The Forestry Forum

General Forestry => Sawmills and Milling => Topic started by: forester2009 on March 06, 2014, 04:53:52 PM

Title: large three phase converters
Post by: forester2009 on March 06, 2014, 04:53:52 PM
Does anybody have experience with rotary phase converters larger then 50 horse power
Title: Re: large three phase converters
Post by: StimW on March 06, 2014, 07:39:12 PM
I doubt if it's practical to try to convert a motor that big.
Here is a forum with a lot of phase converter info. - http://www.practicalmachinist.com/vb/transformers-phase-converters-vfd/

I built a static converter for $45. to use on 5 hp motors and I am running a 50 ton Ironworker, a 35 ton Ironworker and a 15 X 54 Cincinnati Lathe with it.
I got the build instructions from that site.
Title: Re: large three phase converters
Post by: sealark37 on March 06, 2014, 09:05:57 PM
The problem with converting single phase to three phase in the higher horsepower motors usually comes down to not enough amperage at the single phase panel.  If you can provide enough electric current, converting to three phase is merely a matter of using larger components.  Schematics to cover every desire can be found at The Practical Machinist web site.         Regards, Clark
Title: Re: large three phase converters
Post by: drobertson on March 06, 2014, 09:20:25 PM
Not over a 50hp, mine is a 40hp, no issues, steady as a rock.   david
Title: Re: large three phase converters
Post by: scsmith42 on March 06, 2014, 09:20:41 PM
I have a 30 hp RPC and it dim's the lights on the entire circuit when I turn it on!  I can't imagine what a 50 hp one would do...
Title: Re: large three phase converters
Post by: arkansas on March 07, 2014, 06:32:00 AM
I run a 50 Hp converter.  As long as I get it up to speed with a pony. No issues with lights dimming.
Title: Re: large three phase converters
Post by: bandmiller2 on March 07, 2014, 07:40:06 AM
Forester, the 70 I ran was from the factory three phase, it had a larger motor than really needed. My homebuilt bandmill has a 15 hp baldor three phase  plenty of power for the band and hydraulic pump. Be aware if you just replace the engine with the motor you will still need 12v for the controls and puter. I think a good 25hp motor (no over rated rim stuff) would be plenty and leave everything else 12v. My 15hp never gets more than warm to the touch. With an amp probe and time you can balance the legs of a rotary converter with capacitors. Frank C.
Title: Re: large three phase converters
Post by: firecord on March 07, 2014, 01:05:35 PM
I got a 10kw st 3phase gen and 21 hp diesel in for sale sec if interested
Title: Re: large three phase converters
Post by: Larry on March 07, 2014, 01:21:57 PM
Quote from: scsmith42 on March 06, 2014, 09:20:41 PM
I have a 30 hp RPC and it dim's the lights on the entire circuit when I turn it on!  I can't imagine what a 50 hp one would do...

In the terms of service from my local power company they can disconnect my service if I dim my neighbors lights.  As you found out that's easy to do with the bigger converters.  The last one I built uses a pony motor.  I can't believe how easy the rpc starts when its brought up to speed by the pony.