Here's two shots of Delta connected transformers from the Railroad Museum, which are used to power their Trolleys and stuff.
They are definitely Circa 1920-30, and fit in with the era[s] just fine!
This config. uses two 7.5 KVA pots for the outers, and one 10 KVA in the center.
This is a 4 wire closed Delta.
This config. uses two 10 KVA pots for the outers, and one 25 KVA in the center.
This is also a 4 wire closed Delta.
Hope these images can be viewed easilly by all.
Once again - check the "Tech. Ref." area for some shots of the Diesel motor in a locomotive, plus some of Trackside Control Equipment.