I have a customer who has 240 volt, 3 phase delta service and wants to operate a 480 volt, 3phase machine. He picked up a 480 delta to 208 wye transformer hoping to use it for this application. The kva is correct and I have wired step down transformers backwards to step up the voltage but with a 240 input instead of 208 the voltage will be high. I was thinking about adjusting the taps to as low as I can (I think 5%) and maybe using buck/boost transformers to step it down to 480 volt. Any one ever connected a wye transformer to delta? Anyone had any experience with this? Any thoughts? Thanks!