Transformer is a device that uses the principle of electromagnetic induction to change the AC voltage. The main components are primary coil, secondary coil and iron core (magnetic core). The main functions are: voltage conversion, current conversion, impedance conversion, isolation, voltage regulation (magnetic saturation transformer).

Transformers can be divided into distribution transformer, power transformer, fully sealed transformer, combined transformer, dry transformer, oil-immersed transformer, single-phase transformer, furnace transformer, rectifier transformer, reactor, anti-interference transformer, lightning protection transformer, box type transformer test transformer, Angle transformer, large current transformer, excitation transformer, etc. Transformer is the basic equipment of transmission and distribution, widely used in industry, agriculture, transportation, urban communities and other fields. China has about 17 million transformers in operation on the grid, with a total capacity of about 11 billion kva. Transformer loss accounts for about 40% of power loss in transmission and distribution, which has great energy saving potential