PART 3 Flashcards
States that the voltage or potential difference between two points is directly proportional to
the current or electricity passing through the resistance and directly proportional to the
resistance of the circuit.
Ohm’s law
Based on the 2009 Philippine Electrical Code, what is the minimum conductor size in mm2
for
a voltage rating of 0-2,000 volts when using copper wire?
2
A farmhouse requires a minimum conductor size of 2 mm2
which is equivalent to AWG ____.
14
(AWG 14 has 2.08 mm2
conductor size, AWG 16 should not be used in houses.
Except for the drop wire, the common household wires are AWG nos. 10, 12 & 14.)
Which electrical wire in the list below has the biggest cross-sectional area?
AWG 8
Which type of electrical wire has a maximum operating temperature of 90 oC?
THHN
ased on the Phil. Electrical Code, what is the minimum conductor size in mm2
for a voltage
rating of 2,001-8,000 volts when using copper, aluminum or copper-clad aluminum wire?
8
If V is voltage, I is current and P is power, according to Ohm’s law, V is equal to _____.
IR
Ohm’s law is applicable to _____.
Both DC and AC
Ohm’s law applies to both AC and DC circuits as long as mutual _________ of the circuit is
considered.
Inductance
The resistivity of annealed copper in ohm meters at 20oC.
1.72 x 10^-8
The resistance of a certain length of wire can be obtained by multiplying its ________ with
its length and dividing the resulting product by the cross-sectional area of the wire.
Resistivity
A farmstead has its farthest load located 350 linear meters from a single phase power source.
What length of the wire in meters should be used in the voltage loss computation?
700
In connecting electricity from a post to a farmhouse, a ______ wire is needed.
DROP
The minimum wire size for a farmhouse drop wire.
AWG 6
A solar powered slaughterhouse uses electrical stunning gun to make the animals insensible
to pain before the slaughter. What should be the voltage of the stunning gun?
220 Vac
Based on PAES 419:2000, the recommended lighting intensity in lux (lumen/m2
) for fruit
and vegetable processing plant are: 100 for outside the building, 200 for general indoor
locations, and ___ for working tables
500
A poultry layer area requires a brightness of 1,600 lumens. What is the wattage of a daylightcolor LED bulb that shall be used?
100
What is the voltage needed to light a 1-ampere LED bulb having a resistance of 220 ohms?
1 volt
V = IxR
= (1 A) x (220 ohms)
= 220 volts
How many amperes will pass through a circuit having ten 22-watt LED bulbs if the source is
220 volts?
1 watt
I = P/V
= (10 x 22 w) / (220 v)
= 1 Amp
What is the electrical energy consumption of a 15-kw vermin cast production shredder
plugged in a 220-volt source if it requires 2 hours to shred 1.5 tonnes of farm waste?
0.02 kwh/kg
Ec = PcTo / Wi
= 15 kw (2 h) / 1,500 kg
= 0.02 kwh/kg
Solid annealed copper has a resistivity of 1.72 x 10-8 ohm-meter at 20 oC. What is the
resistance in ohm-meter per linear meter of AWG 10 solid annealed copper wire having a
diameter of 2.588 mm?
3.27x10-3 ohms
A 240-volt industrial incubator uses a pair of 25-meter 7-strand AWG 10 copper wire having
a resistance of 3.87x10-3 ohm per linear meter at 65 oC. The heating load of the incubator is
composed of twelve 100-watt heating coils. What is the expected current in the main wire?
0.03 A
In off-grid farmhouse electrification, which one has the lowest operation and maintenance
cost?
Solar Home System
Which one has the highest operation and maintenance cost?
DIESEL GENERATOR
In off-grid barangay electrification located 3 kilometers from the electricity grid, which one
is recommended?
Grid extension
Which electricity source has no greenhouse gas emission?
Solar Home System
Which electricity source has the highest greenhouse gas emission?
Diesel generator
To minimize power loss, which equipment is needed to transform DC electricity from a
centralized solar power plant into AC electricity before transmitting it to distributed 220-volt
farmstead electrical devices?
