VFD Questions

[Brian Holcombe]

I bought a 3ph machine, one is 3HP and I'm considering another that is 10hp.

So, could basic questions. Do I buy VFD's with the identical HP ratings?

These are basic machines, without anything digital going on. One is a mortising machine (Felder 250) and the other is a planer. Anything I should be concerned about?

I'm considering one more machine later on, which is a big big jointer, I'd like to use the 10HP setup for both machines (not at the same time of course), is this possible?

I can manage with electric but I'm not an electrical engineer so talk slowly and loudly :D

Cheers
Brian

[Malcolm McLeod]

IS THIS TOO LOUD..?

What matters is the amps that a given leg of the VFD is subjected to, what amps a motor draws on that leg, and what amps the manufacturer says the VFD will support.

Assuming all 240VAC -
For a 3Hp motor, 3-ph needs 9A, but 1-ph needs ~16A (depending on what motor chart you look at). So, the VFD input has to have components that support 16A, since I assume the whole point of this thread is how to convert 1-ph to 3-ph. Some of the Asian VFDs will say "3Hp, 1-ph or 3ph" - - which means they probably increased the current carrying capacity of at least 2 of the 3 input legs for the VFD.

If VFD just says "3Hp / 3-ph", I wouldn't use it ... unless you can stand the warranty arguments. In this case I'd jump to a 5Hp VFD, which will support 16A on each phase (as you need). This is the much-bandied-about 'de-rating' of a drive - - you use 5Hp VFD on a 3Hp motor.

If they don't list the Hp for a drive, multiply the motor's FLA by 1.7 and make sure the VFD's specs can support this.

Warning - the 10Hp is gonna get painful (...looking thru my 'hobby' filter).

[Malcolm McLeod]

I had to go look up the 10Hp numbers, so replying separately.

First motor chart I looked at uses 230VAC (it's probably old) with a 10Hp motor needing 28A (3-ph) and 50A (1-ph).

So to run at this full capacity, a VFD has to have output circuits designed to safely handle 28A, but the input circuits have to deal with 50A (power in = power out). Typically, this means you'd need a 20Hp (=54A) VFD to support the 10Hp input current.

I haven't shopped for drives this big for home use, but maybe manufacturers have started addressing this market?

[Brian Holcombe]

Thanks Malcolm! Much appreciated and now it makes sense. Woof,,,40 amps for 10hp! Looks like a 15hp covers that and the 3hp will require a 5hp unit. Any issue in oversizing these?

Replied at the same time, I found 40 amp, but you may be right could be 50 Amps. I may rethink this machine, seems like overkill.

[Malcolm McLeod]

Thanks Malcolm! Much appreciated and now it makes sense. Woof,,,40 amps for 10hp! Looks like a 15hp covers that and the 3hp will require a 5hp unit. Any issue in oversizing these?

Replied at the same time, I found 40 amp, but you may be right could be 50 Amps. I may rethink this machine, seems like overkill.

No issues with over-sizing, excepting cost. You can set the VFD parameters to limit the power applied - - so a 20Hp VFD could safely operate a 3Hp motor, if you program it to do so. (I'd probably go "belt & suspenders" with this big a discrepancy, by putting a 3Hp overload/CB inline between the VFD and motor.) You just have to re-program every time you plug the 10Hp motor into it. (We all have different pain thresholds.)

Before you splurge on the 5HP VFD, Huanyang lists 3Hp VFDs on the Bay, seemingly rated for 1-ph OR 3-ph. Several SMCers have gone this route...? Just not me. Yet.

[Brian Holcombe]

Cool, thanks Malcolm! Much appreciated. I think I'll use separate units for each machine.

[Brian Holcombe]

Well, I thought I had this all figured out but apparently not so much. The phase converter must be derated from what I've read for anything above 3hp, which actually seems like for anything 3hp and above and they start getting (as you noted) pretty expensive.

I'm in the territory where it is actually starting to look less expensive to simply buy a rotary converter for the 3hp motor and dump my plans of a 10hp planer and instead get something smaller and single phase. :(

[Peter Christensen]

I bought a CV Max with a 5 hp, 3ph motor to be able to lower the speed when appropriate. I did what the Aussie Max users do and bought a Powtran VDF from China through Alibaba. The VFD can if needed soft start the motor so it draws fewer amps. When I was inquiring with the sales person she checked with their engineers to make sure I got the correct sized unit. It cost, if I remember correctly, a little over $300Can delivered. I suggest you do the same to see what they recommend.

