Three Phase Generator Question

[Pipescs]

Not to be distracted from my various other projects I have been packing away Model Airplane projects. In the process I took a couple of three phase Outrunner Motors out of a drawer and spun them up with an electric drill. No where near their operating speed and checked voltage.

Has anyone ever seen anything on powering these with a steam turbine wheel to act as a large scale generator?

[hammermill]

are they permant magnet motors??? is driving they for a output is easy. feed to a rectifier bank and off you go no exciter needed

[Asteamhead]

Hello Charlie,
You may use any 3-phase brushles motors as generators, sure. In case you want DC voltage output, please connect to a 3-phase rectifier bridge of 6 HF (high freqcency) diodes. But you may use AC by just connecting two phases at reduced output power instead.
Main disadvantage of those outrunner types is limited rpm yet. Inrunner types are matching with a turbine a lot better. This is due to it's low torque but high rpm potential at constant steam consumtion. Wouldn't recommend any reduction gear due to both friction and wear!
Good luck,
Asteamhead

[Pipescs]

Interesting question but I am not going to pursue. My Rust Bucket is getting all my time right now.

[jschoenly]

In my far too many projects on the list, I'm working with the same type motors for a Turbine, probably the early Pyle. If you search for RET's posts on turbines he describes very well a pelton wheel for the turbines he worked on. I made up a prototype wheel and very (VERY) crude jet to spin up a tiny outrunner I bought at a model airplane show. With a multiphase rectifier and a few power resistors I was able to measure nearly 1 watt of power output on the DC side at about 1.5-2 volts (can't remember, didnt' write it all down) running in the rnage of about 25,000 rpm. This was on the output side of a regulator set to 3-3.2 volts so i was obviously not getting the fully voltage. I was trying to find the pictures but I'm at a loss right now. The motor was about .75" diameter and maybe .25 long and the turbine wheel i made was .187" wide x 1" diameter with the double pelton cups. Used a tiny .125 diameter by 1mm woodruff style cutter for the cups and 24 around the diameter.

I plan on trying some much larger outrunners in the future that would still work in our scale sizes and I expect you can get a decent amount of power out for our uses. What I'm not sure is how much of a steam hog they may but, but i did at least prove the concept. Fun project and would like to get back to it. If I only had more time.....

[jschoenly]

Got the pictures (with the help of a friend reminding me of old text messages....)

The only bearings here were the motors and I would not relay on them for long. I have a few designs mostly detailed for real prototypical housings and again - Hopefully - will have some time for this stuff soon...

[Asteamhead]

Please, get some more about brushless turbogenerators (TGs).
You will get the same performance by using a simple gearwheel made of aluminium instead a sophisticated turbine wheel with blades.
To seperate the generator (with bearings) from the steam turbine you may use piston rings in combination with a disk wheel. Both mounted onto the shaft by a slight press fit.
Finest type of brushless motors may be the Faulhaber of different sizes. Swiss made, expensive, sorry!
I recommend to hold the combination in the outer case by means of O-rings.
The (venturi) nozzle may be just 1 / 32 " for a steam preasure of 100 psi or more.
Continous output is >= 8 W @ 8 pounds of steam per hour.
Asteamhead

[thunderskunk]

Well I’m glad I found this... Got me an inrunner 6V to play with thinking “hmm, this motor has three leads. I wonder which one is ground.”

Did not realize it would be three phase. Didn’t even cross my mind. I’m having enough trouble finding a 6V dimmable warm white LED, haha.

[hoppercar]

Wrong chat group

[jscarmozza]

In the Sept- Oct & Nov-Dec issues of Live Steam there was a well done build article for a 3 phase steam generator in 1" scale.

[jscarmozza]

Oops! The year was 1999.

[rkcarguy]

Please, get some more about brushless turbogenerators (TGs).
You will get the same performance by using a simple gearwheel made of aluminium instead a sophisticated turbine wheel with blades.
To seperate the generator (with bearings) from the steam turbine you may use piston rings in combination with a disk wheel. Both mounted onto the shaft by a slight press fit.
Finest type of brushless motors may be the Faulhaber of different sizes. Swiss made, expensive, sorry!
I recommend to hold the combination in the outer case by means of O-rings.
The (venturi) nozzle may be just 1 / 32 " for a steam preasure of 100 psi or more.
Continous output is >= 8 W @ 8 pounds of steam per hour.
Asteamhead

Wonderful craftsmanship as usual Asteamhead!
This post makes me want to play with building one of these even though I don't have a steamer lol. These aren't much different than a turbocharger, just tiny. Most important, is getting a seal that will separate moist steam pressure and heat from the electric motor/bearings without inducing a bunch of drag on the shaft...probably a good trick. I honestly think it would be best to use a motor with a long shaft, and have a vented "center section" with a housing that simply cleared the shaft by a few .001"s. I wouldn't think that a little bit of leakage through the housing would affect the efficiency all that much?