Inverter
A 950-kw cassava flour processing plant is to be powered using hydro. Which electricity
source will you use recommend?
Minihydro
A 3 hectare hillside farm is to be energized. It is 20 meters below a river having a dependable
summer discharge of 50 liters/second. Which electricity source will you use recommend?
Microhydro
The 1-kw lighting of a farmstead is to be energized using hydropower. It is 10 meters below
a creek having a dependable summer discharge of 5 liters/second. Which hydropower will
you recommend for development?
picohydro
An 8-bladed horizontal axis windmill with 12-meter tall tower has 2.5-m diameter rotor.
Estimate the power output in watts using the rule of thumb formula. Average windspeed in
the site is 3.2 m/s.
16
P = 0.1 AV3
, P is power output in watts, A is rotor area in m2
, V is windspeed in m/s
= 0.1 [3.14 x (2.5 m)2
/4] [3.2 m/s]3
= 16.08 watts
How many households can be powered by a minihydro having a power generation output of
500 kw if an average household consumes 1 kw and power loss is 15%?
425
No. of households = (Power Output – Power Loss) / Average household consumption
= (500 kw – 0.15 (500 kw) / 1 kw
= 425 households
A battery bank of a centralized solar power generator needs to store energy in a 48-volt DC
system to power a cassava processing plant. If each battery is 12 volts, how many batteries
are there in series?
4
No. of batteries in series = System Voltage / Battery nominal voltage
= 48 volts / 12 volts
= 4 batteries in series
An off-grid tomato processing plant has 48-volt output battery bank composed of 60 units of
12-volt automotive batteries. How many batteries are there in parallel?
15
No. of batteries in series = System Voltage / Battery nominal voltage
= 48 volts / 12 volts
= 4 batteries in series
No. of batteries in parallel = Total number of batteries / No. of batteries in series
= 60 total batteries / 4 batteries in series
= 15 batteries in parallel
How kilowatts can be generated from a waterfall having a discharge of 1 m3
/s, reliable head
of 100 meters during summers and system efficiency of 60%?
589
A hydropower resource with water outlet 95 meters high from ground surface has fluctuating
discharge of 1.8 m3
/s during summers and 3.5 m3
/s during rainy months. How many
megawatts can be generated at the powerhouse placed below the ground surface with the
turbine water inlet 30 meters below ground level? Assume a reliable system efficiency of
60%.
1.32
A centralized solar power plant with DC to AC inverter is used to electrify a farmstead using
75 watt-peak solar modules of the same brand. How many kilowatts-hours of energy in an
average day of 5 hours sensible sunlight can be generated by 100 units of solar modules if
inversion efficiency is 85%, module matching efficiency is 95% and transmission efficiency
from modules to centralized battery bank is 95%?
29
The board used in Arduino open-source electronics platform based on easy-to-use hardware
and software which is able to read inputs like light on a sensor, temperature reading, a finger
on a button, or a Twitter message and can turn these inputs into outputs like activating a
motor, turning on an LED, turning on a solenoid valve, or publishing something online.
microcontroller
An Arduino microcontroller is used to activate mist sprinkler system for 10 minutes every
time the greenhouse temperature rises above a certain level. What device is best turned on by
the microcontroller to start the mist sprinklers?
Solenoid valve
The name given to Arduino code files which serve as instructions to the microcontroller.
sketch
Part of solar module needed such that solar charging is continuous at slower rate when
partially shaded by trees.
bypass diode
A diode needed as protection against lightning in solar installations.
blocking diode
The common pin, made as the pair to other pins, in integrated circuits (ICs).
ground
An integrated circuit (IC) included as an important part of electronic instrumentation for
gathering speed and discharge real-time data.
timer
Which one is an integrated circuit (IC) used in instrumentation and control?
LM 333
What voltage is appropriate in remote instrumentation?
