Introduction, Principle And Classification Of Three Phase Power Transformers

Introduction to three phase power transformers

A transformer is a device that uses the principle of electromagnetic induction to change the AC voltage. Its main components are primary coil, secondary coil and iron core.

The main functions of the transformer are: voltage conversion, current conversion, impedance conversion, isolation, voltage regulation (magnetic saturation transformer), etc. According to the use, it can be divided into power transformers and special transformers.

How three phase power transformers Work

A transformer is a device used to convert alternating voltage, alternating current and impedance. When alternating current passes through the primary coil of the transformer, an alternating magnetic flux is generated in the iron core (or magnetic core), and a voltage (or current) is induced in the secondary coil.

It consists of a transformer core (or magnetic core) and a coil. Coils have two or more windings, where the winding connected to the power source is called the primary coil and the other windings are called the secondary coil.

The main classification of three phase power transformers

Common transformers can be divided into the following categories:

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 step-up and step-down of three-phase system.

According to cooling method:

1) Dry-type transformers: rely on air convection for natural cooling or fan cooling, and are mostly used for small-capacity transformers such as high-rise buildings, high-speed toll stations, local lighting, and electronic circuits.

2) Oil-immersed transformer: rely on oil as a cooling medium, such as oil-immersed self-cooling, oil-immersed air cooling, oil-immersed cooling, forced oil circulation, etc.

Depending on the application:

1) Power transformer: used for voltage rise and fall of power transmission and distribution system.

2) Transformers: such as voltage transformers, current transformers, measuring instruments, relay protection devices, etc.

3) Test transformer: It can generate high voltage and conduct high voltage test on electrical equipment.

4) Special transformers: such as furnace transformers, rectifier transformers, voltage regulating transformers, capacitor transformers, phase-shifting transformers, etc.

According to the winding form:

1) Double winding transformer: used to connect two voltage levels in the power system.

2) Three-winding transformer: generally used in substations in power system areas, connecting three voltage levels.

3) Autotransformer: used to connect power systems of different voltages. It can also be used as a normal step-up or step-down transformer.

By three phase power transformer iron core form:

1) Iron core transformer: high voltage power transformer.

2) Amorphous alloy transformer: Amorphous alloy iron core transformer is a new type of magnetically conductive material, and the no-load current is reduced by about 80%. It is a distribution transformer with ideal energy saving effect, especially suitable for rural power grids and developing areas with low load rate.

3) Shell-type transformers: special transformers with high current, such as electric furnace transformers, welding transformers; or power transformers for electronic instruments, televisions, radios, etc.