Electricity Prep Exam Test Questions And
Answers Verified 100% Correct
How often should a transformer be inspected? - ANSWER - Once or twice
a year (low maintenance)
- Check for loose or hot connections
What is meant by a transformer "breathing"? - ANSWER - The constant
heating and cooling of the transformer causes it to conceive and expel air
which can lead to the device being covered in sludge and acidity (cause of
many failures)
What enables a transformer to work at a high kVa rating? - ANSWER If
the heat in the transformer can be dissipated at a faster rate lowering the
the temperature rise (type of insulation is important)
What type of cooling do Dry Transformers rely on? - ANSWER Air-
convection (forced cooling)
Other than forced cooling, what else is done to improve the kVa rating of
a transformer? - ANSWER - Submerse the core in an oil which has a
much higher specific heat than air
What replaced PCB in modern day transformers? - ANSWER Silicone
based oils or florinated hydrocarbons.
What is it called when AC action cause a counter current in a coil? -
ANSWER Self-inductance.
Two units of transformers? - ANSWER VA and kVA
Important area of responsibility in relation to electrical distribution circuits?
- ANSWER - Operating equipment
- Deciding what maintenance should be done
- Isolating equipment for maintenance
,- First response to fire or accident
Location of these 2 things are important if the system or portions of the
system have to be shut off at any time. - ANSWER - Load center
- Motor control center
Extra Low Voltage? - ANSWER - Below 30 V
- Low voltage extremely susceptible to voltage drop (load must be in
close proximity to the source)
- Not suitable nor economical for power loads of any size
Low Voltage? - ANSWER - Pose a threat to life
- Voltages sufficient to supply power loads
High voltage? - ANSWER - Can cause arcing through the air which
restricts use of high voltages to utilities in industrial applications and
electrical services buildings
What is a prime factor in determining the selection of voltage? - ANSWER
- Degree of access to equipment
- High voltage must be locked
Voltage ranges can vary how much due to load variances? - ANSWER
5%
Equipment selection in a circuit must conform to what constraints? -
ANSWER Number of phases and voltages.
How do you maintain proper load distribution? - ANSWER Balance the
loading as well as possible between all conductors. (reduces line losses
and energy costs)
If high voltage is used in commercial and residential applications, its
usually restricted to what area? - ANSWER Service entrance and some
feeders.
, High voltage is not often used as a utilization voltage. True or False? -
ANSWER True, with the exception of large pumps or compressors.
Arc tracking? - ANSWER Pumps and compressors collect moisture and
dirt, and could spontaneously energize
Open contacts on a high voltage system ensure the line is de-energized.
True or False? - ANSWER False, downstream conductors may store
some amount of capacitance.
Rules for high voltage lines? - ANSWER - Lines must be interconnected
and grounded
- Disconnect switches must be locked open before maintenance
Recommended distance to keep away from high voltage conductors? -
ANSWER Not less than 2 meters
Medium of communication between equipment designers and equipment
users? - ANSWER Diagrams.
Examples of certain specifications that could be conveyed in a building? -
ANSWER - Special circuitry
- Equipment quality
- Manufacturer
- Aesthetics
- Coding systems
- Terminal markings
Schematic (elementary) Diagrams? - ANSWER - Shows function,
sequence and electrical relationships through graphical symbols of a
specific circuit
- Does not portray any relation to size positioning, shape or location of
component devices, parts or terminals.
Connection/wiring Diagram? - ANSWER - Physical arrangement of
components including all wiring and connections
Terminal/Connection diagrams? - ANSWER - Illustrate locations and
Answers Verified 100% Correct
How often should a transformer be inspected? - ANSWER - Once or twice
a year (low maintenance)
- Check for loose or hot connections
What is meant by a transformer "breathing"? - ANSWER - The constant
heating and cooling of the transformer causes it to conceive and expel air
which can lead to the device being covered in sludge and acidity (cause of
many failures)
What enables a transformer to work at a high kVa rating? - ANSWER If
the heat in the transformer can be dissipated at a faster rate lowering the
the temperature rise (type of insulation is important)
What type of cooling do Dry Transformers rely on? - ANSWER Air-
convection (forced cooling)
Other than forced cooling, what else is done to improve the kVa rating of
a transformer? - ANSWER - Submerse the core in an oil which has a
much higher specific heat than air
What replaced PCB in modern day transformers? - ANSWER Silicone
based oils or florinated hydrocarbons.
What is it called when AC action cause a counter current in a coil? -
ANSWER Self-inductance.
Two units of transformers? - ANSWER VA and kVA
Important area of responsibility in relation to electrical distribution circuits?
- ANSWER - Operating equipment
- Deciding what maintenance should be done
- Isolating equipment for maintenance
,- First response to fire or accident
Location of these 2 things are important if the system or portions of the
system have to be shut off at any time. - ANSWER - Load center
- Motor control center
Extra Low Voltage? - ANSWER - Below 30 V
- Low voltage extremely susceptible to voltage drop (load must be in
close proximity to the source)
- Not suitable nor economical for power loads of any size
Low Voltage? - ANSWER - Pose a threat to life
- Voltages sufficient to supply power loads
High voltage? - ANSWER - Can cause arcing through the air which
restricts use of high voltages to utilities in industrial applications and
electrical services buildings
What is a prime factor in determining the selection of voltage? - ANSWER
- Degree of access to equipment
- High voltage must be locked
Voltage ranges can vary how much due to load variances? - ANSWER
5%
Equipment selection in a circuit must conform to what constraints? -
ANSWER Number of phases and voltages.
How do you maintain proper load distribution? - ANSWER Balance the
loading as well as possible between all conductors. (reduces line losses
and energy costs)
If high voltage is used in commercial and residential applications, its
usually restricted to what area? - ANSWER Service entrance and some
feeders.
, High voltage is not often used as a utilization voltage. True or False? -
ANSWER True, with the exception of large pumps or compressors.
Arc tracking? - ANSWER Pumps and compressors collect moisture and
dirt, and could spontaneously energize
Open contacts on a high voltage system ensure the line is de-energized.
True or False? - ANSWER False, downstream conductors may store
some amount of capacitance.
Rules for high voltage lines? - ANSWER - Lines must be interconnected
and grounded
- Disconnect switches must be locked open before maintenance
Recommended distance to keep away from high voltage conductors? -
ANSWER Not less than 2 meters
Medium of communication between equipment designers and equipment
users? - ANSWER Diagrams.
Examples of certain specifications that could be conveyed in a building? -
ANSWER - Special circuitry
- Equipment quality
- Manufacturer
- Aesthetics
- Coding systems
- Terminal markings
Schematic (elementary) Diagrams? - ANSWER - Shows function,
sequence and electrical relationships through graphical symbols of a
specific circuit
- Does not portray any relation to size positioning, shape or location of
component devices, parts or terminals.
Connection/wiring Diagram? - ANSWER - Physical arrangement of
components including all wiring and connections
Terminal/Connection diagrams? - ANSWER - Illustrate locations and
