Question Bank in Power Plants 1.
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REE Board Exam March 1998 A deep well pumps water into an open reservoir at the rate of 100 gpm. The water table is 200 ft below the output pipe. The system has an overall efficiency of 70%. What shall be minimum hp of the pump? A. 5.3 hp C. 12.4 hp B. 8.7 hp D. 7.2 hp REE Board Exam March 1998 A pump requires 100 HP to move water with a specific gravity of 1.0 at a certain flow rate to a given elevation. What horsepower does the pump require if the flow rate and elevation conditions are the same but the fluid pumped has a specific gravity of 0.8? A. 80 HP C. 60 HP B. 100 HP D. 120 HP EE Board Exam April 1993 An electric motor is used to pump water from a well of 40 ft. deep. The amount of water pumped per hour to the ground level is 237,000 gallons. What is the HP of the motor assuming there is no power loss? A. 43 HP C. 41 HP B. 42 HP D. 40 HP EE Board Exam October 1983, October 1990 A natural waterfalls 50 meters high, consistently discharges 1.3 m3 per second. A minihydroelectric plant is to be constructed at the bottom of the waterfalls. Calculate the electric generator kW rating, assuming 90% mechanical to electrical conversion efficiency and water turbine design efficiency of 70%. A. 401.72 C. 420.42 B. 410.55 D. 425.10 REE Board Exam March 1998 A power plant gets water from a dam from a height of 122.45 meters at the rate of 1000 cubic meters per minute. If the output of the plant is 15,000 kW, what is the plant efficiency? A. 80% C. 70% B. 75% D. 65%
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EE Board Exam April 1995 Calculate the current taken by a motor at 440 V having an efficiency of 90%. Moreover, the motor is used to drive a pump, which lifts 240,000 kg of water per hour to a height of 30 meters. The pump is given to be 80% efficient. A. 58 A C. 83 A B. 75 A D. 62 A
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REE Board Exam April 1994 A three-phase motor driven pump at 1,800 rpm is discharging 500 gpm of water at a head of 25 meters. The pump efficiency is 75%. Determine the hp of the motor.
A. B.
15 HP 12 HP
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14 HP 10 HP
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EE Board Exam April 1993 A hydroelectric station has a turbine efficiency of 80% and a generator efficiency of 85%. Determine the volume of water required when delivering a load of 40 MW for 6 hours if its effective head is 120 m. Water weighs 1200 kg/m3. A. 899,424 m3 C. 845,041 m3 3 B. 945,352 m D. 905,412 m3
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EE Board Exam June 1990, April 1991 A 100 MW hydroelectric station is supplying full load for 10 hrs in a day. Calculate the volume of water, which has been used. Assume effective head of the water as 200 m and the overall efficiency of the station as 80%. Assume 1 m3 of water = 1000 kg. A. 2,232,435 m3 C. 2,345,456 m3 B. 2,293,560 m3 D. 2,371,402 m3
10. REE Board Exam April 1994 A waterfall is 60 meters high. It discharges at a constant rate of 1.0 cubic meter per second. A mini-hydroelectric plant is to be constructed below the waterfalls. The turbine efficiency is 80% and the generator efficiency is 95%. Calculate the kW output of the generator. A. 447.34 kW C. 457.27 kW B. 464.22 kW D. 471.30 kW 11. EE Board Exam April 1989 Maria Cristina falls located at south has a height of 100 meters. It discharges at a constant rate of 2.5 m3/sec. National Power Corporation has constructed a hydroelectric plant below the water falls. If the turbine efficiency is 70% and generator efficiency is 90% calculate the annual energy in kW-hr, if the discharge rate is constant throughout the year. Assume specific gravity constant. A. 13,534,857 C. 13,655,654 B. 13,467,546 D. 13,504,231 12. EE Board Exam October 1983, October 1990 A natural waterfall, 50 meters high, consistently discharges 1.3 m3 per second. A mini hydroelectric plant is to be constructed at the bottom of the waterfalls. Calculate the annual energy in kW-hr that can be generated by the power plant. Assume turbine and generator efficiencies equal to 70% and 90%, respectively. A. 3,519,067 C. 3,612,212 B. 3,462,356 D. 3,345,815 13. REE Board Exam October 1997 A power plant gets water from a dam from a height of 100 meters at the rate of 1000 cubic meters per minute. If the over-all efficiency of the plant is 75%, what is the kW output of the plant? A. 7.550 kW C. 12.262 kW
