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Induction Generator

8723 Views 21 Replies 11 Participants Last post by  coldone
From an old tablesaw motor. 1.5 hp. I used 3 motor run caps 40mfd ea. They're mounted beneath the mule drive. Got 2000 watts, haven't tried loading more yet. 5" pulley on Sears SS-15 (15hp briggs motor), 3" on electric motor. Engine at 1/2+ throttle seems to work good. Loading the gen barely affects the Briggs governor. Don't have a lot of use for it but it was a fun/cheap project anyway. pics below, Rick








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neat project! i am sure you cna find uses for it, 2kw is plenty to run smaller power tools for those project that are just to far from an outlet.
Definately a neat project,and aint it nice to know we can have electricity just by grabbing an unused motor and adding a few capacitors,and spin it with an engine!!..

It may not work well with motor powered tools,one I built was unable to get an electric drill to turn enough to actually do any drilling--it worked well for lights though..I guess from what I read on the site I got the idea from,you'd need a huge motor,to start and run a much smaller one..they said a 1 HP motor used as an induction generator, will onlystart & run a 1/10th HP electric motor. I guess "real" generators are actually specially wound 110/220V altenators,usually brushless,single phase,so they'll start motors better..

I tried using car altenators,while it does work on tools that'll run on DC and AC,I found the "phasing" was too far off, and it destroyed some things I plugged into them,they dont have 60 cycles,more like HUNDREDS of cycles per second..

I'm still going to play mad scientist with a GM altenator and see if I can make a successfull "Weldernator" out of one..one of my Sears tractors will be the power plant,since its so easy to rig up a belt to the horizontal shaft engine..I always did want a "riding welder"!.. :D..be neat to have--you can bust the tractor up,and have the capeability to weld itself back together!!..
I would like to see a wireing drawing of your toy.... Please....
:ditto: :ditto:
I would like to see a wireing drawing of your toy.... Please....
I don't have a diagram but I'll try to explain the wiring. See if this makes sense. If not then just ask and I'll try and clarify it better if I can. Some of this I got from a web page that I can no longer find. It had the capacitor value chart for different motors. That's how I chose 120mfd for the 1.5 hp electric motor that I used.

edit: found a diagram.





The wire that originally plugged into the wall to run the motor is now the receptacle. (Simply changed it from male plug to female receptacle.)
There is a switch added inline to shut off the new receptacle.

The original motor starting capacitor is removed/tossed.

The two wires that went to the original single motor Starting capacitor now go to the first of the 3 new motor Run capacitors. From there the remaining two new motor run caps are connected to the first one in parallel. That's it for wiring!

notes.
Have to use oil filled/motor run caps. About 5$ ea. got mine on ebay. They are made for big air conditioners. Can't use motor starting caps.

Have to run slightly above the electric motors rated speed. This electric motor ran at 3450 so the gas engine now has to turn it slightly faster for it to produce electricity. I'm guessing 3600. That's the reason I chose the smaller pulley on the electric motor, so the gas engine didn't have to run wide open to get the electric to 3600.


disclaimer: :crybaby: only attempt this project if you have a team of highly experienced electrical engineers as well as a team of specialized, well seasoned lawyers overseeing every aspect of the project. And make sure you've paid up your life insurance.
The frequency produced by an alternator is a function of the number of pairs of poles and the rpm. Conversely, the rpm of an AC motor is determined the same way, and depends on the number of poles and the frequency of the AC power.

A two pole AC motor is 3600 rpm at 60 cycles. Nameplate rating might be a few rpm less due to losses. A four pole 60 cycle motor is 1800 rpm. The more poles, the fewer rpm for a given frequency. That's why waterwheells and windmills usually have a lot of pairs of poles; they are driven by a low rpm source.

Now in your car, the engine is turning at, say, an average of 2000 rpm. The alternator is geared up so it spins faster. You also have a lot of poles. Yes, you will have high very frequencies. Your auto alternator is also producing 3 phase AC. It all gets rectified down to 12 volts DC - that's why there are three diodes in there.

If you ran an automobile alternator at the right rpm you would have 3 phase 60 cycle AC.

Due to the difficulties involved with maintaining the exact rpm needed to maintain constant frequency, for a home built application it might be easier to use a car alternator to produce AC, and then an inverter to convert back to 60 cycle AC. Less efficient and more $$$, but easier.

BTW if you are ever in the market for an AC genset, note the rpm. If it is 3600 rpm then the manufacturer is scrimping on copper (two poles in the generator instead of four), and the engine will be screaming along at 3600 rpm. Spend a few more dollars for one that runs at 1800 rpm. Less wear and tear on your engine and your eardrums.
Definately a neat project,and aint it nice to know we can have electricity just by grabbing an unused motor and adding a few capacitors,and spin it with an engine!!..

It may not work well with motor powered tools,one I built was unable to get an electric drill to turn enough to actually do any drilling--it worked well for lights though..I guess from what I read on the site I got the idea from,you'd need a huge motor,to start and run a much smaller one..they said a 1 HP motor used as an induction generator, will onlystart & run a 1/10th HP electric motor. I guess "real" generators are actually specially wound 110/220V altenators,usually brushless,single phase,so they'll start motors better..

