Wiring up a 30HP rotary phase converter

[General Zod]

So I picked this up recently. She's a big momma..

I got a deal on it, otherwise I wouldn't have gotten it.

From what I gather, 240V 1-Φ power goes into A & B, motor goes to T1-T2-T3, the load, which in this case would be a welder connected via a 14-50R/P also goes to T1-T2-T3 (grounded separately of course.

The instructions from the Southern Converter website are lacking to be honest. Hoping they answer my email.

Here is some reference info I found, which seems to share a common theme across the board...

I think I have that right don't I?

 

[Janderso]

Someone that knows something will be along soon. Looks right compared to my 10hp American Rotary set up.
You are set dood. 30 hp should do the job.

 

[reddarc103]

The company will surely reply to you as the diagram looks quite complicated. For more welding-related solutions please visit - RED-D-ARC website

 

[Karl_T]

I would strongly suggest you get a 3 phase load center as a sub panel off your main panel. Wire L1 and L2 to top of this load center. leave "wild" leg L3 not connected.

Put your converter on a breaker off this panel, double check but looks to need a 100 amp breaker.

Now put all your equipment on its own breaker from this panel. really simplifies the wiring. NOTE this way leaves two legs hot to your machines all the time, if you try to start them without the converter running bad things happen. My son leaves the circuit breaker off until he uses the particular machine, not idiot proof.

Karl

here's my son's shop unit

Ultimate 3 phase converter

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...

www.hobby-machinist.com

 

[General Zod]

I would strongly suggest you get a 3 phase load center as a sub panel off your main panel. Wire L1 and L2 to top of this load center. leave "wild" leg L3 not connected.

Put your converter on a breaker off this panel, double check but looks to need a 100 amp breaker.

Now put all your equipment on its own breaker from this panel. really simplifies the wiring. NOTE this way leaves two legs hot to your machines all the time, if you try to start them without the converter running bad things happen. My son leaves the circuit breaker off until he uses the particular machine, not idiot proof.

Karl

here's my son's shop unit

Ultimate 3 phase converter

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...

www.hobby-machinist.com

The system will be wired like the last pic I posted, essentially.

There will be three breakers involved:
100A or 125A, 2-pole at the sub panel to provide 240V 1-ph power as OCDP to the system as a whole.
125A 2-pole right before the rpc panel to serve only as a means of disconnect
40A 3-pole at T1-T2-T3 (not between the panel and motor, just leading to the load) to serve as OCDP to the load which is a welder. It consumes a max I1eff of 36A on 230V 3-ph.

 

[General Zod]

I'm considering adding a soft-start even though the vendor says it's not necessary until one gets to a 60HP RPC size. What would be the simplest way to accomplish soft-start? I cannot run a smaller "pony motor" since there is no motor shaft protruding to attach to.

 

[Barncat]

Interested to see how this progresses. I am in the material acquisition phase of building a 25 hp RPC. Could you tell me the value of the run caps they used?
Why is the contactor labeled as 25hp for a 30hp motor? Is that standard practice?
It may be difficult, but could you drill and tap the shaft stub to add a longer shaft for a pony start? Although if your home electric is robust enough, I don’t think you need to worry about pony or soft start, as long as this isn’t turned on and off many times throughout the day.

 

[General Zod]

The caps have no markings on them that I can see. As for the contactor, I'm not sure. Maybe someone else can elaborate on that.

As for the drilling, there is no way for me to drill the shaft stub perfectly on-center and dead nuts straight in.

 

[Karl_T]

I've not seen a soft start used on an RPC.

Many years ago I tried a 25 hp RPC and starting load dimmed all the lights too much. So, I added a 5 hp RPC to start first, then bring in the big motor a few seconds later. This worked so well, all my later ones are done this way.

 

[General Zod]

I've not seen a soft start used on an RPC.

Many years ago I tried a 25 hp RPC and starting load dimmed all the lights too much. So, I added a 5 hp RPC to start first, then bring in the big motor a few seconds later. This worked so well, all my later ones are done this way.

I did see that in your thread, thanks for the feedback. Unfortunately I cannot do this with mine. Since it is built specifically for RPC applications, there is no shaft to attach a small pony motor to get it somewhat going. I don't even know which direction it turns, lol.