Power transformers are one of the main equipment for power plants and substations.The role of the transformer is not only to increase the voltage to send electricity to the electricity area, but also to reduce the voltage to the voltage used at each level to meet the needs of electricity. In short, both boost and buck must be done by a transformer. In the process of transmitting electrical  energy in the power system, voltage and power losses are inevitably generated. When the same power is delivered, the voltage loss is inversely proportional to the voltage, and the power loss is inversely proportional to the square of the voltage. Using a transformer to increase the voltage reduces the loss of power transmission.

The transformer consists of two or more coil windings wound on the same core. The windings are connected by an alternating magnetic field and operate according to the principle of electromagnetic induction. The installation location of the transformershould be considered for easy operation, maintenance and transportation, and a safe and reliable place should be chosen. The rated capacity of the transformer must be reasonably selected when using the transformer. When the transformer is

running at no load, a large amount of reactive power is required. These reactive powers are supplied by the power supply system. If the capacity of the transformer is too large, it not only increases the initial investment, but also makes the transformer run at no load or light load for a long time, which increases the proportion of no-load loss, reduces the power factor, and increases the network loss. This operation is neither economical nor reasonable. If the transformer capacity selection is too small, the transformer will be overloaded for a long time and the equipment will be damaged. Therefore, the rated capacity of the transformer should be selected according to the needs of the electrical load, and should not be too large or too small.