Question Bank in Power Plants
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5.
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%
6.
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
7.
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
C.
D.
14 HP
10 HP
8.
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
9.
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
B.
15,250 kW
D.
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.
64.