Fault current to Generator Neutral or only to Transformer Neutral

[NickParker]

At LV, a ground fault happens. At Transformer Neutral, fault current will undoubtedly flow. Flow of fault current at the neutral of the generator?

 

[davidbeach]

If there's a delta winding on the generator side of the transformer then no ground fault current to the generator neutral.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[che12345]

Dear Mr. NickParker (Electrical)(OP)11 Jan 23 18:09
"....At LV, a ground fault happens. At Transformer Neutral, fault current will undoubtedly flow. Flow of fault current at the neutral of the generator? "
A transformer is an induction equipment. There is NO solid/physical electrical connection between the primary winding and the secondary.
Therefore, any LV SC current would flow through the secondary start winding Neutral. If the secondary winding is Delta, [no current flow when only one line is shorted the earth]. No current flow to the Generator neutral in any case.
Che Kuan Yau (Singapore)

 

[waross]

A single phase short to ground on a wye secondary will cause a fault current to flow in the corresponding delta phase.
That current will cause a voltage drop in the corresponding delta winding.
The other two windings form an open delta with the same phase angle and characteristics as the shorted winding.
When one transformer in a delta bank is removed, the remaining two transformers form an open delta which develops a virtual transformer with the same characteristics as the transformer that was removed.
So the same current value in each of the three windings.
50% of the current is supplied by the inphase winding and 50% of the current is supplied by the open delta windings.
The open delta windings are running at 50% PF, one leading and one lagging, so the arithmetic works out.
No neutral current on the generator.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[waross]

That is why I like to see a generator looking into a delta transformer bank.
Single phase loads on the secondary are more evenly distributed on the generator windings.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!