Need Help!- Incoming Power Questions

[vebers]

I am not sure this is the right thread but it was a good as I could find. I have a CNC Mill that is rated for 230VAC 3 phase voltage to be withine 94% to 106% of line voltage. My service runs about 245 VAC between legs. The documentation also states that the 3 phase supply shall be balanced to Neut or Grd within the voltage tolerance. Again my service is the wild leg type of three phase. It measures rougly 125v to ground on two legs and around 200v to gound on the third. What do I need to do about this? I am thinking transformer but I have no idea what to get. Any help would be welcome.

[Al_The_Man]

Much depends on what the primary input is mounted in the mill, IOW after the three phase enters the enclosure, is there a 3 phase transformer that feeds everything?
If the drives and motors are fed from 3 phase, they are not so critical about 3 phase balance, but it is not good to have higher voltage than recommended but any controller that is fed from 100~110 voltage can be critical, this is usually the easiest to regulate, as a small 1ph buck/boost transformer can be used for this.
It is a case of assessing what you need depending on the type of motors/drives etc.
Straight 3 phase motors are the most tolerant.
BTW the 245v is only a fraction above 106%.
Al.

[vebers]

Thanks for your reply. This machine is a Cincinati sabre 750 with acromatic 850 control. I bought this machine used and have just got it up and running when the spindle drive started to error fanuc code AL-12 DC over current. My first thought was my hot voltage. I hadn't read about the balanced legs yet. Once I get the drive fixed I want to be sure my ducks are in a row.

As far as I can tell there is no transformer inside the cabnit between the incoming power and the servo drive units for the axis or the spindle.

[vebers]

Looking at the schematic I see a auto-transformer as an option, but I do not think it is installed on this machine. So what do you think is my power problem related to the blown transistor, or did I just have great luck in buying a used machine. lol

[Al_The_Man]

Alarm 12 on a Fanuc spindle is never good.
It usually means shorted IGBT transistors, which to buy individually are expensive.
But often, it can be the IGBT drive board, or the board gets damaged when the IGBT short occurs, either way, if this is the case, replacing the IGBT's can get really expensive if they blow right away because of trigger board damage also.
Sometimes it pays to bite the bullet and send it in for repair.
Al.