It is common to walk on the streets and see electricity networks suspended from poles. As we know, the plants that generate electricity are located far from consumer centers. Therefore, for electricity to reach our homes, it is necessary to build huge distribution circuits, which carry electrical current from power plants to substations.
In the midst of this distribution of electrical energy, there is a lot of energy loss due to the phenomenon called joule effect. These losses are the result of heating the wires when they are traversed by electrical current. In order to reduce such losses, transformers, which are devices made up of two independent electrical circuits that involve a closed iron core.
O generator it is used to raise the electrical voltage generated in the plant and to decrease the intensity of the electrical current. As we know that the joule effect depends exactly on the intensity of the electric current, the smaller it is, the less energy will be lost due to heating.
Therefore, if it is necessary to reduce the electric current, it is enough to increase the number of turns of wire around the iron core in the secondary circuit. In this case, the transformer increases the voltage and decreases the intensity of the electrical current in the secondary circuit, which is why it is called
This increase in the voltage value is made close to the electricity generating plant, reaching values from 10 thousand to 300 thousand volts.
It is worth remembering that the operating principle of the transformer is based on the phenomenon of electromagnetic induction. The device is capable of inducing an electrical current in the secondary circuit when the electrical current is variable in the primary circuit connected to the source of electrical energy.
Changing the number of loops of wire in the secondary circuit in relation to the number of loops of wire in the circuit around the iron core, a change in the value of the electrical voltage induced in the circuit is obtained. secondary. As a result, the electric current also changes in intensity relative to its value in the primary circuit.
The rise in voltage occurs because an electric field is induced in the region where the secondary circuit is located. Depending on the value of this induced field and the length of the wire, the induced voltage will be different as it results from multiplying the value of the induced electric field by the length of the wire.
U = E.l
The greater the length of the wire that forms the transformer's secondary circuit, the greater the voltage induced in it and vice versa.
Close to cities, the voltage in the distribution circuit is reduced to suit different types of consumers: industries, shopping centers, public lighting, homes, etc. Another type of transformer performs this lowering of the voltage value. Therefore, the number of wire turns in the secondary circuit is less than that in the primary circuit.
If the number of turns of wire around the iron core in the secondary circuit is half the number of turns of the primary, the voltage on the secondary will be half the value of the voltage on the primary circuit and vice versa.
By Domitiano Marques
Graduated in Physics
Source: Brazil School - https://brasilescola.uol.com.br/fisica/circuito-eletrico-distribuicao.htm