I looked at an automotive shop job today. Only this evening did I realize that the single-phase compressor (7.5hp) and the TIG machine want *230V*. The service is 120/208V 3-phase.

I know most of the options (I think)... what are the least expensive workarounds for this? Or what is the typical fix?

For the compressor buck boost transformer.Does the TIG welder have taps to change voltage,as a lot of welding equipment is designed for multi voltage use,just change tap to desired voltage.

Just a thought, it might be cheaper and or better to replace the TIG welder with a 3-phase 208 version, if the existing one doesn't have a 208 tap.

I have to double check... it all just dawned on me this evening. The welder is a Miller Maxstar 150. Judging from the online owner's manual it appears to auto-sense between 115 and 230V.

OTOH, the mig machine has both a 200V and 230V rating, so its fine.

As NORCAL suggeste, Buck & Boost X-frmr.
and check the tabs on the welder.

http://acmepowerdist.com/products.asp?PAGE=/selguide/index.aspx

Use the selection guide on the left.

Here is a link from Miller: http://www.millerwelds.com/products/tig/maxstar_150_sth/ This is one of 2 Maxstar models listed but this is copy and paste from same link:"Auto-Line™ Power Management technology circuitry automatically connects to 115 - 230 VAC, single-phase power without removing the cover to relink the power source."I did not read anything stating a 208V rating all data refered to operating @ 115 or 230V .

I'll give Miller's tech line a call on Monday. One local retailer said 208V is fine. Not that I'm going to take their word for it

Based on the price for a 208/230V-20A buck/boost for the welder ($600 ) I predict it will be cheaper to change the motor on the compressor if Devair says no-go.

From the miller web:

Auto line power management tecnoligy circuitry automatically connects to 115 - 230 VAC, single-phase power without removing the cover to relink the power source.


Wonder what type of plug it has.

This tig is a newer type that only weighs 13 pounds and my guess is more capacitors and electronics then transformers.
Other miller units had:
Universal Location Flexibility
Permits direct connection to almost any type of input power—115-575 VAC (varies by product), 1- or 3-phase, 50 or 60 Hz

"Wonder what type of plug it has."

You install your own......

I think the Multi-Voltage Plug(tm) setup on this one is rather innovative:

http://www.millerwelds.com/products/mig/millermatic_passport/index.php

IGBTs , insulated gate bipolar transistors, are changing everything. This machine has the internal intelligence to compensate for power line voltage and has the intelligence to stabilize the arc at the load end.

The Miller phone # seems to be only for getting product info - the same stuff you can d/l from their website.

I called two different local Miller dealers and both assured me the Maxstar 150 would run correctly on 208V.

My customer had only bought the compressor a month ago - and it was still attached to the shipping pallet. The dealer was kind enough to allow him to exchange it for a 3-phase unit.