Below is an inexpensive way to connect and distribute the phases. It is electrical conduit cut in half, providing an insulated mounting surface for the "distribution strips" (which I do not know the proper name of)
Here's the Fitch Williams design (pdf format):
Fitch Williams phase converter
Here are the Hanrahan plans:
And finally the Carlson stuff:
Carlson phase converter plans
Here is my own Fitch William's 10HP RPC. I keep thinking I will go back into it and neaten it up, but for now I just enjoy its great performance. Most of the parts where surplus or otherwise scrounged.
For example, the industrial disconnect switch was found at a local flea market but was a bit rusty and otherwise weather worn. A bit of sanding and new paint and a 10 dollar flea market find returns to its place as an expensive(if new) disconnect.
Total cost for the RPC was about $220.00, including the $100.00 for the idler.
[ 12-11-2006, 09:41 AM: Message edited by: jhg ]
jhg, if my wiring looked that good, I'd leave the door open all the time, giving an occasional blast of air. [img]smile.gif[/img]
Hello all, I wish I had read thru these forums a few months ago as my work threw out a bunch of 3 phase machinery. I passed it up because I thought I could not use it. That I aside I would like to refresh/learn more about AC et al. I have single phase 220 service and would like to set up a small shop. Are there any documents or ebooks that I can be directed towards that would help me?
Klaus, I can't imagine a better resource than the one you are on right now. Go back through the archives and never let a beautiful piece of 3PH machinery die needlessly again.
my work threw out a bunch of 3 phase machinery. I passed it up because I thought I could not use it.
If nothing else, the success stories should inspire you to try. It's one of those fairly simple projects, yet very satisfiying, to say nothing of exceptionally useful.
You'll find knowlegable people here, always happy to answer any question you may have.
My personal opinion, go big. A large 3PH motor doesn't take a lot of juice to maintain an idle, and it's always ready to jump in and run that bigger machine that follows you home. When I decided to build mine, my largest 3PH machine was 1HP. Before I got it online, a 3HP machine adopted me.
My 10HP RPC keeps egging me on to find yet a larger machine. It's asking for a little brother, something like a 20" G&E universal shaper but it's not picky, a #3 Cinci horizontal, maybe a K & T, Van Norman seems to please, a 16" Monarch for a good price got away before I realized that the two wires my power company has running down my street could be induced to supply three.
I've got a good 15HP motor standing by to daisey chain my system into a 25HP version should a medium sized horizontal boring mill stand with a tear in it's eye at the orphanage. [img]smile.gif[/img]
Bigger dreamer than doer, Bob
I have a question about the Fitch Williams RPC design. Why use a transformer to convert from 240V to 120V? Why not just use a neutral wire? Just in case you dont have neutral in that box?
Also, why transform to 120V vs 24V? Is there an advantage either way?
My RPC is mostly done, so I figured I'd post a pic or two... Curently my biggest load is 3hp, but I built a 10hp for expansion room. It is mostly a FW design, but I pulled an idea or two from just about all the designs on the net...
This is the schematic, I actually wired a neural into the box, but it turned out I did not need it so it isn't shown in the above
It is not the prettiest one out there, but I think it came out OK for someone who did not know what a RPC was before this site. The neutral wire is not connected to anything because I did not need it for the indicators. My previous RPC was given to me by a friend, and knowing what I know now, it was wired up pretty poorly.
I got the box at a local auction for $5. Originally I was going to use the hold the button till the motor starts method, but I decided to go with potential relays because I may add remote starting boxes closer to the machinery. The starting circuit is 24VAC and the transformer is hooked to the shop lighting circuit so if I forget to shut the RPC, when I shut the lights off, the RPC shuts off.
The idler sites under a shelf that I keep jacks and jackstands on. I got it from a local guy on eBay for $112.50. It is a 1750 RPM TEFC 10hp Baldor.
This picture shows everything, the disconnect, the cap / contactor box and the idler. I have not hardwired the output to the machininery yet, but that will come soon.
hey 2slow looks nice but i have a couple questions why 2 potential relays ? why 3 sets or fuses with a breaker to boot ? why the 40uF between the l1 l2 ? most plans i've seen dont include that
Quote: “why 2 potential relays ?”
