A generator for an electrical machine having a stator and a rotor is provided. The rotor is rotatable around a center axis and relatively to the stator. The stator is built of a stator stack with a number of adjacently disposed metal plates and the stator further includes a number of stator windings which are at least partially wound around the metal plates with a certain distance to each other. At least one radial duct-like channel is provided between two or more adjacently disposed metal plates by spacers, wherein the spacers are arranged underneath the stator windings in such a manner that the at least one radial duct-like channel is radially open.