# RPC questions



## Tamper84 (Feb 20, 2013)

Well I do believe I have finally found a lathe, more on that on Friday  So it's 3 phase and it is also a variable speed machine. So a VFD is out, plus I would like to have a mill in the future which will be 3 phase as well ( well, most likely) I have a buddy and he has a 7.5 horse 3 phase motor  So does the rpm of the motor matter for building a rpc? Also, we don't know what the motor is valued at, is there a general guideline as to motor price?


Thanks,
Chris


----------



## Tamper84 (Feb 20, 2013)

Oh ya. He does have the starter also. 

Chris


----------



## Ulma Doctor (Feb 20, 2013)

Tamper, 
the motor rpm is not a factor so long as the rpc is up to speed before you start other equipment.
as far as the value of the motor used probably around $200-300 depending on,general condition,manufacturer, service factor,type,mounting,etc.
just a fyi you are gonna need at least a 50 amp circuit to start the rpc.
 I have a 5hp rpc, it starts from a 40amp branch with no issues.
read up on phase balancing,it will save you a lot of money in wasted power. 
your power factor will greatly improve through balancing,threfore cost you less to operate
i hope the info helps out.
mike)


----------



## Tamper84 (Feb 20, 2013)

Thank you Ulma. I will have to research everything actually lol.  I would like to try and build this, but can't find any good right ups on it. Oh I do have a 100 amp circuit for it 

Thanks,
Chris


----------



## DaveD (Feb 20, 2013)

I'd have to say a used 3 phase motor is worth about $10/HP. Buddy to buddy should be $50 for that motor. Check around a few motor shops or Craigslist.  I run a 10hp RPC on a 50 amp ckt.


----------



## Ulma Doctor (Feb 20, 2013)

Tamper84 said:


> Thank you Ulma. I will have to research everything actually lol.  I would like to try and build this, but can't find any good right ups on it. Oh I do have a 100 amp circuit for it
> 
> Thanks,
> Chris



the rpc is really easy to wire up.if you have electrical knowledge, if you don't it is not impossible to do.
if you are interested i can make a posting of my version.
it may take a couple days due to my work schedule, but i'd be happy to assist you if you're not in a rush.
mike)


----------



## Tamper84 (Feb 21, 2013)

Ulma Doctor said:


> the rpc is really easy to wire up.if you have electrical knowledge, if you don't it is not impossible to do.
> if you are interested i can make a posting of my version.
> it may take a couple days due to my work schedule, but i'd be happy to assist you if you're not in a rush.
> mike)


That would be awesome if you could!!! I got plenty of time!!! Thank you!!!

Thank you,
Chris


----------



## Tamper84 (Feb 21, 2013)

A little update. Went down to my buddy's house after work. Scored a 7.5 horse 3 phase motor and a couple of recessed lights for 30 bucks. But the motor is 3740 rpm. Hopefully wont be too too noisey. 

Thanks,
Chris


----------



## Ulma Doctor (Feb 21, 2013)

Tamper84 said:


> That would be awesome if you could!!! I got plenty of time!!! Thank you!!!
> 
> Thank you,
> Chris



no worries, i'll have some stuff to post this weekend!
mike)


----------



## Ulma Doctor (Feb 21, 2013)

Tamper84 said:


> A little update. Went down to my buddy's house after work. Scored a 7.5 horse 3 phase motor and a couple of recessed lights for 30 bucks. But the motor is 3740 rpm. Hopefully wont be too too noisey.
> 
> Thanks,
> Chris



sweet score!!
the rpc will run with a slight buzz, until you put a load on it then it will quiet down until the load is switched off.
mike:thinking:


----------



## Tamper84 (Feb 22, 2013)

Thank you. I think I am going to put it in the shed directly behind the shop. They share a common wall, it will help with the noise. I hope lol. And I have read that the higher the rpm the better the hertz. Dont know.. But as long as this will work to run my lathe, I will love it lol.

