Phase Converters

[Troy Burritt]

What is everyones thoughts on phase converters? I only have 220V Single Phase at the 200 amp panel. I have 1/0 copper wire running 150' from the main meter base on the house on a amp breaker so my max is 150 amp. Anyway most of the larger tools I have on 220V single phase but I was looking at some additional machines that only come in 3 phase. What is everyones recommendations for type or brand of converters and is there another option? I heard of something else but cant remember where or what but it did the same basic thing but was more efficient or better on the machine. Also would I need one for each machine or is their a switching devise that would allow me to use one at a time. Its only me in the shop so I do not need to run many tools at once. Getting commercial power drop to the shop is not a route I would like to go but if that is recommended to be the best solution I can check into it further.
Thanks for any help you can offer.
Troy

[Kirk Poore]

An option is to roll your own:
I have a 10 hp idler motor that I start with a 1/4 hp pony motor. This uses a 60 amp 240V circuit off of a subpanel in my garage. In turn, this feeds a used 3 phase subpanel in my adjacent shop.

I start the pony motor, wait for the idler to spin up, then throw the switch on it, and finally turn off the pony motor and let it freewheel on the belt. It would be "better" if I balanced the voltages of each phase with run capacitors, but all are within about 5% of 240V right now anyway so other than excess hum everything is working right.

There is much discussion of phase converters at OWWM.org and Practical Machinist.

Kirk

[Scott T Smith]

Troy, if you search the forums you will find quite a few posts re phase converters.

For whole shop, most folks use a rotary phase converter. For individual machines (with low HP motors), many folks use a variable frequency drive instead. Static converters typically do not allow the motor to develop to the rated HP, and most woodworkers avoid them.

Brands that have a good reputation in the metal working machine shop world include Phase-a-matic and ARCO (Roto-phase brand).

Many SMC posters have indicated satisfaction with converters by American Rotary.

When searching for a used converter, you may notice ads for "CNC" rated converters. These units maintain a closer balance between phases - typically 2% for a CNC versus 8-10% or greater for a non-CNC model.

CNC rated converters are typically built on motors that are one to two sizes larger than standard converters too, and hence cost much more. They are probably not required for most woodworking machinery.

Hope this helps; you'll find a lot of info in the archives.

[Bruce Page]

Troy, you will get a lot of replies espousing the well earned virtues of the VFD & Rotary phase converters. There’s also the inexpensive & easy to install static converter to consider. I have been running my 2hp milling machine & a 5hp engine lathe off of a single PAM-600HD Phase-A-Matic static phase converter for over 15 years without a single problem. I have even run both the lathe & mill together without issue (just don’t start them up together). The downside of the static converter is a small loss percentage of actual HP output but have never been able to tell any difference between my mill and one running on true 3 ph power.
I think I paid ~$130 for mine. The same unit sells for $198 today.

[Travis Porter]

I currently have a Kay rotary phase converter, but I dream about getting a digital phase converter. One day....

[Rick Christopherson]

An option is to roll your own:
I have a 10 hp idler motor that I start with a 1/4 hp pony motor.

Pony motor converters are about the second worst converter you can use. They are only one step above a non-balanced store-bought static converter. If you added the balancing capacitors, you would have a proper rotary converter, but without them, all you have is a motor starter that takes two motors to work. You would have the same effect if you connected your pony motor to the tool to get the tool to start turning. Your idler motor is not producing appreciable power output on the third leg.

Troy, you will get a lot of replies espousing the well earned virtues of the VFD & Rotary phase converters. There’s also the inexpensive & easy to install static converter to consider. I have been running my 2hp milling machine & a 5hp engine lathe off of a single PAM-600HD Phase-A-Matic static phase converter for over 15 years without a single problem.

The Pony Motor converter is the second worst converter to use, but the unbalanced static converter is the worst.

These store-bought converters are nothing more than motor starters that get the motor spinning, and then they shut off completely, which leaves your motor to run from single-phase power.

Both of the options (pony and unbalanced-static) leave the user with a false sense of security that they are doing something healthy for the motor. Just because you can get the motor to spin does not mean it is healthy for the motor.

