How does an electrical transformer work and what is its purpose?

The electrical transformer is one of the main actors in the power grid, ensuring its supply and efficiency

The electrical grid is a complex network of elements that interact with each other to allow energy to move from one point to another in a stable and secure manner, ensuring that we, as users, have a continuous power supply. This availability is something we take for granted, but it is the result of years of research and development applied to all these components. Today, we want to focus on the operation and function of one of these key pieces: the electrical transformer, or “trafo.”

Before delving into the operation and use of this component of the electrical grid, it’s important to explain why electricity needs to be transformed. This is because the energy generated by power plants is produced at low or medium voltage, depending on the source, which requires it to be raised to high voltage to ensure efficient transmission through the electrical grid, minimizing energy losses during transmission. This is where our protagonist for today comes into play, preventing these energy losses.

In other words, the transformer is the main reason it is possible to transport electrical energy over long distances practically and economically.

To achieve this, the transformer adjusts various properties of alternating current, such as voltage or current, while keeping the frequency and most of the power constant, achieving an efficiency ranging from 96% to 97%. Thanks to the principles of electromagnetic induction, energy flows from one electrical circuit to another without changing the frequency, improving the safety and efficiency of power systems throughout the transmission process.

Thus, we can identify different uses of the transformer:

• Increase or decrease the voltage level within a circuit.
• Adapt the voltage from generation for transmission and distribution.
• Isolate two separate electrical circuits and prevent the flow of direct current between them.

What components make up an electrical transformer?

To carry out all these functions, transformers have various components with their own roles. Let’s take a look at the main ones.

• Core: This consists of a set of magnetic sheets that serve as support for the assembly of other elements and provide a path for magnetic flux.
• Windings: This is the wire or strip, typically made of copper or aluminum, wound in the form of coils (one for high voltage and one for low voltage) that carry electricity from one point to another around the core.
• Insulators: These are materials that insulate the different transformer components and their voltages. Typically, a system of paper layers immersed in mineral or vegetable oil is used.
• Enclosure: This is the sheet metal structure that forms the outer casing of the transformer, protecting all the components.
• Control and Sensing Unit: This component is available in more technologically advanced transformers, such as the transforma.smart, and allows for data collection regarding the operation of the grid and the transformer itself, as well as digital control of the device.

How does a transformer work?

Despite the technological challenge posed by the design of transformers, their operation is relatively simple compared to other elements of electrical equipment, and it is this simplicity that underlies their success.

An electric transformer couples two different electrical circuits through a common magnetic circuit, applying the principles of electromagnetic induction. In other words, a transformer uses the two windings to create a dual circuit linked by a common magnetic linkage (the core).

The current flowing through the high-voltage winding generates a magnetic flux that passes through the core and induces different current and voltage in the low-voltage winding while maintaining the frequency. The relationship between the voltages of the two windings (high and low voltage) is proportional to the number of turns in each of them.

What types of transformers are there?

According to their function, type of electrical system, location, and construction, several types of transformers can be distinguished. Here are the main types 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 commonly used distribution system consisting of three conductors or phases. In this case, the three-phase current is composed of three single-phase alternating currents with the same frequency and amplitude. Compared to the single-phase distribution system, costs are reduced for the same amount of electrical energy transformed and generated.

Electrical transformers can be of two types depending on their function: step-up transformers (increasing voltage) and step-down transformers (reducing voltage).

Electrical transformers by construction type:

• Oil-immersed: This is the most widespread type and has proven to be the most environmentally friendly, in addition to having a longer service life than other types of transformers.
• Dry-type: This is a technological alternative to oil-immersed transformers and, despite not using oil, has a greater environmental footprint.

Electrical transformers by location:

Electrical transformers can be underground or overhead, depending on their location in the electrical system.”

• Outdoors: These transformers are very common on power poles along highways, streets, industrial areas, etc. They are constructed robustly to withstand various weather conditions depending on their installation location.
• Indoor: These are the transformers that can be found in dedicated spaces such as concrete or metal transformer substations, where they have their own enclosure in conjunction with the other components that make up these substations.

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