What are the working principles and functions of power transformers?

Working principle of transformer

Firstly, we need to understand how transformers work. In fact, the principle behind this is not complicated, but it requires some basic knowledge of electromagnetics.

When the primary winding of a transformer is connected to an AC power source, current flows in the winding, generating magnetic flux. This magnetic flux will pass through the iron core, causing alternating magnetic flux to be generated in the iron core. This process is like converting electrical energy into magnetic energy. Then, this alternating magnetic flux will be simultaneously linked to both the primary and secondary windings (i.e. the secondary winding). Due to the effect of electromagnetic induction, induced electromotive forces with the same frequency will be generated in the primary and secondary windings.

If the secondary winding is connected to the load at this time, the current will flow through the load under the action of induced electromotive force, and the magnetic energy in the iron core will be converted back into electrical energy. This is the process in which transformers use the principle of electromagnetic induction to transfer electrical energy from the power source to the load.

The function of a transformer

From a broad perspective, transformers are an indispensable part of the power system. Its main function is to transmit electrical energy without changing its frequency, and it is a static energy converter. In the power system, the total capacity of transformers is approximately 9 times or more the total capacity of generators. Its main function is to increase or decrease the voltage of electrical energy in the power system, in order to facilitate the rational transmission, distribution, and use of electrical energy.

When transmitting electrical energy of the same power, the higher the voltage, the smaller the current, and the smaller the power loss on the transmission line; At the same time, the cross-sectional area of transmission lines can also be reduced, thereby reducing the amount of metal used in the wires. This is the importance of transformers in the power system.

Transformers can be divided into several categories based on their different functions:

Power transformer: mainly used for boosting and reducing voltage in power transmission and distribution systems. We often hear and come into contact with this term. But in reality, we sometimes refer to transformers with low voltage secondary windings as distribution transformers.

Instrument transformers, such as voltage transformers and current transformers, are mainly used for measuring instruments and relay protection devices. This category may not be familiar to newcomers, but in fact, we often come into contact with it.

Test transformer: capable of generating high voltage and conducting high voltage tests on electrical equipment. This is also something we often come into contact with.

Special transformers: including electric furnace transformers, rectifier transformers, regulating transformers, capacitive transformers, phase-shifting transformers, etc. With the development of new energy and energy storage, the types of special transformers are constantly increasing, such as hydrogen production transformers, which also belong to special transformers.