5, 7, AND 9 Vdc
Data transmission to a remote, unelectrified and line-of-sight point is best done through ___.
radio frequency
In automatic control of irrigation dam gates, what switch is useful in the instrumentation?
automatic transfer switch
Switch for automatic pump motor control of sealed water tanks in drip irrigation systems.
pressure switch
Under PAES 418:2002, washing of tomato is done by using ____% chlorox solution applied
by dipping, spraying or wiping with a damp cloth then drying the fruit before packing.
1%
Based on PAES 419:2000, the recommended optimum stack height in meters for storage of both paddy and rice grains.
4.27 or 16
What standard shall be followed in constructing large-scale poultry dressing/slaughtering
plants?
PAES 422-2:2012
Based on PAES 419:2000, the recommended optimum stack height for storage of wheat,
barley and maize grains.
4.57 or 18
PAES 419:2000 requires that food grains stored in a warehouse for bagged storage are in the
range of 12 to ____ % moisture content prior to storing.
14
The Philippine standard for grading and classification of paddy and milled rice grains.
PNS/BAFS 290:2019
The Philippine standard for code of practice and postproduction of organic milled rice.
PNS 42:2019
The Philippine standard for Maximum Residue Limits (MRLs) of pesticide residues in rice
PNS 162:2015
The Philippine general standard for contaminants and toxins in food and feed.
PNS 194:2017
Industrial bottling of virgin coconut oil prints a batch number. What is the main purpose of
this batch number?
product recall
Which one is not a part of a vertical feed mixer?
A. Conveyor B. Hopper C. Discharge chute D. Screw
conveyor
A feed mixer tested to have mixing coefficient of variation of 10-15% is rated as _____.
good
As a standard, stripping efficiency of the mechanized stripping machine shall be at least
80%
What is the percent moisture content in dry basis of a rice sample having 100 grams and 82
grams wet and dry weights?
22
What is the percent moisture content in wet basis of a corn sample having 100 grams and 82
grams wet and dry weights?
18
A dried palay sample was milled using a rubber roller laboratory rice mill. After milling, the
weight of whole milled grains, broken milled grains, and hull were 25 g, 305 g and 170 g,
respectively. The milled rice was classified as Class A. Determine the percent head rice.
5%
A 3.1-tonne capacity Jatropha oil expeller was loaded full with dried Jatropha seeds in 4
minutes. It produced 1200 kg of crude oil in 3 hours. What is its crude oil production rate?
400 kg/hr
A Jatropha oil expeller was loaded with 2.2 tonnes dried Jatropha seeds. It produced 700 kg
of crude oil in 5 hours. What is its Jatropha cake production rate?
300 kg/h
A 21-tonne capacity coconut oil expeller was loaded full with grated copra. It produced 9,000
kg of crude oil in 12 hours. What is the copra cake production rate of the machine at 97%
cake collection efficiency?
970 kg/h
How many tonnes of agricultural waste is needed annually to optimally operate a 27-ampere
9-kw vermi cast production shredder having a capacity of 0.27 tonne of waste per hour? It
optimally operates 16 hours daily during the 3-month peak sunny months and 8 h/day at 26
days/month for the rest of the year.
894
As prescribed in PAES 419:2000, in constructing the walls of a warehouse for bagged
storage of grains, the wall should use _____ mm thick concrete hollow blocks with 12 mm
diameter reinforcing bars at horizontal and vertical spacing of 600 mm.
150
Known as the National Building Code of the Philippines.
PD 1096
Type of the building that is made of steel, iron, concrete, or masonry construction.
TYPE 4
PAES 419:2000 requires that a normal-temperature warehouse intended for storage of bagged
grains shall have a minimum interior height between the beam and floor of ____ meters.
6
Under PAES 418:2002, in constructing a primary processing plant for fresh fruit and
vegetable, the windowsill shall be at least _____ m from the finished floor line.
1
Under PAES 418:2002, in constructing a primary processing plant for fresh fruit and
vegetable, the doors shall have a minimum width of _____ m.
1.5
Habitable rooms provided with artificial ventilation shall have ceiling heights of not less than
______ meters measured from the floor to the ceiling (PD 1096).
B
Smallest dimension in centimeters of concrete hollow blocks in the Philippines.