[Brian Holcombe]

Thanks Peter!

[Steve Jenkins]

Were it me I would and did buy a rotary converter and use it to feed a 3 phase panel. That allows you to easily add more machines

[Brian Backner]

+1 on using a rotary phase converter for running 3P equipment at home. They are relatively easy to source, or to build (Google Fitch-William RPC for one), and they can be any size needed up to the limit of your electrical supply. An advantage is that they do not need to be modified or "tuned" for different motors unless you are running a very finicky CNC machine.

I've attached a PDF of an integrated RPC and 3P breaker panel for your reference. I think I found it on the Practical Machinist website several years ago - their sub forum on electrical issues is a gold mine of information

[Malcolm McLeod]

+1 on using a rotary phase converter for running 3P equipment at home. They are relatively easy to source, or to build (Google Fitch-William RPC for one), and they can be any size needed up to the limit of your electrical supply. An advantage is that they do not need to be modified or "tuned" for different motors unless you are running a very finicky CNC machine.

I've attached a PDF of an integrated RPC and 3P breaker panel for your reference. I think I found it on the Practical Machinist website several years ago - their sub forum on electrical issues is a gold mine of information

Just to be clear a VFD need not be tuned or modified either. Just as you can connect a fractional-Hp motor to a 50A circuit breaker, you can run a 3Hp motor on a VFD supplied and rated for 20Hp. Everything works fine - - until it doesn't. Then you melt something, let the magic smoke out, or have a 'rapid oxidation event'. To prevent this, you can insert a suitably sized circuit protection device between a (big) VFD and a (small) motor. Or, use the current limiting parameters built in to most VFDs.

I don't 'RPC', but I would suspect that the same disaster potential exists between a (big) RPC and a (small) motor. If the RPC will adequately supply a 10Hp motor, then it will melt a fractional-Hp motor, unless you use a interposing CB or turn the RPC 'down'? Maybe this 'turning down' is possible, but I've not seen it discussed.

...Name your poison.

[Brian Holcombe]

Thanks guys, appreciate the discussion.

[John K Jordan]

... let the magic smoke out, or have a 'rapid oxidation event'.


Nice! We've used the "let the smoke out" for decades ("electronic circuits run on smoke - they quit working if you let the smoke out") but I've never heard the "rapid oxidation event" description. It does make me wonder if oxidation is necessarily involved since vaporization by electrons can occur in the absence of oxygen but I can still think of uses, perhaps for the secondary effects which often follow an initial event.

JKJ

[Bill Dufour]

When I bought my lathe it's 3Hp motor was supplied by a one Hp VFD. It worked fine but I never took heavy cuts. I am in the process of replacing the vfd with a 3hp one and wiring it properly to the existing switches. Many of the 3hp and lower vfds are designed for full output with single phase input. Get to 5hp and more and VFD prices skyrocket. I wonder how much the 762HP VFD used in a Tesla car cost? probably as much as a transmission would
Bill D

[Brian Holcombe]

Interesting, which VFD did you buy exactly?

[Mike Heidrick]

A rpc wont melt a fractional motor just like your 200 amp sp service wont melt your 15amp cb in your panel. You don't turn them down. Its pull not push in electricity. You melt one its because you shorted a circuit.

Also never put a circuit breaker device on the output side of a vfd between it and the motor. Vfd direct to motor on output. Read your manual.

Your two machines your considering have zero need for vs so put in a 15hp rpc and panel in the shed or build one if you want to run 10hp loads.

If you are only going vfd, I have teco 7500, fm50, ge fuji mini 300, hitachi xj200, wj200, bonfigilo (sp), and prob a few other drives all on machines that require or are handy with variable speed and most of them done under cnc code. All are great drives. Fm50 is the cheapest. With a large planer though thats a lot of mass to stop so i suggest a drive that can use dc braking with a large resistor or a purchased braking module. Hitachi Wj200 or teco 7500 will do that. The Hitachis are real nice and have great control station modules.

[Brian Holcombe]

Thanks Mike! I’m dumping the idea of 10hp motors in my shop, so I’ve revisited that and plan to cap things off at 5hp~ which I’m fairly comfortable with having one already.

[Bradley Gray]

I have a Kay 10hp RPC that runs everything from a 3/4hp to a 10hp. It is rated to start 10hp at a time and run 30hp. it uses a 60amp 220v single phase circuit. Works for me.

