VFD for 7.5 hp 3 phase to run on 220 single phase

[Mike Leiferman]

Anyone with any experience running a 7.5 hp 220 volt 26 amp 3 phase from a VFD powered by 220 single phase? I would like to know
a) what specific vfd you are using if you recommend it,
b) any issues I should be aware of

The motor is driving a 1995 Lazzari Tema 3000i. The alternative for me is to swap out the nice italian motors for single phase 5 hp main and 1 hp scoring. I doubt I will strain a 5 hp motor, as the Unisaw this is replacing only had a 3 hp and I never made it work to hard. The Lazzari uses either 10 or 12 inch blades, and I imagine the 12 inch blades might take a little more power, but comments from users with 5 hp 12 inch machines would be appreciated also.

Thanks in advance.

Picked up the saw in Detroit over the weekend and have it complete disassembled for cleaning and rebuild. Looked like a basket case when I got it but think it will clean up nicely. Built like a tank.

Mike

[Kevin Jenness]

You will need a separate vfd for the scoring motor. Also, since you can't have any switching between vfds and motors the original controls will be bypassed. If you want to use the existing e-stops they will have to be rewired to cut power to the vfds. Alternatively you can set up remote start/stop stations.

I run a Paoloni P260 saw with12" blades and (approx.) 6 hp motor from a rotary phase converter. It works well since I don't need speed control and I can run other 3 phase machines off it.

I think you could run your saw on a 5hp 1ph main without a problem but the new motors won't be inexpensive and it may be difficult to find a single phase scoring motor that fits. Also, you will have to reconfigure the controls to single phase.

If you are looking for the least expensive solution consider a static phase converter. You will get only about 2/3 of rated power. I have run a slot mortiser (admittedly grossly overpowered at 3hp) on a static converter for 30 years.

[Dan Friedrichs]

There is an excellent thread in the Workshop forum on options for powering a 3-phase slider: https://sawmillcreek.org/showthread.php?296460-Phase-convertors

[Richard Coers]

Start by looking at prices. A VFD for a motor that size is really expensive. I went with a rotary phase convertor and wired in a 3 phase breaker panel in the shop for other 3 phase machines.

[Matt Day]

Since you have 2 motors and a big main motor, I’d suggest a rotary phase converter. For a 7.5hp motor you’ll want a minimum of a 10hp idler, if not 15.

[Patrick Kane]

If you go VFDs, contact Automation Direct. They will set you up with the correct VFD for each of your motors. However, a VFD for a 7.5hp motor is probably pushing $600, and then the scoring motor will need another $200+/- VFD. At $800, you might be better off with another means of conversion.

Unless you are powerfeeding stock, or ripping 12/4 hardwood, i dont think you will ever be disappointed with 7.5hp on a 12" blade.

[Carl Beckett]

I have been looking at something similar albeit a belt sander. (in the workshops threads).

Once you go over 10hp on the VFD the choices drop, and what I have read recommends 2x VFD rating over the machine. So 7.5hp would ideally mean a 15hp VFD. Price goes up. Then you have the second VFD for your smaller motor.

For a rotary phase convertor (what I have now, a 10hp Phoenix), to get it 'properly' wired means something like what Richard writes with 3 phase breakers after the convertor in addition to a fairly large input breaker. A decent size RPC in my area can be had for around $500 used. But install is more than this (wire, panels, breakers, etc) I think I would not purchase a VFD used, and some warn against the chinese versions (which may be cheaper)

Having said that I do have a 12" blade on my smart 300 and it has never bogged (4hp perhaps), so I cant imagine you would over tax the saw by derating a bit (keep the blade sharp). Just my opinion there may be users here that do push it to the limit.

Swapping motors is not crazy. Then you can always plug it in like any other equipment. But if you think you will collect more 3 phase equipment then permanently wiring in a RPC with breakers may be a good route.

[Mike Leiferman]

Thanks for all the responses.

Current single phase equipment includes a 350 mm Minimax J/P, Aggazani 5hp 600 mm bandsaw, and a Hammer sliding table shaper. 3 hp cyclone dc.

I will try to get VFD's to work to keep the saws original motors intact, but if the vfd for the main is not feasible, will replace the main with a 5 hp 1 phase, and get a vfd for the little 4 amp 3 phase scoring motor. Again, everything else is single phase, so want to keep it simple if possible.

[Rod Sheridan]

Buy a 5 hp VFD with single phase input and program it to limit the output to 5 HP.

You’re never going to use even 5 HP.

Add another small VFD for the scoring motor

I’ve modified a few saws that way, works great….Regards, Rod.

[Matt Day]

Why aren’t you considering a RPC? It’s the best way to keep it original (change nothing) and have full power.

