A transformer is a static electrical device, belonging to a motor with zero rotation speed. When the power transformer works in the system, it can transfer electric energy from its primary side to the secondary side through the conversion of electromagnetic energy, and at the same time increase or decrease the voltage according to the needs of power transmission and distribution. Therefore, it plays a very important role in the whole process of electric energy production, transmission and distribution. In the whole power system, the capacity of the transformer is usually about 3 times more than the capacity of the generator.
When the transformer transforms the voltage, it makes its secondary side and primary side have different voltages and currents at the same frequency. Due to the conservation of energy, the changes of current and voltage on the secondary side and the primary side are opposite, that is, when the voltage of a circuit on one side is increased, the current on that side must decrease. The transformer is not and cannot increase or decrease the "amount" of electric energy. In the process of power conversion, because the transformer itself consumes a certain amount of energy, the total energy input to the transformer should be equal to the output energy plus the energy consumed by the transformer itself when it is working. Since the transformer has no rotating parts, there is no mechanical loss when working, and the new product has adopted many energy-saving measures in design, structure and process, so its working efficiency is very high. Generally, the efficiency of small and medium-sized transformers is not less than 95%, while the efficiency of large-capacity transformers can reach more than 80%.