[Malcolm McLeod]

... never put a circuit breaker device on the output side of a vfd between it and the motor. Vfd direct to motor on output. Read your manual.
...

Not that it applies here, but in case anyone is interested - -

Its been a while, but I've worked on an industrial setup with a single, large VFD* (1500Hp, IIRC) operating something like 120 motors on a series of take-away conveyors. The motors ranged from 15Hp down to 2Hp(?) (again, IIRC). The VFD essentially powered a 'variable speed distribution bus' feeding all of the motors. So everything on the bus ran at the same speed. ...All 3-phase, but the concept would be the same if the VFD was supplied 1-phase.

If any motor had shorted, the VFD could have melted the motor and the wiring. To prevent this, each motor had a suitably sized starter and overload between it and the VFD. (This interposing hardware also allowed them to shut-down a specific motor for service without affecting the rest of the line.)

In another case, dough sheeting lines commonly use equipment with a single VFD multiplexed to 5 motors. Operator selects which one he connects to VFD, then runs it to make adjustments, stops it, and switches/connects to the next one. It uses common motor sizes, so VFD is size matched to the motor (and uses internal protections); interposing relays handle the VFD connection to respective motors.

Not that I'd recommend this for Brian, or any home DIYer for that matter, but lots of things are possible when you throw away the manual.;)

**************
*VFD was about the size of a closet that would make SWMBO very happy!!!:D

[Larry Edgerton]

Thanks Mike! I’m dumping the idea of 10hp motors in my shop, so I’ve revisited that and plan to cap things off at 5hp~ which I’m fairly comfortable with having one already.


I would not compromise on the machine because of this little point. I too am an electrical idiot, no offense, and am intimidated by things electrical.

That being said, the difference between a 5hp mediocre planer and a nice planer like my SCM is night and day, and a lot less work as sizes are perfect with little to no tearout. Same can be said for jointers, shapers etc. There are few good single phase machines. I moved out of a shop with 3ph buss bars an all the walls to a small shop with no 3ph available, and so have had to deal with this.

I run a 50 hp rotary converter for the main tools, and use VFD's on small stuff like the drill press and grinder. Nothing that you can not handle. A ready to go rpc big enough to handle what you want is around a grand.

I bought the big rotary because I was going to move my wide belt to my new shop only to discover that the power lines coming to my shop were not big enough to handle the load, and $28K for the power company to upgrade, or I would have a smaller unit.

One thing I would like to do is buy a Phase Perfect and get rid of the VFD's and RPC. I would have to buy a 20hp, but you could do what you want with a 10hp model. I kind of keep waiting for some competition in the market to bring the prices down, but has not happened. For about $3600 you could run anything up to 10hp, quietly, and leave the converter on all day. If you could swing it though, I would go with the 20hp, opens up a lot more possibilities and can be doubled to 40hp if the need should ever arise.

That will be 2 cents.........

[Brian Holcombe]

<p>
This post is acting strangely, so I will try again.</p>

[Brian Holcombe]

Thanks Larry for weighing in on this, I appreciate your opinions and experience. I&#39;m dealing with a one car garage for machines and a basement shop, which is my primary shop, dedicated in the majority to hand tools. So, while I originally wanted some pretty hefty pieces I&#39;ve had to back off to something more realistic and work around the space and capacity which I can manage at the moment.
So gearing up for more capacity makes sense, but in my case the capacity is limited by my physical footprint. I can&#39;t really tighting things up and fit in 2-3 more machines like many of you might be able to do in your shops. I&#39;ve decided where the mortiser will go in the workshop (it&#39;s an easy decision in a one car garage) and that leaves me with enough space for either a jointer or a planer....so yesterday I bought a J/P from Minimax to account for both needs it was available in single phase. That now diminishes my need for excess three phase power and I&#39;m down to accounting for one machine, the 3hp Mortiser.

[John K Jordan]

Brian, from that message it looks like you might be getting the dreaded wonky character formatting. Perhaps this would help?
http://www.sawmillcreek.org/showthread.php?259465-Posts-being-deleted-amp-formatting&p=2745498#post2745498

JKJ

[Brian Holcombe]

Thank you!

[John K Jordan]

Thank you!

Did it work? I'm keeping score. :)

[Mike Heidrick]

A big rpc requires the correct service to feed it too. What size wire and service are you feeding a 50hp rpc with?

