Single piece electric assembly for connecting an off-shore wind turbine with an electric subsea cable, wind turbine, wind turbine cluster and method for mounting such an electric assembly to a wind turbine tower

1. An electric assembly for electrically connecting at least one wind turbine being located off-shore with an electric subsea cable being connected to an on-shore power grid, the electric assembly comprising

a transformer for transforming a first voltage level being provided by the at least one wind turbine to a second voltage level of the subsea cable, and

an external equipment being electrically and mechanically connected to the transformer for controlling an operation of at least the transformer, the external equipment comprises a gas insulated switchgear and an electric connection arrangement which receives a plug connector on a platform of the wind turbine such that an automatic plug in connection between the electric connection arrangement and the plug connector is established therebetween,

wherein the transformer and the external equipment are formed by a preinstalled package, which can be mechanically handled as a single piece, and lowering the single piece onto the plug connector of the platform establishes the automatic plug in connection between the electric connection arrangement and the plug connector.

2. The electric assembly as set forth in claim 1 , wherein

the external equipment comprises an earthing switch.

3. The electric assembly as set forth in claim 1 , wherein

the external equipment comprises an electric disconnector.

4. The electric assembly as set forth in claim 1 , wherein

the electric connection arrangement is configured for electrically connecting the electric assembly to a first cable termination arrangement being assigned to the wind turbine and/or to a second cable termination arrangement being assigned to the subsea cable.

5. The electric assembly as set forth in claim 1 , wherein

the external equipment comprises a cooling device for cooling the transformer.

6. A wind turbine comprising

an electric assembly as set forth in claim 1 .

7. The wind turbine as set forth in claim 6 , further comprising

a tower and

a platform being mounted to the tower and being located outside of the tower,

wherein the electric assembly is located on the platform.

8. The wind turbine as set forth in claim 7 , further comprising

a collecting tank for collecting a fluid being lost from the transformer, and

a fluid communication device for connecting the transformer with the collecting tank in such a manner that a fluid being lost from the transformer is transferred to the collecting tank.

9. The wind turbine as set forth in claim 8 , wherein

the collecting tank is located within the tower of the wind turbine.

10. A wind turbine cluster comprising

a plurality of wind turbines being electrically connected together,

wherein one wind turbine of the plurality of wind turbines is a wind turbine as set forth in claim 6 .

11. A method for mounting an electric assembly as set forth in claim 1 to a tower of a wind turbine, the method comprising

assembling the electric assembly,

transporting the electric assembly as a single piece from an on-shore location to an off-shore location, and

mounting the electric assembly to the tower at the off-shore location.

12. The method as set forth in claim 11 , further comprising

pretesting at least some of the electric functions of the electric assembly at the on-shore location.

13. The electric assembly as set forth in claim 1 , wherein

the external connection arrangement comprises guiding side walls made from an electric conductive material.