# 3 Phase Motors



## thehammer (Jan 31, 2009)

I am considering buying a older PM66 at a great price but has a 3 phase motor. The seller said he knows someone that can make me a converter if I have a 220 outlet for it(which I do) but since i'm not familar with 3 phase motors, i'm not sure if it's worth the trouble and if it work correctly. Any insight would be helpful and appreciated.

Thanks
John


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## Karson (May 9, 2006)

My table saw is three phase. I bought a static phase converter on e-bay. If the price is right on the saw go for it.

I've used phase converters for about 30 years on tools that I've owned.


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## RBWoodworker (Mar 22, 2009)

That's true..you can buy a phase converter from Phase o-matic for about 160 bucks or so, but beware..the converter reduces the HP of your motor by about 1/3rd if I'm not mistaken..correct me if i'm wrong..but other than spending thousands of dollars hiring an electrical firm to swap out your electrical panel..this is the way to go.. my PM66 has a 5hp single phase motor but I bought it that way..


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## marcb (May 5, 2008)

3 letters, VFD for 3 HP or less its the cats pajamas. For 5 HP or more its expensive as all heck.

I would say skip the static phase converter and go for a VFD, the next stup of is an RPC which can power multiple machines.

I run a VFD on my table saw and it works like a NEMA magnetic starter, brake and several other features all in one little box.


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## KentS (May 27, 2009)

I love three phase equipment, but it's not for a small shop. I get great deals at auctions because nobody around here wants it. I just ordered a single phase motor for a Powermatic for a customer to replace his 
3 Phase. The motor, with switch and tax was just under $600. I've not used phase converters, so I can't say how well they work, but it might be a valid option. Good luck.


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## thehammer (Jan 31, 2009)

Well, the PM66 is only 2 HP but I was thinking that I could easily swap it out with a 3-5 HP down the road. I've been using a 1 1/2 HP contractor saw for so many years, even if the phase converter drops it a hair, I may not even notice it. Right???!? I don't know, maybe wishfull thinking. Here is a link to the saw, and thanks for the info so far.

John

http://cgi.ebay.com/POWERMATIC-MDL-66-TABLE-SAW-2-HP-10-LEFT-TILTING_W0QQitemZ270399053446QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3ef50a1e86&_trksid=p4011.c0.m14&_trkparms=72%3A1205%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50


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## marcb (May 5, 2008)

3 Phase has far more torque than a standard induction motor. My 2 HP 3 Phase table saw chews through wood as fast as I can push it through. I've ripped max capacity on it (10" saw, just a bit over 2.5 inches) and just pushed the wood as hard as I could through the entire cut.

5 HP is way too much for a 10" saw, you'll reach the capacity of the blade before you reach anywhere near 5 HP. 3 HP is in reality probably more than you'll ever use except maybe that .01% of cuts that may tap into the potential.

I would guess that the 2 HP VFD from here: http://www.factorymation.com would be what you need. cost is 145 for the vfd, you can also buy buttons and stuff from there to get a nice big red stop button and start button setup that you mount to the fence rail or wherever. I'll try to get a pic of what I have as an example. Total cost with buttons would probably be about 180ish

I say go for it, looks like a nice saw, and 3 phase really kicks butt with its extremely smooth running power.


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## RBWoodworker (Mar 22, 2009)

Now I'm starting to feel dumb.. not sure what all the abbreviations are from the other fella's ..lol anyone care to break down just what VFD is?..lol also as far as the 5 hp goes..I have used everything from the 1/4 hp to 10 hp and for what i do.. (Cut stock that's 3" thick) I need all the power I can get..I guess that's why I bought the 5..but that's just because I needed to extra muscle, but beware..that motor on my powermatic 66 cost over 900 bucks if it ever goes out..yikes!!!!


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## thehammer (Jan 31, 2009)

Yeah, I've worked for 3 different Cabinet Shops and 1 Wood Working Shop and only 1 had a Table Saw (PM66) set up with a 5 HP motor. The only thing the saw was used for was milling. We had 1 other Table Saw (PM66) 3 HP and a 5 HP Sliding Table Saw for the Cabinets. I'm sure the 2 HP will be plenty and when it goes bad, i'll swap it out with a 3 HP. This really helped and hopefully one day my experience will help someone else.

Thanks Again
John


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## marcb (May 5, 2008)

3 phase motors don't really go bad, you might have to swap the bearings but that's it (so a 20 buck fix)

A VFD is a magic box (don't laugh that is the best way to think of it).

You supply it with single phase power, it then does magic and you have true 3 phase power coming out of it.

