ET07 PPF QUESTION PAPER (2)

8/7/2019 ET07 PPF QUESTION PAPER (2)

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Module : Power Plant Familiarization

Full Marks: 150

Time : 2 Hrs.

Mark the correct answer : ( Total marks : 100)

1. Normally the largest drive in the thermal power station isa. Crusher motor

b. Mill motor

c. Feed pump motord. Cooling tower fan

Answer : [ ]

2. The following is desirable component of coal

a. Mineral matterb. Sulphur

c. Volatile

d. Moisture

Answer : [ ]3. The thermal efficiency of power plant of is the order of

a. 91-95%b. More then 99%

c. 75-85%

d. 35-45%

Answer : [ ]4. The purpose of primary air in a boiler is

a. It is primarily meant for providing combustion air to the coal

b. Cooling the boiler wallsc. Talking the ash to the ESPs

d. Talking the pulverized of flue gases is improved Answer : [ ]5. The efficiency of collection in ESP will not improve significantly if

a. The temperature of flue gases is reduced

b. The pressure of flue gases is reducedc. The velocity of flue gases is reduced

d. The ionization of flue gases is improved

Answer : [ ]

6. Teflon tubes in stator winding are used to carry :a. Clarified water

b. DM water

c. Raw waterd. None of above

Answer : [ ]

7. Minimum purity of hydrogen inside the generator casing permissible is :a. 97.8%

b. 98.5%

c. 99%

d. 99.9% Answer : [ ]


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8. [isolators operates under

a. fault condition

b. normal operating conditionc. no load condition

d. interrupting inductive current

Answer : [ ]9. The maintenance of circuit breaker is possible without an outage in

a. main and transfer bus bar arrangement

b. single bus bar arrangementc. single bus bar arrangement sectionalize

d. none of the above

Answer : [ ]

10. For EHV most preferred circuit breaker isa. air blast

b. minimum oil

c. vacuum

d. any of the above Answer : [ ]

11. During normal operating condition, which one is kept ?a. isolator

b. earth switch

c. circuit breaker

d. any of the aboveAnswer : [ ]

12. Lightening arresters are connected between

a. two phasesb. natural and ground

c. phase and ground

d. any of the aboveAnswer : [ ]

13. Protection against direct lightening stocks is provided by

a. earthing of neutralb. ground wire

c. lightening arrester

d. both (b) and (c)

Answer : [ ]14.In minimum oil circuit breaker, oil is used for

e. insulation and are quenching both

f. are quenching onlyg. insulation only

h. none of the above

Answer : [ ]15. AN economizer in a boiler

a. increases steam pressure

b. increases steam flow

c. decreases fuel consumption


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Answer : [ ]

16. In a steam generator basic function of drum isa. to act as storage of steam

b. to act as storage of water

c. to separate salts from waterd. to separate steam from water

Answer : [ ]

17. The coal requirement per KWhr generation in the thermal power plant is of theorder of

a. 0.1to 0.2 kg

b. 0.2 to 0.4 kg

c. 0.6 to 0.8 kgd. 1.0 to 1.5 kg

Answer : [ ]

18. Type of coal used in a power plant is

a. Non-coking bituminous coal.b. Brown coal.

c. Anthracite coal,d. Coking bituminous coal.

Answer : [ ]

19. Sulpher in coal result in

a. clinkering and slagging.b. corroding air heaters

c. spontaneous combustion during coal storage

d. all of the aboveAnswer : [ ]

20. Generally in coal fired power plant the ratio of bottom ash and fly ash is

a. 1:2b. 1:3

c. 1:4

d. 1:6Answer : [ ]

21. Most commonly used cooling tower in a power plant is

a. forced draft cooling tower

b. natural draft cooling towerc. induced draft cooling tower

d. a combination of (a) & (c)

Answer : [ ]22. Instrument air is a used in a power plant for

a. light oil atomization

b. clearing filtersc. burner tilting devices

d. all of the above

Answer : [ ]

23. The combustion chamber is used chiefly for the following purpose


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a. Burning the mixture of air and fuel, with rise in pressure

b. Burning the mixture of air and fuel , with rise in temperature alone

c. Mixing the fuel and air thoroughlyd. For cooling the air after expansion in the turbine

Answer : [ ]

24. The efficiency of the combined cycle power plants are typically in the followingrange

a. 45-50%

b. 30-35%c. 30-40%

d. 60-65%

Answer : [ ]

25. The efficiency of the gas turbine in sample cycle is typically in the followinga. 28-32%

b. 35-40%

c. 15-20%

d. 20-25% Answer : [ ]

26. For a gas turbine, the Self Sustaining Speed (SSS) is arounda. 2100 RPM

b. 1800 RPM

c. 2500 RPM

d. 600 RPMAnswer : [ ]