[Kevin Jenness]

Brian, I have run my 3hp slot mortiser off a static phase converter for 25 years with no problem. It has plenty of power for what it does, and that is the cheapest way out. If I were to set it up today, though, I would put it on a vfd to allow for boring at slower rpm's.

[Brian Holcombe]

Thanks Kevin! After going round and round I think your recommendation and the others are right on. A VFD seems a sensible choice.

John, I made no change but it seemed to clear up on its own.

[John K Jordan]

John, I made no change but it seemed to clear up on its own.

The HTTPS on my browser occasionally comes and goes for no reason I can explain. Maybe something to check if the formatting problem happens again.

JKJ

[Brian Holcombe]

Appreciate the advice gents. I ended up ordering a rotary phase converter. I found it appealing that I could run any kind of three phase motor on it with only consideration being hp.

[Curt Harms]

Not that I'd recommend this for Brian, or any home DIYer for that matter, but lots of things are possible when you throw away the manual.;)



Not all of them good:p

I'm close to buying a VFD for a drill press. It has 5 speeds I'd like more especially on the low speed end. I'll be following this thread.

[Larry Edgerton]

..so yesterday I bought a J/P from Minimax to account for both needs it was available in single phase. That now diminishes my need for excess three phase power and I&#39;m down to accounting for one machine, the 3hp Mortiser.


Very nice solution! A quality machine. What head does it have?

[Larry Edgerton]

Not all of them good:p

I'm close to buying a VFD for a drill press. It has 5 speeds I'd like more especially on the low speed end. I'll be following this thread.


I just put one on my Clausing with a two speed motor and a Reeves drive. I can get it down to 50 rpm now for short stints, something I needed to do for some restoration work with Versatex. Its nice, wish I had done it sooner.

[Brian Holcombe]

Very nice solution! A quality machine. What head does it have?

Thanks Larry! I went with a Tersa 4 knife head.

[Malcolm McLeod]

Not all of them good:p

I'm close to buying a VFD for a drill press. It has 5 speeds I'd like more especially on the low speed end. I'll be following this thread.

Dan did an excellent job detailing his efforts to install a VFD on his DP here (http://www.sawmillcreek.org/showthread.php?250653-How-I-put-a-VFD-on-a-drill-press-for-no-more-belt-changes). Well worth the read!

[Larry Edgerton]

Thanks Larry! I went with a Tersa 4 knife head.


I predict that you will love that head. I run Tersa brand carbide in mine, feel that they are more economical in the long run.

[Alan Lightstone]

Did it work? I'm keeping score. :)

I did for my other post you helped me with, John, so +1

[Alan Lightstone]

With a large planer though thats a lot of mass to stop so i suggest a drive that can use dc braking with a large resistor or a purchased braking module. Hitachi Wj200 or teco 7500 will do that. The Hitachis are real nice and have great control station modules.
Not to hijack the thread, Mike, but I've ordered several 7.5HP tools with DC braking. Is that an issue with my planned Phase Perfect converter?

[Alan Lightstone]

10HP planer, Brian??? I felt like the 7.5HP Felder was overkill. How big a slice are you planning on taking off at a time??? A foot??!!??

I'm not worthy.... I'm not worthy...;)

[Brian Holcombe]

I predict that you will love that head. I run Tersa brand carbide in mine, feel that they are more economical in the long run.

Absolutely! Very much looking forward to it. I plan to use mainly HSS, but likely have a set of carbide knives as well for the occasions that I run harder woods. Often I work with softwoods or softer hardwoods.

[Brian Holcombe]

10HP planer, Brian??? I felt like the 7.5HP Felder was overkill. How big a slice are you planning on taking off at a time??? A foot??!!??

I'm not worthy.... I'm not worthy...;)

Exactly why I dumped my plan for a 10hp planer, just required far too much electric on single phase. I would need to run a 70amp breaker and #4 wire. Seemed a bit ridiculous in my case, so I decided instead that I would go with a Minimax FS 41 Elite S which is currently in transit. The motor is a bit more what I'm used to, drawing a max 30 amps.

It would also require a 20hp converter, ugh.

Big HP motors seem much more reasonable to run on true 3ph electric.

[Larry Edgerton]

Absolutely! Very much looking forward to it. I plan to use mainly HSS, but likely have a set of carbide knives as well for the occasions that I run harder woods. Often I work with softwoods or softer hardwoods.


If you head speed is like my SCM planer you do not have to run 4 carbides, I run two and two dull HS with no noticable difference in cut quality. The carbide I believe, as does Joe Calhoon, cuts better than the M42.

