Electric machine and method to retrofit an electric machine

1. An electric machine comprising:

a stator;

a rotor;

a cooling circuit for at least one of the stator and rotor;

a plurality of fans for cooling the fluid circulation, the plurality of fans being separated from the rotor;

wherein each of the plurality of fans are configured to be activatable independently of any other fan of the plurality of fans; and

at least one one-way valve fluidly associated to the plurality of fans;

wherein when the electric machine is at part load, the plurality of fans are configured to only require power needed for cooling the electric machine at part load conditions.

2. The electric machine according to claim 1 , comprising:

at least one motor for activation of the plurality of fans.

3. The electric machine according to claim 1 , wherein the at least one one-way valve is connected to at least one fan of the plurality of fans.

4. The electric machine according to claim 1 , comprising:

a cooler located at a lateral side of the electric machine, at least one fan of the plurality of fans being connected to the at least one cooler.

5. The electric machine according to claim 1 , comprising:

a foundation for housing the electric machine, wherein the plurality of fans are housed within the foundation.

6. The electric machine according to claim 1 , comprising:

additional fans wherein the rotor is provided with the additional fans connected to one or both shafts thereof, the additional fans being able to provide a part of the cooling fluid for the stator and the rotor.

7. The electric machine according to claim 1 , comprising:

a higher pressure zone (HP);

a lower pressure zone (LP);

a wall between the higher pressure zone and the lower pressure zone, wherein the wall has apertures.

8. The electric machine according to claim 1 , wherein the electric machine is an electric generator.