VFD on old Walker Turner grinder/buffer.

[Voi]

I found an old 1HP Walker Turner 10" grinder. It's 220 V, three phase, AC motor. It's missing the switch and one wheel guard but I think I'd like to get it and set it up for polishing and wire wheeling and keep my Baldor 7" for sharpening.

At any rate, getting 220V to my shop seems to be indefinitely postponed as we go back and forth about adding onto our garage.

I have two, 20 amp circuits dedicated to my shop. Pretty short run from the panel and with 12 gauge wire.

If I remember correctly there are VFD's that take 110V input and get supply three phase output "up to 1HP".

I just want to make sure I can actually run this thing and that it won't sit around until we get 220V out there. If my 20 amp circuit doesn't provide quite enough juice does this mean the grinder won't spin at all or will it spin but just somewhat shy of max RPM?

I thought there was a discussion on this recently but I can't seem to find it.

 

[rsanter]

Yes, they now have VFDs that will go 110 to 220-3ph
1hp is about the max you can do with that

Bob

 

[alex71]

you should be fine. worst case scenario the VFD will shut itself down due to overload, but I don't think you can can work it that hard with a buffing and wire wheel anyway. go for it.

 

[fflintstone]

pics!

 

[930dreamer]

Pics, the grinder should only pull a couple of amps.

 

[454ragtop]

Should work just fine, but it is imperative that max frequency of the VFD be set to 60 Hz, as you don't want to overspeed a grinding wheel.
Jim

 

[Voi]

Some cell phone pics. If anyone has any input on the value of this thing, please let me know. I sort of fell in love with it this morning but refrained from buying it as the husband wasn't there to show me it running.

https://lh3.googleusercontent.com/-.../dvfLJUXanbM/s800/2013-02-18_09-42-54_501.jpg

https://lh3.googleusercontent.com/-.../rDNlIVuV3WU/s512/2013-02-18_09-43-31_972.jpg

No pedestal, switch is underneath (I think) and it's missing one guard. Something else I noticed as well but I've got to run.

 

[Unmarked Bill]

Looks great! If you end up getting it, and using it for wire/buffer, I'd very much like to buy those guards and tool rests.

 

[lzenglish]

Have you priced VFD'S Latley? Last time I checked, they cost more than a buck and boost transformer. Just food for thought. Good Luck.

Wayne

 

[larry_g]

If going with a vfd the switch is of no concern as you cannot have one past the vfd. For power 1 hp is about 760 watts or about 7 amps on a 110v circuit. So a 20 amp 120v circuit should handle it. With the vfd you limit the inrush current so that is nothing to worry about.

lg
no neat sig line

 

[alan camby]

You will loose power with a Static Phase converter.
http://www.use-enco.com/CGI/INPDFF?PMPAGE=562&PMITEM=BV297-3705
I don't see the wiring diagram, but I would bet the input to the static is 220vac single.

IMO any time you put a VFD on a grinder you need to buy a Nema 4(washdown) VFD or get a enclosure for the VFD if it is a open case unit. The VFD will **** in the grinding dust if you do not and the life could be shortened. I have seen some people put the VFD in a separate room and run the controls external to the grinder.
Consider the last 3 on this page.
http://dealerselectric.com/mfg-subcat-item.asp?cID=0&scID=164&mID=-1&Format=

 

[alan camby]

If going with a vfd the switch is of no concern as you cannot have one past the vfd. For power 1 hp is about 760 watts or about 7 amps on a 110v circuit. So a 20 amp 120v circuit should handle it. With the vfd you limit the inrush current so that is nothing to worry about.

lg
no neat sig line

A one horse VFD at 120vac pulls about 18 amps.
If they only pulled 7amp they would sell 2hp vfds that run on 110 20amp circuits.
BTW. The Teco manual shows 17.9 amps and use a time delay fuse of 20 amp or fast acting of 40 amp.

 

[exmaxima]

you should be fine. worst case scenario the VFD will shut itself down due to overload, but I don't think you can can work it that hard with a buffing and wire wheel anyway. go for it.

Absolutely! I put a 1 HP 120v/1P-to-220v/3P VFD on my 1.5 HP Baldor 2x48 belt grinder and it runs with no problems. Most all VFD's can handle substantial overloads for maybe 30 secs before shutdown, and grinders rarely see that kind of use. Mine barely gets warm.

It is most important to ramp up the speed to limit the in-rush current at starting if you have a marginally sized VFD.

VFD's are great on 3P grinders!

 

[exmaxima]

Have you priced VFD'S Latley? Last time I checked, they cost more than a buck and boost transformer. Just food for thought. Good Luck.

Wayne

If his shop only has single phase power, then the transformer will not be able to supply the necessary 3 phase for the grinder. Unless you are talking about using a static converter as well....

The cost starts to add up. You can get the proper VFD for less than $150.

 

[KenS]

One thing about VFDs-- sometimes they don't play well with GFIs.

 

[larry_g]

A one horse VFD at 120vac pulls about 18 amps.
If they only pulled 7amp they would sell 2hp vfds that run on 110 20amp circuits.
BTW. The Teco manual shows 17.9 amps and use a time delay fuse of 20 amp or fast acting of 40 amp.

That is interesting. So those little 110v units have better than 50% loss? Where is all the energy going?

on edit; So I went and read the manual a bit and best I can understand is that rating is for if the max acceleration is set. So They are not running at a big loss but allowing for high inrush.

lg
no neat sig line

 

[exmaxima]

That is interesting. So those little 110v units have better than 50% loss? Where is all the energy going?

The original calculation based on wattage is not valid. It is better to use a motor chart. Most 1 HP single phase motors draw about 11 amps @ 120 vac.

The VFD has to convert single phase power into 3 phase power, and then into a variable frequency output. It is very much like a car power amplifier in that it takes one source of power (12 vdc in a car), converts it into a higher AC voltage via a switching power supply, rectifies it into a high DC voltage, then generates an output thru a Class D amplifier. You can imagine there are losses.

A real -world efficiency of about 80% would not be out of the question.

 

[Voi]

Thanks for all of the input guys. I finally met up with the husband and he ran it for me and I bought (actually traded for) it. It runs very smooth.

I'm going to take the motor from my 3-phase Unisaw over to his place and he's going to let me test it on his three phase source. If it's in running order I may look for a VFD that can run both, although I'll have to wait until I have 220V in my shop for that.

 

[454ragtop]

That's a real nice grinder. What is the HP of the Unisaw motor? If 1 HP also, could still do the 115 volt input VFD. Run the output of the VFD to a 4 pole 3 PH outlet, then put cords with 3 PH plugs directly to each motor, no switches between the VFD and motors. Could set up 2 control stations, or 1 portable one.
HTH, Jim

 

[Voi]

Unisaw is 3 HP so I'll have to wait until I have 220V out there. It's a mess so I'm going to tear it down and get the motor tested later this month. If the saw looks worth restoring I'll research my phase converter options more carefully.