A low-resistance, well-designed, and well-constructed ground grid is necessary to provide improved ____.
a. foundations for equipment
b. lightning protection
c. underground raceways for control cables
d. worker safety
Substation Construction Guidelines Textbook, Chap. 5, Pg. 103, “Introduction,” Paragraph 1, Sentence 1
d. worker safety
One reason a well-grounded substation neutral provides improved power quality is because ____ need a solid ground reference to properly operate switchgear.
a. control relays
b. motor starters
c. overcurrent capacitors
d. surge protectors
Substation Construction Guidelines Textbook, Chap. 5, Pg. 103, “Introduction,” Paragraph 2, Sentence 2
a. control relays
The substation ground grid protects workers and the public from ____ and ____ potentials.
a. hazardous/grounded
b. normal/overcurrent
c. stray/lightning
d. touch/step
Substation Construction Guidelines Textbook, Chap. 5, Pg. 103, “Introduction,” Paragraph 3, Sentence 1
d. touch/step
If a person’s body is bridging across an open point in a ground grid during a system fault, the person can receive a fatal shock.
True or False?
Substation Construction Guidelines Textbook, Chap. 5, Pg. 103, “Introduction,” Paragraph 3, Sentence 1
True
The design of a substation ground grid starts with choosing a site location where ____ is present, which has the ability to dissipate power surges.
a. decomposed granite
b. good earth
c. gravel
d. silt
Substation Construction Guidelines Textbook, Chap. 5, Pg. 103, “Typical Ground Grid Design,” Paragraph 1, Sentence 1
b. good earth
In a substation, the ground grid covers ____.
a. all concrete surfaces
b. out to an area 15’ from the fence
c. the entire area of the substation
d. the entire area of the substation except near the substation fence
Substation Construction Guidelines Textbook, Chap. 5, Pg. 104, Paragraph 1, Sentence 2
c. the entire area of the substation
If multiple ground rods driven eight feet deep do not provide a low enough resistance to meet specifications, ____ in order to achieve lower resistance.
a. a second rod can be joined to the first to go deeper
b. all ground grid connections can be made by exothermic welding
c. the ground grid can be made one-half its size
d. the ground grid wire size can be doubled
Substation Construction Guidelines Textbook, Chap. 5, Pg. 105, “Ground Rods,” Paragraph 1, Sentence 3
a. a second rod can be joined to the first to go deeper
If a ground grid needs lower resistivity, deep-drilled wells back-filled with ____ can be used.
a. a highly conductive clay such as bentonite
b. a highly resistive concrete and stone mix
c. alternating layers of gravel
d. rocky topsoil
Substation Construction Guidelines Textbook, Chap. 5, Pg. 105, “Ground Rods,” Paragraph 1, Last Sentence
a. a highly conductive clay such as bentonite
A substation ground grid is not subjected to a high electrical current.
True or False?
False
Electrical connections on a ground grid need to be fail-safe, so that when there is a rise in potential on the total grounding network in the station, everything will remain bonded together.
True or False?
Substation Construction Guidelines Textbook, Chap. 5, Pg. 105, “Electrical Connections,” Paragraph 1, Sentence 2
True
The type of below-grade connector typically used on a substation grid is a(n) ____ connection.
a. aluminum bi-metal
b. exothermic weld
c. solid copper
d. slplit bolt
Substation Construction Guidelines Textbook, Chap. 5, Pg. 106, Paragraph 1, Sentence 1
b. exothermic weld
Training is required on how to properly install exothermic connectors.
True or False?
Substation Construction Guidelines Textbook, Chap. 5, Pg. 109, Paragraph 2
True
Crushed stone is a good product to cover a substation ground grid because it offers some protection when stepping from the grid to a ____.
a. control house
b. fenced in capacitor rack
c. remote ground
d. switch ground mat
Substation Construction Guidelines Textbook, Chap. 5, Pg. 106, “Covering the Grounding Grid,” Paragraph 2, Last Sentence
c. remote ground
Electrical connections are made at all crossover junctions of the grid.
True or False?
Substation Construction Guidelines Textbook, Chap. 5, Pg. 108, “Procedure,” Number 8
True
An extra metal mesh or platform is installed where switches need to be operated in a substation in order to provide extra protection from ____ for switch operators.
a. insulator collapse
b. lightning strikes
c. static discharge
d. touch and step potentials
Substation Construction Guidelines Textbook, Chap. 5, Pg. 106, “Covering the Grounding Grid,” Paragraph 3
d. touch and step potentials
Workers are protected from touch potentials in a substation because metal equipment such as transformers, switchgear, cable trays, and fences, are all connected to the ground grid.
True or False?
Substation Construction Guidelines Textbook, Chap. 5, Pg. 103, “Introduction,” Paragraph 4, Sentence 1
True
Workers are protected from ____ because the design and spacing of the substation ground grid does not place one foot of a worker at a different potential from the other foot.
a. circulating currents
b. step potentials
c. stray voltage discharge
d. touch potentials
Substation Construction Guidelines Textbook, Chap. 5, Pg. 103, “Introduction,” Paragraph 4, Last Sentence
b. step potentials
The public is protected from touch potentials because the fence is bonded to the ground grid, and the grid extends outside of the fence.
True or False?
Substation Construction Guidelines Textbook, Chap. 5, Pg. 103, “Introduction,” Paragraph 5
True
