Electrical transformer: how does it work and what is it for?

The electrical transformer is one of the main actors in the network, guaranteeing its supply and efficiency

The electrical grid is a complex tangle of elements that interact with each other to ensure that energy moves from one point to another in a stable and secure manner, ensuring that we, the users, have a supply at all times. This availability is something we take for granted, but it is still a technological milestone that is the result of countless years of research and development applied to all of these elements. As such, today we want to focus on the operation and function of one of these key pieces: the electrical transformer, or trafo.

Before going into depth about the actual operation and use of this element of the electrical grid, it may be necessary to explain why electricity must be transformed. The reason is that the energy generated by the plants is produced at low or medium voltage, depending on the source, which makes it necessary to raise it to high voltage to ensure its efficient transport through the electrical grid, minimizing losses in the transport of energy. It is at this point where our protagonist of today comes into operation, which prevents this energy loss.

That is to say, the transformer is the main “culprit” that could be carried out, successfully, the transport of electrical energy over long distances in a practical and economical way,

To do this, the transformer varies different magnitudes of the alternating current such as voltage or intensity, maintaining the frequency and practically all of the power at all times; something in which efficiency terms are achieved in a range between 96% and 97%. Thanks to the principles of electromagnetic induction, energy flows from one electrical circuit to another without changing frequency, improving the safety and efficiency of power systems throughout the entire transportation process.

Thus, we can identify different uses of the transformer:

• Vary the voltage level within a circuit up or down.
• Adjust the generation voltage for transmission and distribution.
• Isolate two different electrical circuits, in addition to preventing the passage of direct current between them.

What elements make up an electrical transformer?

In order to carry out all these functions, transformers have different elements with their own tasks. Let’s take a look at the main ones.

• Core: this is a series of magnetic sheets that also serve as a support for mounting other elements, for the conduction of magnetic flux.
• Winding: is the wire or strip (either copper or aluminum) wound in the form of coils (two, one high and one low voltage) and which serves as a conductor of electricity from one point to another around the core. 
• Insulators: are the materials that provide grounding between the different elements of the transformer and their voltages. A system of layers of paper submerged in mineral or vegetable oil is usually used.
• Enclosure: This is the sheet metal structure that makes up the exterior of the transformer and serves as a container and protection for all the elements.
• Control and sensor unit: This is an element available in transformers with greater technological equipment, such as the transforma.smart, and it allows the collection of data about the operation of the network and the transformer itself, as well as the digital control of the device itself.

How does a transformer work?

Despite the technological challenge involved in designing transformers, their operation is relatively simple compared to other elements of electrical switchgear; and its success lies in its simplicity.

The electrical transformer couples two different electrical circuits through a common circuit (magnetic circuit), applying the principles of electromagnetic induction.

That is, a transformer will use the two windings (windings) to generate a double circuit linked through a common magnetic link (the core).

The current flowing through the high voltage winding generates a magnetic flux that runs through the core and induces a different current and voltage in the low voltage winding, maintaining the frequency. The voltage ratio of the two windings (high and low voltage) is proportional to the number of turns each of them has.

What types of transformers are there?

Depending on their functions, type of electrical system, installation locations and construction typology, we can distinguish several types of transformers. So, let’s see what the main types are by category.

Electrical transformers by type of electrical system

• Single-phase: the electrical distribution system is carried out through a single conductor (cable) or phase.
• Three-phase: the most widely used distribution system, made up of three conductors or phases. In this way, the three-phase current that circulates is made up of three currents single-phase alternating currents of equal frequency and amplitude. Compared to the single-phase distribution system, costs are reduced for the same amount of electrical energy transformed and generated

When the transformer performs a voltage boosting function, and is commonly known as a step-up electrical transformer; and when it performs reduction tasks, it is known as a step-down electrical transformer.

Electrical transformers by construction type

• Oil-immersed: this is the most widespread and has proven to be the most environmentally friendly, as well as having a longer useful life than the rest.
• Dry: a technological alternative to oil-filled transformers that, despite not using this material, generates an environmental footprint top.

Electrical transformers by their installation location

• Outdoors: They are very common to see on voltage poles on roads, streets, industrial estates, etc. They are of robust construction to withstand different inclement weather depending on their installation location.
• Indoors: These are those that can be found in their own space, such as a concrete or metal transformer center, where they have their own compartment in communion with the rest of the elements that make up these centers.

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