I would not be one that would say the size of the transformer equals the load. Another item missing is the size of the conductors on the primary of the first transformer.
As for the derating of the transformer to 80%, I can't find nay evidence that transformers are to be derated.
What's this about Wye/Delta Wye/Wye. It's a single phase transformer not a 3 phase.
Okay guys/gals, lay it on me
