can i use these to build 240-240 isolation transformer ?
i cant find a schematic online they came from a apc
DLA3000RMT2U
it is a 208 input ,should be able to use 240?

 

Two identical transformers wired back-to-back would make an isolation transformer but:
You will get less voltage out than you put in - how much depends on the transformers.
Putting 230V on a 208V transformer is not without risk. If the core saturates it will draw lots of current so if you're trying this make sure you have the lowest fuse you can to avoid damage.

 

after poking around in the unit some more i am not so sure about the 208,,the input on the inside of the unit says 120/240 and it is a black a white and a green ground that to me normally says 120
its the output of the ups that says 208,,but i think the specs for the unit did say 208 input but nothing is looking like 3phase,i have 4 of these transformers if i have to use the 4 to get a good strong stable isolation i dont mind because it is intended for a plasma cutter.i just need to figure the wiring

 

just tested one of them
12vac in on sec
white and black = 166
white and yellow = 193
white and blue = 212
up to 13vac in on sec i get 240 on white and blue

 

can i use these to build 240-240 isolation transformer ?
i cant find a schematic online they came from a apc
DLA3000RMT2U
it is a 208 input ,should be able to use 240?

just tested one of them
12vac in on sec
white and black = 166
white and yellow = 193
white and blue = 212
up to 13vac in on sec i get 240 on white and blue