We have a 3 phase 208Y120 feed and need to boost to power a single phase 240 unit. I personally have not seen the unit but the guys tell me it's a 'Big Screen' display (scoreboard). The question is: can we use a single BB xfmr and follow the basic 208-240 diagram which basically puts everything in series or do we need 3 BB xfmrs and simply use only 2 of the outputs? My concern is that the 208Y will feed the BB from 2 diff xfmrs. Will it cause a phase shift and cook my (single) BB xfmr?
I don't see a problem but I am just guessing. All of our equipment would run 208 or 240, either by tapping the input or just that it had a wide enough mouth. I think it will be seen as just another 1p L/L load.
The rest of the story .... Here's what I didn't know at original post time: They did cook the BB xfmr (that's why the development of the question about potential for a phase shift that I posted). Seems as tho the board needed 2 hots, neutral and ground because it's basically nothing but a big multiwire ckt and needs the neutral. It came from factory with these 4 tails attached and labeled. The sign guy on top of the ladder told our guy 240 volts ... period. No mention of the neutral and our guy didn't go up and look or question it (strike one). So they hooked up a BB, did not pass the system neutral through (strike two) and fused the primary using the proper fuse size for the secondary (strike three). Guess what smoked. We got lucky it was the xfmr, not the board. Thanks for the help and we got the guys straight. Nice video board.