I Need VFD Clarification Please

[MadeByMiller]

I recently picked up a Rockwell 31-710 6x48" belt/disc sander. The specs for the motor on it are:

-3 phase
-230/460 input voltage
-1.5 hp
-5.4/2.7 amps
-3450 rpm

I don't have 3 phase power, so I'm looking to convert this to run off of single phase 220v power with a vfd. I have tried doing my due diligence to research what I need, including searching this forum and the sticky. I'm still unsure of exactly what unit to order. It's my understanding that you should focus on the the amperage, not the hp of the motor when choosing the proper size of vfd - and double the amperage. In this case I would need at least a 10.8 amp vfd then correct? I've seen a lot of people like the TECO brand units (I know to avoid the cheapo Chinese brands). Here is a 10.5 amp TECO vfd - https://www.vfds.com/3hp-230v-teco-n3-vfd-n3203csu - is this what you would recommend? $350 is more than I would like to spend to get this sander up and running, but I don't want to cut corners either. Please help me out and set me straight here, some examples of models that you think would work in my application would help as well. Thanks in advanced folks!

 

[TTMotorsports]

Most likely cheaper to swap the motor down below out to a single phase motor and be done.

 

[MadeByMiller]

Perhaps if I can find a used motor, a single phase motor with similar specs to whats existing is about the same price as a vfd. I'm intrigued at the thought of a variable speed/reversible sander as well.

 

[MattT]

That "double the amperage" de-rate is when you're using a three phase input VFD on single phase power. The drive you linked is single phase input so it doesn't require a de-rate. And is therefore larger than you need.

Quick look on the site you linked found this one which should work. You could go much cheaper than that if you're willing to take a chance on off brand chinese.

https://www.vfds.com/variable-frequency-drives/2hp-230v-teco-n3-vfd-n3202csu

 

[ClappedOutBport]

Most likely cheaper to swap the motor down below out to a single phase motor and be done.

Nonsense.

That "double the amperage" de-rate is when you're using a three phase input VFD on single phase power. The drive you linked is single phase input so it doesn't require a de-rate. And is therefore larger than you need.

Quick look on the site you linked found this one which should work. You could go much cheaper than that if you're willing to take a chance on off brand chinese.

https://www.vfds.com/variable-frequency-drives/2hp-230v-teco-n3-vfd-n3202csu

Correct.

These work fine. Save your dosh. https://www.ebay.com/itm/2-2KW-3HP-...E-INVERTER-VFD-Speed-Control-VSD/222092196433

 

[isb cornbinder]

I bought this same belt/disc grinder a few weeks ago. Like you unit, the one I bought is three phase. With a long term view to what I might need, I bought an American Rotary 10 horsepower rotary phase converter.
I am including a link to a You Tube video.

Kieth Rucker is a person I trust and I made my final choice on his advice.

 

[pstemari]

The Hitachi VFDs are the usual recommendation I see here, and my experience with one in the ERL-1340 was highly positive. Maybe I could have saved $50 by getting a TECO or no name VFD, but the programming the Hitachi was very straightforward and I haven't had any issues with it.

Sent from my Pixel XL using Tapatalk

 

[Davefr]

I'd buy this unit for $120:
Teco, L510-201-H1-U

Yes, it's rated at 4.3 amps and your motor is rated 5.4 amps but the VFD's 4.3 amp output is constant yet your motor's 5.4 amps is at max. load. Put an amp clamp on your sander and I bet it runs well below 5.4 amps in ordinary use.

The VFD will also provide a 150% short term overload factor (ie 6.5 amps max).

For these reasons, it's generally OK to slightly undersize a VFD because VFD prices go up quickly once you cross the 1HP threshold.

I'd also run an autotune on your VFD. That will marry the VFD to the actual motor in use.

If you want to be conservative then get this unit for $175:
L510-202-H1-U (2HP)

I run a 120V L510 rated at 1 HP to drive a 1.5 HP/5.5 amp 3 phase DP motor and it's been fine for several years. (These VFD's will protect themselves in a major overload condition but it's never had to.)

I like the Teco line because documentation is excellent. I've read stories about guys buying no name Chinese VFD's and struggle with the bare bones documentation written in (Chink-lish).

 

[seber]

I did the same for a very similar unit. Replaced the motor for $50. and scrapped the old one for $10. I have a VFD that I use for other motors all wired to the same source but sometimes just replacing the motor makes more sense. If you go VFD I would go with Hitachi. The Teco works fine but makes a lot of RF noise. Your neighbors WILL notice.

 

[dutchgray]

I think a VFD on a belt/disc sander would be more useful than sticking a single phase motor on it as it will allow you to tweak the running speed a bit to suit the material you are sanding.

 

[MadeByMiller]

That "double the amperage" de-rate is when you're using a three phase input VFD on single phase power. The drive you linked is single phase input so it doesn't require a de-rate. And is therefore larger than you need.

Quick look on the site you linked found this one which should work. You could go much cheaper than that if you're willing to take a chance on off brand chinese.

https://www.vfds.com/variable-frequency-drives/2hp-230v-teco-n3-vfd-n3202csu

Oh great, I was way off then! Thank you

I'd buy this unit for $120:
Teco, L510-201-H1-U

Yes, it's rated at 4.3 amps and your motor is rated 5.4 amps but the VFD's 4.3 amp output is constant yet your motor's 5.4 amps is at max. load. Put an amp clamp on your sander and I bet it runs well below 5.4 amps in ordinary use.

