Need Help with Phase Converter Purchase

I am just getting back into machining after being out of it for the last 20 years and have some questions about phase converters, hoping someone can get me in the right direction. I purchased a Jet 1440W-3 but only have single phase power in my shop. I have a 100amp panel to run my shop, currently for a 80 gallon compressor, mig and tig welder, my lathe, soon to purchase 3 phase mill (JTM-4vs) and a ductless AC unit, both the lathe and mill are 3hp. The questions I have are, what size phase converter do I need? I am looking to purchase a used converter, will the one below work? I can pick it up for about $400.00. I don't plan on running the machines at the same time but I could have the compressor and the AC running at the same time in the shop with the mill or lathe. Any help with this would be greatly appreciated.

Ta76455 said:

I can pick it up for about $400.00.

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A Rotary Phase Converter with a 10 HP idler should do yah, a "static" converter, not.

Among other things, no sooner is an air compressor put into the mix, than it wants re-engineered as to unloaders and delayed starts and staggered starts and.. wotever nuisance of the week.

Easier to just use a larger RPC at the outset that is comfortable with the "whenever" starting loads whilst other machines are running and fageddaboudit. The larger 10 HP idler won't waste enough more power than a 5 HP idler to worry about.

The maker of the one you are looking at is local-enough and has a website:

Phase Convertors

See if your label even matches to their current product line. I cannot see it well enough to be sure, but it doesn't seem so.

Suggest you call them and see how old this one is. Start and run capacitors, relay contacts, ,etc. might be a bit... tired. They may offer a refurb service.

If you will be using one at a time, then the minimum size converter is probably a 5 HP.

A 10 HP would allow some serious upgrades in the future, and definitely would not have problems running your loads.

The larger the converter, the more current it will pull even when on idle. While the current will be at a low power factor, and is not much of an issue as far as "power", it does add up at the circuit breaker. You might prefer a smaller size more in line with your loads, considering that the air compressor and A/C may run at the same time.

Ta76455 said:

I am looking to purchase a used converter, will the one below work? I can pick it up for about $400.00.

Click to expand...

Too much for your needs. Five Hp size is better suited.
If you shopped around a little for parts you could build a simple RPC for less than half of that $400.

For what it's worth I am managing to run a 7.5hp RPC on a 10 awg feed, through a 30 amp breaker. Not what I would aim for, and I didn't even expect it to work, but it is what I was given and I had nothing to lose by trying. Doesn't even flicker the lights when starting the RPC. Some day I will get much better power to the equipment, but that's the power I currently have, it's only for my personal use, and nothing is going amiss. I haven't loaded it beyond about 3hp in load, and I am sure that things would get adversely interesting if I started putting more of a load on it. I mention this just to give you the sense that the RPC that you are looking at should run with ease on a 100 amp supply.

Wait. Is the mini-split AC system going to run off the converter as well?

Waitaminnit...

Did I get this right- out of all that you've listed, are only the mill and lathe 3 phase?

If so, don't get a converter. Put VFDs on 'em. You'll get double your money's worth- single phase op, and variable speed spindles with dynamic braking.

One thing escapes me- why, if you've been 'out of machining' for 20 years, why would you jump back in by buying JET?