Transformer Power Calculation Methods Explained

To determine transformer power, multiply the output voltage by the output current. In single-phase transformers, the total power consumption is adjusted by multiplying by 120% (accounting for 80% efficiency). For three-phase transformers, calculations can vary. For example, with a phase voltage of 220V and line voltage of 380V, the rated power is calculated by the formula 1.732 × rated current × rated line voltage. In a case with different power values for each phase, such as 9KW for phase A, 10KW for phase B, and 11KW for phase C, the total power would be 33KW. With a power factor of 0.8, the transformer’s total power becomes 41.25kW.