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)