27. The term Thermal barrier coating , is used in context of the following parts of the

gas turbinea. Generator windings

b. Turbine blading

c. Compressor bladingd. Cernamic tills of the combustion chamber

Answer : [ ]

28. Between the compressor and the turbine of a typical gas turbine, which of thefollowing is true ?

a. turbine has more number of stages of blades

b. compressor has more number of stage of makes more output

Answer : [ ]29. Out of the following pair of statement, which is true ?

a. In summer times, the gas turbine makes more output.

b. In winter times the , gas turbine makes more out put.Answer : [ ]

30. Out of the following pair of statements, which is true ?

a. In day time, the gas turbine makes more power outputb. In night time, the gas turbine makes more output

Answer : [ ]

31. Out of the following pair of statement, which is true ?

a. The compressor handles more hot gases and air, then the turbine


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b. The turbine handles more hot gases and air , then the compressor

Answer : [ ]

32. Out of the following pair of statement, which is true ?a. A gas turbine, rated at 150 MW for standard condition, produced more power

if installed at Dehradun than Delhi

b. A gas turbine, rated at 150 MW for standard condition, produced morepower if installed at Delhi then Dehradun

Answer : [ ]

33.Out of the following pair of statements, which is true ?a. The pressure of the steam generated from WHRB, is more than the pressure

of a conventional coal fired boiler

b. The pressure of the steam generated from WHRB, is less than the pressure of

a convention coal fired boilerAnswer : [ ]

34. The main constituent of Natural gas is

a. Ethane

b. Propanec. Methane

d. Hydrogen sulfideAnswer : [ ]

35. Sweetening of Natural gas the process of

a. Removal of CO2 and Hydrogen from natural gas

b. Addition of LPG in natural gasc. Cold flaring of natural gas

d. Elimination of Hydrogen sulfide from natural gas

Answer : [ ]36. Wet natural gas means

a. Naphtha

b. NGLc. Natural gas with high moisture content

d. LNG

Answer : [ ]37. Naphtha storage is an floating roof tanks to

a. A void vapor formation below roof

b. A void vapor formation above roof

c. To increase lubricity of naphthad. To increase the suction pressure of naphtha forwarding pumps.

Answer : [ ]

38. Which factor does not effect the layout of a Hydro project ?a. Topography

b. Construction power

c. Geologyd. Construction period

Answer : [ ]

39. Run of the river scheme will necessary have

a. Diversion structure


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b. Water conductor

c. Power house

d. All of the aboveAnswer : [ ]

40. A power station is known as peaking station when

a. It generates full capacity when requiredb. It runs on full capacity throughout the day

c. Runs at a fixed time during the day

d. None of the aboveAnswer : [ ]

41. A scheme known as run-off-river if it is having

a. Barrage

b. Dam with small storagec. Trench weir

d. Any of the above

Answer : [ ]

42. Which factor can be attributed to a storage hydro power scheme a. Generation throughout the year

b. Peaking generationc. More firm energy

d. None of the above

Answer : [ ]

43. A pump storage scheme is favoured fora. Generation during night

b. Generation during speak demand

c. Cheaper cost of generationd. Increased power generation

Answer : [ ]

44. A Canal head power house is selected a. When there is huge flow in canal

b. When there is fall in the river bed

c. When transportation of higher capacity machine is not feasibled. When provision of Forebay or surge tank is not feasible

Answer : [ ]

45. Sipe failure is generally associated with

a. Concrete damb. Masonry dam

c. Concrete faced Rock fill dam

d. Roller compactor concrete damAnswer : [ ]

46. Size of head Race Tunnel depends on

a. Design dischargeb. Construction period

c. Geology of project area

d. All of above

Answer : [ ]


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47. Which of the following is generally used for high head application of Hydro Turbine

a. Pelton Wheelb. Bulb turbine

c. Deriaz turbine

d. Kaplan Turbine Answer : [ ]

48. Which basin of India has the largest hydro potential ?

a. Gangab. Brahmaputra

c. Indus

d. West flowing

Answer : [ ]49. With increase in load, radiant super heater has

a. Drooping characteristic

b. Rising characteristic

c. Linear characteristicd. Unpredictable

Answer : [ ]50. Water and sediment in fuel oil can be removed by

a. Heating the oil in the settling tanks

b. Cooling the oil in the settling tanks

c. Burning the oild. Suspension

Answer : [ ]

51. The capacity of ID fan compared to FD fan in a boilera. Same

b. More

c. Lessd. Less or More depending on size of the boiler

Answer : [ ]

52.Maximum energy loss in a boiler occurs due toa. Unburnt carbon in ash

b. Incomplete combustion

c. Radiation losses

d. Fuel gasesAnswer : [ ]

