VMC transformer woes

This morning my brand new Milltronics VM16 was delivered, very exciting. Rigging was no problem, machine looks great, fits well into my small shop.

But!

I start looking over things in preparation to wire it up, stickers everywhere say 240V max (machine is rated 208-240). I measure my line voltage, 243V. My shop is in a ex-factory thats now largely storage so I'm guessing voltages are a bit high since barely any power is being used nowadays.

Manufacturer says no good, get a transformer. Service guy says the same. I find it hard to believe that an overvoltage that small would cause a problem but I'm certainly not confident enough to risk it on a brand new machine.

I hate being cheap but the fact is that I'm a little low on cash after tooling this up and spending another couple thousand on a new bucking transformer isn't so appealing right now. Other thing is I only plan to occupy this space for another 18 months so whatever I buy would likely be useless afterwards.

So, have any of you had similar issues? Does anybody know of a place to get used transformers? (15KVA in particular) Do I really have to suck it up and buy a new one?

I really appreciate any replies, I'm a young guy trying to run a small shop alone and sometimes it's a bit much to handle by myself. Thanks in advance.

I cant believe the manufacturer would tell you that. Did they offer to sell you the transformer too?

Apparently the machine is nominally 220V, the margin extends down to 208V and up to 240V. There has got to be a limit somewhere and of course they can't guarantee nothing bad will happen if it's exceeded. I would imagine running it as is would void my warranty judging from the sheer number of warning stickers.

I just measured the voltage at the input of my 2001 Milltronics ML20 lathe - 244 to 247 volts between legs. We've had no trouble with the drive or control, extept for peripheral stuff like limit switches. HOWEVER - I'm not responsible if it doesn't work for you!

I needed a transformer for a 440 volt machine, I found a used one from a local electrical service company that does a lot of commercial work, maybe you can do the same. Paid $500 for a 30 KVA unit.

EMSCO (763) 571-9005

used transformers and all other elec.

much history
great vendor

Thanks very much for the input.

After initially freaking out and posting I did some further research and discovered how buck/boost transformers work with three phase power. They're not like regular transformers at all!

2 750VA units, <$400, problem solved.

Only about 10 more issues to figure out before I'm really up and running.

Thanks again.

750VA transformer? Just how *small* of a VMC did you get ?

You started wanting a 20HP sized unit and settled for 2HP? What did I miss?

Get some buck and boost tranformers. They are auto-transformers with a high current, low voltage secondary intended to buck (lower) or boost) the incoming power by a certain amount. They come with a wiring diagram and connecting it into the ciruit to lower your incoming voltge to a nice safe number is quite simple.

You don't have to traansform and isolate the full load unless there's a need to.

I would call the power company first. Back about a decade ago I used to install One-Hour Photo machines and they had a tight voltage requirement. At one store in South Florida I found an under voltage issue on the stores line. Called the Power Company and they can out and checked the distribution transformer outside the store that supplied the strip mall. It was ok, then he check at one of the substations and found that they had a faulty piece of equipment that they were not aware of. It was resolved within a half day. Cost Zero, other than my time on the clock waiting for them to fix it. Good luck with it.

Happy New Year to all

Frank

750VA transformer? Just how *small* of a VMC did you get ?

Click to expand...

Maybe thinking 2-7.5kv xfmrs. Maybe meant to write
2 7500VA units, <$400, problem solved. JRouche

Sheys figured it out! The size of a buck boost transformer is related to the size of the voltage change required times the total current. Or in this case if he found a transformer that would reduce the voltage 10%, the transformer would only have to supply 10% of the total power.

I am not sure what he found for transformers but he only needed about 2% drop in voltage to meet the specs so theortically a much smaller transformer than he even stated could have been used (if one with that small of a voltage change exists).

Good luck with that new machine!

Thanks Forrest and Bill, that's pretty much what I ran across. With a 5% decrease in voltage a 750VA transformer is more than sufficient. It's nice to finally understand what an autotransformer is. (no isolation!)

Now on to figuring out how to modify post processors. Hopefully no more surprises.