In this paper the self-excitation system of synchronous generator based on capacitor discharge through excitation winding is described. The system comprises three-phase synchronous generator with connected in star scheme stator winding with neutral wire and independent excitation winding. When revolution speed of synchronous generator is at proper level then signal is passed to electronic charging generator and capacitor is gradually charged up to necessary voltage. When voltage level is proper high electronic generator is stopped and signal is passed to thyristor control unit which generates firing pulses to all thyristors simultaneously and capacitor is discharged in oscillating way through excitation winding arising proper excitation current which provides self-excitation of synchronous generator. In the paper operation of system, calculation of processes and results of experimental investigation is described.