Saturation curves of delta-connected transformers from measurements

An algorithm is described for the computation of the saturation characteristics of three-phase delta-connected transformers from measured V_rms-I_rms curves and no-load losses at rated frequency. For these transformers, positive sequence excitation tests are usually carried out with the delta connection closed. While triplen harmonic currents are present in the delta-connected windings, they do not appear in the line connections to the three-phase source. This paper presents an algorithm which accounts for the missing triplen harmonics on the line side in the derivation of the saturation characteristics