I needed about 775uF of starting capacitance to start my 10 HP idler. The Steveco potential relay contacts are only rated for 50 amps, and it only takes about 550uF to generate 50 amps using the equation I = 2 * Pi * f * C * V where Pi is 3.14, f is the frequency in Hz, C is the capacitance in farads, and V is the voltage in volts. Substituting I = 50amps (the Steveco contact rating), f = 60Hz, V = 240VAC you get
50 / (2 * 3.14 * 60 * 240) = .000553 F = 553 uF
Since I needed 775 uF that gives ~ 70 amps which is more than a single Steveco could handle
There are a few solutions to the potential relay contactor current limitation problem. One is to have one potential relay control a second magnetic contactor that switches the caps, the other solution is to break the staring circuit into multiple pieces and use multiple potential relays. For my situation it was cheaper to use 2 potential relays so I went that route.
Quote: “why 3 sets or fuses with a breaker to boot ?”
I guess I did not really need the 50 amp fuses in the disconnect switch in addition to the 50 amp breaker, but I was able to purchase a fused disconnect switch surplus for less than what a non fused one would cost new, so that is why that set of fuses is there.
Since my idler motor FLA is 28.5 amps, I added the 30 amp fuseblock to give some level of overload protection to the idler, although I plan on adding a true overload in the future. Also had I not fused the output wire at 30 amps, I would have been required to run 6awg wire to the idler since it would only be protected by the 50 amp breaker and 50 amp fuses. With the 30 amp fuses I could have run 10awg to the idler, but I ended up using 8awg that I got at half price since it was the last 10 ft of the roll and it ended up costing less than 10 awg. The 8 awg should have a little less voltage drop, but it probably is insignificant since the run is so short.
The 30 amp fuseblock on the output side is there so that I can run 10 awg wire as distribution throughout the shop. 10/3 with ground is expensive and hard enough to bend, I did not want to have to run anything heavier for the long shop distribution lines. The generated leg would never be over 30 amps anyway so I figured fusing at 30 amps was a good idea.
You may wonder why I didn’t just run a 30 amp breaker and 30 amp fuses in the disconnect. I wanted my load side to be able to get the full 30 amps, as well as my idler motor to be able to get it’s FLA. To do this I would have actually needed ~80 amp input, but I did not want to deal with the very heavy wire that would be needed. I went with 50amp, since that meant 6 awg wire which wasn’t too bad for the short runs.
Quote : “why the 40uF between the l1 l2 ? most plans i've seen dont include that”
The 40 uF cap between L1 and L2 is a “power factor” correction cap. It is installed to reduce the amperage flowing through the lines. It does not reduce wattage consumption much, since it is just reducing reactive current, but it does reduce the current through the L1 and L2. I got that from the Fitch Williams Paper . It is also mentioned in the Bob Sweeny article .
Ok here goes. . .
I had mentioned I had created a drawing for a 20 HP rotary converter that I am currently building. I hope the drawing will show up here
What are you doing for your delay timer, KT?
Well funny thing is It was riveted into a box, don't know the specs on it. I will be taking everything out of the box and arranging it differntly in next week or so. I should have more info then. Most any timing circuit relay that can handle 220 vac and the amps of the start capacitor relay coil should work. Item# 137-B www.surpluscenter.com will do the trick for $20.00 or so
I hope to get the drawings made of my load distrobution box with the circuit breaker contact arangment sone.
Oh by the way I ordered 6 each 60uf Run Caps the other day, they are too tall to fit my project 9". I ordered some shorter ones, I now have 6 Caps extra laying around.
I aquired 2 Delta Lathes, 3 Delta drill presses and a Bridgeport mill along with 2 Phase-A-Matic static converters. I am running all the machines off of a 30Amp dryer outlet. The mill and the drill presses run fine with the static converter. I needed to smooth out startup on the lathes so I purchased a 1HP 3p dayton motor for an idler from grainger. I put it in the lathe power loop with 1 of the static phase converters.
