Building a Phase Converter - Part 1 

The best phase converter video I’ve seen yet.

Exactly the series I needed! Open wire diagram and great explanation. Too many people complicate this and make it hard when it's not. Thanks very much. I have 3 phase in my shop now :)

This is how RU-vid should be done. Thanks for the efforts. They have been well received.

I have to totally be honest with you Birdranch. This is the first video I have seen that totally goes over all the relevant points in down to earth language. I am wondering why others on RU-vid have not figured out how to be so simple and to the point. Frankly this is just refreshing to see and hear your explanations. Great job fella. You should get an award for being number one. YOU ROCK FOR SURE. VF

Absolutely the best rotary phase converter series on youtube. Thanks for taking the time to enlighten us. I bought a used, homemade one, with no diagram, not connected to the pony motor, and i was pulling my hair out trying to figure it out. Thanks again!

Re-watching this as I have one to build. Couldn't help but notice the old school Amprobe like the one that I have had since I was a cub. :)

Great video on sizing and methodology of inserting the capacitors. Everyone else just seems to gloss over this very important step. Well done!

This is a fantastic display of how a rotary phase converter works! This was very helpful for understanding how a RPC functions, one component at a time. Very well broken down. Nice work!

Wow! Did I ever! It is the first time in all the time spent figuring out how to do this - that I feel comfortable! Thank you! Subscribed! And will watch the rest of the series.

First off great video series, the most common sense explanation of a rotary phase converter build and testing on youtube.

For my college course I'm building a 120v stepdown to 15v 1ph AC then making a 15v rotary phase converter... You have no idea how much this video helps.

What an excellent understandable tutorial you have put together for someone wanting to build their own converter! Wish I would have had this 20 yrs ago when I built mine and did all these very same steps as I figured out my start and run caps. You have made a seemingly complex subject very understandable for a first timer!! Kudos to you and all your efforts to help someone else you don't even know. Just Excellent!!😃

Thank you! I bought a Phoenix phase converter and it came from the factory out of balance. I didn't realize this till recently. They said to add capacitors to fix it and this was a great resource!

Been looking into making one of these for a While and this is the first video that makes it make sense. Awesome video!

Doug I have read & watched so much crap over about three years trying to build one - this is by far the very best tutorial - you are a genius - I have to deal with trying to step up to 415v with a reverse wired transformer but your set up is ace.

Wow! Breaking it down to the essential components was very helpfull. Thanks for taking the time to make this series.

This is better than learning at some schools. Salute for the effort sir!

Followed this Great Build making me a 10HP 3 phase for my shop! Works perfect for my Horizontal Milling machine and Grinder. Tuning Capacitors was lot of trial and error, Thank you from bottom of my heart I can troubleshoot and repair my own Unit! Randy

So far this was the best phase converter video I have seen. Thanks.

Thank you so much for your instructions. Now I can build my own with confidence. I was confused about amount of capacitors. Again, please keep us awake with anything news under your knowledge.

This is a well explained video. I watched other videos about these rotary converters but I never got a full explanation on how they work and how to balance them. Thank you. 👍

Your video helped me 4 years ago when I built my first RPC. Been utilizing it again to rebuild a new and improved version of it now that I moved. I was having trouble somewhere so I pulled everything out of the cabinet and screwed it all down to a piece of plywood so I could see everything and what do you know, worked perfectly. Any time I need to learn something or have questions about something, RU-vid is one of my first resources. After 10 plus years of utilizing YT I think your video here is probably the best video I’ve ever watched. As far as making something that seems so daunting, become easily achievable. (And I put some thought into that statement before posting it) Anyways, Thank you for the resource! I may account for 200 or so of the views. 👍

This guy is brilliant .followed everything step by step and it is working better than my 5.5kw vfd

I watched your videos on this and it worked perfect! I built one using your instruction video. Thank you!!! Excellent video

This is one of the best video illustration and tutorial on the subject. Thank you

Finally a video that explains things , is well made and complete. good job. Thanks

Just commenting again - this is exceedingly well done. I prefer this version over adding in yet another motor to remove the back emf resisting the initial start. Literally less moving parts.

This answers so much. Sir, you are a boone upon other tradesmen.

Best series of videos on this subject by far. Detailed yet clea well done

Superbly explained and great reference document. One concern I have about rotary idler phase convertors like this is that the phases are +/- 90 degrees instead of +/- 120 degrees as in utility-supplied 3-phase systems. The L1 and L2 inputs are 180 degrees apart. 120 volts each (to ground and the power company's neutral) and 240 volts between the two phases. The synthesized idler leg driven by the pony motor and capacitors is right between L1 and L2, thus 90 degrees to each one. You will notice that if you measure your "ghost" voltage to ground, it will be about 240 volts rather than 120 volts like L1 and L2. This means ground isn't in the middle of your Wye any more. There are three phases and the voltages between them are all close to 240 volts, but they are not equal amplitude with respect to ground and they are not 120 degrees of offset between phases. Because of this, motor magnetics will not be optimally aligned and you should de-rate motors driven by this compared to the same motor driven from a true, 120 degree, 3 phase power supply.

