Classification and use of transformers

The purpose of transformer

A transformer is a static electrical device that transforms alternating current.

Classification of transformers

Transformers can be divided into the following categories according to their uses: power transformers for power transmission and distribution, including step-up and step-down transformers, etc.; special transformers for special power supplies, including welding transformers, rectifier transformers, electric furnace transformers, medium frequency transformers, etc.; instrument transformers for measurement, including current transformers, voltage transformers, autotransformers (voltage regulators), etc.; small power transformers for automatic control systems; impedance converters for communication systems, etc.

Basic working principle of transformer

Two high and low voltage windings with N1 and N2 turns are wound on the same iron core. The AX winding connected to the power supply and absorbing electric energy from the power grid is called the primary winding (primary winding), and the ax winding connected to the load and outputting electric energy to the external circuit is called the secondary winding (secondary winding). Transformer Working principle When the primary winding is applied with voltage U1, the primary side will have current I1 flowing through it, and an alternating main magnetic flux Φ with the same frequency as U1 will be generated in the iron core. The main magnetic flux will simultaneously link the primary and secondary windings. According to the law of electromagnetic induction, induced potentials E1 and E2 will be generated in the primary and secondary windings. Under the action of E2, the secondary side will generate load current I2 and output electric energy to the load.

Transformer Principle
According to the law of electromagnetic induction, we have: where k is the transformer ratio.

If the winding internal resistance and leakage flux are ignored, the voltages at the primary and secondary winding terminals are approximately: