Serving distribution with tertiary winding
Serving distribution with tertiary winding
(OP)
We are looking at using our tertiary windings to serve our 13.8 kV dsitribution system. Presently our tertiary's hardly do anything--they serve the station load and provide protection with their polarizing currents, etc.
Typically we use two 250 MVA 230/115 kV auto-transformers with the tertiary rating of 30 MVA and up.
I know we will need a grounding transformer, although I admit I don't have a good understanding for the need unless it is related to a grounded delta placing full line to line voltages on the distribution as measured line to ground.
Anyway, looking for some thoughts on this--I searched here and read up on this topic from its 2005 posting.
What I am really interested in is practical experience and perhaps a one-line drawing or two that show a system being fed by a tertiary winding.
We would like to add some distribution to existing 230/115 kV stations with minimal expense...is using the teritary a good idea or is it a waste of time?
Thanks!
Typically we use two 250 MVA 230/115 kV auto-transformers with the tertiary rating of 30 MVA and up.
I know we will need a grounding transformer, although I admit I don't have a good understanding for the need unless it is related to a grounded delta placing full line to line voltages on the distribution as measured line to ground.
Anyway, looking for some thoughts on this--I searched here and read up on this topic from its 2005 posting.
What I am really interested in is practical experience and perhaps a one-line drawing or two that show a system being fed by a tertiary winding.
We would like to add some distribution to existing 230/115 kV stations with minimal expense...is using the teritary a good idea or is it a waste of time?
Thanks!






RE: Serving distribution with tertiary winding
RE: Serving distribution with tertiary winding
Thanks for the insight...
RE: Serving distribution with tertiary winding
RE: Serving distribution with tertiary winding
I have seen the tertiary windings used for distribution inside power plants where the exposure should (theoretically) be less.
It's a tradeoff between purchasing transformer capacity, transformer losses, and system reliability.
Grounding transformer would be needed since the delta tertiary is ungrounded.
"The more the universe seems comprehensible, the more it also seems pointless." -- Steven Weinberg
RE: Serving distribution with tertiary winding
I recall seeing tertiary's used for distribution in "3rd world" countries--obviously the economics outweighed any reliability concerns in that situation.
So, to recap what I have learned the issue is that you run the chance of allowing the transformer protection to "see" distribution faults which could lead to loss of the transformer (i.e. breakers opening) for a distribution...is this correct?
RE: Serving distribution with tertiary winding