# How does the electric motor and generator vary?

what is the key difference between the windings of the electric motor and electric generator?

• Can you elaborate on what you mean by this question? Why are you asking it? The more you explain, the better we can answer the question. (Well, up to a point) Jun 15, 2011 at 7:15
• I.E. Could be more specific about the motors (AC, DC, linear, step,...) and generators (DC, three-phase,...). In general: By varying current and voltage in coils you force magnets to move. In generators by varying the position of magnets you induce voltage in coils. Jun 15, 2011 at 7:25

Electric motors vary... a lot: size; shape; purpose; AC or DC; linear, rotational, etc.

Electric generators, likewise, vary... a lot.

Having said that, a DC motor can be thought of as a DC generator with the energy conversion process running in reverse: A DC motor converts electrical energy into mechanical energy, and the generator converts mechanical energy into electrical energy. AND the neat thing is that this process can run either direction in the very same device.

Electric cars are doing this now: the electric motor which powers the wheels also acts as an elecrodynamic brake when you want to slow down. The motors use the car's kinetic energy to power each wheel motor as a generator, reclaiming electrical energy to recharge the car's batteries which got the wheels rolling in the first place.

• You have forgotten electro-dynamic brake used in trains since 70's. But many of them have only large resistors and coolers an the roof Jun 16, 2011 at 7:51

AC motors driven by a mechanical force are a generator the same as a car alt. is. the car alt. like the motor needs to be excited. the motor will put out its rating once at its rated speed and the field excited. The car alt. voltage regulates the field. Then rectifies AC to DC for the car.

The most obvious difference is that an electric motor need some current to drive it. While electric generator doesn't need any electric drive. Also, this distinguished difference is caused by what they made for. One creates electricity and one uses it.