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Give me 3 phase or give me death - Rotary Phase Converter

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Project by Mainiac Matt posted 09-26-2019 06:27 PM 1063 views 0 times favorited 12 comments Add to Favorites Watch

Another project completed on Mainiac time, as the original rotary phase converter (RPC) plan was drafted and the metal stand fabricated in 2004. But after I scored a used 3 HP single phase TS my need to run a salvaged industrial three phase machine was no more.

Enter 2019 and I’ve started working on a home brew bandsaw mill project, that will be driven by a three phase electric motor and I had to blow the dust off of the RPC build and figure out where I stood.

The motor, the metal for the stand, the control box and the motor contactors, fuse block, terminal block and switches were all industrial salvage. The only out of pocket cost to me was paying my bud to weld up the stand, the twist plugs and the capacitors…. All totaled I have ~$80 into this…. and a lot of hours. (similar size converters purchased new run about $1K)

If anyone wants to take on a project like this, I highly recommend doing a mock-up and bench test on a plywood panel, as this helps your figure out where to place the components and where you can make connections.

Shown running a 5 HP vacuum blower on the bench. Phase Voltages are balanced to within +/- 2 volts when under load.

There is one mystery wood component in this build to qualify it as a project post….. a cork gasket on the motor box.

:^)

-- Matt -- I yam what I yam and that's all what I yam





12 comments so far

View pottz's profile

pottz

7097 posts in 1549 days


#1 posted 09-26-2019 06:53 PM

i dont think a cork gasket counts-lol.

-- sawdust the bigger the pile the bigger my smile-larry,so cal.

View bigblockyeti's profile (online now)

bigblockyeti

6139 posts in 2286 days


#2 posted 09-26-2019 07:44 PM

That’s a mighty fine looking converter, cork counts any day in my book! Is the motor you scored 10hp or did you build the converter to run up to a 10hp load?

-- "Lack of effort will result in failure with amazing predictability" - Me

View Mainiac Matt 's profile

Mainiac Matt

9374 posts in 2893 days


#3 posted 09-26-2019 08:47 PM

Is the motor you scored 10hp or did you build the converter to run up to a 10hp load?
- bigblockyeti

I started with a 10 HP idler motor…. but it had an internal fault and I had to go back to the drawing board….
The next largest motor I could get (for free) was a 7.5 HP motor.

I’ve driven a 5 HP vacuum blower with this and the current it pulled was well below the rating of the idler motor.

All the internal wiring and contactors are sized for 10 HP though, so If I ever do score a 10 HP, I can upgrade easily. I’ll just have to play around with the run capacitors to re-balance the phase voltages.

-- Matt -- I yam what I yam and that's all what I yam

View DS's profile

DS

3350 posts in 2985 days


#4 posted 09-27-2019 01:56 PM

Wow! Matt! Way to bring it together. Color me impressed.

Correct me, if I’m wrong, but, it looks likes you’ve done something like this before.
If I did it, it would probably still look like a rats nest on my bench. (A functional rats nest, though, and not nearly as tidy as yours)

Congrats!

-- "Hard work is not defined by the difficulty of the task as much as a person's desire to perform it.", DS251

View GR8HUNTER's profile

GR8HUNTER

6708 posts in 1277 days


#5 posted 09-27-2019 02:12 PM

sexy looking GREAT JOB :<))

-- Tony---- Reinholds,Pa.------ REMEMBER TO ALWAYS HAVE FUN

View Mainiac Matt 's profile

Mainiac Matt

9374 posts in 2893 days


#6 posted 09-27-2019 03:06 PM


Wow! Matt! Way to bring it together. Color me impressed.
- DS

Yah… Martha Stuart picked out my paint colors :^P

She went to the paint shelf and found two lightly used rattle cans of Rustoleum… one battleship gray and the other cream colored. Price tag, $0

She’s a thrifty one she is.

-- Matt -- I yam what I yam and that's all what I yam

View woodworkfkdn's profile

woodworkfkdn

296 posts in 70 days


#7 posted 10-03-2019 07:46 PM

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