Induction motor generator capacitor

[H012]

OK - this is a lot closer to what I thought than how I read your posts...no offence. By NE you mean Nebraska?

1) 100W of load is very "light" - no pun intended.
2) Your main Gen is 10KW (watts -- I am sure not 10KV)- and 85% loaded... when all of the appliances are running - 100W is only 1%... 85 vs 86%... IMO - a non-issue to add the lights ( however I understand that as a backup - you may not want this gen running 100% of the time).
3) The no batteries in the basement rule - can probably be re-read, or challenged - the issue is when charging LEAD ACID batteries give off Hydrogen (so an understandable regulation) - but the basic battery back up sump pump I am sure violates this "rule" - does the local home depot sell these... perhaps ask them how the "kit" is allowed since these are installed in basements. Next - the "rule" has merit- you really do not want to be generating hydrogen in your basement - with no proper ventilation - with a little thinking I am sure you can find a way to ventilation. .
4) How long do you want the lights to last - etc...

OK .. getting long winded...sorry wet an rainy here in the N.E. Northeast... Really the question - what is a good and minimal cost way to supply 100W of load in a backup situation.

If you do not want to run the gen 100% of the time - find somewhere to add a Lead Acid battery and automotive inverter - 200W.

3rd to Last point -- LED lighting is efficient, at the end of the day this means it gives off little heat - if you have hot summer days, with the AC running all of the waste heat you pay for - you pay for again to remove from your house. Personally I would look to utilize the LED lighting as much as possible, even if you have a Battery charger, then inverter - then the LED lights - less heat than incandescent bulbs - so when you look at utilizing the LEDs for more than just back up - they are more valuable and perhaps worth a little more expense than "free".

2nd to last point - this is not boring, it is valuable to everyone to see the challenges faced, and how important it is to drill down to the real "problem" - I recently came across a good quote " A question well asked is already half answered"

Last - This is not professional advice... ahem...

I live in the North East, central New Jersey to be exact. Here were I live floods real bad 5 inches of rain a day is a disaster. So imagine Hurricane Sandy. I ran my generator 24 hours a day for 17 days straight. The grid here is antique. Wind blows the wrong way the power goes out. It's awful. I think the inverter is a good idea for a back up. I will follow up later as I have to go to work.

 

[jim hardy]

You're a machinist ?

Try a search on ""make alternator from induction motor"

Folks are sticking PC disc drive magnets to induction motor rotors to make low voltage alternators, at other power.com
But results are mixed.

Still don't know if your LEDs Ned 110 or 12 volts...
And what wil spin your generator ?

 

[H012]

You're a machinist ?

Try a search on ""make alternator from induction motor"

Folks are sticking PC disc drive magnets to induction motor rotors to make low voltage alternators, at other power.com
But results are mixed.

Still don't know if your LEDs Ned 110 or 12 volts...
And what wil spin your generator ?

My house lighting is 120 volt Led's The emergency lights will be 24 volt. I did as a" just to try " project a ceiling fan motor
PM generator. I machined the metal ring for rotor clearance and glued 12 n52 neo magnets to the ring with a .0005 in. air gap
between the stator and the ring. My finding was that due to the small gauge wire on the rotor poles I produced at 1300 RPM's
56VDC not bad but it dropped to zero VDC if I hooked any kind of small load on it meaning these small motors can't produce
enough amps/watts to do anything. Am I right? Can't believe everything you see on you tube! The failure didn't upset me that
much, in the back of my mind even with my limited electrical knowledge about gauss/flux ect.. I had my doubts it would do very much. I am a master machinist by trade Making components is easy for me electrical engineering that's a whole different level.
Not that I'm not smart enough but at 58 yrs. old Nah. I'll leave that alone.

 

[jim hardy]

I too am 58 years...

At 24 volts a hundred watts is only around four amps, which wouldn't be a large rotating machine.

Or two lawn tractor batteries in a doghouse nearby...

