Phase Converter Good Or Bad

[randyc]

No dispute with any of the rotary converter comments - rotary converters are highly efficient and far simpler than most people assume. Of course Ulma Doctor is all over that topic, as he usually is about most stuff

But I have to put in a small plug for static converters. They are dirt cheap and do a good job if one doesn't need every last foot-pound/minute of horsepower, LOL.

I've been using one on my horizontal/universal mill for some years now, powered from the 220 volt single phase welder outlet. No problemo (and 2 horsepower from the 3 horsepower motor still removes a LOT of chips).

I mention this mainly for those who are slightly frightened by high voltage electricity - as they SHOULD be. Some may feel more comfortable hooking up a relatively simple static converter if they are intimidated by the challenge of constructing a rotary converter.

To each his own, right ?

I'll have to disagree with a statement made previously:

"Static converters" do not convert single phase to three phase. They convert three phase motors to single phase...

Static converters DO convert single phase AC to three phase AC with all of the consequent advantages like instant reversing.

 

[Brain Coral]

That answers that question.
Thanks.
I guess I'll be looking to do a Rotary.
I have a 7.5HP 3 phase I took off a industrial Compressor I got at an Auction just laying around collecting dust.
I could use it to build a rotary converter, but I know nothing about how to wire a rotary box or what all is needed for it.
I can wire regular 110 or 220 with no problem.
Read all kinds of info on them but still can't quite grasp the how to of them.
I would need very detailed instructions on parts and connections.
I know I could buy it already assembled, but $$ is the deciding factor.

Hello Mike,

Here is another option for you.

http://www.wnysupply.com/index.cfm/fa/items.main/parentcat/25258/subcatid/0/id/328115

I bought their 10hp RPC panel last fall and hooked it up to a 10 hp 3 phase motor that I had lying around. I ran a 50 amp 220v single phase circuit to the panel and then wired in the motor. It was easy and relatively cheap and it runs like a champ.

Brian

 

[GK1918]

Phase O Matic three years and counting (so far) no problems 'yet'. and I can still smoke a belt

 

[roadie33]

Thanks Brian.
That looks to actually be affordable.
Do they send good instructions with those kits?

I just can't see why all of the other places want so much for the same thing. They don't even include the motor for the high prices they are charging.

 

[uncle harry]

a 400 microfarad 377 volt rated start capacitor would be just fine.
Furnas is the company that manufactured the contactor (it didn't come out of a heater).
any 3 pole 40 or 50 amp rated 220 volt coil contactor would work for your situation- Ebay has tons of them
i have a few in stock if you have trouble, although you shouldn't have much trouble finding one.
the start/stop switches are manufactured by square d .
they are momentary contact- the start switch(es) are 2 normally open switches controlled by the same pushbutton
the stop switch is a normally closed single pole switch. both start/stops are rated for 3amps at 240 volts (not much current goes through the start/stop circuit)
you don't necessarily have to use furnas and square d any products that are NEMA certified or UL listed are more than sufficient for what were doing here.
Surplus vendors are excellent sources for inexpensive goodies, i shop surplus vendors all the time.

i'd be happy to assist you in building a unit. as long as you get minimum 220v 3a rated switches, a 40 or 50 amp 3 pole 220v coil, 2 40 amp fuses and holder or a 40 amp 2 pole overload relay, a 400 microfarad start cap, some wire, disconnect device(plugs or 2 pole knife type switch or drum switch)
from my video you'll see the system is quite simple.
heres a video of the 7.5 hp starter box i made for another member a while back

I like the double pole pushbutton approach. I have a small sub-fractional 3 ph centrifugal pump that I might just use this approach on as a coolant pump. I would be a little concerned about the contact rating for the pushbutton for large horsepower starting this way though.

 

[gi_984]

I debated the same thing when building up my shop. How to run 4 different 3 phase machines. Looked at static and home made rotary converters as well as VFD. Based on a lot of favorable reviews I went with these guys. Excellent quality and I just push one button and get clean reliable 3 phase power. Had it for over 2 years without a single hiccup. Comes with a purpose built Baldor idler motor. I've got the 7.5 HP version. I can run all four machines (almost 5 HP) at the same time with ease.

https://www.americanrotary.com/products/view/ar-pro-series

 

[randyc]

I'll have to disagree with a statement made previously:

"Static converters" do not convert single phase to three phase. They convert three phase motors to single phase...

Static converters DO convert single phase AC to three phase AC with all of the consequent advantages like instant reversing.

John, my humble apology for disputing your post. Ulma Doctor has corrected my misconception although I'm still troubled by how a motor running on single phase can instantly reverse. No other single phase motor in my shop is capable of doing that - only the 3-phase motor connected to the phase converter. (I'm also at a loss as to why the device is called a "phase converter" if it's not converting phases ...)

 

[Ulma Doctor]

I like the double pole pushbutton approach. I have a small sub-fractional 3 ph centrifugal pump that I might just use this approach on as a coolant pump. I would be a little concerned about the contact rating for the pushbutton for large horsepower starting this way though.

Hi Harry,
the control switches see less than one amp- the contactor is taking all the load (amps)
the switches operate the contactor coil, and on half of the start switch it allows the start caps charge to be dumped into the generated leg for starting purposes.

 

[John Hasler]

John, my humble apology for disputing your post. Ulma Doctor has corrected my misconception although I'm still troubled by how a motor running on single phase can instantly reverse.

It's internally two phase.

(I'm also at a loss as to why the device is called a "phase converter" if it's not converting phases ...)

Marketing.

 

[Alan Douglas]

It creates unbalanced three-phase: the third leg is not necessarily at the same voltage, and it will have different degrees of phasing to the other two legs (hard to explain without vector diagrams). The phase and voltage of this third leg will also vary with load.