The VFD will also provide a 150% short term overload factor (ie 6.5 amps max).


For these reasons, it's generally OK to slightly undersize a VFD because VFD prices go up quickly once you cross the 1HP threshold.

I'd also run an autotune on your VFD. That will marry the VFD to the actual motor in use.

If you want to be conservative then get this unit for $175:
L510-202-H1-U (2HP)

I run a 120V L510 rated at 1 HP to drive a 1.5 HP/5.5 amp 3 phase DP motor and it's been fine for several years. (These VFD's will protect themselves in a major overload condition but it's never had to.)

I like the Teco line because documentation is excellent. I've read stories about guys buying no name Chinese VFD's and struggle with the bare bones documentation written in (Chink-lish).

Thank you very much for the detailed info and examples. If I were to go the slightly undersized route, is anything stopping me from just going with a 110v input 1hp vfd? It would be nice to not need a 220v circuit for it. Maybe a unit like this - https://www.amazon.com/dp/B01J8K3UVI/?tag=atomicindus08-20

 

[seber]

Be aware that running a 1 1/2 hp motor on 110 vac will draw around 12 to 13 amps running. Starting current MAY give you a circuit tripping problem.

 

[MadeByMiller]

Be aware that running a 1 1/2 hp motor on 110 vac will draw around 12 to 13 amps running. Starting current MAY give you a circuit tripping problem.

Great point. I'm thinking of going with the TECO L510-202-H1-U (the 2hp unit) just so I know I can push the sander as hard as I need to. I'd hate to have to worry about not being able to run the machine as hard as the motor is capable. What else do I need to get the sander up and running with a vfd? I know I'll need to build or buy a dustproof enclosure for it, and I'll obviously need the proper plug and wiring for it. Some people run remote switches as well, or retrofit the existing machine switch somehow. Is there anything else that goes into adding a vfd?

 

[American Locomotive]

I would not undersize the VFD on a belt sander. You can get away with stuff like that on a drill press, where you would really rarely use the full power of the machine. You cannot say the same about a big belt sander, especially if you're really hogging away at some metal.

Get a 2HP VFD and be done with it. The proper way is to put the VFD in an enclosure and either remote mount the drive interface panel (most VFDs allow you to do this) or setup separate remote controls for the drive. Keep in mind that the drives do dissipate considerable heat, so you enclosure should probably be vented with dust filters.

 

[MadeByMiller]

I would not undersize the VFD on a belt sander. You can get away with stuff like that on a drill press, where you would really rarely use the full power of the machine. You cannot say the same about a big belt sander, especially if you're really hogging away at some metal.

Get a 2HP VFD and be done with it. The proper way is to put the VFD in an enclosure and either remote mount the drive interface panel (most VFDs allow you to do this) or setup separate remote controls for the drive. Keep in mind that the drives do dissipate considerable heat, so you enclosure should probably be vented with dust filters.

Thank you. As mentioned above, I believe I will be going with the 2hp L510-202-H1-U.

 

[MattT]

I would not undersize the VFD on a belt sander. You can get away with stuff like that on a drill press, where you would really rarely use the full power of the machine. You cannot say the same about a big belt sander, especially if you're really hogging away at some metal.

The proper way is to put the VFD in an enclosure and either remote mount the drive interface panel (most VFDs allow you to do this) or setup separate remote controls for the drive. Keep in mind that the drives do dissipate considerable heat, so you enclosure should probably be vented with dust filters.

It's do-able without venting/fans if the enclosure is sized for it. Though it'd probably be easier/cheaper to use a NEMA 4, or better, drive if the OP wants to do the job properly.

The FM50 ain't the greatest drive but good enough at an excellent price for NEMA 4X.

https://dealerselectric.com/item.asp?cID=2&scID=187&PID=49291

 

[Davefr]

Oh great, I was way off then! Thank you



Thank you very much for the detailed info and examples. If I were to go the slightly undersized route, is anything stopping me from just going with a 110v input 1hp vfd? It would be nice to not need a 220v circuit for it. Maybe a unit like this - https://www.amazon.com/dp/B01J8K3UVI/?tag=atomicindus08-20

That's the exact VFD I use on my 1.5 HP DP and it's been flawless.

However American Locomotive makes a good point that if you're really going to be pushing this sander continuously then upsize the VFD to 2HP and not worry about it.

I would also consider an enclosure if you're going to create a ton of dust.

 

[American Locomotive]

I personally like the Automation Direct GS2 series of drives. They're an older design and lack some more modern features (like Sensorless Vector Control), but they're well priced, extremely high quality and come with a decent warranty. They're filled with top-quality Japanese capacitors, top-shelf Delta cooling fans, etc... I'm actually quite sure they're just private-labeled Delta VFDs, likely from one of Delta's older series.

The nicest thing about these drives is that they're extremely easy to setup, and the menu system is really intuitive.

https://www.automationdirect.com/ad...uency_drives_(vfd)/micro/drive_units/gs2-22p0

 

[Mr. T]

I personally like the Automation Direct GS2 series of drives.

We have a bunch of these where I work. If you’re not trying to do anything fancy with them they hold up quite well.

So if you’re just using it to get 3 phase at 60hz they do the trick.

Also nothing wrong with a 4x enclosure but I wouldn’t hesitate to use something cheaper. You could probably get an adequately sized pull box for very little money. Put some foam tape on the top edge of the cover (or the whole way around) to keep the dust from falling in.