CNC Mill Transformer

[Al Skierkiewicz]

Originally Posted by sparksandtabs

-The power rating on the mill is 7kVA.
I am not trying to be negative when i say this but everything all of you are saying is common senseexcept for the delta/Y connection or whatever it was we do need to check on that.

I have called a couple places already and we are probaly gonna have a custom transformer made

You will not find a place to make you a custom transformer for the expense you think. A custom device is extremely expensive.
As to Y and Delta, they refer to the way the power is supplied by a transformer from the power company. A "Y" wound motor cannot be wired to a "delta" output transformer. Many installations use the "Y" which is four wires, three power and one neutral. There are stock transformers available that will do the 208/440 transformation in the 10kVA range that would be suitable. Even at that rating a transformer will run over $1000 and might be up to $2000 delivered and installed. Please contact a local electrical contractor who does these types of installations every day. They will give you a quote and other advice as needed. Hook up the wrong way and your $100K mill is nothing but a precision pile of metal.
Now to the discussion of the backup battery, it is possible that the mill runs on DC and that the battery provides power during a power failure that would otherwise damage a job in progress. It is still possible that the mill has taps internal that would allow it to run on several different voltage inputs. An electrician who specializes in this type of installation would be able to help.
Dude, take the advice and get someone who knows, please.