# Ultimate 3 phase converter



## Karl_T (Mar 14, 2020)

I will soon be helping my son build what I'll call the ultimate 3 phase converter.  he has just built the ultimate shop for his life - a 30' x 40' super insulated building with in floor heat. 

This will be the fifth rotary converter I've built over the last 25 years.  There is a five year old post on the fourth one: https://www.hobby-machinist.com/threads/25hp-3pahse-conveter-with-load-center.26944/

This unit will be similar to gen 4. Some features. It will use a 3 phase load center for all fusing. Each machine will have its own circuit breaker for this panel. In addition there are two idle motors, a 7.5 hp and  25 hp with each motor having its own circuit breaker.

Both idler motors have a motor starter in the converter panel. Also plenty of both start capacitors and run capacitors. Timers will be used to bring in motor1 along with start caps for motor1 then drop the start caps and bring in run caps for motor1.  Another timer will then bring in motor2 a few seconds later. finally run caps for motor2 a few more seconds after that.

The unit will be set up so he can just turn off the circuit breaker for motor2 when smaller 3 phase loads are used - not use the larger motor at all.

A push to start, push to stop buttons will be used to start and stop the unit.

OK, today the kid just got the empty panel mounted.  I told him get the power wiring done and then I'll come over and do the logic wiring and debug.


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## brino (Mar 14, 2020)

Watching!




Thanks for sharing your build!
-brino


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## Martin W (Mar 14, 2020)

I like the idea of 1 large motor and 1 small motor. 
Cheers
Martin


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## Karl_T (Mar 14, 2020)

Yep, my gen 3 had a large (15hp) and then a huge motor (25hp) . dims all the lights. Gen 4 had a 5 then a 20. here's a you tube - hardly can tell when it comes in.





smaller start motor is a great way to go if you need a large unit.


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## Karl_T (Mar 14, 2020)

OK, first question from the kid. He's got a 12 lead 480 volt wired motor and found this:

12/1  Out

11/3  Out

10/2 out

7/4 capped

5/8 capped

6/9 capped

I found this info on line


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## Karl_T (Mar 14, 2020)

I think he has 12 lead wye hi voltage - 2nd from right top row.
He should wire it 12 lead wye low voltage - upper left in pic.

Correct???


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## stuarth44 (Mar 14, 2020)

Karl_T said:


> I will soon be helping my son build what I'll call the ultimate 3 phase converter.  he has just built the ultimate shop for his life - a 30' x 40' super insulated building with in floor heat.
> 
> This will be the fifth rotary converter I've built over the last 25 years.  There is a five year old post on the fourth one: https://www.hobby-machinist.com/threads/25hp-3pahse-conveter-with-load-center.26944/
> 
> ...


nice,thought abt it, but 42 amps by law can be taken from switcboard here, so my lathe is 12hp, i'd gobble near 140, so i continue to get my jiuce from a Lincoln Vantage gen/welder,it gives good power but uses a fair bit od diesel, bringing 3ph in would be 5---7 k


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## Karl_T (Mar 15, 2020)

The kid just sent me pics of his work over the weekend. he's got Friday off work, so we made a date to do the logic and debug.


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## Karl_T (Mar 15, 2020)

BTW, a fella named Fitch Williams helped me tune my gen1 and gen2 converters back in '98. His write up is still the best I've seen on how to build and tune a rotary converter. I just re read it for the 20th time.

<EDIT> Here's another GREAT write up. put here for reference


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## Karl_T (Mar 16, 2020)

OK, plan "A" for Friday.

1. wire start/stop buttons to bring in motor1 contactor, a delay off timer, and a delay on timer.

2. wire delay off timer to close small contactor for start caps. This contactor should stay closed for about 1 second after pushing "start" button.

3. wire small contactor in 2) to two each 300 MFD start caps between L1 and the "wild" leg on L2. Documentation indicates 50 -100 MFD start caps per horsepower. NOTE the start caps are all wired so its super easy to add or remove one during tuning - just pull a spade connector on or off.

4. Wire about 200 MFD of run caps between T1 and T2 (wild leg) on motor1 contactor. Wire about 150 MFD of run caps between T2 (wild leg) and T3. SAME NOTE caps are all wired so it is super easy to add or remove with spade connectors. 

5. wire delay on timer2 to motor2 contactor. Set it to about 5 seconds delay before bringing in motor2



6. We will try to bring in motor2 without start caps. If this is a problem, a third delay off timer will be needed to again bring in the start cap contactor for a second.



7. . Wire about 200 MFD of run caps between T1 and T2 (wild leg) on motor2 contactor. Wire about 150 MFD of run caps between T2 (wild leg) and T3. SAME NOTE caps are all wired so it is super easy to add or remove with spade connectors.



8. need voltmeters to watch things as we debug.


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## MrWhoopee (Mar 16, 2020)

I like it! Having just paid the bill for the first extensive use of the 7.5 hp RPC, I can really see the wisdom of a 2 motor plan.


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## Karl_T (Mar 18, 2020)

Just had a talk with the kid...

So many have called in sick where he works that they shut down all but one production line. He says he's most likely a Corona carrier right now. As my wife is high risk for serious illness, we decided I should not come over.