I built a distribution box from a 120A breaker box and used 2 15A breakers to protect the 2 circuits in my system.
I have 2 circuits from the supply, one is static and the other, which the lathes are powered by, is static or rotary with a 3p switch for the rotary idler. The mill runs off of one static outlet of my distribution box, the drill presses are supplied from the other static outlet through a junction box. Each outlet is supplied from a NEMA 20 three phase plug and outlet. The supply is a NEMA 30 3P chord that plugs into the single phase dryer outlet. TheSupply is chorded with 3X8 600v cable.
I am able to run all of the equpment simultaneously (all machines running at idle) and everything starts smoothly. My next project is to add VFDs to the lathes and mill for better speed control and more precise current protection.
I'll add one to the mix. The following web page has the schematic and functional description for a phase converter I built last year to power a VMC.
Pony-start 20HP balanced RPC
My new retirement “Toy Shop” has two pre-packaged CNC style rotary phase converters The one is a GWM 5 HP and the other is a DesCO Electrical Industry10HP. I have them setup to run either one or both in tandem for maximum output. Each converter has its’ own relay so that it will not be back fed when only running a single converter. From this relay cabinet the power is distributed to a three-phase load center with breakers for all my equipment. The three-phase output is 240 Volts and works great for all my machines, except for my 2D Kearney Trecker Rotary Head Mill. That I have a 3KW dry type three-phase transformer that boosts the power to 480Volts.
My first RPC. A variant of FW's design. I want to keep it simple as can be. And the little baby that it drives.
The EMO & lighted push-button are in series with each other. Push button energize run contactor which in turn energize the start contactor.
A NEMA 14-30R is used for output so I can easily switch from one machine to another.
Enclosure ... $28 Lowes
5hp GE idler ... $0 from a friend
EMO switch ... $4 Halted Surplus
Lighted push-button switch ... $0 from a friend
Square-D 30A/3/Dp contactor ... $41 Grainger
Square-D 40A/3/Dp contactor ... $47 Grainger
Start Cap 270-324MFD 220-250V... $14 Grainger
Run Cap 80MFD 370VAC ... $18 Grainger
Run Cap 50MFD 370VAC ... $20 Grainger
Run Cap 15MFD 370VAC ... $10 Grainger
35' 8/4 SO cable ... $60 Buckles & Smith
Yellow 10-12 Ring Lug ... $2 Halted Surplus
Pass & Seymour NEMA 14-30 P&R ... $30 Lowes
NEMA 14-50 dryer conversion ... $30 Lowes
Total cost of 5hp-RPC parts ... $304 + 16 hrs.
Seeing my 10EE run for the first time ... priceless.
Here's pics of the RFC I put together for my shop about 5 years ago. Since then I've had 3 phase installed in the shop as I added more equipment than I wanted to run on a converter.
The converter motor is 7-1/2hp that I cut the output shaft and plugged the end housing so nothing was exposed. All of the parts/material were from salvage or ebay. I installed a 20 amp breaker inside the cabinet and corresponding outlet on the bottom of the cabinet for the mill I was running. I didn't want the main 50amp fuses to be the protection for the running equipment Left room on the right side of the panel for another "branch" circuit breaker.
The meters helped in tuning the capacitors.
There's a separate start circuit and start capacitors. Runs really quiet.
The motor is mounted on a pc of urethane along with the front cart edge being cushioned.
I live in South Africa and have only recently heard about RPC's. Been looking at your chats on this and would like to know whether anyone can put me in touch with the Fitch Williams design since I do not seem to be able to trace it on the web. I am planning on building a RPC that should be able to power 3x woodworking machines 2 are 7,5Hp and one is 5,0Hp. Although they will not run all at the same time it might happen that two will run simultaneously. Also our single phase is 220/250VAC and the three phase is 380VAC. I am planning on doing the 380VAC by going through a step-p transformer. Any comments/input/advice from you guys out there that have gone through a similar situation.
Try this link Fitch Williams
The search function also works well
Try reposting more specific questions as a new post, I think this post is meant for RPC's already built.