Three-phase Transformer and Its Structure

The three-phase transformer is considered to be the backbone of the power distribution system. It is used to deliver huge energy. Its main function is to step up and step down the voltage at different stages of the power grid. However, it is also possible to use three interconnected single-phase transformers instead of three-phase transformers, but the use of three-phase transformers has some advantages, including:

It takes up less space than three single-phase transformers

Cost-effectiveness

The overall bus structure, switchgear, and installation of the "three-phase transformer" are not too complicated

Three-phase transformer structure

The construction method of the three-phase transformer is as follows

Three independent single-phase transformers are connected to perform the three-phase operation, the so-called core-type three-phase transformer

Use a single-phase three-phase transformer, combining all three-phase iron cores and windings into a structure, called a shell-type three-phase transformer

Core structure

The core consists of three legs or limbs. Each branch contains cylindrical primary and secondary windings. The core is generally composed of three legs on the same plane, and the legs adopt a laminated structure. Each branch has high and low voltage windings. The low-voltage winding is more insulated from the iron core than the high-voltage winding. The low winding is located next to the iron core, with proper insulation between the iron core and the low voltage winding. The high-voltage winding is located above the low-voltage winding with appropriate insulation between the low-voltage windings. The structure is shown below.

Shell type three-phase

In terms of three-phase transformers, three-phase transformers are more independent than core-type transformers. Each phase has its own magnetic circuit. The structure of the three-phase iron core transformer and the three-phase shell transformer are similar.

The working principle of a three-phase transformer is similar to that of a single-phase transformer. Due to the mutual inductance, power is transferred from the primary winding to the secondary winding. The biggest disadvantage of a three-phase transformer is that even in the event of a failure in one phase, the entire transformer must be removed from service for maintenance.

The above information is provided by the transformer manufacturer.