[Walky]

I have an old AC motor which belonged to my grandfather (which passed away some years ago), and I'm having a hard time figuring out how to make it work.

It's a three phase motor, but it seems it's some kind of hybrid, since I know this was at one time wired directly to one phase mains (no converter). My general AC knowledge is very limited, and my understanding of three-phase motors and wiring is absolutely none.

I need to wire it to one phase mains.






(sorry for the picture quality, just took the motor out yesterday and only had the phone's camera at the shop).

The three upper binding posts are labeled X, Y and Z. The joined bottom posts are labeled U, V and W. Hope that gives a clue.

I'll be very grateful about any help I can get about this, this motor seems like a nice candidate for a lathe build, and also has some emotional value so I'd rather give it a good use instead of just letting it rust in a corner.

Thanks.

[Al_The_Man]

Does it have any kind or brushes or slip rings that you can see?
Or if a polyphase motor, it is designed to run on 3ph or 2ph but not 1ph.
Al.

[Walky]

I'll take a flashlight to the workshop next time and check if I can see anything through the front or back vents. The info plaque shows 3-phase delta/star configurations (I think the current one is star), so maybe it was internally modified by a third party?. Is that common or even possible?

Thanks!

[Al_The_Man]

If that old it might be worth taking it apart and cleaning anyway and also fit new bearings while your at it!.
Al.

[MR.20C]

I'll take a flashlight to the workshop next time and check if I can see anything through the front or back vents. The info plaque shows 3-phase delta/star configurations (I think the current one is star), so maybe it was internally modified by a third party?. Is that common or even possible?

Thanks!

Tag says 220/380 ,......


You say he ran it off single phase 220, how is that possible ? I recently had an experience with this. My Oliver 88D from 1929 was originally manufactured as a 440vlt 5hp/3Ph motor, manufacturer -woods motor , well,... The tag is stamped (over stamped) 220 but everything else on the tag was left ,Inc the amps...6.9..

Go figure.

B,

[Al_The_Man]

You say he ran it off single phase 220, how is that possible ?
Go figure.

B,

I agree, that is why it would be nice to find out the exact construction?
I would guess it is a simple 3ph star/delta motor?
Al.

[Walky]

Well, it seems I now have something interesting to do during the 70+ minutes cutting job I need to do tomorrow, I'll disassemble it and hopefully take some (decent) pictures of the innards.

[Al_The_Man]

, I'll disassemble it and hopefully take some (decent) pictures of the innards.

I just took my grandson on a tour of the local Electrical Museum, I'm sure there was one of those there!
Al.

[Walky]

I just took my grandson on a tour of the local Electrical Museum, I'm sure there was one of those there!
Al.

Was it one-phase?

Just kidding

[Al_The_Man]

No but there was one of Edison 6kw dynamo's!
Edison 2.5KW Dynamo - SmokStak
Al.

[Walky]

No but there was one of Edison 6kw dynamo's!
Edison 2.5KW Dynamo - SmokStak
Al.

That's a nice to look motor, I guess the 6kw version must have a considerable size?

Well, here are some pictures of my motor:

http://img546.imageshack.us/img546/8273/motor1large.jpg
http://img440.imageshack.us/img440/8223/motor2large.jpg
http://img811.imageshack.us/img811/4889/motor3large.jpg
http://img32.imageshack.us/img32/3955/motor4large.jpg

The front bearing is stuck, which is a surprise since the shaft was turning. It seems unlikely that it got stuck when opening the motor, so I guess the whole bearing was sliding on its pocket. I don't have proper removal tools so I'll have to improvise on that. It will take some time to clean the motor, it was full of dirt (at least no spiders came out to say hello).

This isn't looking too promising on the one-phase issue, though.

[Al_The_Man]

Yeah, definitely showing its age!
So far everything looks like the 1ph is out?
Al.

