Rotary Phase Converter Designs and Plans

We have laws agginst distributing that stuff down here....




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Think Snow Eh!
Ox

I'll throw my $.02 in here I suppose, I'm no electrician. I've built a 10hp self-starting, 20hp pony start, and 60hp "regular" start RPC. The 20hp is no longer pony start, and is what I'd call a "regular" start. That meaning it starts off 3ph power being generated.

It's a bit of a messy drawing, but it was functional. Originally the 20hp used a 1.5hp 120v pony motor to jog it up close to speed, then engage power to 20hp while disengaging power to 1.5hp pony motor.
I seem to have a problem with getting cabinets that I think will be big enough, but end up being super cramped. It was a little better on the 60hp RPC build though. The 20hp now starts off the 3ph being generated by the 10hp, and the 60hp starts off the collective 30hp now being generated by 10hp and 20hp RPC's. I don't have a photo of the 60hp cabinet handy at the moment. I did use illuminated pushbuttons though, for added "fun", on the 20hp and 60hp units. Probably why the drawing is a bit messy, the extra wiring to go along with it. I believe this was the final rev of the drawing.


Here's the diagram I used to build the 10hp self-starting RPC.

15hp I built I don't know why people go thru the extra cost or complexity of adding the power loss contactor. 2 reasons I didn't do it. 1 that should be built into your machine already. 2 if you had actual grid 3 phase and power is lost then restored you'd be in the same boat. just remember to shut it off.
Video of it running a very small load. I built this for a friend to run a 2hp Mill but he intends on getting bigger equipment later.
YouTube
Here's a video of it running a 5 ton military surplus air conditioner while I was tuning it.
YouTube
I know how dangerous it was to grab the gauges. I have kids now so I do take more precautions now.
20 hp unit I'm building for same guys grandfather.he has a 10hp lathe and was using a 10hp RFC but it burned up as you could imagine. Total loss. So he's getting a new one from scratch.


Then I'm building my own 30 HP unit for my equipment.
It's the green motor in the 2nd pic. But mine is a 3600 rpm motor so it's the same size as the 1800 rpm 15hp and smaller then the blue 1800 rpm 20 hp motor.
I've been using a 20hp 480v VFD to run my equipment up to this point but I hate changing all the settings every time I switch machines. I'm stepping up 240 to 480 with a single phase transformer then only inputting 2 hot legs into a 3 phase vfd. So I'm limited on 50% ish of my rated output so it runs my 10 hp 120 gallon Kellogg air compressor ok when I set a 5 sec start ramp.
Here's a video of that. Don't mind the 3 phase transformer sitting there it's not hooked up. $50 seamed like a deal I couldn't pass for something I didn't need. So now it just sits there.
YouTube

Not entirely sure that your reference to "power loss contactor" is what you think it is. They're not any more complicated or expensive than your standard contractor, really, but it's much safer. Momentary button energizes the coil, and a "loop" if you will, maintains coil energy after momentary button is released. If there is anything more than a power flicker it'll de-energize the coil and not turn back on until you press the button again. It really is that simple. Not any more expensive, it's a contractor with 1-4 additional "low amp" contactors on it, if that makes sense. When i built mine, they went any more expensive on fleabay than a contractor with no other contacts on it.

pianoman8t8 said:

Not entirely sure that your reference to "power loss contactor" is what you think it is. They're not any more complicated or expensive than your standard contractor, really, but it's much safer. Momentary button energizes the coil, and a "loop" if you will, maintains coil energy after momentary button is released. If there is anything more than a power flicker it'll de-energize the coil and not turn back on until you press the button again. It really is that simple. Not any more expensive, it's a contractor with 1-4 additional "low amp" contactors on it, if that makes sense. When i built mine, they went any more expensive on fleabay than a contractor with no other contacts on it.

Click to expand...

I'm aware it's just another contactor. But now I'm buying 2 instead of one then I'm adding another switch and wiring. And I always use contactors with 240v coil so I don't need a transformer. A lot of guys use what they have lying around so then end up using a 110v coil or 24v coil that needs a step down transformer or a neutral. Then if they are using the ground wire as a neutral they don't have a ground. Your ground should not carry working current. All at this power loss safety is built into your machine already isn't it.... So why the redundancy? If you loose power in a shop with 3 phase when the power comes back on it just comes back on doesn't it. All my machines utilize this technique with their built in contactor hooked to their individual start stop buttons. Just seams like bells and whistles to me. But to each their own. If someone wants to use it. I won't talk em out of it just tell em why I don't. If your machine doesn't already have this built into it and you start you RFC and your machine is on your in the same boat as a power loss without the safety built into the RFC.

Green machinist said:

I'm aware it's just another contactor. But now I'm buying 2 instead of one then I'm adding another switch and wiring. And I always use contactors with 240v coil so I don't need a transformer. A lot of guys use what they have lying around so then end up using a 110v coil or 24v coil that needs a step down transformer or a neutral. Then if they are using the ground wire as a neutral they don't have a ground. Your ground should not carry working current. All at this power loss safety is built into your machine already isn't it.... So why the redundancy? If you loose power in a shop with 3 phase when the power comes back on it just comes back on doesn't it. All my machines utilize this technique with their built in contactor hooked to their individual start stop buttons. Just seams like bells and whistles to me. But to each their own. If someone wants to use it. I won't talk em out of it just tell em why I don't. If your machine doesn't already have this built into it and you start you RFC and your machine is on your in the same boat as a power loss without the safety built into the RFC.

