From what I've heard, this used to be quite a common method of stepping up the voltage from 12 KV in the towns to 25 KV when urban feeders were extended into rural areas. This is a single phase example of one that's actually run to step down. In this case, the main line was redone to 25 KV (14.4), but they decided to leave this tap at 12 (7.2) requiring the addition of this bank. The high side on the left goes through the first transformer stepping it down to 347 and then to the 2nd transformer stepping it up to the desired 12 KV.