The present invention relates to a slip ring assembly for providing electricity to or from a rotor rotating in relation to a stator in a generator or an electrical motor. The slip ring unit rotates around a centre axis and has at least one first slip ring with an outer surface, a diameter, and a width. Also, the assembly has at least one conductive means, such as a brush, having conductive contact with the surface of the slip ring, and a housing in which the slip ring unit and the conductive means are situated. Furthermore, the assembly has a suction means in connection with the housing for suction of gas from within the housing out through a suction outlet in the housing. In addition, the housing has a suction inlet which is connected with a guiding means. The guiding means has an aperture facing the slip ring surface, and the aperture is positioned at a predetermined distance from the surface of the slip ring so that the gas is able to cool the surface of the slip ring. Also, the invention relates to a generator and a wind turbine having such a slip ring assembly.