The conversion of the kinetic energy of the flowing air into a mechanical rotary motion by the rotor is characterised by the laws of aerodynamics and the demand for lightweight construction. Associations with aircraft construction come to mind and are also technologically justified. A completely different picture presents itself to the viewer inside the nacelle. The components for converting mechanical energy into electrical energy represent conventional power plant technology. It could be concluded that this area is “state of the art” and therefore cannot pose any particular problems. This view is only partly correct.