A slip ring unit for an electrical machine is provided for accommodating a carbon brush system. The slip ring unit includes at least one insulating segment having shaped sections for cooling parts of the electrical machine. The insulating segment having the shaped sections is shaped from the insulating segment as a fanwheel, wherein the insulating segment having the shaped sections forms a fan to distribute a cooling air flow to the parts of the electrical machine to be cooled. The slip ring unit has boreholes on the sides of supports of the slip rings for passage of cooling air.