CNC Mill Transformer

[Al Skierkiewicz]

Originally Posted by sparksandtabs

From our sponser we recieve a very very nice CNC mill and we have found out that the part they told us is the transformer is actually the battery backup. So we are in need of a transformer that will step up 208 to 440. I do not know what wattage it need to be but if you know anything about CNC mills you can probally figure it is wayy up there.

Sparks,
The part of which you are asking can be one of about a thousand different transformers. As stated before, a 208 to 440 is usually a three phase device. The motor is wound for three phase and that is how it turns and has power. In an industrial setting there is usually 208 and 440 outputs available through the main transformer for the building. Now granted, the transformer you seek only feeds one device, but these transformers are usually very large in size as they are intended to feed a 200-400 amp load or in many cases something even larger.
What we need to know is the "plate" rating. There should be a plate on the mill that states input voltage and input current, horespower, single phase or three phase, etc. Most often it is near the power input but can be on the motor itself. I have heard that some devices actually have a transformer inside which must be strapped by an electrician for the correct input voltage. The connections would be behind a plate with electrical warnings. The warnings are there for your protection. Don't attempt any electrical wiring on this device, leave it to a pro.