A magnet wheel and a stator winding which are necessary for an excitation device are included in a synchronous machine. Energy is transferred to the magnet wheel through inductivity, preferably, energy to a super-conductive coil, by the excitation device. Protection against the magnetic field produced by the current in the winding head is provided in the form of a specific system which is used to reduce the corruptions of the interfering fields of stator and rotor winding.