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What Is an Induction Generator?

Induction generators are commonly used in wind turbines.
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  • Written By: John Markley
  • Edited By: Melissa Wiley
  • Last Modified Date: 11 July 2014
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An induction generator, also called an asynchronous generator, is a type of alternating current electrical generator. The generator's rotor is placed within a rotating magnetic field, and the rotor is then spun by an external source of mechanical energy so that it rotates more rapidly than the magnetic field. The rotating shaft begins dragging the magnetic field field forward, sending electricity flowing into the generator's coils. Induction generators are less complex and more rugged than other forms of generators and can continue effectively producing power if their rotor speed changes. An induction generator needs an external supply of electricity to create its rotating magnetic field and start operating, but once it has started generating power it can continue running on its own, provided it has a source of mechanical energy.

Induction generators are commonly used in wind turbines, which use wind to provide the mechanical energy to move the generator's rotor. The generator's ability to function at varying speeds allows the turbine to remain in operation in varying wind conditions. Small hydroelectric power sources, sometimes called micro hydro generators, also use induction generators. These generators are equipped with a device called an induction generator controller, which prevents the induction generator from damage and allows it to keep functioning during variations in water flow. Owing to the simplicity of their design, very small induction generators capable of powering household appliances can be built with readily available parts, such as the motors of washing machines.

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Wind turbines often use a design called a doubly-fed induction generator, in which the rotor windings are connected to an electronics converter that can import or export reactive power to or from the generator as needed. This allows the generator to stay synchronized with the power grid during variations in wind speed. It also makes the power system as a whole more stable by allowing wind turbines to continue running and providing power to the grid uninterrupted in the event of a voltage dip in the grid, a capability called low-voltage ride through.

Induction generators are distinguished from synchronous generators, in which the rotor and the magnetic field rotate at the same rate. Synchronous generators can produce electricity more efficiently than induction generators, but need to be powered at a constant rate. The underlying principles of the induction generator can be applied in reverse to create an induction motor, in which the rotor is made to rotate more slowly than the magnetic field in order to convert electricity into mechanical energy.

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Discuss this Article

hamje32
Post 3

@allenJo - Actually, induction generators can be scaled up to power your house from what I understand. I think you can get wind turbines for your home. These are smaller turbines than what are used for industrial purposes but they do work.

Using a wind turbine induction generator does pose the obvious problem of what to do when the wind is not blowing. I think they may have a bank of capacitor circuits to store the energy.

Some survivalists also merge wind turbine technology along with solar power. Between the sun and the wind, you should have enough power to run your house. The only downside would be the initial startup costs however.

allenJo
Post 2

@Charred - You are probably imagining something like an electric generator that uses solar power instead. With the induction generator you do need something to “kick start” the power, but once set in motion, it keeps going on its own.

Obviously a lawn mower powered induction generator is not the kind of thing you would use to power up a whole house. The do it yourself plans you find on the Internet are more proof of concept than anything else.

Charred
Post 1

I’ve been on the survivalist forums where they actually show you how to build an induction generator using parts from the washing machine. One thing they point out is that you need something to start the generator. In this case the guy one the forum uses a lawnmower gasoline engine.

So that begs the question, what’s the point of building your own induction generator if you need the external power source? I guess I am not an expert on these matters but I don’t think these are good solutions for people wanting to get “off the grid” so to speak.

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