VFD for three phase from single

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Brian
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VFD for three phase from single

Tue Aug 29, 2017 2:09 pm

Curious as to the group's experiences with VFD's for phase conversion. I have a line on a three phase machine that I'm considering but of course the power conversion is a bit of a hang up for me.

I use a VFD on a milling machine at my father's shop to success but at 2hp and moderate RPMs I have never really felt like it is a high stress setup. Considering a 16" jointer in three phase, looks like a nice machine and all. I never really read much about VFD's for woodworking equipment, so has the collective here any experience with VFD's and 5hp+ motors.
John Whitley
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Re: VFD for three phase from single

Tue Aug 29, 2017 4:27 pm

I'm curious what you find out, Brian. I've already committed to one three phase machine, a 5HP planer. I could do a VFD and leave it at that, but at this stage of my VFD education, I'm not clear how workable that is either. I'm currently leaning towards a phase converter, possibly opening the door to other three-phase gear. Then I get to consider what other equipment in the shop could/should be three phase. Dust collection? Table saw? What does that imply for the overall electrical design? etc.

You may already have found it, but the Transformers, Phase Converters, and VFD sub-forum on Practical Machinist has been a helpful resource.
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Brian
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Re: VFD for three phase from single

Tue Aug 29, 2017 9:31 pm

Thanks Gents, quite a bit of info to digest here!
crannygoat
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Re: VFD for three phase from single

Mon Sep 04, 2017 4:03 pm

I can verify from first hand experience that VFD's and machines with a brain (capacitors and such) are not compatible. I imported a used Martin t-54 from the Netherlands, and installed a VFD to correct the input frequency to 50 HZ. Fried the soft start relay and braking relay.

@Daruma, I wish I had posted here about my plans before implementing them. You seem to be the only person in the world who actually knows something about VFD's. Including the many technicians and commercial electricians I spoke with!


My two cents regarding phase conversion, if one can fund it at the power supply, you open the door to 3 phase machines of every type, and of course still have 110v available. 3 phase is way cheaper to run, and the motors tend to last longer. A VFD can only change phases for one machine as far as I know.
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Brian
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Re: VFD for three phase from single

Mon Sep 04, 2017 10:24 pm

I ended up taking a pass on that machine, wanting instead to go full boat and get a 20" jointer.

I would love to do a phase converter at the power supply and go from there, I just think it's impractical for my current shop...anything larger I would consider it a practical necessity. I can source single phase machines for most of what I want for my one car garage.
MBarnes
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Re: VFD for three phase from single

Tue Sep 05, 2017 7:39 am

VFD are like CVTs in cars, continuously variable speed at the final drive. The VFD is only to supply the motor directly. You will need some form of acceptable 3-phase for the rest of the machine, hence the converter. As mentioned above:
[/I can verify from first hand experience that VFD's and machines with a brain (capacitors and such) are not compatible. I imported a used Martin t-54 from the Netherlands, and installed a VFD to correct the input frequency to 50 HZ. Fried the soft start relay and braking relay. quote]
the rest of the machine needs its normal 50 or 60 cycle power. You will damage electronics if you use a VFD to supply the whole machine.
A VFD is used to perform speed control on a motor. You can do regenerative braking, like they do in electric cars to recharge their battery. You can also use them to perform power factor correction in large industrial settings.
I don't know the cost difference is but if you are planning to use more 3-phase equipment, I would think having the utility company install a 3-phase service is better. Large 1-phase to 3-phase converters probably get quite expensive, and they will be more prone to failure (at your expense) than the utility's supply. Make sure you look into repair costs if you go with a converter.
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Chris Pyle
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Re: VFD for three phase from single

Mon Oct 16, 2017 11:59 am

Hi Brian,
This is a bit late and I know you aren't considering the original machine but I had very good interactions with Eaton support to get my VFD squared away. I put one on my jointer and had some issues and they were able to walk me through it on the phone. Can't speak to longevity but many people seem to hold Eaton in high esteem. I know of at least one guy who is using a 5hp model, I think he paid $330 on Zoro with a 25% off? I purchased mine from Zoro as well but it was closer to $270 with the 25% off coupon.
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Brian
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Re: VFD for three phase from single

Wed Oct 18, 2017 10:32 pm

Awesome, much appreciated!

FWIW I think I'm going to stick to single phase for machines at least while I'm working at home. Once you get up sizes large enough to offer a safety margin for 7.5hp motors they get pretty expensive.
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Chris Hall
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Re: VFD for three phase from single

Thu Oct 19, 2017 6:48 pm

"Single phase" and "20" jointer" however do not generally appear in the same sentence AFAIK - - I can only think of Northfield as a manufacturer who provides single phase as an option on its belt drive version of jointer. And they don't make a 20" jointer anyhow. Are you aware of another make of 20" jointer with single phase motor?
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Brian
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Re: VFD for three phase from single

Thu Oct 19, 2017 8:20 pm

SCM makes one for their minimax line, of which I'm considering the Elite S which pretty near to a SCMI machine as far as I have been told.

Still not totally settled, I've been also considering the Felder 941 (16") as the 20 consumes so much space for me.

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