Click to expand...

In my case my self starter occasionally stalls on start so if power loss happens and I'm not right by it, it could burn up the motor.

TD-4242, should have over current protection device for that anyway.

My simple converterView attachment 285592

Idler motor is a Weg 3460 rpm.

peterh5322 said:

http://www.metalworking.com/dropbox/_1998_retired_files/FRW-n.txt

http://www.metalworking.com/dropbox/_1998_retired_files/FRW-1.jpg

http://www.metalworking.com/dropbox/_1998_retired_files/FRW-2.jpg

http://www.metalworking.com/dropbox/_1998_retired_files/FRW-3.jpg

http://www.metalworking.com/dropbox/_1998_retired_files/FRW-4.jpg

http://www.metalworking.com/dropbox/_1998_retired_files/FRW-5.jpg

http://www.metalworking.com/dropbox/_1998_retired_files/FRW-6.jpg

Click to expand...

Are the old Fitch Williams designs available anywhere? The metalworking.com website is dead. I built my RPC using one of Fitch's designs 15 years ago and now I would like to modify it and add a Steveco potential relay.

-Dave

rimcanyon said:

Are the old Fitch Williams designs available anywhere? The metalworking.com website is dead. I built my RPC using one of Fitch's designs 15 years ago and now I would like to modify it and add a Steveco potential relay.

-Dave

Click to expand...

I made a 10hp about 10 years ago and used the Fitch design. I don't think it is needed to put in a potential relay. Just look through these posts and see if you can find a post that contains the circuit for the potential relay.
I use the on button and press it for maybe a third of a second. Pretty much I press it as fast as I can. Why do you want to use the potential relay? Someone else going to be starting it? [emoji16] Just keep a couple of hundred extra capacitors on hand.
Did you use electrolytic capacitors in the start circuit?

https://www.practicalmachinist.com/...r-designs-plans-101231/index3.html#post335009

This may help.

iCloud

A picture of my homemade unit

Green machinist said:

I'm aware it's just another contactor. But now I'm buying 2 instead of one then I'm adding another switch and wiring. And I always use contactors with 240v coil so I don't need a transformer. A lot of guys use what they have lying around so then end up using a 110v coil or 24v coil that needs a step down transformer or a neutral. Then if they are using the ground wire as a neutral they don't have a ground. Your ground should not carry working current. All at this power loss safety is built into your machine already isn't it.... So why the redundancy? If you loose power in a shop with 3 phase when the power comes back on it just comes back on doesn't it. All my machines utilize this technique with their built in contactor hooked to their individual start stop buttons. Just seams like bells and whistles to me. But to each their own. If someone wants to use it. I won't talk em out of it just tell em why I don't. If your machine doesn't already have this built into it and you start you RFC and your machine is on your in the same boat as a power loss without the safety built into the RFC.

Click to expand...

If a 3 phase system is wired properly thru a pushbutton stop/start contactor, the motor does not come back on after power loss. The fourth contact in the three phase contactor is wired in parallel to the start switch and holds in the contactor when you release the pushbutton.

First 3 Phase Portable Power Project

Hello, newbie here attempting our first 3 phase generator portable power plant to run our 10 hp 3 phase farm plant/material grinder. We’re well into the project and having trouble(s). I have an overall photo with text data added to show the entire build (on a trailer) and I have photos of all the various components (nameplates). If I should post this somewhere else on the website please let me know. Great site! Thanks and thanks for any help, feedback, questions. Aaron

One of the photo posting how to threads

https://www.practicalmachinist.com/...res-south-bend-forum-372508/?highlight=photos

have fun

Jamie said:

Ok guys;
Here is my contribution to the cause. I'll just
move it up from a previous posting.
First is a picture of the finished RPC.
Motor and base actually came from an abandend
Commercial Air Conditioning unit, the motor
was new, so I took it. Recyclers only charged
me $20.00 bucks for it. For $5.00 more they let
me take all the caps and relays I could carry.
The case was a Junction box the recyclers sold
me for another $5.00. With a few odds and ends
the total cost was under $60 dollars.

These are the schematics that I used. They're
based upon an original set of schematics of a
friend of mine, with my modifications.
ie: letting the L3 Voltage rise, determine when
to cut-out the start capacitor.

Jamie

Click to expand...

Nice looking unit, is it possible to get a clearer image of the schematic please . thanks for sharing

Hi, nhengineer . i like the look of your setup and would love a copy of your setup if possible . im struggling to run a 3 phase radial saw and need something like this . Kind regards Pat

I have built many RPC’s up to 30 HP. Not hard at all. Personally I don’t like potential relays. I opt to use a time delay relay. I have RPC’s 30 years old. If I can help please ask.

I see that this thread are not as active as it was, and I want to say thank you to all of you, I have learned extremely much here. I have not had any practical need for it since 3 phase is exremely common here in Norway, I even have that to my cabin. :-) and that is good for the puming from a drilled borehole (Well) of 80m depth. (87 YDS) Thank you all!