Rotating electric machine comprising a main electric machine, an excitation machine whose rotor is adapted to rotate with a rotor of the main electric machine and produce magnetizing power to the main electric machine, and a controllable rectifier bridge electrically connected to the excitation machine for feeding a field magnetization current to a rotor winding of the main electric machine and comprising controllable semiconductor components for controlling the field magnetization current. The rotating electric machine comprises a controllable circuit connected in parallel with the rotor winding and adapted to lower the magnetization of said rotor winding. The controllable circuit is a self-controlled circuit configured to self-act depending on the voltage across said rotor winding and comprises a discharge resistor dissipating the field magnetization current to lower the magnetization of said rotor winding.