Beginner Question: Ground Fault Current

[powertrainee]

I have a beginner type question on ground fault current. I am reading Chapter 4 of Electric Power Distribution Equipment and Systems where it says, "Ungrounded primary connections do not supply ground fault current to the primary distribution system...Grounded wye primaries may provide an unwanted source for ground fault current"

From what I understand, ground fault current is caused by an unintended path to ground (i.e. a line-to-ground fault). I think my confusion lies in the wording of supply and source. What is meant by "do not supply ground fault current..." and "source for ground fault current"?

Thanks

 

[waross]

The "source" "supplies" the currents.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[rbulsara]

More hint: You need a completed circuit path back to the "source" for a current to flow. Draw a circuit of ground fault current path for an ungrounded system.

Rafiq Bulsara

http://www.srengineersct.com

 

[electricpete]

You may want to look at the zero sequence representation for various transformer connections.

=====================================
(2B)+(2B)' ?

 

[jghrist]

From what I understand, ground fault current is caused by an unintended path to ground (i.e. a line-to-ground fault).

True, but you need a source of zero-sequence current in addition to a line-to-ground fault for current to flow. The source might be the grounded wye windings of a delta-grd wye transformer.

Conversely, you might have a source of ground current, but without an unbalanced load or a line-to-ground fault, no current would flow from the source.

 

[Miguel Villarroel]

It refers about delta primary distribution system in comparing with wye system, i.e. if you need to transport a bulk to some distance cross country, ungrounded delta is a plus, but if you need to share out in a dense area grounded wye is a plus; of course if you use a wye grounded to transport a bulk faraway is unwanted, then it depends on the application that you're giving to the network...

If there was no electricity there would be no internet. Good point, don´t you?