[MR.20C]

Yea,
That looks like 3ph to me, but, you can get yourself a 110 to 220 VFD inverter to run that motor, fairly inexpensive,,,,

It still has possibilities IMO




B,

[Walky]

It seems so. I'm completely lost with this, as my father assured me that it was working wired to one phase by just joining some wires. I remember the motor working on my grandfather's back shed (house was sold after he died, to there's no way to check now), being it probably the only noticeable electrical machine in the place (which would surely not justify an in-house three phase power installation).

Anyway, the "good" news is that the workshop space I'm using right now actually seems to have a 3 phase connector near a switch (at least doesn't look like a one phase plug), but the workshop is really, really old (guillotine switch old, really) and I was trying to stay away from any old connections if possible (there are other functional 3-phase machines in the shop with different connections, so it's probably working too, but they don't use the same kind of connector). I will take some pictures of the connector, since I haven't found anything like it on Google. I hope you can help me check if it's usable, and how to use it.

BTW, is screwdriver hammering an acceptable way of removing the bearing?.

Thanks!

[Walky]

Yea,
That looks like 3ph to me, but, you can get yourself a 110 to 220 VFD inverter to run that motor, fairly inexpensive,,,,

It still has possibilities IMO




B,

What do you mean by inexpensive?
It'd probably be more cost effective (at least for my priorities) to buy a one phase motor instead of getting even the cheapest chinese VFD. Then I'd just save the old motor for when I can finally move to a "real" workshop with proper and up-to-date one and three phase connections.

BTW, Chilean mains (one phase) are 220V

[MR.20C]

Screwdriver....hammer. ....I would not do that, rent a puller.
As far as the prongs.....usually that is a 4 prong on 3ph if I am not mistaken.

What you pay for a single phase motor , you can get a used VFD for less.....

Just an option,,,



B,

[Walky]

Screwdriver....hammer. ....I would not do that, rent a puller.
As far as the prongs.....usually that is a 4 prong on 3ph if I am not mistaken.

What you pay for a single phase motor , you can get a used VFD for less.....

Just an option,,,



B,

I haven't been able to find many used one phase input VFDs locally (most are 3 phase), cheapest one right now is $75.000 (roughly 150 USD), and the cheapest used one phase motor is $25.000 (I think I might be able to get one cheaper or free if I ask around). I'm not really in a hurry with this project anyway, I've spent so much on CNC stuff that I can't afford to spend anymore for some time. I really appreciate your suggestions, though.

So, no hammering?. Maybe I'll take the rotor to a car repair shop and ask them to do it (thankfully it's full of those near my bearings supplier) as long as they don't ask an eye and a leg for it. I don't think they're available for rent locally, but maybe even buying the puller might be worth it, as new tools are always welcome (actually, I've also been needing a gear puller for some time).

I can't remember right now if the plug is 3 or 4 prongs, it might as well be a set of binding posts instead of prongs, or maybe something else. I'll clean it (it's full of dust) and take some pictures.

Thanks!

[robotek]

I used to run 3 phase motor (just like yours) on one phase power supply by adding a capacitor. Usually the "star" connection diagram is for higher voltage (380V in your case) and "triangle" - for lower. Based on pictures, it is wired as a "star".
The way to run it, you have to wire it accordingly to your power supply voltage. In case of a "star" the three free nuts are your 3 phase connection points. To rewire it into "triangle" you would have to unscrew those little nuts in the junction box and replace those jumpers so there is three of them, separate, parallel to each other like so "III". These will be your connection points.
Then connect your one phase power supply to any two connection points and the capacitor between one free connection point and any of those power-connected points (if reverse needed, connect your capacitor to the other power-connected point).
For capacitor size, there is a formula that I don't know. (It comes down to few uF per kW). Mine was huge (like 20uF) and I used it to "crank" start the motor only. Once started, motor will run if don't overloaded.
Capacitor has to be NOT polarized! Paper-insulated would work. Rated voltage has to exceed the power supply by 30% or so.
Good luck!