"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