Originally Posted by
T-Man
When you change primary connections, you change rotation. So if the leads of the Floating Neutrals were hooked to the H1 bushings you would have one rotation, and if you installed the new bank with the floater hooked to the H2's. the second time the rotation would change.
If you vectored this out you would not only see the rotation change, you would also see the polarity of the three phase bank change also. (do not confuse this polarity change with an additive or subtractive transformer winding) I'm saying in one case the vector diagram of the delta triangle would be pointing up and in the other example the vector diagram would be pointing down.
So if A phase on the secondary was the upper most point of the triangle in example one, it would be the one pointing down in the second example. The left and right points would stay the same. Draw it out and you will see.