A permanent magnet generator doesn't need a voltage regulator. Voltage will be proportional to rpm and if lightly loaded, reasonably constant. Two possibilities come to mind,,,,
Automobile fan motor driven overspeed
And
Treadmill DC motors I've seen are 2 hp 90 volt 6000 rpm permanent magnet machines of high quality. That'd be around 16 amps capability.
One of those driven about 24/90 X 6000 = 1600 RPM ought to be close.Got a Recycle yard nearby with an electric motor pile? MIne charges 30 cents per pound.

have fun

Old jim

 

[H012]

I too am 58 years...

At 24 volts a hundred watts is only around four amps, which wouldn't be a large rotating machine.

Or two lawn tractor batteries in a doghouse nearby...

A permanent magnet generator doesn't need a voltage regulator. Voltage will be proportional to rpm and if lightly loaded, reasonably constant. Two possibilities come to mind,,,,
Automobile fan motor driven overspeed
And
Treadmill DC motors I've seen are 2 hp 90 volt 6000 rpm permanent magnet machines of high quality. That'd be around 16 amps capability.
One of those driven about 24/90 X 6000 = 1600 RPM ought to be close.Got a Recycle yard nearby with an electric motor pile? MIne charges 30 cents per pound.

have fun

Old jim

Yea I actually converted my old drill press to a treadmill motor drive man it works great. I think I will try a treadmill motor. As a
matter of fact they are not hard to find. every 3 or 4 months the city let's people clean out their garage Usually if I drive around
I'll run across a treadmill. A power plant issue I have already to drive a treadmill motor.
Thanks for the input

 

[jim hardy]

Wow what a slip. --- I'm 68 not 58... Guess I feel younger here . Great company has that effect.

On your drill press conversion : Did you use the electronic speed control unit from treadmill ?

 

[RonL]

Wow what a slip. --- I'm 68 not 58... Guess I feel younger here . Great company has that effect.

On your drill press conversion : Did you use the electronic speed control unit from treadmill ?

At 70+ numbers start to lose meaning:D
I just love treadmill motors:) it's so easy to use a simple speed control and full bridge rectifier, but low voltage to run slow speeds has to be very carefully protected in some way.

 

[H012]

Wow what a slip. --- I'm 68 not 58... Guess I feel younger here . Great company has that effect.

On your drill press conversion : Did you use the electronic speed control unit from treadmill ?

I did use the controller from the treadmill. There is a lot of info on the MK series controllers which most treadmills use for conversion. The treadmills I do find most have bad rollers for the belt. The motor I put on the drill press is a 2.5 Hp , more than I need really but it doesn't have to work that hard. I like using the controllers with the motor because it also controls speed by sensing load.

 

[H012]

I wanted to update everyone after a month of testing. I ventured off my original reason to do some research and testing. on different motors
First: general purpose motors are a waste of time. on any level they produce 100+ volts but no power. Now to the 1 1/2 Hp 115/220v commercial motor I originally started this thread with: I started with 2/ 40uf capacitors wired parallel into the motor capacitor leads. I loaded the
capacitors with 115 volt before starting up. When I ran the motor asynchronous It produced 110 volts but when I put a 100 watt light as a load
the light output lumens fluctuated . So as a test I started adding more capacitors 40uf at a time as I have a bunch of these. as I added more capacitors the better the output stability. I arrived at 200uf total where the sine/cosign wave was stable. 56 hertz. I next unhooked the load and turned off the generator, i wanted to see if it would self excite after sitting a day. It does! I was actually surprised. My conclusion is that although an induction motor will generate with only a small capiactor to excite it the unit will not stay generating when a load is put on it. I am no electrical engineer but it seems that enough capacitance is needed also to act as a battery am I wrong? Also the 2 5/8 hp tread mill motor.
when i hooked up to a battery the to an inverter to the same 100 watt bulb stalled the 3.5 hp briggs engine In my opinion I just need a bigger power plant. maybe a 5.5 hp. Any opinions are welcome .
. .