We will do it long distance. So, this project may take quite a while.

Karl


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## Karl_T (Mar 19, 2020)

OK, I am pretty experienced at wiring, but self taught. I put in a wire and test logic, then do another yada yada. When its wrong I fix as I go. I am not able to just sit down and write up an electrical diagram.

My son has almost no electrical logic experience. I have just done it for him.

So, I am breaking the logic wiring into baby steps. Below is my letter to him on getting the start caps working with a timer relay and a small contactor. See any problems?

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OK, you got two timer relays and one standard relay.


Both timers have the coil on pins 2 and 7.


Both timers have an NO contact from Pins 1 to pin 3


Lets build your logic one step at a time.


white wire on pin 7 to your common block.


"TEST" wire on pin 2 to someplace you can touch or switch 120      VAC. This will go to the standard relay later.


Another, very short, wire from pin1 to pin2 - hot wire for NO      contact.


run a wire from pin3 to the coil on your start relay contactor.


run a white wire to the other side of the coil on the start relay      contactor to your common terminal block.


Now test this assembly - touch test wire to 120VAC. Relay should      energise after time delay and close start relay contactor.


Get this right and we will do next step.


Up to you but i would number each wire and make up a spreadsheet      of where it is connected on each end and its function. then, in 20      years, you can quickly see what this does for quick repairs.


Dad


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## Karl_T (Mar 19, 2020)

OK here is letter 2 on getting a RED stop pushbutton and a GREEN go pushbtton to work with the standard coil in the previous post pic. Anybody see a problem here???
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when ready set up and test start stop push buttons.


1. "TEST" wire from one contact on RED button to switched 120 VAC      - will go to L1 on your motor 1 contactor when all done.


2. wire from other contact on RED button to NO contact1 on GREEN      button.


3. wire from NO contact1 on GREEN button to pin1 ?? on relay


4. wire from NO contact2 on GREEN button to coil on relay -      should be pin2 ??


5. white wire from relay coil common pin7 ?? to common terminal      block.





Now test assembly. With red button out, push green button - coil      should close.


release button - coil should open.


Push in red button - green button should no longer work.





Now lets make that coil self latching. Run very short wire from      NO contact on relay pin3 ?? to hot wire on its coil pin2 ??





Now re test => push green button and relay should stay on.


push red button and coil should drop.


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## JimDawson (Mar 19, 2020)

Karl, that is painful for me to follow     But I think correct.  It's interesting to see the differences in the way that people process logic problems.  I would have to draw a ladder diagram to do it, I just process graphical information better than a narrative.

You do realize that the Dayton time delay relay is an Interval On, thus pins 1-3 close on energize and open on timeout or when power is removed from the coil.  Which is great for starting the motor in this case.

I don't know what the logic is on the ATC time delay relay.


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## Karl_T (Mar 19, 2020)

Thanks Jim, appreciate the double check.

I do ladder logic with difficulty.  I can read it, very hard to write it. No way can the kid work from that. he needs step by step - put this wire here. It was real hard for me to write it out this way. I "see" logic in my mind and have done some terribly complex stuff in <many> years past. I mostly used primitive computer programs for this. You know I still like Camsoft - mostly cause it is GREAT with logic. Galil is another good primitive programming language. Both better than machine language and assembler. I even did a lot of stuff with Fortran and even more with GM-Fanucs first attempt at a robot programming language. GOTO meant move to this point in 3D space.

I ASSUME all simple timer relays are powered on start then drop after timeout. I know you can buy complex multi function units. These are dumpster dive ones.  if it don't work he may have to "BUY" one.

Karl


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## JimDawson (Mar 19, 2020)

Karl_T said:


> I ASSUME all simple timer relays are powered on start then drop after timeout.



Not true at all.  There is On Delay, Off Delay, Interval On, Recycle, and a couple others I don't remember right now.  You have to look at the labeling.  And in this case I think the Interval On or On Delay would work for this application.


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## Karl_T (Mar 22, 2020)

Ok, we got motor1 running and balanced with run caps. It sure took a LONG time on the phone to get a start stop self latching circuit working. had a couple basic mis-understandings.

The timer relay for motor2 is the standard delay on. While I know how to clobber this to work by taking the start-stop circuit power, we agreed he should get the correct relay. I won't be around in 20 years to help when it breaks down.

So, he's looking for a timer relay where the coil comes in after the set time. what's the correct name for this?

BTW, The kid stole a real nice CNC lathe at an auction last fall. He hooked it up yesterday for the first time. Everything came up and ran just fine - he can't do the spindle yet - needs motor2 running. See it here: https://www.hobby-machinist.com/threads/cnc-lathe.80345/

I am thinking this one, delayed start from mcmaster Carr:


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## JimDawson (Mar 22, 2020)

Delayed start seems correct


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## hman (Mar 22, 2020)

Might also be called "on delay" relay by some suppliers.


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## Karl_T (Mar 25, 2020)

VICTORY!

Got everything running smooth, can hardly feel the second, 20hp, motor come in. 

Got it balanced with this result
Voltages
L1-L3    245    line
L1-L2    244
L2-L3    246

Close enough?  

Thank, everybody, for all the help.

karl


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