How to Calculate Transformer Power in Different Configurations

Transformer power is calculated by multiplying the output voltage by the output current. For single-phase transformers, the power is typically calculated by multiplying the total power consumption by 120%, assuming an 80% efficiency. For three-phase transformers, the calculation depends on the phase and line voltage. For instance, with a phase voltage of 220V and line voltage of 380V, the rated power can be determined by the formula: 1.732 × rated current × rated line voltage. For three-phase systems with varying power across phases, like 9KW for phase A, 10KW for phase B, and 11KW for phase C, the total power is 33KW. If the power factor is 0.8, the transformer’s total power becomes 41.25kW.