Rural Electrification Flashcards
For motors with a marked service factor not less than 1.15, the multiplying factor to be used in determining for size of overload protection shall be ____.
a. 110 % c. 120 %
b. 115 % d. 125 %
d. 125 %
For a motor starter to be in sight of the controlled motor, it must NOT be more than ___ meters away.
a. 20 c. 25
b. 10 d. 15
d. 15
Flexible metallic tubing smaller than
___ electrical trade size shall NOT be used in wiring.
a. 20 mm c. 12 mm
b. 15 mm d. 32 mm
b. 15 mm
Consist of a group of wire twisted to form a metallic string.
a. Duplex wire c. solid wire
b. loomex wire d. stranded wire
d. stranded wire
Transformers that are installed in unsupervised locations and rated over 600 V are protected by fuses on the primary side and cannot exceed ____ percent of the primary full load current.
a. 150 c. 200
b. 300 d. 250
b. 300
Ratio of the maximum demand of a system or part of a system to the total connected load of a system or
the part of the system under consideration.
a. power factor
b. utilization factor
c. capacity factor
d. demand factor
d. demand factor
Type NM (non-metallic sheathed cable) shall be permitted for ____ work in normally dry locations.
a. exposed c. both a and b
b. concealed d. neither a nor b
c. both a and b
Conductors used only for grounding shall be _____.
a. green, green with yellow stripes, or yellow
b. green, yellow with green stripes, or bare
c. green, green with yellow stripes, or bare
d. green, yellow, or bare
c. green, green with yellow stripes, or bare
The lowest standard size of disconnect
is ____.
a. 20 A c. 30 A
b. 60 A d. 15 A
c. 30 A
Branch circuit conductors supplying a single motor shall have an ampacity NOT less than ____ percent of the motor full load current rating.
a. 115 c. 120
b. 125 d. 130
b. 125
Where the overload relay selected using the factor 125 % is not sufficient to start the motor or carry the load, the multiplying factor shall be increased but shall NOT exceed ____ percent.
a. 130 c. 140
b. 150 d. 160
c. 140
An exposed wiring support system using a messenger wire to support insulated conductors.
a. Metal clad cable wiring
b. Concealed knob and tube wiring
c. Messenger cable wiring
d. Messenger supported wiring
d. Messenger supported wiring
In replacing a busted fuse, which of the following is important?
a. same size and type
b. same type but different rating
c. same size but different rating
d. different size and type
a. same size and type
Which of the following wires has 75 ohm impedance?
a. Foam-filled twin lead
b. Flat twin lead
c. Coaxial
d. none of these
c. Coaxial
Consists of three or more flat copper conductor placed edge to edge separated and enclosed within an insulating assembly.
a. Armored cable
b. Sheathed cable
c. Flat cable assemblies
d. Flat conductor cable
d. Flat conductor cable
Rigid metal conduit shall be shipped in standard lengths of ___.
a. 3,000 mm c. 6,000 mm
b. 4,000 mm d. 5,000 mm
a. 3,000 mm
The term given to an insulated stranded wire.
a. Durability c. Cord
b. Pendant d. Receptacle
c. Cord
In which method of starting a motor is the starting current a minimum?
a. star-delta
b. direct on line
c. resistance starter
d. autotransformer
a. star-delta
Which of the following sizes of fuse is NOT standard?
a. 80 A c. 60 A
b. 125 A d. 75 A
d. 75 A
The smallest electrical trade size of
intermediate metal conduit.
a. 15 mm c. 20 mm
b. 12 mm d. 25 mm
a. 15 mm
The Philippine Electrical Code (PEC) is intended for ____ application by
government bodies exercising legal
jurisdiction over electrical installation.
a. advisory c. mandatory
b. optional d. all of these
c. mandatory
Before starting any installation work, alteration, repair or extension on any electrical system, what type of permit is needed?
a. Building permit
b. Electrical permit
c. Working permit
d. Mayor’s permit
b. Electrical permit
This type of cable is a fabricated assembly of insulated conductors enclosed in a flexible metal sheath.
a. Ground wire
b. Medium voltage cable
c. Messenger Wire
d. Armored cable
d. Armored cable
Which of the following electrical
conductor has the highest resistance?
a. 3.5 mm2
b. 2.0 mm2
c. 5.5 mm2
d. 20 mm2
b. 2.0 mm2
Electrical equipment may be best mounted on a concrete wall by using one of the following. Which
one is this?
