A transformer is 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. It was a long time ago.
The device of the transformer is quite simple. In its simplest form, it is a core of electrical steel plates, on which two windings are wound. The first winding, called the primary winding, is connected to the power 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 an EMF (electromotive force) in the secondary winding. For all transformers, the concept of a transformation ratio is used. This is a characteristic of the ratio of the voltage on the primary winding to the voltage on the secondary winding. You can also calculate the transformation ratio 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 step-up. And if the secondary voltage is less than the primary - then step-down. The current in the windings always has an inverse relationship with the voltage, and hence with the number of turns. Therefore, the primary winding is made of a wire of small cross section, but with a large number of turns. And the secondary winding is the opposite: fewer turns, but a larger wire cross section. The core and yoke are assembled from sheets of electrical steel, as it conducts magnetic flux perfectly. The sheets are insulated from each other to reduce eddy currents and reduce core losses. This assembly method increases the efficiency (coefficient of performance).
The transformer device allows you to classify this machine according to several other criteria. For example, according to the number of phases, transformers are divided into three-phase and single-phase. They are also divided according to purpose. Basically, power and special transformers can be distinguished. The device of the power transformer is designed for the transmission and distribution of electrical energy. Special transformers can be very different - these are welding, measuring, testing, furnace, and instrumental. Autotransformers can also be attributed to them (in this electrical machine, the secondary and primary windings are connected into one electricalcircuit, creating an electrical connection as well, not just a magnetic one).
These transformers do not differ too much in design, since the principle of operation is virtually the same everywhere. Speaking about the device of a welding transformer, for example, we can say that in addition to a conventional power transformer, a special device has been added that regulates the welding current.
