Hi,

I need some guidance/education on control transformers. Here is what I'm looking to do:
I have 3phase lathe I'm converting to CNC. 3phase in is high leg delta 240v. I'm using this for the spindle and drives, which works great so far. In addition I need single phase 120v to power computer, 24v power supply, 5v power supply and misc relays.

The 3 phase in does not include a neutral wire, just a ground. I do not plan on pulling in a separate neutral. I would like to buy a control transformer that provides 120v with a neutral or use the existing transformer in the machine if possible.
I assume I can wire a control transformer to my 2 legs that are not the high leg, which gets me 240v single phase in on the input. The output will be stepped down to 120 if wired for 2:1.
How is the neutral generated?
The reason I ask is that the current old transformer in the machine gives me 120 when I check the output taps, but each output to ground gives me 80v and 40v. Isn't neutral and ground supposed to be at the same potential?
Unfortunately I have no info on this transformer, its off a Hardinge AHC lathe.
Any suggestions welcome.

Thanks
-OT