Best video series on Homemade phase converter.

Your video is the best I’ve seen on the subject matter. Great work, thank you. 👍🏻👍🏻👍🏻🇬🇧

Thank you. I just bought a 3 phase welder at a auction. At the time I had know idea it was 3 phase.

ah thank you very much for this. i just got a big three phase motor and wanted to build a rotary converter but couldn't find instructions on balancing. couple dudes show their converters with a bunch of capacitors but don't explain how they determined what to use and where. also that document is suuuper helpful. thumbs up

Thanks a lot for the diagram and instructions !! really appreciate it !! please do not be tired of posting education videos like this !!

"Admittingly missing some safety options" , I giggled at that. Almost everything I own is missing safety options . Borrowed time is my motto i guess. Nice video !

Its OK to have a sense of hummer. Some video makers think they have to burn up tools just for the show. That's OK if you are just entertaining . I see you're video as educational. That's why I clicked to watch it and I did learn from it. Ty

Good morning from Trinidad W.I. I recently acquired a delta 10" unisaw for my home workhop. The tablesaw is powered by a 5hp 3ph motor. I have since been pondering if to change the motor to a 1ph. Studying this video series. You make this so easy that I am gonna try this. Thanks for an excellent demo.

Probably one of the best, easiest video to understand. Thank you.

I would like to thank you very much for a great and easy to follow video. By following the videos I was able to build a 10 hp rotary convertor and it works great. If its ok and somebody is interested, I will list the cap values for the 10 hp.

It is the best video that I have seen on the internet, thanks for your time. I'm from Guatemala, Centroamerica and is difficult to find information about this system in spanish. You video is very good. Thanks.

As you said, this gives a much clearer idea on the capacitor use. One thing that has always confused me and you get all kinds of different answers on forums is the phase differences. You have an input power that that is 240 volt single phase where the two 120 lines are 180 degrees apart. Your pony motor and output power are 240 volt three phase but the phases are 120 degrees apart. So, is what your saying here is that using the capacitors are actually electrically moving the phases so they end up close to 120 degrees apart. I guess I am having trouble visualizing how you can start a 120 degree motor with 180 degree phasing power. Thanks, Tom

❤thanks much for that video i follow it and made a rotary converter to run two peices of tools did as you said just have to balance the legs still alittle lost on what are the requied voltages per leg but it is the BEST❤❤❤

Hi It's Oliver again I really appreciate your quick response and explanation your explanation of the project is fantastic your make it look so simple compared to all the other videos Kind Regards and Thanks a lot Oliver

Awesome video. It's all about tuning the phase shift via capacitors.

Best explanation of a rotary phase converter build...well done!

Thank you so much. Excellent video series. Best on RU-vid. Actual guide

Super helpful! I've been using a 5hp phase converter for years. Problem is, it will not start a 7.5 hp motor in my 18" planer. Using this set-up to run my 7.5 means that "the board" becomes a "static" converter and my 7.5 will run at about 5hp output--which is plenty; it replaced a 3hp motor in a planer. Totally concise, and I have not even glanced at the paper you linked to.

This is so perfectly explained, I think I’ll be making one for my lathe, thank you!!!

Awesome 🤩 video, thanks, I needed to know the capacitor values and you showed me!

Thank you very much Great information It really helps clear the view of how to accomplish a build God bless you n your work

Very good explanation. One thing you could do for your starter capacitor is to hang a centrifugal switch on the motor; that output shaft isn't doing anything else but spin anyways. That would be closed when the motor is off and open up as soon as it comes up to speed. No worries about a relay that might burn out.

Excellent hands on demonstration! Thanks for sharing!

wohhh... this video is the best thanks this is the step by step on how to do it this is how should teacher teach in the school

Awesome video, very good job of explaining the theory behind the concept

Thank you for taking your time to explain this process..... One thing I would have liked to have seen in the video.... Would have been, how you came up with the start capacitor size or formula..... but Awesome job...... I have sent several friends to watch this video......

Great video, very understandable, thanks for making it

I'm impressed that you have this many viewers and no disliked . its a little dry but I was not looking for a clown show. Good job.

Thanks for the video ...very helpful and informative concepts...salute to the content creator....

