Wye delta transformers are problematic UNLESS you float the wye point. Unbalanced voltages will cause severe overheating. Phase loss on the supply may cause overloading. Float the primary star point and the problems go away. You may have voltage transients with switching operations, but overall, floating the wye point is the way to go.
respectfully.
IM SORRY FOR SUCH A POOR EXPLANATION ,OUR INTENTION IS TO USE THIS 500 KVA XMR TO STEP UP 1200 AMPS AT 120/208 VOLTS TO 480 AT A DISTANCE OF 700 FEET AND THEN STEP IT DOWN TO 120 /208 ONE MORE TIME USING ANOTHER XMR WITH THE SPECS BUT SINCE THERE ARE BOTH THE SAME A WAS THINKING IN THE POSSIBILITY OF REVERSING ONE SO WE DONT HAVE TO BY A NEW ONE
THANK YOU GUYS IN ADVANCE
You don't have to change the taps. but if I was doing this project I would probably set the taps so that the no load voltage was a little high, so as to compensate for the voltage drops in the two transformers.
respectfully
OK, to answer your original question, you can use it as you mentioned, by reversing feeding one of them.
You may choose to leave the 480V delta to delta connection ungrounded and monitor it for a ground fault or corner ground the delta side at the source end.
Waross mentioned setting the taps for the no-load voltage a little high. This can work provided the load variation is not too great or the total impedance is not too great. If there is much variation in load, I would be concerned about voltage regulation.
I have done this type of installation before without any problems.
If you are going to purchase the transformers, consider going with 600V instead of 480V. This way you will have less of a voltage drop. It is a little cleaner than messing with the taps.
