Classification of Transformer (Ⅰ)

There are many types of transformers. In order to achieve different purposes and adapt to different working conditions, the type of transformer can be classified according to its use, the material structure of the winding and iron core, the number of phases, the working frequency, the voltage regulation method, the cooling method, etc.

Classification according to use

Transformers are divided into power transformers and special transformers

Power Transformers:Power transformers can be divided into step-up, step-down transformers, distribution transformers, plant transformers and so on.

Special transformers:Special transformers mainly include electric furnace transformers, rectifier transformers, welding transformers, high-voltage test transformers, instrument transformers, high-voltage test transformers and voltage regulators, pulse transformers, etc.

Classification according to transformer construction

By winding structure

According to the structure of the winding division, it can be divided into single winding, multi-winding, and single-coil transformer is also known as auto-coupled transformer; multi-winding transformer by double winding, three winding, six winding (voltage regulator transformer visible) and other components.

By core structure

According to the winding method of winding on the core rod, the core can be divided into two structural categories: core type and shell type.

Core Transformer:Core transformer of the primary and secondary winding combination in the two core column, the structure is relatively simple, there are more gaps in the installation, easy installation, iron consumption is also less; large capacity, high voltage transformer is usually core type.

Shell Transformer:The iron core of the shell transformer surrounds the upper and lower parts and both sides of the coil. The structure of the transformer has good mechanical properties, and the core is easy to radiator, but its iron consumption is more, the production process is more cumbersome. Small capacity, low voltage transformer is usually shell type.

In addition, there are toroidal transformers, metal transformers, blade transformers, C- type transformers, ferrite transformers.

Classification by phase number

Transformers can be divided into single-phase transformers, three-phase transformers and multi-phase transformers according to the number of phases.

Single-phase transformer

Two sets of coils are wound on the same core to form a single-phase transformer. Usually used to transform single-phase AC voltage and current, the general rated capacity is relatively small. Single-phase transformers are widely used in electronic circuits, welding, metallurgy, measurement systems, control systems and tests.

Three-phase transformer

1. Three-phase transformer unit

Structure: It consists of three identical single-phase transformers, which are called three-phase group transformers or three-phase transformer groups.

Features: The corresponding magnetic circuit is a group magnetic circuit, each phase of the three phases has its own independent magnetic loop, and is not related to each other. Therefore, when the three-phase symmetrical three-phase voltage is applied to the primary side, the main magnetic flux and the no-load current of each phase are symmetrical to each other.

2. Three-phase core transformer

Structure: It is formed by connecting three iron cores in one piece according to the structure shown in Figure 7. In the case of three-phase flux symmetry, the main magnetic flux inside the middle core column is zero, so the middle iron column can often be omitted. The three-phase iron column can usually be arranged on a plane to facilitate production and save materials.

Features: The three-phase core transformer corresponds to the core magnetic circuit. The core magnetic circuit has interrelated characteristics. The magnetic circuit of each phase forms a closed loop with the other two-phase magnetic circuit. The length of the three-phase magnetic circuit can be different, and the magnetic resistance can also be different.