[Mitch schiffer]

I have several 7.5 hp motors I run them each with there own vfd. I have had good luck with the fuji brand they make vfds that are designed to support single phase input. I believe this is the model of the ones I have FRN007G1S-2U. I got mine from Marshall wolf automation.

[Michael Schuch]

I have been running my 7.5hp RedStar radial arm saw on a Fujitsu VFD of proper rating for near a decade now. I have never had a problem.

I ran it for several decades on a home built RPC before that... I REALLY don't miss the hum of the idler motor on the RPC!

How comfortable are you with wiring? A big VFD and a second small VFD for the scoring blade with those nice Italian made motors would be awfully nice and probably a lot cheaper than new motors... but only if you are comfortable digging to the wiring on the saw.

[Rick Fisher]

Check if the saw has a break on the main motor and if it does make sure you tell the company selling you the VFD. It may or may not be an issue.

[Jared Sankovich]

Check if the saw has a break on the main motor and if it does make sure you tell the company selling you the VFD. It may or may not be an issue.
Friction brake motors on euro machines are a pain with a vfd. The solution is to disengage them or don't use a vdf.

[Mike Leiferman]

Thanks for all the input. Will look at the FUJI vfd's. I am not too concerned about doing the wiring - but have a friend who is an electrician if I stumble, or to look things over before I push go. I don't think the motor has an integral brake - we took it to a friend who has three phase to test it and it kept spinning after power was turned off. I assume that would mean there isn't one or it's broken.

[John Erickson]

You may want to use a 15-20 hp VFD and connect it to a breaker sub panel so you can connect all additional 220v 3ph machinery off one VFD.

[Jim Becker]

You may want to use a 15-20 hp VFD and connect it to a breaker sub panel so you can connect all additional 220v 3ph machinery off one VFD.

Can that even be done? My impression has always been that a VFD needs to go direct to a motor which is why a 3 phase slider with scoring would need two of them. But perhaps I'm mistaken about that...

[Kevin Jenness]

Can that even be done? My impression has always been that a VFD needs to go direct to a motor which is why a 3 phase slider with scoring would need two of them. But perhaps I'm mistaken about that...

That is my understanding as well. No switching between a vfd and the motor it controls. A rotary or digital (Phase Perfect) phase converter is what you want for powering multiple machines.

I suspect the least expensive and simplest solution given that the o.p. is ok with less power would be a static converter for each motor.

[Bruce Wrenn]

I ran it for several decades on a home built RPC before that... I REALLY don't miss the hum of the idler motor on the RPC!I find this interesting as the RPC I built for my neighbor several years back is almost totally quite. The starter motor is connected directly to the rotary with a coupler, no belts

[Jared Sankovich]

Can that even be done? My impression has always been that a VFD needs to go direct to a motor which is why a 3 phase slider with scoring would need two of them. But perhaps I'm mistaken about that...

No.. well you can do it once.

[Malcolm McLeod]

You may want to use a 15-20 hp VFD and connect it to a breaker sub panel so you can connect all additional 220v 3ph machinery off one VFD.

You can do this, but it requires a certain level of discipline & thought - or automation - that few small shop users will find acceptable. (Tho' when you throw phase conversion in with it, I'd advise the Mr. Leiferman to run away.) Details are beyond the scope of this thread, but basically motor '1' has to be completely stopped and braking off before you disconnect it from the VFD and then connect motor '2' - each via its own starter relay. It is called "multiplexing" and once upon a day past, I was hired to fix an abominably crappy OEM implementation of this (1 VFD >> 5 motors). Timing is everything. Oh, and all the motors will need the same basic specs: poles, voltage, FLA, etc..

You can also hardwire 1 VFD to multiple motors if the VFD has the proper capacity - - I've seen a 250Hp VFD connected to 50 x 5Hp motors - all running at once. They will all receive and so run at the same frequency.

[Malcolm McLeod]

No.. well you can do it once.

Most high quality, properly sized VFDs will simply fault and require reset before next attempt. The DC bus voltage goes nuts when the load comes off and then slams back on.

[Michael Schuch]

I find this interesting as the RPC I built for my neighbor several years back is almost totally quite. The starter motor is connected directly to the rotary with a coupler, no belts

This is one of those I need to address but have never gotten to it things. I have 2 different possible 10hp idler motors that I can use. An old cast iron frame motor and a much newer steel framed motor. Both have Zircs on the shaft bearings to lube the bearings. I have tried molly grease and lithium grease which will quiet the motors for a few hours then they will slowly come back to noisy. They both might just have bearings that are going bad but I think I am probably not using the correct type of grease? The grease I use is pretty much what ever is in the grease gun at the time. Is there a light weight grease or oil that I am supposed to be using? I do pull the back plug before I apply grease through the zirc. Just that there is a back plug kind of makes me think that I am supposed to be using something with a thin enough viscosity that it would run out with out the back plug. I have done some Googling on the subject of electric motor lubrication but have never found a definitive answer.

