Disclosed is an assembly encompassing a three-phase machine and a frequency converter. Said assembly has the following characteristics: the three-phase machine comprises a stator and a rotor; at least the three circuits of the stator and/or the rotor can be operated in an insulated manner relative to each other for the three phases of the rotary current while being connectable to one separate terminal point of the frequency converter, respectively, so as to be insulated relative to each other; and the frequency converter is embodied with a D.C. link having a grounded neutral in such a way that a voltage or current which is symmetric regarding the potential to ground can be output at any moment between the two associated terminal points of each circuit.