I have acquired a big(4kva) three phase transformer. the primary is a star
configuration and the secondary a single voltage delta. it is wound on three
limbs of an iron core.
I can separate each of the primary and secondary windings to give three
pairs each wound on a limb of the core.
I suspect this is perfectly normal - but I've never looked at one before.
Playing (on paper) with the turns ratios, my application of voltage step up
from 240 to 415 would be satisified by putting each primary in series across
the mains and putting each secondary in series. each winding would get less
voltage than originally designed thus not exceeding the original turns per
volt.

Provided I connect each winding start to finish in the right order, is there
anything to stop me using it in this way?

I've done a bit of a search on three phase transformers but not
surprisingly, I've not found anything about using them for single phase
applications.

I'd be grateful for any info.

regards

Bob

"why is is that I always want to use things for purposes that they were not
designed for??"

"Bob Minchin" wrote in
message

I have acquired a big(4kva) three phase transformer. the
primary is a star configuration and the secondary a
single voltage delta. it is wound on three limbs of an
iron core.

Are you sure..? From my (admittedly limited and a long time ago)
experience, it's usually the secondary that's wired in star formation so
you can get three single phases plus a neutral for distribution from a
high voltage source (also usually 3 phase).

Can't help with the rest I',m afraid, my electrical engineering college
days are long behind me..!

73 Ivor G6URP

"Ivor Jones" wrote in message
...
"Bob Minchin" wrote in
message

I have acquired a big(4kva) three phase transformer. the
primary is a star configuration and the secondary a
single voltage delta. it is wound on three limbs of an
iron core.

Are you sure..? From my (admittedly limited and a long time ago)
experience, it's usually the secondary that's wired in star formation so
you can get three single phases plus a neutral for distribution from a
high voltage source (also usually 3 phase).

Can't help with the rest I',m afraid, my electrical engineering college
days are long behind me..!

73 Ivor G6URP


Hi Ivor,

I think it must be a special.
The secondary is marked 170v delta
and the primary is 0,200,208,380,415,480 star.

I'll test my application out at low voltage first just in case i let the
smoke out!

regards

Bob

Ivor Jones wrote:
"Bob Minchin" wrote in
message

I have acquired a big(4kva) three phase transformer. the
primary is a star configuration and the secondary a
single voltage delta. it is wound on three limbs of an
iron core.

Are you sure..? From my (admittedly limited and a long time ago)
experience, it's usually the secondary that's wired in star formation so
you can get three single phases plus a neutral for distribution from a
high voltage source (also usually 3 phase).

Can't help with the rest I',m afraid, my electrical engineering college
days are long behind me..!

73 Ivor G6URP

Ivor,

In the U.S., it's common to have lighting circuits connected with Delta
wiring, and the "Wye" input is consistent with a commercial mains Wye
setup.

Using Delta wiring in the lighting plant saves a lot on wiring and
equipment: the usual practice is to ground one "corner" of the Delta
transformer, thus obviating the need for a separate ground wire as in
Wye-connected circuits. In addition, an Engineer can specify "Delta
breakers", which are arranged to fuse only the two "hot" legs of the
Delta feed: since one leg is grounded, no breaker is required, thus
saving 1/3 of the cost in equipment.

FWIW.

Bill

--
73,

Bill W1AC

(Remove "73" and change top level domain for direct replies)