A three-phase transformer is a static apparatus with three pairs of windings, designed to convert voltage when transmitting electric current over long distances. This conversion can be done using three single phase transformers. But the complex apparatus has significant dimensions and weight. A three-phase transformer is free from these disadvantages, due to the fact that three windings are located on a common magnetic circuit.
The main task of such an apparatus is to transform the parameters of the electric current in such a way that the losses during heating of the wires are minimal. To solve this problem, it is necessary to reduce the current strength and increase the voltage value to 6-500 kV so that the power value remains constant. After the delivery of the electric current to the consumer, the voltage must be reduced to the required value - 380 V. And this problem is also solved by three-phase devices