I tried using car alternators,while it does work on tools that'll run on DC and AC,I found the "phasing" was too far off, and it destroyed some things I plugged into them,they dont have 60 cycles,more like HUNDREDS of cycles per second..

I'm still going to play mad scientist with a GM altenator and see if I can make a successfull "Weldernator" out of one..one of my Sears tractors will be the power plant,since its so easy to rig up a belt to the horizontal shaft engine..I always did want a "riding welder"!.. :D..be neat to have--you can bust the tractor up,and have the capeability to weld itself back together!!..
Thanks for that info--I thought an altenator would produce the same "cycles" no matter what speed it was spun at,now I know different!..too bad they use 3 phase,if it were single there'd bo no need to use an inverter to make the 12V DC output 110V AC..I figured if your going to spend 200 bucks on an invertermyou shoulda just bought yourself a REAL ready made generator,instead of all this "experimenting"..

(You should see what a 13" TV set does when you plug it into 110V 3 phase current your "modified" GM atenator produces--can you say IMPLOSION boys and girls!!!..I think my heart lost a few years THAT day!..it started smoking,ythen the picture tube blew up!--it works great on lamps ,but not much else!).I was not brave enough to try welding with 100+ volts and 3 phase,I figured I'd get killed,so I'm leaving that to someone braver than me!..
I have ran a few decent beads on DC with an altenator,but I think it wont last very long ,the diodes will probably pop above 30 volts,but maybe with larger extenally mounted ones a 140 amp altenator would make a decent DC welder..

BTW,I googled "induction generator" and found that site..its still up,just not easy to see..
Hey Tractorholic, Was it the one with the hand drawn chart that showed what capacitor value to use for different hp motor? That's the one I'd like to find again. I had a printout of the chart but it got soaked in oil or something.

I'd like to try the alternator idea next. Using 1 or 2 deep cycle batteries and an inverter. I have a 700/550 watt inverter and an old gm alt. It'd be fun to see how long it would run the lights and tv and other light loads between charges. Added benefit! It would double as a front weight!

I used the one above with my sawzall and it worked great. It draws 9 amps. Still haven't loaded it enough to cause it to stop generating. Have to try a skilsaw or something next.
The motor I used drew 18 amps at 120v when it was a still a motor so I'd like to find out what it will do for amps as a generator before it stops working. LEt us know if you get the weldernator going! Sounds like a fun project. Rick
Your wiring diagram shows 4 caps and they are in series.
850uf is a motor start cap not a run cap.
Is that the diagram that you used?
Hi coldone, I used 3 motor run caps 40mfd each in parallel to get 120. I should delete that diagram. Wasn't paying attention when I added it. Good Catch! Thanks, Rick
The site I found by googling "Induction Generator" was the first one that came up--the http is www.QSL.NET/ns8ol/induction_generatorhtml....another site called "altenator secrets" has a lot of good info on using altenators for other purposes besides keeping your battery charged too..I found it by googling "altenator secrets"....
The link above came out wrong, and I cant edit it for some reason..just google "Induction Generator" and the first site on the list that pops up is the one I'm refering too...it shows how to use the capacitors and also use dc electrolytic capacitors in place of motor run capacitors too...
I'm in need of a three phase gen set for my shop equipment. Can this be done with three phase motor coupled to an 18hp twin maybe?
hivolt, I think you'll find that won't work as you want.

Earlier it was put forth that a 1 hp motor spun will only power something like 1/10th of its power. Motors do generate when spun but at very low levels, its not optimum.

You should check what those 3 phase motors in your shop draw. If its low enough you might be able to run one off a 110 volt genset with a VFD?
I was hoping to get around the phase converter. My 110V Gen set doesn't have enough schwoop to power those saws. Yeah well it was worth a try.

I do have a 5hp 240V motor. hmmm 1/10 you say...:050:
What is the most amount of poles an easy to find motor has ??? 4 ? 8 ?
The number of poles determine the RPM of the motor. For a single phase motor it's two poles for a ~3600 (3450 usually) RPM motor which is the most common. Four poles is ~1800 (1725) RPM.
What is the most amount of poles an easy to find motor has ??? 4 ? 8 ?
Could you use a DC motor instead of an AC motor I have seen 100 volt DC motors in the junkyard
Sure you can use a DC motor,if its a permanent magnet one,othewise you'd have to devise a way to energize the feild if it isnt,just lik an old car's generator--but you will get only DC out of it so its useless to run any AC devices,and as far as welding with one,I doubt that would work,unless its a HUGE motor that would put out 100 amps--I have seen one dc welder online made from a DC fan motor a guy got off a city bus that looks a lot like an old VW Bug generator,but I think you'd be better off using a big aircraft generator or maybe a 24V altenator off a semi instead if your looking to make a welder...

There are plans online that show you how to use a 3 phase electric motor run off 110V single phase to make a 3 phase rotary coverter out of it--I think Kbeitz mentioned that in another thread awhile back..you'll need a BIG 3 phase motor to run a much smaller one though..
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