Connecting the single phase 480V across two primary windings will result in in the windings being in parallel this will mean each winding sees 50% of the input voltage so the output will also be only 50%.
Connect to two primary windings, 480V each.
Originally Posted by jim dungar
If you connect two of the windings in parallel (i.e. jumper C->B, and then feed 480V to A and B/C) you will get about 120V from two of the secondary windings. However, because you have changed the intended relationship between the primary H1-H2-H3 and X1-X2-X3 terminals the (2) resultant 120V outputs will not combine to create 240V.
Please examine the following diagram carefully...
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