 

[zoki85]

That's a typical behaviour of async. generator. As you spin the machine, due to remanent magnetism in iron of the machine there will be induced small emf E₀, which will start to force current I_C0 through the connected condenser and stator winding, this current will induce higher voltage etc. This process ends when output voltage reaches magnitude E_s determined by magneto-voltage curve of the machine and the condenser current line at operating frequency (see http://gifyu.com/images/SelfExcited.png). After you excite the generator, you can hook a load to it as you did. Dependence of relative voltage drop on condenser size is very steep near nominal load point, but is much less critical for relatively light loads as shown qualitatively http://gifyu.com/images/2kw-380V-50Hz-star.png

 

[H012]

That's a typical behaviour of async. generator. As you spin the machine, due to remanent magnetism in iron of the machine there will be induced small emf E₀, which will start to force current I_C0 through the connected condenser and stator winding, this current will induce higher voltage etc. This process ends when output voltage reaches magnitude E_s determined by magneto-voltage curve of the machine and the condenser current line at operating frequency (see http://gifyu.com/images/SelfExcited.png). After you excite the generator, you can hook a load to it as you did. Dependence of relative voltage drop on condenser size is very steep near nominal load point, but is much less critical for relatively light loads as shown qualitatively http://gifyu.com/images/2kw-380V-50Hz-star.png

Great read! This makes sense.The whole reason I went to this level of testing of induction motors was to educate myself and be able to set straight 95% of the myths out there on the web that presume to say yea grab an induction motor and make a generator. From all the help you guys have offered and doing my own research it's not that cut and dried so to speak Thanks, and by the way I'm still trying to get a 3 phase
motor to test. I will update if interested.

 

[jim hardy]

Also the 2 5/8 hp tread mill motor.
when i hooked up to a battery the to an inverter to the same 100 watt bulb stalled the 3.5 hp briggs engine In my opinion I just need a bigger power plant. maybe a 5.5 hp. Any opinions are welcome .

The DC motor stalled the gas engine? That really suggests that the DC machine saw a dead short across its terminals... what's in that inverter ? Is it still working?
Have you belted the machine RPM down so that it only makes 15 volts or so?

i'm confused for now...

 

[H012]

The DC motor stalled the gas engine? That really suggests that the DC machine saw a dead short across its terminals... what's in that inverter ? Is it still working?
Have you belted the machine RPM down so that it only makes 15 volts or so?

i'm confused for now...

Sorry it took awhile to get back. My clock is different due to the fact I work nights. Anyway I did have a short, when I put the end bell back on the motor I got one of the wires pinched. luckily the inverter has a protection circuit. After fixing this every thing worked great but maintaining 15volts
is problematic when I plugged in my vacuum cleaner up [ I chose the vacuum cleaner because I wanted to see what happened under a heavier draw.] at 9 amp draw the 3.5 hp Briggs motor motor struggles to maintain constant rpm. . I need to work more on the pulley ratios to run the gas engine faster. Right now the engine is only running 1300 rpms.. It's not simple as this treadmill motor really produces a lot volts as motor rpms increase. 15volts is nothing for this DC motor to produce. Thanks for the reply.

 

[jim hardy]

Briggs uses custom springs in the governor and there's a zillion different ones (I'm thinking of the vane in airflow type governors). I can see how it'd struggle to control near idle...force on vane is quite light there.

Sounds like you're mighty close.

Sorry for my intermittency of late, am traveling and access is sketchy.

Thanks for the updates, I immensely enjoy learning from others !

Old jim

 

[H012]

Briggs uses custom springs in the governor and there's a zillion different ones (I'm thinking of the vane in airflow type governors). I can see how it'd struggle to control near idle...force on vane is quite light there.

Sounds like you're mighty close.

Sorry for my intermittency of late, am traveling and access is sketchy.

Thanks for the updates, I immensely enjoy learning from others !

Old jim

That's why I want to put a bigger pulley on the treadmill motor. That way I can increase the briggs RPM up to it's most efficient power band.
Right now at 1300 engine RPM it's under it's power band which is 2600 -3600 rpm sweet spot. according to Briggs and Stratton Tech.
Will let you know how it goes. Regards Ray

 

[H012]

This is my final update to this thread. My final conclusion is yes I achieved the voltage and amperage desired to use an induction motor as a small generator. The problem is the engine has to run to hard to overcome the magnetism's clamping effect at asynchronous speed. Using a straight up induction motor as a generator cannot and would not be fuel efficient. Companies who have designed induction generators have made specific winding inclinations and arrangement to overcome problems.
I want to thank all who shared their ideas and thoughts. H. Ray Mills