Need advice on purchasing VFD for running 3 phase equipment on single phase power

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Forum topic by SweetTea posted 12-22-2016 10:56 AM 2450 views 0 times favorited 5 replies Add to Favorites Watch
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371 posts in 856 days

12-22-2016 10:56 AM

So I recently came accross a local guy that has a Powermatic PM-66 table saw (needs restoring) and a 3HP shaper table that I would like to purchase and use in my shop.The only problem is these machines are 3 phase and my shop only has single phase power. So I would like to purchase a VFD to run these.

I know absolutely nothing about 3 phase power or VFD’s so I need some suggestions on which ones to get. I have no problem buying a used one. I am of course on a budget too. If the VFD’s necessary for this are too much ($) then I will forgo the PM-66 and just get the 3HP shaper.

Can you guys help me figure out which VFD’s would best suit my needs?

5 replies so far

View Marshall1's profile


8 posts in 740 days

#1 posted 12-22-2016 11:50 AM

I am not an authority on this subject but familiar with the application of a VFD for phase conversion. I am involved in the pump industry and this is common practice to convert single-phase power to three-phase. Best to simply go to your local electrical supply company and talk with them. You will need the details of the motor nameplates (minimum: Horsepower, Full Load Amps (FLA), Voltage, RPM, Service Factor, enclosure type) for them to accurately size the drive. A rule of thumb is that you will need a drive double the Hp of the load item. So, you are looking at a VFD that can handle 6 Hp. Couple of other suggestions, keep it simple. Ask for a basic drive with touch pad programming vs one that requires software of a connection to a laptop to program. Your start loads will be minimal/low This is the load on the motor (and drive) when the equipment first starts. Since you do not have a large mass or heavy starting components, you do not need a drive capable of handling heavy start loads. As them also if there is any special enclosure needed for the VFD. Hope this helps.

View Nubsnstubs's profile


1419 posts in 1927 days

#2 posted 12-22-2016 02:50 PM

I’m not an authority either, but if you are the only person in your shop using the equipment, and have 2 pieces rated at 3 hp each, you don’t need a 6 hp vfd because you can only operate one piece at a time. On the output of the VFD, attach a duplex plug, and plug in both machines. Of course, since you’re a one man shop, you can only use one at a time.

I’m using a 3 hp rated vfd on a 2 hp motor, and was thinking about getting a DC with a 1 hp motor, but I think there is a problem with running 2 pieces at the same time on one VFD. ............... Jerry (in Tucson)

-- Jerry (in Tucson)

View Loren's profile


10477 posts in 3844 days

#3 posted 12-22-2016 03:12 PM

You’ll invest less money building a rotary
converter than buying 2 VFDs.

You can get by with a 5hp one with a panel
by Phase-Craft and a 5hp 3 phase motor
which should cost about $100 for the motor.

Anyway, I had a VFD briefly I ran a 1hp 3-phase
machine on. You should be aware that they
can’t be expected to last for years and years
and they are said to be a bit hard on 3 phase
motors. Additionally, the price of VFD units
does go up once you get above a couple
of HP in phase conversion capacity. My VFD
had a fan in it and slots so it wasn’t, imo,
ideally suited to a woodworking environment

I got started with 1 3-phase machine and the
VFD but within a month or 2 I bought another
3-phase machine at auction and took a serious
look at building a rotary converter… or rather,
hooking one up, because there’s not much to
it when using a pre-wired phase converter panel.

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7037 posts in 2395 days

#4 posted 12-23-2016 01:03 AM

About $200 per machine… and if you mount on the machine, then it basically becomes 240Vac plug-n-play as if it just had a single phase motor. IMO, the long list of benefits of a VFD far outweigh what you can get from an RPC, and I wouldn’t even consider a static phase converter. You can get no-name drives off the bay, but I prefer the Teco (Westinghouse) ones from a regional distributor where you can get support if needed. For a sensorless vector drive (recommended, particularly for the shaper), the L510-203 is a good choice, or for slightly less, a V/Hz drive like the FM50-203 will be fine. If your FLA is less, you might be able to go with one of the 202 drives instead.


-- Brad in FL - In Dog I trust... everything else is questionable

View unbob's profile


810 posts in 2100 days

#5 posted 12-23-2016 03:34 AM

I have been running 3phase equipment for decades with a simple put together rotary converter. I am looking to add a VFD to my shaper so as to be able to trim the speed, and use the other control features. For many reasons, its best to use one VFD for one machine.

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