Electrical Machines, 2nd Edition

2 Three-phase Transformers

The generation of electric power is three-phase in nature and the generated voltage is 13.2 kV, 22 kV or higher. Transmission of power is carried out at high voltages like 132 kV or 400 kV Before transmission, it is required to step-up the voltage and for this a three-phase step-up transformer is required. Similarly, at the distribution substation, the voltage must be stepped down and it is necessary to reduce the voltage level up to 6,600 V, 400 V, 230 V and so on. Here, a three-phase step-down transformer is required. Therefore, it is economical to use three-phase transformers for transmission and utilization purposes. Earlier it was common practice to use three suitable single-phase transformers rather than a single ...