The numbers are interesting. Remember that WebSparky's 95-year-old transformer in Cleveland showing a 6,600/11,400V primary on its nameplate? With external bushings {connections} and jumpers, it could be served with 6.6kV with primary in delta and 11.4kV connected in wye.
https://www.electrical-contractor.net/ubb/Forum4/HTML/000256.html