10X20X40
For buildings of more than one storey, the minimum ceiling height of the first storey shall be
_____ meters and that for the second storey 2.40 meters and succeeding storeys shall have an
unobstructed typical head-room clearance of not less than 2.10 meters above the finished
floor (PD 1096).
2.7
All buildings located in areas where there is no sanitary sewerage system shall dispose their
sewage to imhoff tank or ___________ and subsurface absorption field (PD 1096).
septic tank
A tank for sewage consisting of an upper or sedimentation chamber with sloping floor
leading to slots through which the solids settle to the lower sludge-digestion chamber.
Imhoff tank
Based on the Building Code, when excavating near adjoining buildings the owners of
adjoining buildings shall be notified in writing at least how many days before excavation?
10
As provided in the Building Code, when curing concrete made from ordinary portland
cement, the concrete shall be maintained above 10 degrees Celsius and in moist condition for
the first how many days at least?
7
When curing concrete made from high strength portland cement, what is the minimum curing
time in days as provided in the Building Code?
3
What percentage of concrete strength is reached at the end of the first week?
70%
The initial setting of concrete starts in the first how many hours after concrete mixing?
2-3
Wood stick or board nailed horizontally at the stake which serves as the horizontal plane
where the reference points of building measurements are established.
batter board
In building construction, which step comes next to checking building permit?
loading boundaries
To establish an accurate 90-degree corner in a building layout, what will you use?
whole plywood
Material other than portland cement, aggregate, or water that is added to concrete to modify
concrete properties.
admixture
What is the equivalent compressive strength of ordinary concrete in kg per square centimeter
for 2,500 psi?
176
To attain about 3,000 psi compressive strength in non-air entrained concrete, how many liters
of water should be added per bag of cement?
25
When using 0.75 inch nominal maximum size of coarse aggregate, what is the estimated
percentage of air content by volume in concrete?
4-8
When made of normal weight aggregate, what should be the maximum water-cement ratio of
concrete that is intended to be watertight when exposed to fresh water?
0.48
For a concrete agricultural structure made from normal weight aggregate and in contact with
sea water, what should be the maximum water-cement ratio for it to be watertight?
0.44
The weight in kilograms of a 6-meter long standard 10 mm diameter reinforcing bar.
3.7
The cross-sectional area in square millimeters of a standard 16 mm diameter reinforcing bar.
201.1
In a wall footing, the horizontal steel reinforcement is said to be normally adequate if steel
cross sectional area relative to concrete cross sectional area is ________.
0.2-0.3%
What is the least number of longitudinal bars in a tied concrete column?
4
What is the minimum diameter of longitudinal bars in a tied concrete column?
16mm
Based on ACI Code, what is the minimum diameter of lateral ties in a tied concrete column
for 32 mm or smaller longitudinal bars?
10 mm
Based on ACI Code, what is the minimum diameter of lateral ties in a tied concrete column
for 36 to 57 mm and bundled longitudinal bars?
12 mm
Based on ACI Code, the maximum spacing of lateral ties in a tied concrete column should
not be more than _____ times the diameter of the longitudinal bars.
16
Based on ACI Code, the maximum spacing of lateral ties in a tied concrete column should
not be more than _____ times the diameter of the lateral ties.
48
Based on the standards of American Concrete Institute (ACI), what are the minimum width
and minimum concrete depth, respectively, of a square independent column footing carrying
9 tonnes load if soil pressure is 2,000 psf?
3.33’, 10”
(Based on ACI Table of Safe Load for Square Independent Column Footing)
Using the standards of American Concrete Institute, specify the total number and size of
horizontal reinforcing bars needed for a concrete square column footing of a farmhouse
carrying 18 tonnes load if soil pressure is 2,000 psf and concrete compressive strength is
2,500 psi.
16 pcs.12 mm
Based on ACI Table of Safe Load for Square Independent Column Footing
Determine the lateral ties spacing for a concrete column of a farmhouse having 36 cm x 40
cm side dimension. It uses 22 mm longitudinal bars and 10 mm lateral ties.