53. Film boiling occurs at

a. Very low pressureb. Atmospheric pressure

c. Medium pressure

d. Very high pressureAnswer : [ ]

54. Why is it desirable to turn the ejector on for 15-20 minutes daily when a steam

turbine is not running ?

a. To increase efficiency


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b. To cool the turbine

c. To draw moisture out of casing

d. To avoid bending of shaftAnswer : [ ]

55. A dense white smoke from a chimney indicates

a. Insufficient airb. Too much air

c. Correct air

d. Less turbulenceAnswer : [ ]

56. A thermal power plant designed to operate in cold climate is operated in hot climates

it will develop

a. More powerb. Less power

c. Same power

d. More or less depending on the size

Answer : [ ]57. For a given horsepower in impulse turbine, compared to a reaction turbine has

a. Less rows of bladesb. More rows of blades

c. Equal rows of blades

d. It can be anything

Answer : [ ]58. Axial shift in steam turbines accurs due to

A. Thermal expansion of casing

b. Wearing of thrust padc. Differential expansion of casing and rotor

d. Axial thrust

Answer : [ ]59. If the back pressure of condensing steam turbine rises, then heat rate of turbine will

a. Increase

b. Decreasec. Remain unaffected

d. First increase upto a certain limit and then decrease

Answer : [ ]

60. The difference between super saturation temperature and the saturation temperature atthe corresponding pressure is called

a. Degree of super saturation

b. Degree of under coolingc. Degree of super heat

d. Degree of saturation

Answer : [ ]61. The commonly used material of pipes in condensers

a. Mild steel

b. Stainless steel

c. Cost iron


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d. Admiralty

Answer : [ ]

62 The compressor capacity with decrease in suction temperaturea. Increases

b. Decreases

c. Remains unaffectedd. It depends on compressor capacity

Answer : [ ]

63. The air fuel ratio in gas turbines is of the order ofa. 15:1

b. 30:1

c. 40:1

d. 50:1Answer : [ ]

64. The property most important for material used for gas turbine blades

a. toughness

b. fatiguec. creep

d. corrosion resistanceAnswer : [ ]

65. The safety valve setting at drum of boiler as compared to that at super heater is

a. less

b. morec. independent

d. equal

Answer : [ ]66. For the same draught produced the power requirements of induced draught as

compared to forced draught are

a. lessb. more

c. same

d. independent of draughtAnswer : [ ]

67. In a surface condenser for steam power plant

a. steam flows through tubes and water across tubes

b. water flows through tubes and steam across tubesc. water and steam mix together and flow through tubes to the hot well


Answer : [ ]68. Differential expansion in steam turbine is due to

a. thermal expansion of turbine casing

b. wearing away of thrust bearingc. unequal expansion of rotor and casing

d. both (a) & (b) above

Answer : [ ]

69. The water used to cool various equipments is called as


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a. CW water

b. ECW water

c. Service waterd. Fire water

Answer : [ ]

70. The coal mill has the following functiona. stores the coal before firing to boiler

b. Crushes the coal into fine powder for proper burning

c. Measures the coal and feeds it to the boilerd. All of above

Answer : [ ]

71. Some of the gas turbine stations of NTPC receive lean natural gas becausea. LPG is removed from natural gas before supply

b. Supply pressure of natural gas is low

c. Methane is removed from natural gas before supply

d. None of the above Answer : [ ]

72. Buchholz relay in a transformer is installeda. inside the transformer oil tank

b. between pipe connecting transformer tank and oil conservator

c. inside the conservator

d. any where aboveAnswer : [ ]

73. oil in transformer is used for

a. greasing purposeb. insulation

c. cooling

d. both (b) & (c)Answer : [ ]

74. In boiler the steam temperature is

a. More then the boiler tube metal temperatureb. Equal to the boiler tube metal temperature

c. Less then the boiler tube metal temperature

d. More then the fuel gas temperature at the zone

Answer : [ ]75. Hydrazine (N2 H4) dosing in boiler is carried out to

a. Kill algae and bacteria

b. Reduce O2 contentc. Decrease pH value

d. Reduce CO2 content

Answer : [ ]76. Boiler expansion takes place in which direction

a. Upward only

b. Downward only

c. All direction


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d. No expansion is allowed

Answer : [ ]

77. Periodic measurement of air gap in ht motors is an essential check fora. Motors with sleeve bearings

b. Motors with antifriction bearings

c. Vertical motorsd. (b) & (c) above

Answer : [ ]

78. Purpose of booster pump in feed water system isa. To increase the delivery pressure of BFP

b. To increase the suction pressure of BFP

c. To supply lube oil to BFP

d. To give a priming effectAnswer : [ ]

79. Condenser tube leakage is detected through the following sensor

a. pH of condensate

b. Silica in condensatec. Conductivity in condensate

d. Hardness in condensateAnswer : [ ]

