# motor/generator conversion experiment



## Alhenry92 (Sep 14, 2012)

Hey guys,
If this sounds stupid, please forgive me, i'm just fascinated on how generators work at the moment, but its something new everyday.
Lately I've had an urge to make a generator. Nothing big, but able to power maybe a couple of 15 amp receptacles. I have a 1/3 hp motor and a 1/4 hp motor. Is it possible to make a generator using 120 volts?


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## wildleg (Apr 12, 2009)

yes .


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## Alhenry92 (Sep 14, 2012)

alright how do i make it work with what i have then?


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## Mouser (May 4, 2011)

Google "How to build a generator"


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## oldtimer (Jun 10, 2010)

Alhenry92 said:


> Hey guys,
> If this sounds stupid, please forgive me, i'm just fascinated on how generators work at the moment, but its something new everyday.
> Lately I've had an urge to make a generator. Nothing big, but able to power maybe a couple of 15 amp receptacles. I have a 1/3 hp motor and a 1/4 hp motor. Is it possible to make a generator using 120 volts?


 
Why would you want to power up an electric motor to operate a generator to produce electricity ?

Perpetual Motion ?


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## JRaef (Mar 23, 2009)

Basic basic basic crash course, so you can see the problems you are in for:

An AC motor can indeed become an INDUCTION generator. But that means it can ONLY generate electricity when ALREADY CONNECTED to the grid and powered by a "Prime Mover", a machine such as a windmill, water or steam turbine, combustion engine, something like that. If you connect an AC motor to a prime mover all by itself without a grid connection, it's just another load on the prime mover.

And to the other point if you use an electric motor AS the prime mover for the induction generator, you have losses in BOTH motors, so you have a net loss (waste) of energy. 

An Induction motor _becomes_ a generator by having the prime mover turn the rotor FASTER than the synchronous speed of the motor. The connection to the grid is necessary because an induction motor has no magnetics in it, the coils are ELECTROMAGNETS, so something has to POWER the electromagnets first, called "magnetic excitation". Without that, no power output. In theory once it is generating, you would think it could create it's own magnetization energy, but as you USE the power from the now-generator, you at the same time rob the generator of it's excitation and the energy drops down to nothing. There are ways to tap into that capability though by using capacitors to STORE some excitation power just long enough to make it work. It is done all the time by "home power" enthusiasts, but the process is a long read not suited for this forum. Google is your friend though.

For AC power generation, one alternative is to use a Permanent Magnet Generator, which has rare-earth magnets permanently installed to supply the necessary magnetism to make it generate. Another alternative is to use an AC Alternator, which has separate windings in the rotor and a way to energize them with a separate source of electricity, such as a battery or a small DC generator that is attached to the same shaft of the prime mover. The analog to this in the motor world is a "Synchronous Motor".


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