What is a transformer?
The transformers are electrical elements that are crucial for the distribution and domestic use of electrical energy. Transformers increase or decrease the voltage of alternating current, but that theoretically does not change their power.
What parts make up a transformer?
- Core: the center of the transformer. The electromagnetic field circulates in it; this field is produced by the windings. Its function is to keep that magnetic flux contained to prevent any losses produced by the eddy currents.
It is usually made of stacked metal sheets, but depending on the type of transformer, it may be made out of different materials and with different shapes, such as the shell-type, toroidal, etc. Some special transformers may have no core; these are known as coreless or air-core transformers.
- Coils: they are usually composed of copper wires wound around the core. They are what produce voltage fluctuations. The number of turns (spirals) of each coil has a direct relationship to the voltage; the more turns, the more voltage.
A transformer has at least two coils: a primary one through which the current enters, known as the primary coil, and a secondary through which the current exits, called the secondary coil. The number of turns in the primary coil corresponds to the input voltage, and the number of turns in the secondary coil corresponds to the transformer’s output voltage.
Normally, the windings are wound one on top of the other – the one with the highest voltage over the one with the lowest voltage – to make better use of the magnetic field and prevent losses.
The three-phase transformers have three coils for the primary winding and three coils for the secondary winding. The three-phase transformer is composed of three single-phase transformers, one for each phase; their electromagnetic fields do not interfere with each other.
- Insulation: the elements of a transformer (core, primary winding, and secondary winding, and each turn) are separated from each other by insulation because each of them has different tensions.
High-voltage transformers typically use a paper layer soaked in mineral oil to isolate the core from the windings and the windings from each other. The consecutive turns are usually isolated by a thin layer of copper lacquer. Non-consecutive turns can be isolated from each other by lacquer or paper, as needed.
Depending on the specific characteristics and functions of transformers, they may have more components, such as:
- Control board.
- Various types of relays, mechanical or electronic protective elements of the transformers for various types of imbalances.
- Expansion tank to contain the increased volume of the liquid elements in oil-immersed transformers.
What is an ideal transformer, and why doesn’t it exist?
An ideal transformer is always a theoretical transformer. When designing a transformer, there are no losses of any kind; however, in practice, it is impossible to build such a transformer – real transformers always have losses.
One of the phenomena involved in transformers’ energy loss is the eddy currents: eddy currents that appear in variable electromagnetic fields, creating electromagnets that oppose the effect of the magnetic field.
Despite the fact that it is impossible to build, the ideal transformer is useful for understanding the operation of actual transformers.
What is a transformer used for?
At macro levels, a transformer makes it possible to transport electrical energy while minimizing losses. By using high-voltage cables for long distances, the energy losses that occur are minimal. Thanks to transformers, the electric current changes its voltage near the point of arrival and consumption rather than doing so at the point of generation or storage.
At domestic levels, the transformer is highly present. Most appliances that are used in everyday life work with a voltage lower than that obtained from the outlet. Almost all appliances have current transformers in their cables or interior that allow them to function, though the power supply current may be higher than their requirements.