 10 lamps of 100 watt each are connected in the circuit, the number of revolutions

per minute will be

(a) 60 (b) 80

(c) 120 (d) 4800

92. How many 60 watts CFL lamps of 20 lumens per watt are required to illuminate a

conference hall of 60 X 40 mtrs. To a luminous intensity of 100 lux,

(a) 150 (b) 100

(c) 200 (d) 400

93. A 40 watt fluorescent tube giving 20 lumens per watt, illuminates a room at an

luminous intensity of 50 lux. What is the area of the room

(a) 12 sq. mtr (b) 16 sq. mtr

(c) 20sq. mtr (d) 24 sqmtr

94. The rating of control switch of the 1.5 tonne AC should be

(a) 16amps. (b) 32 amps.

(c) 64 amps.

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95. The current flowing in a closed circuit consisting of a 12V battery supplying energy

to 4 series connected resistance of 1 Ω, 2 Ω, 3 Ω and 6 Ω is

(a) 4Amp. (b) 3Amp.

(c) 1Amp. (d) 2Amp.

96. An electric heater draws 1500 watt from a 250V source. The power it will draw if

connected to a 150V source will be

(a) 2500 W (b) 540 W

(c) 1500W (d) 1250W

97. In thermal power plant, the dust of flue gases is trapped by

(a) Precipitator (b) Economizer

(c) Super heater (d) Air pre heater

98. For hoist and cranes which motor should be selected

(a) 3 phase induction motor (b) Synchronous motor

(c) DC series motor (d) DC shunt motor

99. Sheath is used in the cables to

(a) Prevent the moisture from entering the cable

(b) Provide the strength to the cable

(c) Avoid the chances of the rust on the stands

(d) Provide proper insulation

100. A floating battery is one

(a) Which is getting charge

(b) Which is feeding load

(c) In which battery, voltage is equal to charger voltage

(d) Which gets charged and discharged simultaneously

.