how can you measure the vector group of a large power transformer?

To measure the vector group of a large power transformer, you can perform a phase shift test using a three-phase supply. Connect the transformer to the supply and measure the phase angles of the primary and secondary voltages. By comparing these angles, you can determine the phase displacement and identify the vector group. Additionally, using a power quality analyzer can provide precise measurements of phase relationships, confirming the transformer’s vector group classification.