Transformer classification is mainly divided into four ways: by phase number, by cooling mode, by use, and by winding form.
 

By phase

Single phase transformer which used in single phase load and three phase transformers.
 

By cooling mode

The dry type transformer depend on air convection to achieve the natural cooling or increase the fan cooling which mostly used in high buildings ,high-speed charging station electricity, local lighting and electronic circuit. The oil-immersed transformer depend upon oil as cooling medium which has oil-immersed self cooling,wind cooling and forced oil circulation.
 

By the use

The power transformer used in transmission distribution system which rise and down the voltage.

The instrument transformer such as voltage transformers and current transformers which used for measuring instruments and relay protection devices.

Testing transformer can produce high voltage which can conduct high voltage test on electrical equipment.

Special transformers, such as furnace transformer, rectifier transformer, adjusting transformer, capacitor transformer, phase shifting transformer.

By the winding form
The double winding transformer which used in connecting 2 voltage classes.
The three-winding transformer used for regional substation for power system which also used be common transformer.

By iron core
Core type transformer used for high voltage power transformer.
Amorphous alloy transformer, amorphous alloy iron core transformer is a new type of magnetic conductive material that no-load current decreases by about 80% which is an ideal distribution transformer with energy saving effect which especially suitable for rural power grid and developing areas with low load rate.
Shell type transformer used for high current, such as furnace transformer, welding transformer or power transformer for electronic instrument, TV, radio, etc.