a. wooden plug c. expansion bolt
b. load plug d. plastic plug
c. expansion bolt
The following copper conductors have the same cross-sectional
area but are made up of different number of strands. Which one has
the least resistance to AC current?
a. 19-strand conductor
b. 7-strand conductor
c. single solid conductor
d. 37-strand conductor
c. single solid conductor
Operation at substantially constant load for an indefinitely long time.
a. Periodic duty
b. Intermittent duty
c. Continuous duty
d. Short time duty
c. Continuous duty
In rigid metal conduit wiring, conduits shall be supported at least every
a. 2,500 mm c. 3,500 mm
b. 3,000 mm d. 2,000 mm
b. 3,000 mm
Auxiliary gutter shall not contain more than _____ current carrying conductors at any cross section.
a. 36 c. 30
b. 32 d. 24
c. 30
A machine that converts mechanical energy to electrical energy.
a. generator
b. motor
c. transformer
d. capacitor
a. generator
What type of electrical conductors has a trade name “moisture resistant thermoplastic” ?
a. TW c. THHN
b. THW d. All of these
a. TW
Liquidtight flexible nonmetallic conduit shall NOT be used where the voltage of the contained conductors is in excess of _____.
a. 600 V c. 250 V
b. 300 V d. 1000 V
a. 600 V
A point in a wiring system at which current is taken to be used in some equipment.
a. Grounded
b. Conductor
c. Service entrance
d. Outlet
d. Outlet
In concealed knob and tube wiring, the clearance to be maintained between conductor is
_____.
a. 55 mm c. 76 mm
b. 45 mm d. 50 mm
c. 76 mm
Operation of equipment in excess of normal full load rating or of a conductor in excess of rated ampacity.
a. Overload c. Overcurrent
b. Overvoltage d. Surge
a. Overload
When circuit breakers are installed in enclosed switchboards, they are derated to a certain percentage. What is this percentage?
a. 60 % c. 70%
b. 80% d. 50%
b. 80%
A short length of conductor used to make a connection between terminals or around a break in a
circuit.
a. jumper
b. guy
c. bonding conductor
d. tie wire
a. jumper
A gas circuit breaker is using a gas called SF6 as its interrupting medium. What does SF6 stands for?
a. sulfur fluoride
b. sulfur ferrite
c. sulfur hexafluoride
d. none of these
c. sulfur hexafluoride
A conductor having no covering or electrical insulation.
a. bare conductor
b. concealed conductor
c. encased conductor
d. exposed conductor
a. bare conductor
Fixture wire shall NOT be smaller than _____.
a. 1.25 mm2
b. 2.0 mm2
c. 0.5 mm2
d. 0.75 mm2
d. 0.75 mm2
All circuit conductors between the service equipment or the generator switchboard of an isolated plant, and the final branch circuit
overcurrent device.
a. overcurrent protection
b. branch circuit conductors
c. feeder
d. service entrance
c. feeder
What is the temperature rating of THW insulation?
a. 60 o C c. 75 o C
b. 90 o C d. 110 o C
c. 75 o C
Branch lighting circuits shall be
protected by overcurrent devices not rated more than
a. 40 A c. 30 A
b. 20 A d. 50 A
b. 20 A
Which of the following conductors is NOT applicable on wet locations?
a. Type THHN
b. Type THW
c. Type RHW
d. Type THWN
a. Type THHN
A surge of unidirectional polarity.
a. Skin effect c. Flashover
b. Corona d. Impulse
d. Impulse
Main and equipment bonding jumper shall be of _____.
a. copper
b. aluminum
c. either a or b
d. neither a nor b
a. copper
The minimum insulation level for
neutral conductors of solidly grounded system shall be ______.
a. 500 V c. 600 V
b. 300 V d. 750 V
c. 600 V
Connection between conductive or
inductive metal object in an element of lighting protection system to accomplish electrical continuity.
a. Connectors
b. Interlink
c. Counterpoise
d. Bonding
d. Bonding
The grounding electrode conductor shall be_______.
a. copper
b. aluminum
c. copper-clad aluminum
d. all of these
d. all of these
Fuses shall be plainly marked with ______.
a. ampere rating
b. voltage rating
c. interrupting rating
d. all of these
d. all of these
Fixture wire shall NOT be used _____.
a. for installation in lighting fixtures
b. for connecting lighting fixture to the branch circuit conductors
c. as branch circuit conductors
d. none of these
c. as branch circuit conductors
If the trade name of the conductor is “heat-resistant rubber”, what type letter is it?