It also has some really useful features. It acts similar to a NEMA starter giving protection to the motor from too much power being drawn. Many also have a power break feature that dumps power through an external resistor for quick stopping (great on a bandsaw, works fine on a tablesaw don't let anyone tell you different). Most can detect if the motor is slowing and give it a torque boost making powering through those tough grain areas a breeze.

My VFD also somehow managed to detect the 2 kickbacks I've had and shut the machine down thus really slowing the piece down (not that I was any where near the piece, but its nice that my door wasn't destroyed)

VFD's also have variable frequency output (Variable Frequency Drive is what it stands for). Induction motor speeds are based off of the frequency of the power (60 Hz in the US) Most go to 66Hz. Depending on the style of circuitry used you might have a low torque issue on the low end of the spectrum.

The frequency part is good for Drill Presses and Lathes and what not, but not really a feature that needs a lot of going into for a Tablesaw or most other equipment.

Its the best solution to a single machine need for 3 phase power. After that you need to look into RPC's which depending on the size can power an entire shop or a couple machines at once.

Some shops that use an RPC for 3 phase power also have a VFD on the most frequently used machine (RPC's are at their most simple a Static Phase converter that use a stand alone 3 phase motor to generate the 3rd phase of power) this way they don't have to run the RPC the entire time in the shop in case they want to use the saw.


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## thehammer (Jan 31, 2009)

See, that's what I like about this site. Woodworking, it seems is the least of the knowledge here, even though I don't understand everything being said. It's good to see it broken down for someone like me. This VFD sounds like something I need to look into. Thanks Again.

John


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## SCOTSMAN (Aug 1, 2008)

I dont see why anyone would need variable speed on a saw like this but many other machines like lathes etc work great with it I have many machines I own a 3 phase static 7.5hp and a rotary 5.5 hp newly bough last year and a vfd 5.5hp for my milling machine.I need another vfd variable frequency drive which gives speed control the only one of these that does anyway if you get ioffered 3 phase don't be put off having this supplied to your house might be cheaper than you thing think it over.There are a lot of good machines out there going for low money simply because they are 3 phase and all hobbiests or most of them are wary of this but it is the way to go in my humble opinion regards Alistair


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## marcb (May 5, 2008)

*I dont see why anyone would need variable speed on a saw like this*

As I stated it is a feature that isn't really something to worry about in a Tablesaw, all the other features that a VFD offer make it a prime candidate for a tablesaw however.

Static phase converters suck away power (its basically a kick in the butt to get the motor started then running it off single phase 220) and a RPC needs to be started and stopped when 3 phase is needed. Neither of which is ideal for 1 machine occasional use.

With a VFD you get over current protection, torque boost, and a starter with remote push button station capability, and if wanted power breaking. All for about 140 USD which is equal or less than the other options, especially if you need to put in a good magnetic starter on the machine.


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## TopamaxSurvivor (May 2, 2008)

The some one who is going to make you a converter will probably take a three phase motor and connect it to 220 single phase. Then connect the three phase equipment to to the previously mentioned motor. It will get your equipment running, but it's not very efficient. If you can find an old three phase motor cheap, it will work. You have to remeber to give it a spin when you start it. It will not spin on it's own. If you spin it the wrong way, yoiur equip will be going backwards. Stop and spin it the other direction )

If you use a VFD, you will have to over size it by at least 1/3 to run it on single phase input. Since they turn the juice to DC, then back to AC, it doesn't really matter what the input is as long as it is the same voltage range. With the VFDs avialable today, I wouldn't bother with a phase comverter.

If it were me, I'd just swap the motor for a single phase 2 hp and wire it 220 v.


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## TopamaxSurvivor (May 2, 2008)

Sorry to say, 3 phase motors do occasionally go bad just like anything else man made ;-(( There is very little to go wrong excpt the bearings if they are not over loaded or over lubed. If you check one with a high voltage mega ohm meter and get a reading of 10 k or under, the motor will eventually go bad. The mfrs will say 10 k is good, but in my experience over the last 40 yrs, it ain't!! The meggar should read near infinity in most cases when checking motor insulation.

Another poiint to consider, modern VFDs on old motors will, in most cases, burn out the motor insulation. The older motors were desinged to be used at 60 cycles. Modern VFDs put out unlimited cycles of switching action to fool the motors into thinking they are running on 60 cycle 3 phase. This can also cause a lot of noise in electrical power systems if it isn't properly filtered out.

When we change out installations to VFDs on various applications, we always change the motor to a rated motor these days. The older motor are not going to be able to handle the drive in most cases,, especially if the motor is more than 20 years old.

marcb, I have no doubt your VFD was able to detect a kickback and stop the motor if the parameters were set up tight enough. It could even go into barking mode if yoiu programmed it to.