In my opinion your videos on how to follow the Fitch Williams design are hands down the best available on the net....kudos for doing an excellent job. I see it's been about 6 months since you replied to comments/questions, but here it goes anyway..... My question is how you arrived at your goals for voltage when balancing it. I don't want to make this a long reply, so I'll skip the blah blah and hope you understand. I multiplied my initial number by 1.03/1.08 to determine my goals, and to double check my understanding of what I was doing, I looked at your numbers and did the same math. I can't figure out how you came up with your goal voltage numbers for Cp and Cs, so I guess I don't understand HOW to do the math to achieve the goal for my setup. Can you explain the math on how you arrived at your goal voltages based on your initial voltages?

Great job......nicely put together and thank you.

Thank you so much that just taught me so much i had no clue before i watched this video your a great instructor. im subbed with thumbs up

Great Job! Thank you for all explanations....

I love this guy already. Guns are welcome but don't touch my tools. Reminds me of my old boss that ran a semi truck repair shop. Step one of being an apprentice was to get my own damn tools. lol

You didn’t’ t talk about this but I would to know what voltage you get between A and Common B and common and G and common . I really like how you did your video made it easy to understand that make up on the board the way you did

I will do,thanks for share...

In your phase convertor build I was curious what HP motor you used. Your video was excellent! I have a 20 hp motor 3 phase that I'm going to use. Ty

Very Educational. This has clarified a lot of my questions. I need one to run my 3hp 3ph lathe.

Thanks for taking the time. Awesome video

Thanks and hello from Las Vegas millwrights

I love how you break it down I wish I had your contact to help me with a small project

The way you laid it out was great, I can actually understand it all. The thing is I need an output of 415 Volts, how would I achieve that?

Well done! Thank you, SBR.

I tried to turn over a 10 hp 3 phase motor with single and a pull-start. It would hum, not attempting to speed up, until blowing the 10 amp breaker. What do you think is causing this?

Very Informative..Thank you Very Much

Does it matter if you use more capacitance that is needed? I slapped 240 uf(all I had laying around) on my first legs and it balanced within 1v.

This is fantastic.

Best explanation

Fantastic video. after you added the first run cap (about 12:23) you stated "now we an tell which letters were which" at the 3 phase power output, but didn't tell us which were which! please explain which are which and how you know. thanks

You know you can get a current draw switch from the common, start, run of an old refrigerator compressor which will take the place of you having to push a start button, it will then be all automatic when you turn your power switch on. Great video :)

Sir your experience very very well thanks

Fck yeah ! I have seen many videos building the converter by far the most help full

Nice job

Good job

How does one calculate the starting cap value? I have a 20HP motor. I can't seem to find any guidance other than the general rule of 7uF per HP

This is brilliant the way you explained how to make a rotary phase converter . Something I like to build. Was the cost alot cheaper than purchasing one already made love to know.

Is there a table for phase converters showing minimum size circuit breaker protection protection per horsepower. I looking to connect a 100 hp 240v phase converter???

Used to play with modeling software that could probably get you in the right range after some measurements.

Great , Man , you are so strong teacher , thank you so much , i really learned a lot with easy Method.

Thank you, you were a huge insperation for my RPC build. I posted a video of my build to my youtube channel for anyone interested.

Using a Baldor 5hp and have it setup this exact same way. Trying to go through the process of tuning it with capacitors. I crank it up and this is what I get: L1 + L2 = 245 L1+ Ghost = 205v L2 + Ghost 205v L1+Ghost+90mf = 213v L1+ Ghost + 90mf + 94mf = 216v L1+ Ghost + (BigA$$) 125mf = 290v, and the motor is flying way faster than it should. I’m just trying to get it close with a box of random large run capacitors I have before investing in anything, and I can’t get the voltage to climb on L1+Ghost with any combination of 90mf, 94mf, 70mf, and a 50mf. I haven’t had success with L2+ Ghost either. Do the capacitors have to be in parallel? Sequence? Does it make a difference? Do I have a bunch of bummed capacitors? Why is the 125 WAY too much on a single line?

great explanation great thank you

Very good

Very informative. Thank you

Could you run a 3 phase welder using this rotary phase changer maybe?

Gracias amigo es exelente y pedagogico me sirve de mucho sobre todo el modo de enclavar el contactor sin contacto auxiliar. very good.

Wow great job Sir ...!!!

Can you tell me what size start capacitor I need to begin a converter build with a 20 hp motor and the information you used in your video where can I get it thank you

you never checked for phase clocking. you can have the same voltage to ground on all 3 but wildly dif, between the 3. how do you fix that?

How do I calculate what capacitors I can use for a 30 HP phone motor? I need to power a compressor with a 10 HP motor and a heater ventilation system. Great video. Thanks for sharing.