Can electric motor generate electricity if rotated manualy / with water turbine?

Question

Can electric motor generate electricity if rotated manualy / with water turbine?

Answer 1

A normal ac motor has a squirrel cage rotor that is made to turn with a changing magnetic field. If you move a magnet in a conducter it will generate a voltage, therefore the rotor will not really generate a useable voltage. It does generate a little bit but if you load it it will go close to 0 Volts. If you have a correct magnet in place of the rotor it will generate a voltage.

Answer 2

Surely. An electric motor can generate electricity only if it is rotated at a speed that is greater than its synchronous speed. So it doesn't matter if you rotate it with water turbine / manually. You just have to rotate it at a greater speed than its synchronous speed.

Answer 3

If it is a permanent magnet motor, yes. Else you will need to electrify the field coils to get current, like an alternator in a car, this is the most efficient way actualy.

Induction motors will also create a tiny amount of current that you will only be able to see on an oscilloscope. This may be due to the rotor being magnetized slightly, i have never looked into it.