476477

476479

[Bruce Wrenn]

Swap out existing bearing for new sealed ones. Plug the holes where the zerks are. Part of your hum could be caused by your capacitor bank.

[Mike Leiferman]

An update: I bought a Vevor 10 hp VFD from Mr. B. to try on the main 7.5 hp 3p motor. Hooked it up to a 30 amp 220 v breaker and the motor and fiddled with the settings for about an hour and got it to run nicely. My hope is that I can mount this vfd for the main as well as another smaller one for the scoring motor in an enclosure, and just run remote contact switches to the vfd's to start and stop. Will update again if I can get that figured out.

10hp vfd cost $200. I have heard these cheap vfd's can muck up motor bearings, and since the motor is 25 yrs old, will take it apart and put in some cool ceramic bearings since the old bearings are probably original, though they sound fine.
I have also they can mess with the motor, but my impression is that is more common when running the motor at a speed other than it was designed for, which I won't be doing. So have to cross my fingers on that.

[Matt Day]

A 10hp VFD for $200? I hope it works well for you, but a quality 3hp VFD is usually around $200.

A VFD should have no effect on bearings, maybe windings but not bearings. Bearings don’t care if you’re running slower than designed, but too much speed will do it. But even that, woodworking motors don’t spin fast enough to really matter.

Don’t use ceramic bearings, just use normal greased rubber sealed steel bearings.

[Jared Sankovich]

A 10hp VFD for $200? I hope it works well for you, but a quality 3hp VFD is usually around $200.

A VFD should have no effect on bearings, maybe windings but not bearings. Bearings don’t care if you’re running slower than designed, but too much speed will do it. But even that, woodworking motors don’t spin fast enough to really matter.

Don’t use ceramic bearings, just use normal greased rubber sealed steel bearings.

The issue is currents generated in the motor shaft by the vfd that grounds through the bearings. It's a known issue with vfds and the reason for ad hoc grounding brushes and insulated bearings on some applications.

[Mike Leiferman]

Mike Schuch
I followed your suggestion, bought a 10 hp 7.5 kw vfd for the 7.5 hp main motor, and a smaller one for the 1.2 hp scoring. - Vevor VFD's - and they run the motors fine when started via the VFD's integrated keyboard. I want to use remote contact switches to turn the vfd's on and off, but cannot make any sense of the wiring diagram supplied with the vfd. Do you know of any instructions for general VFD remote switching?

[Matt Day]

Could you post a link to these 10hp VFD’s for $200?

Never mind, found it. How can these be quality at $200? Experiences anyone?

[Mike Leiferman]

Attached my guess at wiring diagram for remote stop start of Vevor vfd.

any suggestions welcome

[Mike Leiferman]

Matt,
Not sure about the quality of the VFD because still trying to figure out how to get remote start to work. Seems to run the 7 hp 3 phase motor fine from 220 single phase. I would suggest calling custormer service before purchasing any brand on line, to see if anyone answers the phone who knows what a vfd is.....
The instructions for the Vevor are less than stellar.
Mike

ps - I am not intending to use the variable frequency to vary speed or to brake - just a table saw.

[Mike Leiferman]

attached possible wiring diagram for remote stop start for Vevor vfd in lieu of original panel controls

suggestions advice appreciated

Have seen other diagrams where the output of the momentary switches goes to "relay out" terminals, which makes no sense to me. But am not an electrician.

[Jared Sankovich]

Could you post a link to these 10hp VFD’s for $200?

Never mind, found it. How can these be quality at $200? Experiences anyone?

Is it a 10hp 3ph vfd? You need to double the size of a 3ph vfd run on single phase. As an example the fugi 60amp vfd (20hp) only outputs 27a on single phase input.

Edit I see it's a 35a unit. It would output about 15 amps on single phase input .

[Mike Leiferman]

It is a single phase input, 3 phase output. The motor is about 7.5 hp, the vfd is rated at 10 hp.

[Jared Sankovich]

It is a single phase input, 3 phase output. The motor is about 7.5 hp, the vfd is rated at 10 hp.

The vfd is rated based on 3ph input. They all work (well most anyway) on single phase input. You just get half the output. It's a 5hp output on single phase. Best case would be 17.5 amps.

[Mike Leiferman]

Jared -
you know more about these than I do. The unit is described as having 50 amp output, so if halved, would be 25 amp. But this saw is replacing the Unisaw I have had for 15 yrs now that is powered by a 3 hp motor, and I have never strained it. I am not expecting to work the 7.5 hp motor in the slider anywhere near its capacity. If the vfd dies, I will buy a bigger one next time, and chalk it up to learning.

