Split phase rotation

Hello Toplinesman

I have used a small hand-held unit, over the last 40+ years, which consists of neon lamps showing either: RYB or RBY, inside a waterproof housing.

You are referring to the earlier 3 phase motorised rotation meter, and I don't now have one here to check with.

With your test, did you need to start the motor rotating by hand ?

Kind Regards....

I don't know if this has any connection with the rotation meter question, but I have been running my three phase lathe and Bridgeport motors for over 40 years by hooking regular 2 wire 220 household volts to a 3 phase motor which does nothing but spin freely, it doesn't drive anything so there is no load. I start it by winding a piece of cord around the shaft to get it spinning before hitting the switch. From the switch I take three wires to the 3 phase motors on the machines and just switch them on in a normal manner. The motors drive and reverse quite normally.

".....all reports will be on one side of one piece of paper".

Winston Churchill

Hello Winkster, I too have a Bridgeport mill at home. I have been doing a bit a research to build a 3 phase rotary converter and all that I have found shows using capacitors to run it. Could you give a little more information about your set-up such as idler motor Hp, RPM? How is the idler wired into the circuit?

I also have a 9 foot tall Buffalo drill press and want to add a lathe. My wife has put her foot down and wants to see me use what I have before buying anything else.

Hi Mechanic, I thought the best I could do was photograph it and since I can't figure out how to post pictures directly to this site I have posted the pix on a Webalbum. As previously mentioned I did this in 1964 and it has worked perfectly ever since. Good luck with the missus.

http://picasaweb.google.com/winkelmannster/ThreePhaseConversion?authkey=ngGFMVSW4hg

"....all reports will be on one side of one piece of paper"

Winston Churchill

CR4 Admin: removed broken links

Thanks Winkster. I will be giving this a try. I already have an idler motor that was to be my foundation for a converter. Does it matter which direction the rope is pulled or can the idler run either way? Such as in the way the motor is wired to the 220 circuit. I would assume that a change in the idler motor rotation would also change the mill or lathe motor rotation. Or, since we are talking AC would it matter? My background is not electrical. Sorry for the novice questions.

It works in either direction - an associate who worked with me when I had the lathe in my shop had the habit of winding the cord in the opposite direction so the operating switch would be reversed. It was not a problem. When I closed my shop and brought it home I added the Bridgeport and another lathe to the system. Now the idler motor drives all three machines at the same time and the idler spins merrily all day long. It gives a little groan when I reverse direction on the drive motors but quickly recovers. It has never overheated or popped a relay.

......."all reports will be on one side of one piece of paper"

Winston Churchill

Thanks very much. I will try this out soon.

Toplinesman, does it reverse rotation if change the leads? are you talking 120/240 volt single phase, ( is this split?), or 120/208 volts with 2 hot lines & a neutral which is common in many apartment buildings and/or industrial, commercial places, which I would call close to 3 phase open delta

Hello

It is a split 180 degree system. i.e it is a 3 wire, 2 phase and neutral system.

Not 2 phases of a 3 phase system which would of course be 120 degrees out.

Cheers.

toplinesman' i know a scott transformer is 2 phase 4 wire 90 degrees apart. you would tie 1 wire from each phase to make a common tie point (neutral?) this would look like the letter "L" rather then a Wye "Y" which would be 120 degrees apart

toplinesmen' if took a single phase 240 volt circuit & you put a center tap at the 120 volt point would this be a split phase, i don't feel this would be the case, i feel this would be a 120 volt to 120 volt for 240 single phase.