That's it in a nutshell for the novice reader. All you technical types, make a few corrects none of them understand ;-))


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## marcb (May 5, 2008)

*If you use a VFD, you will have to over size it by at least 1/3 to run it on single phase input*

That depends on how the mfg labels the VFD, I straight up ignore the HP rating and just look at the FLA amps. Match that up to your motor and you're fine for single phase input vfd's.

And the insulation thing depends on many things. I've seen plenty of people running old motors fine. Probably depends on exactly how old. Powermatic didn't make the 66 until the 60's. Pretty sure you're fine on that end.


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## TopamaxSurvivor (May 2, 2008)

Like I said, there are a lot of technical issues. If you size a three phase drive on the full load with 1 phase input, it is going away!! Maybe not today, but it will go away.

Lots of old motors will run fine, some will run fine for a while and some will last a day. Connecting modern drives is a game of roulette with old motors. That is why we have drive rated motors now.

I told a steel plant they were going to blow up a 200 hp DC motor. They didn't listen, they did it 2 days later. When they got the new one, I told them they still had the problem. They blew it up too ) You can get a way with a lot of things, including using an old 3 phase motor as a converter, that doesn't mean it is right or very efficient.

I was told once my price was way too high for putting in a 3 phase rotary phase. They used the cheapy price with an old motor for a converter. Then there were 2 questions. Why do we have to spin it to start it every day? A year later, why did the compressor motor only last a year? Because cheapest is best!! )


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## TopamaxSurvivor (May 2, 2008)

Scotsman, VFD= variable frequency drive. It isn't that you need a variable speed for the saw, it is the most efficient way to get from single phase to 3 phase these days. You can get a small VFD for $100-200. The same thing in a REAL rotarty phase with be close to $1000! An electronic phase converter will not run anything that starts under load like a pump or compressor, but a VFD will. Hope that explains it )


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## thehammer (Jan 31, 2009)

OK, just so I can understand it better. All I have to do is run a dedicated 220 line from my sub-panel to the Table Saw and the VFD would connect to the 220 line and the Table Saw would connect to the VFD. RIGHT???

John


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## davidroberts (Nov 8, 2008)

go to the factorymation site. March gave you the link above. write down all of the information you can read on the motor. a tech. will walk you through it. they sell 4 or 5 variable frequency drives (VFD) a day to amatuer ww'ers buying 3phase equipment for a 1phase workshop. like me and you. they know what you need. cost is about $150. first class company with quality help. buy anything powermatic you can afford. 3phase is just a small bump in the road. btw, you will get a quarter size paper manual on how to hook it up. it's way to small to read. download the full size color .pdf file off their website. don't buy one custom made IMHO.


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## TopamaxSurvivor (May 2, 2008)

John, You got it. That's in a nutshell.


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## thehammer (Jan 31, 2009)

I Snooze - I Loose!!! In the day I spent investigating this 3 Phase problem, someone else picked it up. O Well, guess I'll keep looking.

Thanks for all the advice, at least I learned a little something.
John


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## TopamaxSurvivor (May 2, 2008)

Sorry about the loss John ;-(( Guess I should have said there would be a small amount of programing to start it up (in most cases). Plus the physical hookup. (just in case a lurker readsd this) )


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## thehammer (Jan 31, 2009)

Well, there's still one more Powermatic out there I need to go see. It's only a 64A but it's still plenty for what I do. Better then the Rigid I'm using now.

John


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## marcb (May 5, 2008)

*Like I said, there are a lot of technical issues. If you size a three phase drive on the full load with 1 phase input, it is going away!! Maybe not today, but it will go away.*

Maybe they rate VFD's different now (or its the sellers I've used), lots of single phase input (only single phase input) drives out there so its easy to size the drive you need.


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## TopamaxSurvivor (May 2, 2008)

If you have a specificly rated single phase input drive, I'm sure it will be rated for the 3 phase out put. I don't know of any such animals. But I haven't searched for them either. If you have some like that, then I stand corrected.

You can just put single phase into a 3 phase drive, but it needs to be over sized for the rated out put. There will not be any input info for such use. Over size it or it will go away The drive guy I get them from told me there were no single phase drives any more. Maybe that is just his line. They are getting so cheap anymore, I suppose they don't bother to make them when you can do anything you need to with a 3 phase drive including feeding it with single phase.


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## jerryz (Jun 4, 2009)

By the way Grizzly offers Static Converters at very reasonable prices, they have 5 version available to suit your power (motor) requirements the electronic version are great and work by converting your 220V ac household electrical input to 3 phase.
The most expensive one capable of running a motor from 6 to 10HP ciosts 229.95
The one capable of running a Motor sized between 2 to 5HP costs 189.95
Plus shipping, here is the link to the Grizzly site:
http://www.grizzly.com/products/category.aspx?key=275030

Enjoy


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