As it was explained to me, because the carbide in an insert like the Tersa knives does not need to be braised it can be finer grained, no need for places for the braise to grab on to. I have noticed the same thing with insert cutters, the carbide seems sharper.

Curious to hear your impressions when you get to play with it. I respect you opinion as well.

[Brian Holcombe]

Thanks for your insights on this Larry! I may well try that out, ideally I'd like to have one setup that I can use for the majority of the material that I plane.

I've noticed that with solid carbide cutters for my router, they do cut better than braised insert cutters. I had wondered if it were entirely cutting geometry or if they were simply better material.

I'll likely add them in with my first or second order of cutters, the HSS cutters are going to earn their keep for a little while. :D

[Bill Dufour]

For most big wwing machines a VFD does not need to use power braking. Who cares how long it takes a planer or jointer to coast to a stop? Might be important on a tablesaw, definitely on a drill press for some operations.
Bill

[Larry Edgerton]

One thing I consider a huge advantage with Tersa is that the knives change so quickly. I change them out before they are totally trashed and keep them around and pop back in when I have questionable rough stock, like dirty, footprints, etc. First pass with the old knives and then put the new one back in.

If you would like a set for this right off of the get go PM me an address and I will send you a set. Mine are 520's so you may have to cut, but that is not a big deal.

[Brian Holcombe]

Thanks Larry, much appreciated!

I totally agree, I have spoken to a few other people who very much prefer tersa over spiral heads.

Best Regards
brian

[Larry Edgerton]

I have been buying from these guys for a few years. Service is good but allow about three extra days as they are in Canada. Prices are fair. Watch out for fake clones sold as genuine, even in original looking packaging. The clones I tried suck.

https://tersaknives.com/

I would copy this as the mods may delete link, not sure what the rules are exactly.

Will get a set off to you in the next few days. I have cut with a die grinder and a cutoff wheel.

[Brian Holcombe]

Thanks Larry! Very much appreciated!

I will buy from them, I did some hunting around and they seem to have the best pricing on the genuine article.

[Larry Edgerton]

https://www.ebay.com/itm/German-M42-HSS-TERSA-Planer-Blade-Knife-235mm-SCM-Rojek-Wadkin-Axminster-Jet/161784340329?epid=1560146211&hash=item25ab191f69:g:ewUAAOSwb-tZw4rH

This is a fake. As you can see they make it sound like the real deal.

[Larry Edgerton]

This tool will fit all of the allen heads that you need to access for normal service. I have a SCM saw, jointer and planer and it works on all of them. Super handy, but you may want to wait until the tool is in your possession to check. I was putting new knives in my jointer and it reminded me.

https://www.parktool.com/product/3-way-hex-wrench-aws-1?category=Hex%20%26%20Torx%C2%AE%20Compatible%20T ools

I think that is all I have for you..........:D

[Brian Holcombe]

Thanks for all your help, Larry! I will put it to good use.

RPC arrived today, so I’ll be setting that up shortly.

[Dave Cav]

Brian, I'm looking forward to a full report on the J/P. Sounds like a great machine.

To get back to the VFD/RPC discussion for a minute, I have six machines I'm running off VFDs, all five horse or under. Most of my VFDs are TECOs purchased from Factorymation. Their tech support staff were very helpful in my selecting my biggest VFD, a 7.5 HP model used on my thickness planer which has a 5 HP motor. Given the number of machines I'm running it might make sense to have an RPC or Phase Perfect, but what I like about using VFDs is that I didn't have to run a second, three phase distribution system and breaker panel, and that the VFD eliminates the need for a magnetic starter. Given that all of my 3 phase machines are vintage old iron, and some came without starters, and the others were pretty sketchy, this is a pretty big deal.

[Brian Holcombe]

Thanks Dave! Looking forward to it as well, I’ll certainly post up my experience once I have some hours on it.

Thsnks also got your comments on the VFD. I’m running the RPC for one machine do far so I was able to have it setup with one internal breaker. Interesting thougt, I never really thought about the starter. I use a VFD in my Father’s shop, he has one on his Bridgeport Mill but he had it setup by an electrician friend so he didn’t have much to say about the particulars of it.

[Brian Holcombe]

The RPC is super quiet, I honestly forget it’s running if the machine is on.

Here is a shot of the new J/P

https://brianholcombewoodworker.com/wp-content/uploads/2017/12/img_8939.jpg