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15,250 kW
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5,250 kW
14. REE Board Exam October 1997 A power plant consumes 100,000 lbs of coal per hour. The heating value of the coal is 12,000 BTUs per lb. The over-all plant efficiency is 30%. What is the kW output of the plant? A. 105,500 kW C. 142,500 KW B. 205,000 kW D. 175,000 kW 15. REE Board Exam October 1998 A certain coal fire power plant has a heat rate of 2.88 x 106 calories per kW-hr. Coal cost Php2,500 per ton. How much is the fuel cost component of producing one kW-hr if the heating value of the fuel is 13,000 BTU per lb? A. Php2.50 C. Php1.00 B. Php1.75 D. Php1.25 16. REE Board Exam October 1997 A coal power plant has an over-all plant efficiency of 28%. Coal with a heating value of 12,000 BTUs per lb cost Php1.50 per lb. What is the fuel cost of producing one kW-hr? A. Php1.90 per kW-hr B. Php1.75 per kW-hr C. Php1.52 per kW-hr D. Php1.62 per kW-hr 17. REE Board Exam April 1994 A plant has a total generating capacity of 800 kW. The coal consumption is 1,900 lbs per hour. Heating value of the coal is 9,500 BTU per lb. What approximate per cent in heat in the coal is converted into useful energy? A. 12.3% C. 8.7% B. 15.0% D. 17.5% 18. REE Board Exam October 1997 A 100 MW coal fired power plant has an average heat rate of 9500 BTUs per kW-hr. The plant load factor is 75%. The heating value of the coal is 12,000 BTUs per pound. Calculate the amount of coal usage for one day. A. 1.425 x 106 pounds B. 2.235 x 106 pounds C. 2.235 x 105 pounds D. 1.826 x 106 pounds 19. REE Board Exam October 1998 A diesel generator burns fuel with a heating value of 18,000 BTU per lb. The diesel engine has an efficiency of 30% and the alternator has an efficiency of 95%. Determine the fuel cost component of producing one kW-hr if the diesel costs Php2.80 per lb. A. Php0.15 C. Php3.28 B. Php2.15 D. Php1.86 20. EE Board Exam April 1993 A 500 kW electric lighting cost Php1,000 per kW installed. Fixed charges are 14%, operating cost is Php1.50 per kW-hr. The plant averages 150
kW for 5,000 hours of the year, 420 kW for 1,000 hours and 20 kW for the remainder. What is the unit cost production of electric energy? A. Php1.96 C. Php2.15 B. Php1.84 D. Php2.05 21. EE Board Exam October 1989 A coal fired power plant with 3,000 kW rated capacity costs Php15,000 per kW installed. Annual operating cost Php12 million; annual maintenance cost Php8 million; annual depreciation Php15 million; interest on investment per year 8% and cost of coal Php800 per ton. If one pound of coal is needed to generate 1 kW-hr, find the total annual cost to operate the plant. Plant capacity factor is 50%. A. Php46.45 million B. Php43.38 million C. Php40.28 million D. Php42.32 million 22. REE Board Exam October 1998 To produce one kW-hr, a power plant burns 0.9 lb of coal with a heating value of 13,000 BTU per lb. What is the heat rate of the plant? A. 6,250 BTU/kW-hr B. 11,700 BTU/kW-hr C. 9,500 BTU/kW-hr D. 8,700 BTU/kW-hr 23. REE Board Exam March 1998 The current loads of four circuits are as follows: Circuit no. 1 = 35 A Circuit no. 2 = 46 A Circuit no. 3 = 72 A Circuit no. 4 = 57 A If the diversity factor is 1.5, what is the minimum ampacity of the feeder conductor? A. 126 amps C. 84 amps B. 189 amps D. 152 amps 24. REE Board Exam October 1998 The power customer has four circuits of 220 V, three-phase. The circuits have maximum demands as follows: Circuit no. 1 = 35 A Circuit no. 2 = 46 A Circuit no. 3 = 72 A Circuit no. 4 = 57 A The diversity factor is 1.5, the load factor is 50%, and the power factor is 80%. What is the maximum kVA demand of the customer? A. 46 kVA C. 80 kVA B. 26.5 kVA D. 53 kVA 25. EE Board Exam April 1980 A substation transformer is serving the following loads: Demand Classification Total Load Factor Lighting 300 kW 60% Power 1200 kW 80% Heating 500 kW 90%
If the diversity factor among the load types is 1.5, determine the maximum demand on the transformer. A. 2000 kW C. 1225 kW B. 1060 kW D. 1180 kW 26. REE Board Exam October 1998 The power customer has four circuits of 220 V, three-phase. The circuits have maximum demands as follows: Circuit no. 1 = 35 A Circuit no. 2 = 46 A Circuit no. 3 = 72 A Circuit no. 4 = 57 A The diversity factor is 1.5, the load factor is 50%, and the power factor is 80%. What is the approximate kW demand of the customer? A. 15 kW C. 21 kW B. 43 kW D. 53 kW
