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