Basic Knowledge of Transformers

One of the main reasons for the AC voltage and current we use in our homes and workplaces is that AC power can be easily transmitted through high voltage and long distances, and transmitted to various places through cables. And then through the transformer conversion to achieve our standard voltage in daily work or life.

The main reason why the power grid is transmitted through high-voltage electricity is because the high-voltage electricity has a lower current under the same power, so the loss of the voltage along the transmission through the cable is lower. These higher AC transmission voltages and currents can be reduced to lower, safer and usable voltage levels, and can be used to power electrical equipment in our homes and workplaces, all thanks to the basic voltage transformers.

The voltage transformer can be considered as an electrical component rather than an electronic component. A transformer is basically a very simple static (or fixed) electromagnetic passive electrical device. It works according to the principle of Faraday's law of induction, converting electrical energy from one value to another.

The transformer achieves this by connecting two or more circuits together using a common oscillating magnetic circuit generated by the transformer itself. Transformers work on the principle of "electromagnetic induction" in the form of mutual inductance.

Mutual inductance is the process by which one coil magnetically induces a voltage to another coil located near it. Then we can say that transformers work in the "magnetic domain", and transformers are named because they "convert" one voltage or current level to another. 

A transformer can increase or decrease the voltage and current level of its power source without modifying its frequency or the amount of electrical power transferred from one winding to another through a magnetic circuit.

A single-phase voltage transformer is basically composed of two electrical coils, one is called the "primary winding" and the other is called the "secondary winding". In this tutorial, we define the "primary" side of the transformer as the side that usually receives power, and the "secondary" as the side that usually provides power. In a single-phase voltage transformer, the primary is usually the higher voltage side.

The two coils have no electrical contact with each other, but are wound together around a common closed magnetic iron circuit called the "core". This kind of soft iron core is not solid, but is composed of individual laminations connected together to help reduce the loss of the iron core.

The two coil windings are electrically isolated from each other, but are magnetically connected by a common iron core, allowing power to be transferred from one coil to the other. When current passes through the primary winding, a magnetic field is generated, and a voltage is induced in the secondary winding as shown in the figure.