Anybody making there own 3-phase?

[Larry]

Building a new rotary phase converter.  Bit different than anything I have made in the past.  10 HP idler with a pony start.  It will power shop machines but will also have the capacity for an additional idler if I want to power a sawmill or something of the like.

Rear view of the mount.




This is the front.




The first motor I ever used that would start spinning on its own.  I suppose it does pull close to 80 amps before its up to speed.  With the pony start I don't think it pulls hardly any amps...I was gonna check it but the Fluke fizzled.




Controls waiting to be cleaned, along with a general rehab.  The starter is a AB sized big nuff for an additional idler.  Fused 3-phase disconnect on the right...looks brand new...cost $1.00 at the auction.




Comments, ideas, or pictures of your RPC welcome.

[footer]

Ill get some pictures up soon. Just recently built one but havent taken pictures yet. I mounted all the components on a board to make sure everything worked as planned before mounting in an enclosure. I used capacitor start/capacitor run with a switching relay to kick out the start capacitors.

[J_T]

Mighty close to mine i got a 25hp an flip my belt off after i get it running . Don't know how long it will run but for a while i ran a 15hp motor off a 10hp converter or less as the motor plate is missing . 8)

[eamassey]

I have ran one (same one) for years.  Hunreds of hours of service.  I used a 7-1/2 motor and use capacitors to start it up through a momentary push button switch.  (Just no need to use throw-off belt, or motor-starter-motors--capacitors are easy.) It powers a 3 hp lathe.   I seem to have plenty of available power, but the (lathe) motor does not start as well as one might like.  I could better tune the power with "motor run capacitors", but it will never be quite as good as native 3-phase. 

Another option available is a variable speed drive-- single phase input, 3-phase output.  Avaiable up to about 25 hp.  Reasonable up to about 3 hp, high priced above that.

   

[Larry]

I would put a VFD on that lathe in a heartbeat...just to get variable speed.  You could save a few dollars and get one with 3-phase in and out.

I'm running a TECO FM-50 3 horsepower on the shop bandsaw.  I don't use the variable speed much but the braking is great for bigger saws.

[bandmiller2]

Larry,thats interesting about reducing the start amps,you'll have to take some amp readings and tell us.What if your start motor would pivot on its base with flat pulleys on boath shafts.You could get everything spinning then remove the start motor,mayby save a little drag.As mr. Massey has done I start my 5hp converter with a capacitor and momentary push button.U S Motors co. makes what they call their varydine system[if I recall right] a three phase motor driving a three phase gen. with a variable reeves drive belt.This system is used to control the speed,through frequency change,of a number of motors usally on conveyers.I drove mine with a single phase motor but had to regulate the voltage with a rheostat manually too much of a pain in the a$$.Does anyone know the efficiency of these converters??

[Larry]

I don't know what the efficiency would be on a VFD but I would guess quite high.  Horsepower is a little mis-leading when talking about a VFD.  All they care about is amps and they can be programed to shut down.  I have a friend running a 5 HP Unisaw on a 3 hp VFD same as mine, but he doesn't push it hard.