a. Type RH c. Type RHW
b. Type THW d. Type MTW
a. Type RH
Which of the following cables is NOT used as an electrical cable?
a. Flat Cable
b. Optical Fiber Cable
c. Armored Cable
d. Steel Cable
d. Steel Cable
A generator may lost residual magnetism because of
a. vibration
b. over-excitation
c. heating
d. varying loads
c. heating
A diagram showing the physical location of the components: coils, contacts, motors and the like in
their actual positions that would be found on an installation.
a. Ladder diagram
b. Schematic diagram
c. Wiring diagram
d. Power flow diagram
c. Wiring diagram
At starting the motor current is high
due to
a. Counter emf is high
b. Counter emf is zero
c. Supply voltage is high
d. armature circuit resistance is open
b. Counter emf is zero
Shunt generators are most suitable for parallel operation due to their ______.
a. constant voltage characteristics
b. drooping voltage characteristics
c. increasing voltage characteristics
d. variable voltage characteristics
b. drooping voltage characteristics
If the series field is connected in series with the armature, and the shunt field is connected across the combination, what type of DC generator is this?
a. Shunt generator
b. Series generator
c. Long shunt compound generator
d. Short shunt compound generator
c. Long shunt compound generator
The start winding of a split-phase induction motor is switched out of the circuit by a device called
a. magnetic contactor
b. zero speed switch
c. centrifugal switch
d. proximity switch
c. centrifugal switch
Electrical symbol represented by a
rectangle with a letter PB inside.
a. push button
b. pull box
c. battery panels
d. panelboard
b. pull box
Relays which verify the condition of the power system or in protection systems.
a. Auxiliary relay
b. Regulating relay
c. Programming relay
d. Monitoring relay
d. Monitoring relay
The no load power input of a transformer is approximately equal to what losses in a transformer.
a. Iron losses
b. Copper losses
c. Ventilation losses
d. All of these
a. Iron losses
What should you do to prevent a
shock when working on a high voltage supply?
a. Open the filter capacitor
b. Closed the filter capacitor
c. Discharged the filter capacitor
d. Charged the filter capacitor
c. Discharged the filter capacitor
When cleaning a commutator, which of the following shall not be used?
a. clean cloth
b. sand paper
c. emery
d. all of these
c. emery
A Merz-price protection is suitable for
a. alternators
b. transformers
c. transmission lines
d. feeders
a. alternators
How would determine, from visual
observation of the armature winding. Whether the generator is a lap or a wave sound.
a. direction of the end connection
b. connection to the commutator
c. connection to the field winding
d. connection to brushes
b. connection to the commutator
Generally, all AC electric motors
operate on the principle of induction or
a. conduction
b. repulsion
c. capacitance
d. magnetism
b. repulsion
Insulating liquid commonly used for
insulating and cooling transformers and for arc interruption in oil circuit breakers.
a. mineral oil
b. askarel
c. silicone oil
d. all of the above
d. all of the above
This term means that the motor will stop when there is a supply voltage failure and the motor will restart
automatically when the supply voltage is restored.
a. No voltage release
b. No voltage control
c. No voltage protection
d. None of these
a. No voltage release
Manually operated three position three-pole rotary switch, which carries a hp rating and is used
for manually reversing electric motors.
a. Knife switch
b. Drum switch
c. Break-make switch
d. Rocker switch
b. Drum switch
Which of the following is NOT a
reduced voltage starting method?
a. Star-delta starting
b. Autotransformer starting
c. Primary resistance starting
d. Part winding starting
d. Part winding starting
Which of the following statements
describe as synchronous motor?
a. It is not self-starting
b. It requires both AC and DC supplies
c. It is used for power factor improvement
d. All of these
improvement
d. All of these
Coils placed at the neutral point
midway between the main poles of a DC machine.
a. Interpole windings
b. Equalizer windings
c. Compensating winding
d. Damper windings
a. Interpole windings
When the emfs in the two windings of the transformer are opposite in direction, the polarity of the windings is
a. additive
b. subtractive
c. either a or b
d. neither a nor b
a. additive
Which of the following is the best
advantage of a DC motor over an AC motor?
a. It is easier to reverse its speed
b. It has a higher speed rating
c. It has a better speed control
d. All of these
c. It has a better speed control
Which of the following protection
features, a motor starter is not readily needed?