efficiency of 30% and the generator has an efficiency of 95%. Compute the fuel cost of producing one kW-hr if the fuel costs Php6.00 per liter. Given the density of the fuel as 900 grams per liter. A. Php5.00 C. Php3.00 B. Php2.00 D. Php1.00 32. REE Board Exam October 1998 A 100 MW power plant has a heat rate of 2.88 x 106 calories per kW-hr. It is a base load plant and runs at full load 24 hrs a day. How many tons of coal is needed per day if its heating value is 13,000 BTU per lb? A. 250 C. 830 B. 625 D. 960
27. EE Board Exam April 1990 A certain power plant has a reserve capacity above the peak load of 10 MW. The annual factors are load factor = 59%, capacity factor = 41% and use factor = 46%. Determine the installed capacity. A. 33.45 MW C. 32.77 MW B. 31.85 MW D. 30.47 MW
33. REE Board Exam September 2000 The following are the given loads of a particular circuit: 5 - 15 HP motors 3 - 5 HP motors 8 kW - lighting loads 3.5 kW - miscellaneous loads Calculate the maximum demand if the demand factor is 65%. A. 78.64 C. 51.12 B. 45.81 D. 120.98
28. EE Board Exam April 1990 A certain power plant has a reserve capacity above the peak load of 10 MW. The annual factors are load factor = 59%, capacity factor = 41% and use factor = 46%. Determine hours per year not in service. A. 952 hours C. 924 hours B. 965 hours D. 937 hours
34. EE Board Exam October 1994 Power plant curves or graphs showing the direct relationships of the peak load and the generated energy of the said plant is A. load curve/graph B. load duration curve C. modified load curve D. none of the above
29. EE Board Exam April 1993 A central generating station has an annual factor report as follows: Plant Capacity Factor = 50% Load Factor = 60% Use Factor = 45% Reserved = 10,500 kW Determine the rated capacity of the station. A. 63,000 kW C. 65,000 kW B. 60,000 kW D. 70,000 kW
35. REE Board Exam March 1998 In fission, energy is produced when A. chemical compound split into its constituents B. nuclear particles combine C. nuclear particles split D. molecules combine
30. REE Board Exam October 1998 The metering of a power substation was read and gave the following data: kW-hr = 200,000 kVAR-hr = 180,000 Maximum Demand = 380 kW Billing days = 30 What is the load factor? A. 68% C. 80% B. 73% D. 62% 31. REE Board Exam September 2000 A diesel generator set burns fuel with a heating value of 18,000 BTU per lb. The engine has an
36. REE Board Exam March 1998 In the list below, which one is not a type of present day nuclear power plant? A. boiling water reactor B. fusion-fission reactor C. low pressure reactor D. fast breeder reactor 37. REE Board Exam October 1997 The energy of present nuclear plants comes from A. the fusion of radio active materials B. the friction of high speed electrons against protons C. the destruction of very tiny particles released when atoms split D. the heat produced by the collision of high speeed protons
38. REE Board Exam October 1997 The ratio of the average load on the plant for the period of time considered to the aggregate rating of all the generating equipment A. capacity factor B. load factor C. utilization factor D. diversity factor Unsolved problems 39. REE Board Exam April 1997 An effective removes of dust, carbon particles and other from the flue gas of the power plant is called A. electrostatic precipitator B. soot blower and collector C. mechanical collector D. dust scrubber 40. EE Board Exam April 1990 A thermal power plant using dry organic material such as wood and other wastes for its fuel A. geothermal power plant B. diesel power plant C. dendro power plant D. hydro power plant 41. REE Board Exam April 1994 Type of water wheels used in hydraulic plants A. propeller C. reaction B. impulse D. all of these 42. REE Board Exam April 2001 A hydroelectric plant generates 100 MW at an available head of 200 m and an overall efficiency of 75%. What quantity of water in cubic meter per second is required? A. 1,200 C. 26 B. 122 D. 68 43. REE Board Exam October 1998 A ten year investigation of rivers potential gave an average water flow of 25 cm per second at the bottom and 90 cm per second at the surface. The average cross section at the same location is 80 sq m. What is the average flow rate in cubic meter per hour? A. 165,600 C. 46,500 B. 57,600 D. 5,760
