What are the types of commonly used transformers? What is the purpose?

Classified by purpose:

Power transformers are commonly used transformers for increasing and decreasing voltage in power transmission and distribution.

Test transformers to generate high voltage and conduct high-voltage tests on electrical equipment.

Instrument transformers, such as voltage transformers and current transformers, are used for measuring instruments and relay protection devices.

Special purpose transformers, such as electric furnace transformers for smelting, rectifier transformers for electrolysis, welding transformers for welding, and regulating transformers for testing.

According to the number of phases:

Single phase transformer, used for single-phase loads and three-phase transformer groups.

Three phase transformer, used for raising and lowering voltage in three-phase systems.

Divided by winding form:

Autotransformer is used to connect ultra-high voltage and large capacity power systems.

Double winding transformer, used to connect two voltage levels.

Three winding transformer, connected to thirty voltage levels, generally used in regional substations of power systems.

According to the type of iron core:

Core transformer, used for high-voltage power transformers.

Shell type transformer, used for special transformers with high current, such as electric furnace transformers and welding transformers.

Divided by cooling method:

Oil immersed transformers, such as oil immersed self cooling, oil immersed air cooling, oil immersed water cooling, as well as forced oil circulation and water internal cooling.

Dry type transformers rely on air convection for cooling and are generally used for small capacity transformers such as local lighting and electronic circuits.

Inflatable transformer, using special chemical gas (SF6) instead of transformer oil for heat dissipation.

Evaporative cooling transformer, using special liquid instead of transformer oil for insulation and heat dissipation.