Why can transform voltage?
When you passed the substation, you heard a noise inside. It’s a working transformer! Transformers are tools that convert the level of voltage from high to low or from low to high.
Why can a transformer change the level of the voltage? Let’s look at the structure of the transformer first. There are many different types of transformers and their sizes, too. But their basic structure is the same. They are two coils on the same iron core. These two windings are called the primary and secondary windings separately. External current enters the primary and comes out from the secondary. If the number of turns on the primary is more than that of the secondary, the secondary voltage will drop. That is a pressure reducing transformer. Conversely, if the number of turns on the primary is less than that of the secondary, the secondary voltage will increase. That means turbocharger.
The working principle of a transformer is not complicated. Based on the principle of induction, when an electrically conductive object is in a changing magnetic field, an instantaneous conductor can induce an electric current. Connect the transformer to the AC network; the current is passed to the transformer’s primary winding. Then, an electric current will generate a magnetic field. Because the current direction of the alternating current is continuously changed, a changing magnetic field in sync with the current is generated. This magnetic field forms a closed enamel along with the iron core of the transformer. Because the magnetic field strength and direction are constantly changing, inducing a current in the secondary coil. Since the voltage per turn of the coil is equal, the more turns of the secondary winding, the higher the secondary winding voltage.
What if DC is fed to the transformer? Since the direct current is always in one direction, the generated magnetic field’s direction will not change either. Therefore, on the secondary winding, the voltage cannot be induced either. So a transformer can only change the voltage of the alternating current.
Transformers are almost indispensable in places where electricity is used. In a power plant, electricity is generated from generators through a large transformer, increasing the AC voltage too high voltage electricity up to several tens of thousands or hundreds of thousands of volts. Then through the line, Power transmission to places where electricity is used such as factories, schools, households, etc. Through long-distance high-voltage transmission, it can greatly reduce the power consumption on the power lines. Electricity to use it must go through a transformer to lower the voltage to several hundred volts, providing for the factory to run the machines or for the family to use electric appliances. Of course, even smaller transformers can lower the voltage in the lighting network to only a few tens of volts, supplying home appliances like televisions, radios, etc.
When using a small transformer every day, touching it with your hand, the transformer is always hot. This is because when electricity flows through the transformer, heat is generated. The transformer used in high-voltage systems, due to the electric current’s heat, causes the transformer to become very hot. To keep the transformer working properly, it is common to place the transformer in the oil tank. Doing so can both allow it to cool quickly while preserving good electrical insulation performance.