Rotary transformer

1. A system for high power transmission on an installation comprising:

a first part and a second part rotating relative to each other, wherein at least one of said first and second parts is anchored and the other part is allowed to rotate relative to the anchored part;

a rotary three-phase transformer having primary and secondary windings;

wherein the first part is provided with a first transformer part comprising at least one of said primary or secondary windings;

wherein the second part is provided a second transformer part comprising remaining winding of said primary or secondary windings;

wherein said primary and secondary windings are arranged to face each other;

an air gap is provided between the primary and secondary windings and their corresponding parts of transformer cores;

wherein the first and second parts comprise a central opening having a chosen diameter; and

wherein at least one of said first and second parts extends through the central opening.

2. The system according to claim 1 , wherein a floating vessel is an offshore floating weather vaning vessel, wherein the first part and the second part are constituted by a rotating hull and a turret being able to rotate relative to each other.

3. The system according to claim 2 , wherein the floating weather vaning vessel is a Floating Production Storage and Offloading-installation.

4. The system according to claim 2 , wherein the primary windings and associated parts of the transformer core(s) are mounted on a deck on the turret or on the rotating hull and the secondary windings and associated parts of the transformer core(s) are mounted on a deck on the hull or on the turret opposite of the primary windings.

5. The system according to claim 1 , wherein the rotary three-phase transformer is a transformer with cast resin windings or other dry cable winding technology.

6. The system according to claim 1 , wherein tertiary windings of the rotary three-phase transformer are arranged on the first or second parts.

7. The system according to claim 6 , wherein the tertiary windings are mounted on a deck on a turret or on a rotating hull of an offshore installation.

8. The system according to claim 1 , wherein the rotary three-phase transformer is constituted by three one-phase transformers with vertical air gaps.

9. The system according to claim 1 , wherein the rotary three-phase transformer is constituted by three one-phase transformers with horizontal air gaps.

10. The system according to claim 1 , wherein the installation is a weather vaning wind turbine, wherein the first and second parts are constituted by a tower and a nacelle rotating relative to each other.

11. The system according to claim 10 , wherein a rotating element is a shaft provided inside a length of the tower, wherein a first end of the rotating element is connected to the nacelle and a second end of the rotating element is connected to the one of the primary or secondary windings and their corresponding parts of the transformer cores.

12. The system according to claim 11 , wherein the three-phase rotary transformer is arranged in a lower part of the tower.

13. The system according to claim 10 , wherein a rotating element is a fastening brim provided on the nacelle for fastening of one of the primary or secondary windings and their corresponding parts of the transformer cores.

14. The system according to claim 13 , wherein the three-phase rotary transformer is arranged in an interface between the nacelle and the tower.

15. The system according to claim 13 , wherein the three-phase rotary transformer is arranged in an upper part of the tower.

16. The system according to claim 1 , wherein the rotary three-phase transformer is an oil filled transformer.

17. The system according to claim 1 , wherein the transformer cores comprise a pile of laminated tin plates for Eddy current limitation.

18. The system according to claim 1 , wherein the system is operable to supply power to an electrical grid.

19. The system according to claim 1 , wherein the system is intended for offshore applications.

20. A system for high power transmission on an installation comprising:

a first part and a second part rotating relative to each other;

a rotary three-phase transformer having primary and secondary windings;

wherein the first part is provided with a first transformer part comprising at least one of said primary or secondary windings;

wherein the second part is provided with a second transformer part comprising remaining winding of said primary or secondary windings;

wherein said primary and secondary windings are arranged to face each other;

an air gap is provided between the primary and secondary windings and their corresponding parts of transformer cores;

wherein the first and second transformer parts comprises at least one removable section, said at least one removable section comprising transformer legs with corresponding windings; and

wherein the primary and secondary windings comprise a number of separate windings on said at least one removable section.