35.2 cm
Based on Farm-to-Market Road (FMR) standard, PAES 421:2009, if the slope of an FMR
exceeds ___%, concrete-lined or masonry-lined ditch should be provided.
4%
Granular material of mineral composition such as sand, gravel, shell, crushed and uncrushed
stone or lightweight materials.
aggregates
The minimum carriageway of one-lane and two-lane farm-to-market roads, respectively,
excluding the road shoulders, shall be ______.
2 and 4 m
In lateral and sub-lateral irrigation canals where the available roadway width is 3 meters, the
carriageway and shoulder, respectively, of the farm-to-market road shall be _______.
2 and 0.5 m
In main irrigation canals where the available roadway width is 6 meters, the shoulder and
carriageway, respectively, of the farm-to-market road shall be ______.
1 and 4 m
For gravel and bituminous farm-to-market roads, the minimum slope from the centerline
towards the ditch shall be ______.
3%
For concrete farm-to-market roads, the maximum slope from the centerline towards the ditch
shall be ______.
1.5%
For farm-to-market roads constructed along the main, lateral and sub-lateral irrigation canals,
the run:rise side slope of the earth embankment shall be ______.
1.5:1
In farm-to-market roads, the minimum radius of curvature for flat, rolling and mountainous
terrains, respectively, shall be ______.
500, 150 & 50 m
In a bituminous farm-to-market road, what course is the third layer from the top?
Aggregate subbase
As an engineer, what thickness of the portland cement concrete pavement will you use in a
two-lane farm-to-market road?
20cm
In concrete farm-to-market road construction, what plus or minus in thickness variation will
you allow in the portland cement concrete pavement?
20 mm
As a minimum, all culverts and storm drains used in relation with farm-to-market roads
should be designed using a storm of two-year return period and duration of ______.
24 hours
Culverts and storm drains have ideal slope of 2-4 %. What is the absolute minimum slope for
culverts and storm drains?
0.5%
In concrete farm-to-market road design, what class A concrete thickness will you use in
triangular concrete-lined ditch?
15 cm
In concrete farm-to-market road design, what wall thickness will you use in rectangular
grouted riprap ditch?
25 cm
As a contractor, what project management amount in terms of estimated direct cost
percentage will you charge aside from the 10-15 % profit in farm-to-market road projects?
5%
Based on PNS/BAFS/PAES 216:2017, what is the mean roughness coefficient for rigid
concrete?
0.013
The standard diameter of both vertical and horizontal reinforcing bars in open channel
construction.
10 mm
In open channel construction, what class of concrete mix should be used?
Class A
The standard spacing between vertical bars in open channel construction.
20 cm
In open channel design, what is the standard concrete wall thickness of lateral trapezoidal
open channel?
15 cm
The standard gage number of G.I. tie wire for open channel construction.
16
In class A, B or C concrete, how many cubic meters of sand should be mixed to produce 1
cubic meter of concrete?
0.50
In open channel construction, how many 40-kg bags of cement are needed per cubic meter of
concrete?
9
In constructing open trapezoidal concrete open channels, how many 900-gm packs of water
proofing compound are needed per cubic meter of Class A (1:2:4) concrete mix?
9
In concrete canal construction, how many 40-kg bags of cement are needed for a 20-km
lateral channel if it requires 0.6 cubic meter concrete per linear meter? Use 5% safety factor.
113,400
How many truck loads of sand are needed for 30-km main irrigation canal requiring 3.5 cubic
meters concrete per linear meter? 1 truck load is 2.5 cubic meters. Use 5% safety factor.
22,050
How many truck loads of gravel needed for an 10-km main irrigation canal requiring 4 cubic
meters concrete per linear meter? 1 truck load is 2.5 cubic meters. Use 6% safety factor
16,960
Determine the cement budget for 36-km irrigation canal if it requires half cubic meter
concrete per linear meter and cement costs Php200/bag? Use 5% safety factor.
Php 34,020,000
The number of 10-mm horizontal reinforcing bars in a 3.2-meter tall trapezoidal canal wall is
2,836 pieces. Following the standard bar spacing 20 cm x 20 cm, how many vertical
reinforcing bars are needed?
