Grounding/Ground Grids Flashcards
A low-resistance, well-designed, and well-constructed ground grid is necessary to provide improved ? .
worker safety
One reason a well-grounded substation neutral provides improved power quality is because ? need a solid ground reference to properly operate switchgear.
control relays
The substation ground grid protects workers and the public from ? and ? potentials.
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
The design of a substation ground grid starts with choosing a site location where ? is present, which has the ability to dissipate power surges.
good earth
In a substation, the ground grid covers ? .
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 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 highly conductive clay such as bentonite
A substation ground grid is not subjected to a high electrical current.
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
The type of below-grade connector typically used on a substation grid is a(n) ? connection.
exothermic welded
Training is required on how to properly install exothermic connectors.
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 ? .
remote ground
Electrical connections are made at all crossover junctions of the grid.
True
Electrical connections are made at all crossover junctions of the grid.
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
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.
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
