Power Transformer: How Does It Work And What Are Its Uses?

The power grid is a complex network composed of numerous interacting components that ensure the stable and secure transmission of energy from one point to another, guaranteeing a continuous power supply for our users. This power supply is commonplace, yet it is the result of years of research and development on all its components. Today, we will focus on the operation and function of one key component—the power transformer (hereinafter referred to as "transformer").

Before delving into the operation and use of this component of the power grid, it is necessary to explain why power conversion is necessary. This is because the energy generated by power plants is typically at low or medium voltage (depending on the source), and needs to be stepped up to high voltage to ensure efficient transmission of electricity within the grid and minimize energy losses during transmission. Our focus today is on preventing these energy losses.

In other words, the transformer is the primary reason for enabling the long-distance, cost-effective transmission of electrical energy.

To achieve this, the transformer regulates various characteristics of alternating current, such as voltage or current, while maintaining a constant frequency and most of the power output, thereby achieving an efficiency of 96% to 97%. Thanks to the principle of electromagnetic induction, energy can flow from one circuit to another without changing the frequency, thus improving the safety and efficiency of the power system throughout the transmission process.

Therefore, we can identify the different uses of transformers:

Increasing or decreasing the voltage in a circuit.

Regulating the voltage generated by power generation to meet transmission and distribution needs.

Isolating two independent circuits to prevent direct current from flowing between them.

What components make up a power transformer?

To achieve all these functions, a transformer contains a variety of components, each with its own function. Let's look at the main components.

Core: It consists of a set of magnetic sheets that serve as support for the assembly of other components and provide a path for magnetic flux.

Winding: This is usually made of copper or aluminum wire or strip, wound into coils (one for high voltage, one for low voltage) to carry current from one point in the core to another.

Insulator: These materials are used to insulate the various components of the transformer and their voltage. A multi-layered paper structure impregnated with mineral or vegetable oil is typically used.

Enclosure: This is the metal plate structure that forms the transformer's casing, protecting all components.

The control and sensing unit, available in more technologically advanced transformers (such as Transforma.Smart), allows for the collection of data on the operation of the power grid and the transformer itself, as well as digital control of the equipment.

How does a transformer work?

While transformer design presents technical challenges, its operation is relatively simple compared to other electrical equipment components, and this simplicity is precisely what contributes to its success.

Transformers utilize the principle of electromagnetic induction, connecting two different circuits through a common magnetic circuit. In other words, a transformer uses two windings to form a double circuit connected by a common magnetic circuit (the iron core).

The current flowing through the high-voltage winding generates a magnetic flux through the iron core, inducing a different current and voltage in the low-voltage winding while maintaining a constant frequency. The voltage relationship between the two windings (high-voltage and low-voltage windings) is proportional to their respective number of turns.

What types of transformers are there?

Transformers can be classified into several types based on their function, electrical system type, installation location, and structure. The following are the main types categorized by category.

Power transformers can be classified according to the type of power system: Single-phase power distribution systems use a single conductor (cable) or a single phase.

Three-phase power distribution systems, the most common type, consist of three conductors or three phases. In this case, the three-phase current consists of three single-phase alternating currents with the same frequency and amplitude. Compared to single-phase distribution systems, three-phase distribution is less expensive for converting and generating the same amount of electricity.

Based on function, power transformers can be divided into two types: step-up transformers (increase voltage) and step-down transformers (decrease voltage).

Power transformers can be classified according to their structure: Oil-immersed transformers are the most common type, proven to be the most environmentally friendly, and have a longer service life than other types of transformers.

Dry-type transformers are a technological alternative to oil-immersed transformers; although they do not use oil, they have a greater environmental impact.

Power transformers can be classified according to their location: Power transformers can be located underground or overhead, depending on their location within the power system.

Outdoor transformers are very common on utility poles in highways, streets, industrial areas, etc. They are robustly constructed and can withstand various weather conditions, depending on their installation location.

These indoor transformers are located in dedicated spaces, such as concrete or metal transformer substations, and they have their own enclosures and are stored together with other components that make up these substations.