Comments on: Can a capicitor start AC motor be used as a generator?

By: j p

j p — Tue, 08 Dec 2009 03:38:30 +0000

Well you already figured it out that this doesn’t work.
I would suggest to forget the idea with a capacitor start electric motor. If you take the motor apart then you’ll see that the armature or rotor in this case does not have a winding to be used for excitation. This is the trick, in order to generate power you must create a rotating magnetic field that can be regulated first, this is not the case here. I would suggest to use an old car alternator, then charge a battery with the power coming out of this and use an inverter to get a stable (in Voltage and Frequency) AC out of it.

By: FredHH

FredHH — Tue, 08 Dec 2009 03:34:01 +0000

Any motor CAN be made to work as a generator.

A “squirrel cage” type AC motor, that has no permanent magnets in the rotor and uses the rotating magnetic field of the supplied AC to create magnetism in the rotor… will need to be started as a motor, then driven FASTER by whatever power source you are trying to employ.

As soon as you start trying to drive the motor faster than the supplied AC is trying to turn it… you are generating electricity, rather than using it.

There’s a neat effect here…. if you AC start the generator, then engage the drive you will have automatically synchronized with the power grid. As long as you don’t try to drive it TOO FAST, the squirrel cage design will keep it synchronized.

So… your motor CAN be used to generate power. But you’ll have to run it as a motor then start driving it with your windmill. Once its turning… you can flip the breaker off that connects it to the “Grid” and use the “free” energy.

However… the AC you generate will not have a reliable frequency if you disconnect from the grid.

If you leave it connected to the grid… every time the wind slows below a certain speed, the AC grid will be driving the windmill like a huge fan… and will be likely to burn the motor up, because to use it as a generator you need more than DOUBLE the fan blade area as the motor would normally drive.

By: natarajan l

natarajan l — Tue, 08 Dec 2009 02:50:54 +0000

I do not understand what you are doing. if a wind generator is to be made, then the wind turbines should rotate and this rotation should be coupled to the generators and the generator will generate voltage and if sufficient voltage is generated (In US it is 110 V AC) and if the have the capacity to have enough power then they will run your AC motors or if you DC motors then the voltage and power generated should be equal or more than the motor’s driving power. If you do not generate any power/voltage or produce very little power then the motor will not run and will load on the generator and the voltage will go down to zero.

Are you connecting the motor as generators and coupling them to the wind generator? then I very much doubt whether they work. If they are synchronous motors, then they can run as generators and vice versa.

So everything properly and consult an electrical engineer. There is a chance that you may get electrocuted.