a. No-voltage protection
b. Single phasing protection
c. Ground fault protection
d. Overload protection
c. Ground fault protection
Split phase motors are all noisy
because they vibrate at a frequency ____ the operating frequency.
a. equal to c. twice
b. thrice d. less than
c. twice
Transformer with only one winding.
a. Single-phase transformer
b. Current transformer
c. Potential transformer
d. Autotransformer
d. Autotransformer
Which of the following electrical
machines has the highest operating
efficiency?
a. Motors c. Generators
b. Transformers d. Converters
b. Transformers
The most effective method of starting a large squirrel cage motor is by the use of
a. transformer reduced voltage method
b. star-delta switching
c. dropping resistors
d. partial winding method
a. transformer reduced voltage method
During the short circuit test on transformer,
which side is shorted?
a. High voltage side
b. Low voltage side
c. Neither side
d. Both sides
b. Low voltage side
In a circuit breaker, the current which exists at the instant of contact separation is known as
a. recovery current
b. surge event
c. interrupting current
d. restriking current
c. interrupting current
Lubrication commonly used by
gearmotors.
a. water c. grease
b. oil d. talc
b. oil
For efficient operation, induction motors are always designed with a small
a. airgap
b. voltage drop
c. inductive reactance
d. impedance
a. airgap
This winding is connected in series with armature winding of a DC generator to compensate the field flux distortion due to armature reaction.
a. series field windings
b. interpole windings
c. compensating windings
d. shunt field windings
c. compensating windings
What important data can that be gathered after the open circuit test on transformer?
a. rated power output
b. resistance and reactance of windings
c. core or iron losses
d. voltage and current ratios
c. core or iron losses
Which of the following electric material is equipped with slip rings?
a. DC motor or DC generator
b. split-phase motor
c. AC generator
d. repulsion type motor
c. AC generator
Best suited motor to drive small
electric fans.
a. Universal motor
b. Shunt motor
c. Capacitor run motor
d. Resistance split-phase motor
c. Capacitor run motor
The terminal voltage of this DC
generator varies widely when a change in load occurs. Which one is this?
a. Series
b. Long shunt compound
c. Shunt
d. Short shunt compound
a. Series
Interrupting capacity of a circuit
breaker is expressed in
a. MVA c. cycles
b. kV d. kA
d. kA
What is the magnitude of the starting current in an induction motor compared to its full load current?
a. 9 to 12 times
b. 2 to 3 times
c. 4 to 9 times
d. 3 to 4 times
c. 4 to 9 times
The speed of a synchronous motor
_______.
a. is constant
b. increases with load
c. decreases with load
d. any of these
a. is constant
Which of the following losses in DC
machines vary with the load?
a. stray power losses
b. core losses
c. copper losses
d. all of these
c. copper losses
Transformers are rated in
a. HP c. kW
b. kVA d. kVAR
b. kVA
The inner strand of ACSR is made of
a. brass c. copper
b. steel d. lead
b. steel
For dwelling units, the demand
factor for the first 3000 VA of load is
a. 95 % c. 85 %
b. 100 % d. 80 %
b. 100 %
A cable provided with a wrapping or
metal usually steels wires or tapes, primarily for the purpose of mechanical protection.
a. metal clad cable
b. metallic sheathed cable
c. armored cable
d. flat conductor cable
c. armored cable
Insulators used to support wires
under cross arms are
a. pin
b. spool
c. suspension
d. strain
c. suspension
What is the maximum operating
temperature of type THWN conductor?
a. 75 o C c. 60 o C
b. 90 o C d. 110 o C
a. 75 o C
A conductor encircling a building and interconnecting all ground terminals.
a. bonding c. air terminal
b. interlink d. counterpoise
d. counterpoise
A protective device for limiting surge voltages by discharging or by passing surge current.
a. Arrester
b. Lightning rod
c. Circuit breaker
d. Thermocouple
a. Arrester
What does the symbol consisting of rectangle with solid shading indicates?
a. fuse cut-out
b. telephone exchange
c. safety switch
d. lighting panelboard
d. lighting panelboard
Disruptive discharges between
electrodes of a measuring gap.
a. lightning
b. flashover
c. surge
d. sparkover
d. sparkover
Air conditioning load has a demand
factor of _______.
a. 80% c. 125%
b. 100% d. 150%
b. 100%
An overcurrent device with a circuit
opening fusible part that is heated and severed by the passage of overcurrent through it.
a. overload relay
b. fuse
c. thermocouple
d. magnetic contactor
b. fuse