2,836
What is the cement budget for 18-km canal requiring 2/3 cubic meter concrete per linear
meter? Cement costs Php200/bag while transport costs Php 10/bag. Use 5% safety factor.
Php 23,825,907
The Food and Agriculture Organization of the United Nations (FAO) recommends 1.5
liters/second net irrigation supply per hectare of lowland rice. If the canal is rectangular with
base equal to water depth, velocity is 1.2 m/s and area is 50 hectares, what should be the
canal base and wetted canal depth excluding freeboard? Assume system efficiency of 16%.
0.62 m
A gravity dam weighing 73,000 tonnes is to be constructed with length along dam axis of 1
km and base of 100 meters. What should be the minimum soil bearing stress? Use factor of
safety against sinking of 2.
1.5 tonnes/sq.m.
A 1-meter thick trapezoidal section of a concrete dam has resisting moment about the dam
toe of 280,000 tonne-meters. The water exerts 4,050 tonnes horizontally at 35 meters above
the dam toe. What is the factor of safety against overturning?
1.98
A concrete dam with 50,000 sq.m. submerged vertical upstream wall is to be constructed
against a 546 tonnes/sq.m. average water pressure. Coefficient of friction at dam base is 0.83.
What should be the minimum dam weight? Use factor of safety against sliding of 2.
65,783,133 tonnes
The toxic component of biogas.
Hydrogen sulfide
The by-product of biogas production commonly used as soil conditioner after air drying.
sludge
The amount paid to project owners from CDM fund for carbon emission reduction projects.
Carbon credit value
The acronym of the Inter-Governmental Panel for Climate Change.
IPCC
Best kind of biogas plant for large animal farms having effluents with low solid content.
Covered lagoon
Plastic sheet for constructing balloon and bed lining in covered lagoon biogas plants.
High density polyethylene (HDPE)
By how many times is methane destructive to the environment than carbon dioxide?
21 times
Toxic by-product of geothermal power plants
Hydrogen sulfide
When using covered lagoon biodigester, what is approximate methane content in biogas?
70%
What is the minimum methane content of biogas in order to operate biogas-fueled
generators?
65%
When using 1:1 water-manure ratio, what is the approximate methane content of biogas?
60%
A device to convert biogas to electricity.
Biogas generator
A board constructed across the bottom of the biogas digester to prevent early exit of slurry.
Baffle board
Covered lagoon biodigester, minihydro and solar energy projects are evaluated for financial
feasibility. Only one feasible project can be funded. Each of them requires PHP 20,000,000
investment. The financial internal rates of return are 8%, 9% and 10%, respectively. Annual
discount plus inflation rate is 11%. Which project shall be implemented?
A. Covered lagoon biodigester
B. Minihydro
C. None
D. Solar
none
(since all their IRRs are less than the discount plus inflation rate)
In the Clean Development Mechanism (CDM), how much will the project owner of a new
covered lagoon biodigester receive annually from CDM fund for the first 10 years if his
biodigester produces 8,000 tonnes of methane and 3,000 tonnes of carbon dioxide per year.
Assume that the current carbon credit costs US$8 per tonne of carbon equivalent.
US$ 1,368,000
What is the daily biogas consumption in cubic meters of an industrial boiler using 12 units of
50-cm gas burner 8 hours a day? The consumption of each gas burner is 1.3 cu.m./hour.
125
Estimate the biogas production in cubic meters per day from a large balloon type digester
using 1:1 water-manure ratio. The source farm has 1,100 heads of porkers of mixed ages. Use
a retention period of 30 days. The mean daily manure production of porkers is 2.2 kg/head
while the specific gas production for 30-day manure retention period is 0.063 m3
/kg.
153
How many heads of breeding cattle are needed as source of manure to generate 80 m3
of
biogas a day if the retention period is 25 days and water-manure ratio is 1:1. The mean daily
manure production of breeding cattle is 13 kg/head while its specific gas production for 25-
day manure retention period is half of that of chicken dung
206