The thing I am struggling with and need advice on is remote switching.
Thanks,
Mike

[Malcolm McLeod]

attached possible wiring diagram for remote stop start for Vevor vfd in lieu of original panel controls

suggestions advice appreciated

Have seen other diagrams where the output of the momentary switches goes to "relay out" terminals, which makes no sense to me. But am not an electrician.

Disclaimer: I have never worked with the Vevor VFDs, but have worked with 10-11 other VFD brands over the last several years.

I assume the 'blue' wiring is from the OEM manual. This indicates the inputs are sourcing: there should be (logic level) voltage already present at each input terminal; when the external switch closes, it connects that terminal to the GND terminal (common control signal), which pulls that input terminal voltage down and the VFD brain sees this as 'true'.

So, I would not wire this as you have shown. Back to the disclaimer: There may be other drawings or parameter settings for this VFD which indicate support for such, but based on the drawing above - - don't. As shown, for dirt simple solution to your saw motor application, I would assume you need a single maintained switch wired from FWD/STOP to GND (Common Control Signal). Close it to run; Open to stop. If power fails, you should turn the switch OFF (:: open).

You will have to read thru the manual for programming parameters. These will determine how the VFD interprets the inputs. Write down any and all parameter changes you make, they're handy if you need to reverse something or replace the VFD. There are likely hundreds of parameters - - there are probably 2 or 3 that require attention for your application. Ignore the rest.

One parameter will likely enable all these external inputs. Until this is enabled, most VFDs default to the onboard keypad for all start/stop/reset/speed signals. Other parameters will define HOW these inputs are used - - assuming again that the 'blue' functional descriptions are the default, so if all you need or want is the FWD/STOP, no additional parameter edits are required.

Passing the output of momentary switches thru the onboard relay output terminals is likely intended to prevent restarts on recovery from a power failure. The relay output is probably programmed to change state when running, so the momentary switch turns the VFD ON, the relay holds it ON, and if it quits for any reason (power fail, fault, etc), the relay opens and then it can't restart until you press the button again. ...Probably.

For your consideration: many VFDs support taking the keypad off the body of the drive and locating it in a convenient spot. It is connected to the VFD body by a communication cable (often a simple CAT5 ethernet cable). This offers the advantage of not altering any parameters, and full functionality of display info and buttons. The disadvantage is that in high cycle operations, the membrane keypad wears out (...think about the 'enter' key on a fuel pump or point-of-sale CC reader).

[Mike Leiferman]

Malcolm
Thanks for taking time to provide this clear and detailed response!
The parameters that allow remote operation (turn off the keypad) are in the bubble I copied from the manual, item 8.2, so I think I have those set correctly.
I understand that the keypad can be relocated, but wanted to use larger buttons for my old eyes.
The part I had no idea about was the possibility that the "relay" would hold a signal from the momentary switches. The way I had it wired, when the on switch was depressed, the motor starts and runs as long as you hold it down, which is nice, but not quite how I wanted it to work...;) Adding a leg to the remote might be the answer.

Perhaps the second mistake I made in purchasing this "economical" vfd, is that the support for it is next to nothing. I was thinking "how hard can it be" and am beginning to understand.

Thanks
Mike

[Jared Sankovich]

Malcolm
Thanks for taking time to provide this clear and detailed response!
The parameters that allow remote operation (turn off the keypad) are in the bubble I copied from the manual, item 8.2, so I think I have those set correctly.
I understand that the keypad can be relocated, but wanted to use larger buttons for my old eyes.
The part I had no idea about was the possibility that the "relay" would hold a signal from the momentary switches. The way I had it wired, when the on switch was depressed, the motor starts and runs as long as you hold it down, which is nice, but not quite how I wanted it to work...;) Adding a leg to the remote might be the answer.

Perhaps the second mistake I made in purchasing this "economical" vfd, is that the support for it is next to nothing. I was thinking "how hard can it be" and am beginning to understand.

Thanks
Mike

You want 3 wire control, that diagram doesn't appear to show that.

[Mike Leiferman]

saw is now running both motors via separate vfd's. VFD's reside in an enclosure with remote momentary buttons for stop and start. Still working on getting the original emergency off button connected and working, need to add an additional contactor to that to notify each vfd separately.

Used cheap Vevor VFD's Now have the numerous settings figured out and documented, as well as a wiring diagram for the remote stop start switches if anyone needs, just dm me.

Thanks for all the help everyone! Will post some pics when I get the saw placed in the shop.
Mike

[Malcolm McLeod]

saw is now running ...


Good on ya'!

EStop button (contacts) can go in series with the respective Stop buttons, or you can typically define a VFD input as 'inhibit' (terminology varies by manufacturer) and wire the EStop's contacts to both of these inputs.