I've never seen one like that before, but it looks like it's actually four windings set up to be configurable for a whole mess of possible voltages.
As it stands now it looks like you've got two parallel wyes in the low-voltage compartment. The horizontal jumpers running between all the top bushings would be your neutral point and the vertical jumpers connect the phases of the two wyes in parallel.
I can't follow what's going on in the high voltage side well enough to say for sure, but it looks like it's set up for paralleled deltas.
Can you grab a nameplate photo?