BTU per lb cost Php1.50 per lb. What is the fuel cost of producing one kW-hr? A. Php1.90 per kW-hr B. Php1.75 per kW-hr C. Php1.52 per kW-hr D. Php1.62 per kW-hr 46. REE Board Exam October 2000 A diesel power plant has an overall efficiency of 30%. If the calorific value of diesel is 18,000 BTU/lb and cost Php6.00 per liter, how much is the fuel cost of production per kW-hr of energy? Take the density of diesel as 900 grams per liter. A. Php1.91 per kW-hr B. Php1.85 per kW-hr C. Php2.12 per kW-hr D. Php2.45 per kW-hr 47. REE Board Exam October 1998 The feedwater is usually heated before it is injected to the boiler for the following reason except one. Which one is this? A. improves the overall performance of the plant B. recovers part of the flue gas heat which is otherwise lost to the atmosphere C. derating types of preheaters permit the removal of dissolved gases from the feedwater D. increases the efficiency of the boiler 48. REE Board Exam October 1998 A proposed hydroelectric station has an available head of 30 m, a catchment area of 50 x 10 6 sq m, the rainfall for which is 120 cm per annum. If 70% of the total rainfall can be collected, calculate the power that can be generated. Assume the following efficiencies: Penstock 95%, Turbine 80% and Generator 85%. A. 253 kW C. 214 kW B. 678 kW D. 925 kW 49. While calculating the cost of electric power generation, which of the following is NOT considered a fixed cost? A. interest on capital investment B. taxes and insurance C. most of the salaries and wages D. repair and maintenance
44. REE Board Exam September 2002 A power plant is driven by turbine at a rate of 10 cubic meters per second and with a head of 235 m. If the plant efficiency is 0.65, calculate the power plant output. A. 10,000 kW C. 35,000 kW B. 15,000 kW D. 25,000 kW
50. Maximum demand of an installation is given by its A. instantaneous maximum demand B. greatest average power demand C. average maximum demand over a definite interval of time during a certain period D. average power demand during an interval of 1-minute
45. REE Board Exam October 1997 A coal power plant has a boiler, turbine and alternator efficiencies of 35%, 86% and 93% respectively. Coal with heating value of 12,000
51. A diversity factor of 2.5 gives a saving of ____ percent in the generating equipment. A. 60 C. 40 B. 50 D. 25
52. Mark the WRONG statement. High load factor of a generating equipment A. leads to lesser charges per kWh B. implies lower diversity in demand C. gives more profit to the owner D. can be obtained accepting off-peak loads 53. In a generating station, fixed, charges at 100% load factor are 6 paisa/kWh. With 25% load factor, the charges would become ____ paisa/kWh. A. 1.5 C. 24 B. 10 D. 3 54. When considering the economics of power transmission, Kelvin’s law is used for finding the ____ A. cost of energy loss in bare conductors B. most economical cross-section of the conductors C. interest on capital cost of the conductor D. the maximum voltage drop in feeders 55. A 3-phase balance system working at 0.9 lagging power factor has a line loss of 3600 kW. If p.f. is reduced to 0.6, the line loss would become ____ kW. A. 8100 C. 5400 B. 1600 D. 2400 56. Mark the WRONG statement. While considering power factor improvement, the most economical angle of lag depends on the ____ A. cost/kVA rating of phase advancer B. rate of interest on capital outlay C. rate of depreciation D. value of original lagging p.f. angle 57. EE Board Exam October 1990 A 55,000 kW thermal plant of National Power Corporation delivers an annual output of 238,000,000 kW-hr with a peak load of 44 MW. What is the capacity factor? A. 49.4% C. 48.2% B. 42.4% D. 44.6% 58. A deep well pumps water into an open reservoir at rate of 150 gpm. The water table is 200 ft below the output pipe. The whole system has an overall efficiency of 80%. What shall be the minimum hp of the pump? A. 9.45 hp C. 5.12 hp B. 7.15 hp D. 8.53 hp 59. Which of the following is least efficient? A. Diesel Gen-Set B. Combined Gen-Set C. Gasoline Gen-Set D. Coal Power Plant 60. An industrial load of 25 kVA has an overall power factor of 0.8 lagging. A group of resistance heating unit was installed and the plant power
factor is found to be 0.895 lagging. What kW of resistance heating unit was installed? A. 4.3 kW C. 5.3 kW B. 3.4 kW D. 6.4 kW 61. What do you mean by “demand” of the customer? A. Voltage need B. Voltage, frequency, phase need C. Voltage, frequency need D. kVA load 62. Fusion energy is produced when A. chemical compounds combined B. fuel burns C. nuclear particle divides D. nuclear particle combined 63. A. B.
C. D.
A. B.
C. D.
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