VFDs

[Larry Maas]

I know some of you have experience with VFDs so I'm hoping you might have some suggestions and info. Both my lathe and mill are three phase units, still sitting idle because I haven't figured out the way to wire them in yet. I have a rotary phase converter but it draws 40 amps, which is just about all I've got for power, nothing left over for lights and other minor luxuries. So I thought maybe a VFD would be a more practical solution, if in fact it would draw less amperage. I was hoping I could run either machine with the same VFD, just one at a time, don't know if that's possible or not. The lathe is 3 KW or about 4.1 hp, the mill is 3 hp. With a rotary phase converter (RPC), it takes double the hp RPC as the motor it's running, is this the same with VFDs? Is it best to get one with a braking system in it, even for the mill? Does that require a separate heat sink? Also wondering about the rheostat to control RPMs, I think that would be an asset. Are there any reservations about no ULC stamp on the side of it? 

Any thoughts, suggestions, warnings etc. would be appreciated. Electrical stuff is all alchemy to me. I've got a couple of projects that are dying on the vine while I've been trying to sort this out. Thanks to all. 

[David Wrate]

Hey Larry, I run my 1.5hp 3-phase mill off a Teco 220v vfd. I also ran my surface grinder off a 110v Teco vfd  I bought both from e-motorsdirect.ca. 

I would suggest that ideally it is better to have two vfds because you will likely program them differently. 

I would definitely get units with external braking resistors. My mill easily overwhelms the internal braking resistor if I set the brake time too low.

Call the folks at e-motorsdirect. They are really excellent to work with. 

David

On Jul 23, 2021, at 9:10 PM, Larry Maas <lsm...@hotmail.com> wrote:

I know some of you have experience with VFDs so I'm hoping you might have some suggestions and info. Both my lathe and mill are three phase units, still sitting idle because I haven't figured out the way to wire them in yet. I have a rotary phase converter but it draws 40 amps, which is just about all I've got for power, nothing left over for lights and other minor luxuries. So I thought maybe a VFD would be a more practical solution, if in fact it would draw less amperage. I was hoping I could run either machine with the same VFD, just one at a time, don't know if that's possible or not. The lathe is 3 KW or about 4.1 hp, the mill is 3 hp. With a rotary phase converter (RPC), it takes double the hp RPC as the motor it's running, is this the same with VFDs? Is it best to get one with a braking system in it, even for the mill? Does that require a separate heat sink? Also wondering about the rheostat to control RPMs, I think that would be an asset. Are there any reservations about no ULC stamp on the side of it? 

Any thoughts, suggestions, warnings etc. would be appreciated. Electrical stuff is all alchemy to me. I've got a couple of projects that are dying on the vine while I've been trying to sort this out. Thanks to all. 

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[roryn...@gmail.com]

I run lots of smaller machines with VFDs.  I do have one unit that powers both a drill press and bandsaw.  To switch between machines I wired in a universal 3 phase changeover switch.  Here's a link to the one that I bought.  https://www.amazon.ca/gp/product/B07ZKYDHF8/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1.  The switch required the user to figure out the terminals and install jumpers but once I figured that out, it was pretty simple.    If you go this route, I would definitely get a VFD that has an extension cable for the control unit.  For the machines that I have wired (up to 2 HP) the internal braking has been adequate.

Earlier this year I posted some information and pictures on this site.  https://groups.google.com/g/victoria-hobby-machinists/c/N-69EYGx9a0

[Alex Kunadze]

Hi Rory,

Do you have a good source for smaller 3 phase motors? The usual places mostly have 3hp an up monsters....

Cheers,

Alex.

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[David Wrate]

I bought the motor for my mill at emotorsdirect. 

David

On Jul 24, 2021, at 9:40 AM, Alex Kunadze <krol...@gmail.com> wrote:



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