A transformer is called an electromagnetic machine designed to increase or decrease the voltage in the network. The transformer device was invented at the end of the century before last by a Russian engineer named Yablochnikov. That was a long time ago.
The device of the transformer is quite simple. In its simplest form, it is a core made of plates of electrical steel, on which two windings are wound. The first winding, called the primary, is connected to an energy source. The second winding, secondary, is connected to the consumer - to the load.
If a current is passed through the primary winding connected to the source, then this current will create a magnetic alternating flux in the core, which will induce EMF in the secondary winding (electromotive force). For all transformers, the concept of transformation coefficient is used. This is a characteristic of the ratio of voltage on the primary winding to voltage on the secondary winding. Also, the transformation coefficient can be calculated by the ratio of the number of turns on the windings. W1 / W2 = k, where W1 is the number of turns of the primary winding, W2 is, respectively, the number of turns of the secondary winding.
Speaking about the device of the transformer, it should be said that these electrical machines are divided into step-up and step-down. In the event that the voltage on the secondary winding is greater than on the primary, such a transformer is called a step-up. And if the secondary voltage is less than the primary - then lowering. The current in the windings always has an inversely proportional relationship with the voltage, and therefore with the number of turns. Therefore, the primary winding is made of a wire of a small cross section, but with a large number of turns. And the secondary winding - on the contrary: fewer turns, but a larger cross section of the wire. The core and yoke are assembled from sheets of electrical steel, as it conducts magnetic flux perfectly. The sheets are isolated from each other to reduce eddy currents and reduce core losses. This method of assembly increases efficiency (efficiency).
The transformer device allows you to classify this machine for several more reasons. For example, according to the number of phases, transformers are divided into three-phase and single-phase. They are also divided according to their purpose. In general, power and special transformers can be distinguished. The power transformer is designed to transmit and distribute electrical energy. Special transformers can be very different - it is welding, and measuring, and testing, and furnace, and tool. Also, autotransformers can be attributed to them (in this electric machine, the secondary and primary windings are connected into one electrical circuit, creating also an electrical connection, not just a magnetic one).
These transformers do not differ too much in design, since the principle of operation is practically the same everywhere. Speaking about the device of the welding transformer, for example, we can say that in it, in addition to the usual power transformer, a special device is added that regulates the welding current.