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Thread: 120v VFD for a Belt Grinder
02-14-2010, 12:10 PM #1
120v VFD for a Belt Grinder
Well here's what I'm doing. I'm building a 2x72 Belt grinder. Reason is I'm a beginner knife maker. So building it myself is cheaper.
I'm planning on using a 1.5 hp 3 phase motor and only have 120v available
Well anyway. What i'm wanting to know is this VFD General Purpose Drive, IP20<br>Up to 15hp, Single or 3 Phase<br>AC Tech SCM/SM - wolfautomation.com
a good one. And how much more involve is hooking it up other than power to and from
Thanks for any and all help here. This is my first experience with a VFD
02-14-2010, 01:19 PM #2
I have an ACTech SM015S VFD. It is the largest 120v unit they have (of this series) and is rated for a 1.5hp motor….mostly likely the unit you would be looking at.
It came on a 1hp Bridgeport …I have since used it on e a number of other smaller 3 phase motors… bench grinder, fan etc. all less than 1 hp.
It has performed flawlessly for its intended purpose… however; I have never pushed to its max…which is up where you would be using it. It came with the optional remote switch setup that works well. However, I will changing this so that I can use larger buttons including emergency shut off. I just don’t like the small blister type buttons.
As far as wiring it is very straight forward…however the catalog lists it at 24 amps on a 120v circuit …that’s a hefty line…If I had a choice I would have opted for a 220v unit just to keep the wire sizes down…
This was my first VFD after using a RPC for years…I’ve been pleasantly surprised at how well it works…
02-14-2010, 01:28 PM #3
atually I'm hoping it will be used to keep the speeds down. The faster it goes the more heat and thats not a good thing to the belt or steel.
thanks for the re assuance on the drive and the info too. I didn't know it pulled 24 amps not sure if I can pull that anywhere. You said you used it on other than the rated hp. Is that a problem. I was under the impression that they had to match. Or will it work up to the rating?
02-14-2010, 05:42 PM #4
The Wolfautomation site has a number of links for the info at the lower RH corner of the page.
Much better VFD people than myself should be able to answer weather you have to have a close match between VFD and motor...or as most everything else having extra capacity is a good thing...
I am still wondering about running two motors at the same time from one VFD....i.e. a Bpt head and a table drive or a surface grinder and a vacuum fan etc...
02-14-2010, 06:38 PM #5
if the mismatch isn't too bad, you can use a bigger VFD, but usually you want one that is not more than maybe 3:1 larger, since current limits etc need to be adjusted down.
Big ones with 120V input are not happening, too much current, so usually 1 or maybe 1.5 is a s big as they get.
It will only draw current for the power/speed you use, so it is perfectly possible that you won't need as much current as it suggests. You can set the motor current limit lower, and it will not draw too much.
But I don't see how you will use 1.5 HP , that much grinding power on a knife will heat the blade.... the power goes somewhere, you know, and ends up as heat, mostly.
02-15-2010, 12:26 AM #6
alrighty thanks for the help guys
it's much appreciated
02-15-2010, 04:35 AM #7
Thanks for the input...I'll try to resist the urge for more power...
On the question of two motors at the same time...obviously we are talking that their combined ratings do not exceed that of the VFD...and that their would be no switches between either of the motors and the VFD...are there limitations / precautions here somewhere?
I've read all I could find on this and search did not turn up much of anything...
02-22-2010, 08:30 AM #8
Alright well. I gues I got a bit over zealous when I made my purchase. It seems the 120v to 240v VFD I bought is single phase 240v. I do have a Single phase motor. But I've been reading about problems using a VFD on a Single Phase motor. Something about the Caps engaging when the motor is less than full speed, due to a centrifugal switch. I don't know if what I was reading is an old problem they have remedied. Or if it's an on going problem. I dont see how they would make something like that if there is a known problem.
Could I get a little insight on this please
The link in my first post is to the Drive I purchased
02-22-2010, 09:54 AM #9
Sorry to say, the VFD rite of passage seems to require spending a couple evenings puzzling over the manual.
A VFD should only be used to run 3 phase motors. You won't be running your 1 phase motor off it.
Your VFD sounds like it is set up to accept 240 single phase as an input (?), which it will then convert to variable frequency 3 phase power for a 3 phase motor. It also sounds from the initial description that it can be configured to accept 120 single phase as an input.
Good news is that used 3 phase motors are often cheap.
02-22-2010, 10:39 AM #10
I also have a 3hp unit from these people. It works very well and the only thing I have to say on it is I did not use the remote. Don't need it.
02-22-2010, 07:33 PM #11
I think I just got scared.If you go to the link It shows you can select options. if you choose the 120v input option and the 1.5hp option it says single phase input. I was scared that was the output on it.
Now reading through the option selections again. I think they are making sure you want the single phase input model.
I read through the Manual and it shows that it is in fact a 3 phase output. And I do have 3 phase motors. The Single Phase one I had was band new so I was kinda stoked to use it. Oh well I got others i can use
02-22-2010, 08:06 PM #12
The ACTech # SM015S VFD...120v 1ph in...220v 3ph out...rated for 1.5hp...
02-22-2010, 08:09 PM #13
that's the one
02-22-2010, 10:47 PM #14
We try to resist tangents inside of threads, it gets confusing. If this doesn't satisfy your multi-motor issue, start a new thread please.
No problem using multiple motors as long as you accept ALL of the following conditions (some you obviously knew already)
1. Each motor must have its own separate Overload Protection, each one wired in a way that will shut down the VFD if ANY motor overload trips.
2. You should not (must not) have switching devices downstream of the drive.
3. All motors will run at the same speed.
4. The VFD must be sized for the total combined FLA at a very minimum, many people suggest at least 10% extra because of the fudge factors inherent in the above mentioned overload protection devices.
5. You give up the benefits of Vector Control, i.e. speed accuracy and low speed torque. Even if your drive is capable of it, you must disable it by selecting the old V/Hz mode, otherwise the drive will not function correctly.