80. Oil flame is sensed in a furnace by the following sensor

a. Fire ball scanner

b. Discriminating scannerc. Both of the above

d. None of the above

Answer : [ ]81. Buchholtz rely is provided in power station for

a. Turbine protection

b. Generator protectionc. Transformer protection

d. Bus duct protection

Answer : [ ]82. In the event of a power station block out one of the following equipment must be

ensured to be run on DC supply :

a. Fan lubricating oil pump

b. Scanner air fanc. Seal air fan

d. Cooling water pump

Answer : [ ]83. The type of boiling to be maintained in a boiler

a. Nucleate boiling

b. Film boilingc. Evaporative boiling

d. Both (b) & (c) above

Answer : [ ]

84. Generator core is laminated to


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a. Reduce eddy current loss

b. Reduce hysterisis loss

c. Reduce ohmic lossd. Reduce dead weight of stator

Answer : [ ]

85. Gas turbine use following type of air compressora. Centrifugal

b. Reciprocating type

c. Lobe typed. Axial flow type

Answer : [ ]

86. In DM plant, the value of pH in DM water produced is

a. 5b. 7

c. 9

d. 10

Answer : [ ]87. The function of a circuit breaker is to

a. Burn the circuit in case of abnormal electrical conditions endangering electricalequipment

b. Break the circuit in case of abnormal electrical condition endangering electrical

equipment

c. Burn itself in case of abnormal electrical conditiond. None of the above

Answer : [ ]

88. Which one is operated first to isolated an electrical circuit ?a. Fuse

b. Isolator

c. Earth switchd. Circuit breaker

Answer : [ ]

89. Which one I heavier ?a. Bottom ash

b. Economiser ash

c. Air pre-heater

d. All are having equal weightAnswer : [ ]

90. During loading coal rake moves under the silo at a speed of

a. 0.6 km/hrb. 0.8 km /hr

c. 1.2 km /hr

d. 2.0 km /hrAnswer : [ ]

91. The door operating mechanism of MGR wagon is

a. Mechanical

b. Pneumatic


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c. Electrical

d. Electro- pneumatic

Answer : [ ]92. Heavy fuel oil in a thermal power station is heated n the service tank to improve its

a. Atomisation

b. Calorificc. Pumpability

d. Vaporisation

Answer : [ ]93. Rubber disc self clearing idlers are located at

a. Head end of the conveyor

b. Tail end of the conveyor

c. Near gravity take-up aread. Near belt weighers

Answer : [ ]

94. In a gas turbine, steam or DM water are injected in the combustion chamber to

controla. Nor emission

b. Sox emissionc. Unburnt fuel

d. CO

Answer : [ ]

95. Reactor is used in long transmission line fora. Compensation of line resistance

b. Compensation of line inductance

c. Compensation of line impedanced. Compensation of line capacitance

Answer : [ ]

96. Metal detectors are used in coal handling plants to detecta. Magnetic materials

b. Non-magnetic materials

c. Both (a) & (b)d. Either (a) or (b) depending on the load

Answer : [ ]

97. Ash collection in ESP is due to

a. gravityb. Electromagnetic induction

c. Hitting of ash particles with plates

d. Corona effectAnswer : [ ]

98. In the normal running of a gas turbine, the maximum load (MW) is restricted by

a. Pressure controlb. temperature control

c. Flow control

d. Speed control

Answer : [ ]


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99. Which of the following equipment is an accessory ?

a. Safety valve

b. Feed check valvec. Feed water pump

d. Stop valve

Answer : [ ]100. The condition of steam in boiler drum is always

a. dry

b. wetc. saturated

d. superheated

Answer : [ ]Short questions : ( Total marks :20)

1. The length of blade in a steam turbine keeps on increasing as steam flows from

high pressure entrance side to condenser side; why?

2. What is the purpose of a barring gear with steam turbine?

3. What is the function of steam trap?4. Expand ESSS.

5. Why Micalastic insulation system for stator winding is used ?6. Arrange the following fuels for use in gas turbine, from MOST PREFERRED TO

LEAST PREFERRED:

i. Furnace oil

ii. Natural gasiii. Naphtha

iv. Diesel

7. Why high air-fuel ratio is used in gas turbines ?8. One kg of steam sample contains 0.8 kg dry steam; what is its dryness fraction ?

9. What are determined by ultimate analysis of coal ?

Descriptive question: (Use the backside of the pages) (Total marks: 30)

1. Briefly describe (only through diagram ) the cycle for modern steam power plant.How its efficiency can be improved ? What are the limitations in improving the

cycle efficiency ?

2. Briefly describe switchgears of a power plant ?

3. Describe the process of water treatment in a power plant.

ET07 PPF QUESTION PAPER (2)

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