Thanks,
Chris


----------



## Ulma Doctor (Feb 23, 2013)

Tamper84 said:


> Thank you. I think I am going to put it in the shed directly behind the shop. They share a common wall, it will help with the noise. I hope lol. And I have read that the higher the rpm the better the hertz. Dont know.. But as long as this will work to run my lathe, I will love it lol.
> 
> Thanks,
> Chris



No Worries Tamper!
the noise shouldn't be too bad unless the motor bearings are worn.
I put a video on YouTube for you. CLICK ON THE LINK BELOW!


http://www.youtube.com/watch?v=xD8xwh_P8mI


I made a simple non-balanced RPC, that will work for any HP rating, providing you change the microfarad rating in respect to the motors HP rating, and have a supply circuit of sufficient capacity.

DO NOT USE THIS TYPE OF CONVERTER ON SYSTEMS THAT REQUIRE BALANCED POWER BETWEEN PHASES:nono:
DO NOT WORK ON ANY CIRCUIT UNTIL MAIN POWER HAS BEEN DISCONNECTED AND ALL CAPACITORS HAVE BEEN DISCHARGED:nono:
DO READ UP ON PHASE BALANCING)
DO READ UP ON POWER FACTOR, JUST FOR FUN! LOL, BUT SERIOUSLY IT'S IMPORTANT TO UNDERSTAND WHY WE WANT TO BALANCE PHASES.)
I'LL BE POSTING A WIRING DIAGRAM AS SOON AS I CAN DRAW IT UP, IT'S AFTER MIDNIGHT GONNA TRY TO GET SOME BEAUTY SLEEP. I'LL BE THE FIRST TO ADMIT THAT I NEED A BUNCH MORE.....:lmao:
THANKS FOR WATCHING AND ENJOY!
MIKE)

shoot me a message if you need one built for any application including tolerance based balanced units.
[video=youtube;xD8xwh_P8mI]http://www.youtube.com/watch?v=xD8xwh_P8mI[/video]


----------



## Tamper84 (Feb 23, 2013)

Ulma Doctor said:


> No Worries Tamper!
> the noise shouldn't be too bad unless the motor bearings are worn.
> I put a video on YouTube for you. CLICK ON THE LINK BELOW!
> 
> ...



THANK YOU!!!!!  I can't thank you enough!!!!  :man:Now I need to figure out what I need and how to hook it all up. I've never dealt with this stuff before but I am willing to learn. Thank you very much. 

Thank you!!
Chris


----------



## Ulma Doctor (Feb 23, 2013)

You are most welcome, Tamper.
I joined this forum to learn things from others and to assist others if i can.
I'll get the wiring diagram together for you, and post it as soon as i can.
mike)


----------



## Ulma Doctor (Feb 23, 2013)

Here you go tamper!!!!



let me know how it goes, message me if you have questions, i'm happy to help out!
Mike)


----------



## Tamper84 (Feb 23, 2013)

Thank you mike!!! I really do appreciate all of this. I'm sure I will have a bunch of questions! I need to start gathering more parts now!!

thank you,
chris


----------



## dfletch (Feb 23, 2013)

I thank you as well Ulma Doc. I have been watching this thread with interest and appreciate the info you have so generously provided. Thanks again.

Doug


----------



## Ulma Doctor (Feb 23, 2013)

dfletch said:


> I thank you as well Ulma Doc. I have been watching this thread with interest and appreciate the info you have so generously provided. Thanks again.
> 
> Doug



you are welcome too, doug.
if i can assist, i'll do my best to help!
mike)


----------



## Ulma Doctor (Feb 23, 2013)

i have made another short video that may answer some questions, it may bring more....

http://youtu.be/nX5v2xw51D8

[video=youtube_share;nX5v2xw51D8]http://youtu.be/nX5v2xw51D8[/video]


let me know if it helps out!
mike)


----------



## Tamper84 (Feb 24, 2013)

Thank you again Mike!!! I can't tell you how much I appreciate all of the help. Hopefully I can repay all of this one of these days!!

Thank you,
Chris


----------



## Ulma Doctor (Feb 24, 2013)

Tamper84 said:


> Thank you again Mike!!! I can't tell you how much I appreciate all of the help. Hopefully I can repay all of this one of these days!!
> 
> Thank you,
> Chris



Chris,
your appreciation is more than enough repayment for me.
the only thing i would ask is that you help someone else if or when you can.
let me know how she turns out!!
mike)


----------

