grounding in a substation Flashcards
Substations are unique because they do not have any of the same hazards as other areas of the electrical industry.
false
Asymmetrical current flow, as found in a substation, is current that at the beginning of flow becomes significantly offset from the ?
zero axis of a normal symmetrical current
The high fault current levels available in substations require ?
larger grounding cables and clamps
Loops that carry induced current are formed in substations because ?
the use of multiple grounding points are all connected to the substation grid
Asymmetrical currents are ?
non symmetrical currents
Asymmetrical current in a substation is caused by ?
the larger amount of inductance present from reactors and transformers.
The effect of asymmetrical currents on aluminum welded grounding connection points is that they often ?
break off under the force
The difference between symmetrical and asymmetrical current is that an asymmetrical current ?
has greater initial peaks than symmetrical current
If instrument transformers are not grounded during testing, ? may develop.
high voltage
When working between grounds in a substation, be sure that there are no outside line connections between the grounds.
true
Voltage dividers (transformers) must be disconnected and grounded when testing because ?
transformers are bi directional they step voltage up as well as down
When performing maintenance work in a substation, a key recommendation is to keep the personal protective ground connected from the bus or equipment to the grid ?
as close to the worksite as possible
Mechanical forces during asymmetrical current flow ?
increase as the square of the current increases
In a substation, the use of multiple grounding points such as grounding switches and personal protective grounds will form a loop, allowing current flow. The use of multiple connections to the grid ?
divides the current among multiple paths