A balanced static converter is almost as efficient as a rotary converter, but you will not find these (at least not normally) for sale by commercial vendors. If a static converter is rated for a broad range of motors, then it is an Absolute sign that it is not balanced, and is nothing more than a motor starter; not a converter.

The worst thing you can do with a 3-phase motor is drop a phase, yet these pseudo phase converters do just that very thing.

[Chip Lindley]

I'm a Rotary Phase Converter user from wayy back in the '80s. I've run many bargain 3ph. machines up to 5hp. with an Arco Model A, 5hp RPC. It will run a 5hp. shaper and 3hp. DC simultaneously. The Model A was itself a bargain, bought at auction for a paltry sum compared to NEW.

For a price, modern technology provides us with state-of-the-art Variable Frequency Drives and Digital Phase Converters (both solid state/no moving parts) DPC's are the equivalent of an RPC, where more than one machine can be run at the same time. (up to the Amp rating of the converter) VFD's are not nearly as convenient. Each 3ph. machine must be matched to it's own specifically rated VFD. These get expensive for motors above 2hp. In addition, VFDs with 230v input (house current) are not as available used as the more common 460v units.

Static converters have been mentioned. These are more economical and provide 2/3 the rated hp. of a machine's motor. A 5hp machine putting out 3.33hp may still be quite usable in a home shop.

But, IMO, rotary phase converters provide the best bang for the buck for a shop with several 3ph. machines of varying hp. They are the only alternative for many who need to run a big machine (20hp. wide belt sander) off of 230v. house current. RPCs seem to get cheaper now in the used market, as many convert to electronic technology. It's hard to hurt an industrial RPC. My ARCO is built like a tank.

[Jeff Heath]

I will second the choice of American Rotary. They are in Milwaukee, Wisconsin. I bought a 7.5 hp unit from them. They send very good wiring instructions with the unit. 2 hours of setting it up, including a trip to the hardware store for wire connectors, and I was in business. I ran a 3 hp jointer and a 5 hp table saw with it. Starts with a push of a button, and I hang it on the wall in my shop. I bought it on ebay.

Jeff

[Brian Ross]

I have been running 20 hp unit from American Rotary for the past 4 years. It runs a 10 hp slider and 5 hp DC. I just purchased a second 20 hp unit to twin with the first one as I have a wide belt sander that requires the extra power. The service and tech support from American rotary is second to none. 24/7 tech support is real. My first unit is connected to a 60 amp breaker on a 100 amp sub panel.
My problem has been finding an electrician that believes in Phase converters. They both have taken a lot of coaching by AR.

Brian

[Mark Bosse]

Almost every machine I have seen at or below 10 hp can be easily changed from 3p to 1p.

A whole lot cheaper.

[Bill Leonard]

Almost every machine I have seen at or below 10 hp can be easily changed from 3p to 1p.

A whole lot cheaper.

Mark,
How is this done? I recently took a Baldor 5hp 3ph into the local electric motor repair shop with a request to convert it to 1ph. Was told that it was not economically feasible. I went with a Phase-a Matic converter instead which obviously reduces the 5hp to ~3.3. I would much rather have the full 5hp with 1ph.

[Bill Leonard]

Bump
I'm really curious if there is a way to go from 3ph to 1ph economically, or am I missing something in my interpretation?

[Alan Bienlein]

Bump
I'm really curious if there is a way to go from 3ph to 1ph economically, or am I missing something in my interpretation?

Depending on the machine change the motor. Now if you think you might be purchasing more used eguipment that could be three phase then you would be better off buying or making a phase convertor.

[David Freed]

I used American Rotary before I closed my shop. If I ever need to run 3 phase again it will be with American Rotary.

[Rick Christopherson]

Mark,
How is this done? I recently took a Baldor 5hp 3ph into the local electric motor repair shop with a request to convert it to 1ph. Was told that it was not economically feasible. I went with a Phase-a Matic converter instead which obviously reduces the 5hp to ~3.3. I would much rather have the full 5hp with 1ph.

No, the previous answer was ad-hoc and not really true for any motor in the realm of a home workshop. You cannot convert the motor for a reasonable cost.