Induction Motor as a Generator

[Halfcrazy]

Ok I know that i can spin an induction motor a little faster then its nameplate and it will backfeed the grid. My real questions are Where can one find a good deal on an induction motor and what HP would you need to look for to dump say 3kw back. Also is there anything special one needs? I am under the impression you just spin the thing up and when it is at speed throw the switch and then put the power to it? I talked to my local Power Co and he was ok with it as part of my grid tie system as long as I could exhibit that it will stop flowing power when the grid is disconnected.

I understand that I will not save money and this isn't the goal. just an experiment with an odd purpose

[Halfcrazy]

Yeah I have another option that seems easier but a little more pricey. I have a 24 volt battery based Grid tied system with the outback GVFX3524 so I am thinking maybe it is eaiser to just buy a cheap 24 volt inverter/charger and feed it with the lister?

[mike90045]

Also is there anything special one needs? I am under the impression you just spin the thing up and when it is at speed throw the switch and then put the power to it?

Boom   

  You use the grid to get it up to speed as a motor, then engage the clutch from the driver engine, and as you overspeed, it changes from motor to generator.   If you just "throw the switch" and are "not in phase", I think that will be pretty bad.

Most units drop power as the grid goes down, but some have enough core magnetism or self-capacitance, to keep putting out power.  Likely wont last long as you try to power a de-energized grid, but hey, I'm not the lineman making repairs

[mobile_bob]

here is yet another pitch for Bill Rogers book, he offers the correct method of using a single phase motor
as an induction generator and have it work properly with high efficiency
there is a bit of switchgear as the windings have to be switched after startup from motor to generator operation
to get full output and high efficiency

Bill covers this topic very well in his book, and if you are seriously considering such a project, buying the book
would be very helpful in my opinion in getting it right.

for the OP:

if you buy Bills book and don't think it is worth what you paid for it, let me know and i will buy it from you.

(i already have a copy, however that is how useful i believe you will find the book.)

we need more books like Bills, and the only way to get them is to either write them, or buy them from those who do.

bob g

[Halfcrazy]

Bob where can one purchase this book? I will gladly buy it tonight I love to read and learn this stuff.

[mobile_bob]

Bills book can be purchased at

utterpower.com

bob g

[quinnf]

http://utterpower.com/bill_rogers.htm

What Bob said.  Very worthwhile book authored by a fair dinkum frood who really knows where his towel is.

Quinn

[vdubnut62]

I'll third it.  Yes! Go buy the book. It could save your tail.

"authored by a fair dinkum frood who really knows where his towel is."           

I beg your pardon?
Ron

[quinnf]

Ron,

You really need to read the Hitchhiker's Guide to the Galaxy.  And Heinlein (The Moon is a Harsh Mistress).  The former is a must read for anyone who wonders why the world is the way it is.  Bill has, and knows the reference is a compliment of the highest order. 

Pithy quote:  "You're so un-hip, it's a wonder your bum don't fall off."  

Quinn

[vdubnut62]

Ahh! That's just what I needed, a jolt to the old gray matter!  Due to old age, I missed the reference.  I do happen to have a copy of "The Hitchhiker's Guide"  boxed up somewhere...... Been years since I've seen it though, hope the Wife hasn't donated it to charity. Missed that particular Heinlein, will have to look it up.  
Sorry all, I'll slink away quietly now......
Ron

[highwater]

Newbie here, first post....

I have sent 2 separate emails, in the last 10 days or so; to the address listed on utterpower webpage for ordering the book/CD combo, but I have not received a reply. Does anyone know if they are alive over there? Or is one of you folks possibly one of them folks

I have a 20hp 3ph GE induction motor and one of those 2cyl Cat label Perkins sitting on the floor, that I might mate up for a grid down backup.

Thanks for having me. I can see I will learn a lot here.

Randall

[mobile_bob]

welcome aboard,

George over at utterpower is in and out a lot, and he might have missed your email.

just keep after him, he will get back soon i am sure.

bob g

[Halfcrazy]

I ordered the book and lister cd I never did here from anybody but it showed up here 3 days later. The book is worth every penny and I just may venture down the Induction motor rd one day now that I fully understand the workings.

[rcavictim]

IMLE (In My Limited Experience) induction generators made by resonating an induction motor with capacitors have very poor regulation and it might be easy to overvoltage your load and let the smoke out.  A poor substitute for a real alternator generator head.  I'd consider it if I had a used car lot full of overhead incandescent lamps as the only load, or resistance heaters, that sort of thing.  They are not well suited to drive inductive loads and make poor power for starting motors.  If your load is near unity power factor and constant they could be a cheap way to make power.  You won't have to worry about brushes wearing out.

[Westcliffe01]

Hmmmm  The "breezy" wind generator from Prairie turbines has been around for eons and has been exhibited at alternative energy shows for years too.  And as far as I know, there are people using the breezy in a net metering type situation.  They even have a specific page on their website devoted to this application: http://www.prairieturbines.com/gridandbuild.htm Now I will admit that they use a microprocessor to control the thing and there certainly is no clutch, just like there is none in virtually any normal machine application.

I'm pretty sure that the utility company defines the hardware needed for the grid tie and it apparently works just fine.  The output is single phase and while the efficiency may not match expensive commercial rigs, neither does the cost.  Entry cost is $45 for the book and plans and $65 for the micro controller, which is not open source.  They sell all the hardware, weldments, slip ring etc etc, depending on what you can afford or scrounge.  It is a pretty big generator and with its wide blades it produces output at lower wind speeds.   The same geometry means that a heavy tower is needed, since the blades produce a lot of drag at high windspeed, which is why they survive high wind events quite well, provided the guys stay attached...