On harmonics from a power transformer used in the excitation circuit of a power group

One presents some aspects related to the behavior of a three-phase power transformer used in the excitation circuit of a power group. The excitation transformer is directly supplied from the three-phase generator terminals. It supplies a fully controlled rectifier with thyristors, through which the main generator´s excitation winding is supplied. The currents flowing through the primary and secondary windings of the excitation transformer are recorded. The data acquisition systems used during the recording process were especially designed and realized for this application. Using an original software, the recorded waveforms for currents and voltages were processed. The significant harmonic distortion from the transformer´s primary and secondary winding proves their significant distorting regime, that affects their lifetime.