There are many classification methods for transformers, according to different classification methods, but also have different transformers.

One. According to the number of phases:

1, single-phase transformer: used for single-phase load and three-phase transformer group.

2, three-phase transformer: used for three-phase system's rise and fall voltage.

Two, according to the cooling mode:

1. Dry-type transformer: relying on air convection cooling, generally used for local lighting, electronic circuits and other small-capacity transformers.

2. Oil-immersed transformer: relying on oil as cooling medium, such as oil-immersed self-cooling, oil-immersed air-cooling, oil-immersed water-cooling, forced oil circulation, etc.

Three, by use:

1, power transformer: used for transmission and distribution system's rise and fall voltage.

2. Instrument transformer: such as voltage transformer, current transformer, measuring instrument and relay protection device.

3. Test transformer: it can generate high voltage and carry out high voltage test on electrical equipment.

4, special transformers: such as electric furnace transformers, rectifier transformers, transformer adjustment.

Four, according to the winding form:

1, double winding transformer: used to connect two voltage levels in power system.

2, three winding transformer: generally used in power system regional substation, connect three voltage levels.

3, auto transformer: power system used to connect different voltages. It can also be used as a common boost or down transformer.