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

4.7K views 5 replies 6 participants last post by  unbob  
#1 · (Edited by Moderator)
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?
 
#2 ·
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.
 
#3 ·
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)
 
#4 · (Edited by Moderator)
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
either.

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.
 
#5 ·
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.

Cheers,
Brad