VFD or phase converter

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VFD or phase converter

Post by richcorr » Mon Apr 29, 2019 4:08 pm

I purchased an Atlas Copco Gx2ff Rotary Screw Compressor, 3 phase. Getting 3 phase to my shop is not an option. What is my best option, a VFD or phase converter. I am not super knowledgeable on this subject. Suggestions would greatly be appreciated.
230v 60 Hz 2,2 Kw

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Re: VFD or phase converter

Post by cuttinparts » Mon Apr 29, 2019 4:21 pm

I am no electrician or expert on the topic but believe a phase converter would be your best solution. I would think a VFD would be used in an application that required a variable frequency to allow motor rpm to be modulated like in a mill so you could vary the spindle speed to the appropriate rpm. Maybe someone else has more info for you on this topic. Sounds like a sweet compressor though!

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Re: VFD or phase converter

Post by djreiswig » Mon Apr 29, 2019 5:54 pm

You can get VFD's that will convert single phase to 3 phase.
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Re: VFD or phase converter

Post by sphurley » Mon Apr 29, 2019 10:36 pm

There are three kinds, Static (Phase O Matic) just a relay and a capacitor, Rotary, (start a three phase motor with a static unit and then it's output is 3phase, and Digital, (VFD falls into this also) which can be the best in the long run (larger upfront cost but may save it on Electric bill)(Phase Perfect).
Don't get cheap, you have a really nice compressor.
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Re: VFD or phase converter

Post by TrinityFabworks » Tue Apr 30, 2019 7:58 am

I run my bridgeport off of a cheap amazon VFD, and the thing works like a charm! They also had great customer service when I was getting it all set up originally. If this is your only 3 phase equipment, I would just buy a vfd. Very simple to use, and very affordable. Mine will run a 5hp motor and it only cost like $230. It's very small, and starts with the click of a button.

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Re: VFD or phase converter

Post by tcaudle » Mon Jun 10, 2019 4:11 pm

A compressor presents some challenges. A big 3P electric motor has a HUGE start requirement. . The motor is fully loaded so it has to start it and the load spinning A VFD is an electronic device and to begin with it has to have about 30% more capacity to go from single phase to 3P at any level. To run that motor at 230 you need about 16A (about 4000 watts) . To start it you will need at least 3 times that. A rotary converter stores energy in the inertia of the motor so it can handle a short term surge better. Also you can add an "idler" 3P motor that adds to the primary rotary motor's capability . You can build your own 3P converter pretty easy. Simply find a large 3P motor and get a Converter panel already built from someone like American Rotary. Get about double the motor HP and converter panel than your compressor is rated at.

We have three large machines on rotary converters Haas VMC; BridgePort CNC mill and 48 inch metal shear. I have smaller machines I run with VFD .

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Re: VFD or phase converter

Post by Old Iron » Tue Jun 11, 2019 8:04 am

Tom's reply is spot on.
I've got a 60 ton press break and I run it with a 30 hp rotary phase converter.
I got mine from this company. Here's a 10 hp control panel for $294 just buy a 10 hp used three phase motor and your in business.
https://www.northamericaphaseconverters ... nel-cp-10/


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