Electrical substations

Do you know how an electrical substation works?

Electrical network Energy efficiency Smart Grids

Electrical substations are essential elements for everything to work correctly and safely in the electricity grid. In substations, electrical energy is transformed, controlled and distributed to end users, but do you know how they work and what types of electrical substations there are?

Substations are crucial for the proper control of electricity

Electricity substations are an essential element for the operation of the electricity grid as well as for ensuring a stable and secure supply of electricity. 

Substations are responsible for receiving the electrical energy that is generated in power stations and power plants to raise its voltage and connect with large lines that carry the energy to cities and large consumption centres. There the voltage is reduced again to connect with medium voltage lines that will take the energy to the transformation centres we have in our streets where it will finally be reduced to the low voltage we use in our homes. 

Substations are crucial for the proper control of electricity and for the integration of renewable energies into the grid. 

The first electrical substation was built in 1882 in New York, although it was not until 1930 that the introduction of distribution transformers allowed substations to control electrical energy with greater precision, which favoured more efficient distribution and greater flexibility in the management of the electrical network.

The evolution of substations has been marked by the need for greater capacity and efficiency in the production and distribution of electricity. As demand has increased, substations have become larger and have adopted more advanced technologies while offering greater safety and reliability in the supply of electricity.

Components of an electrical substation

1 2 3 4 5 6 7 8 9 10 11 12 Illustration

1 Gantry for high-voltage line input


2 Line voltage transformer


3 Isolation and line earth switch


4 Circuit breaker


5 Current transformer


6 Busbar isolating switch


7 Main busbar


8 Busbar voltage transformer


9 Power transformer


10 Medium voltage connection


11 Auxiliary services transformer


12 Control building and cubicles

Types of electrical substation

There are different types of electrical substations according to various criteria. For example, substations can be classified into different types according to their location or site: 

  • Indoor substations: These are substations that are hidden in buildings in order to better integrate into the urban environment and avoid their visual impact. 
  • Overhead substations: These are substations located above ground, on the surface. These substations are ideal for rural and peri-urban areas where there is sufficient space for their construction and there is no need to hide them. In addition, overhead substations are easier to maintain and repair than underground substations.
  • Offshore substations: These are located at sea and their main function is to supply electricity from offshore wind farms to another substation installed on land. These substations are characterised by being very robust and resistant to adverse weather conditions and vibrations produced by waves.
  • Mobile substations: These are a special type of substation because, as the name suggests, they can be transported from one location to another as needed. They are used in emergency situations, such as in natural disasters or during the construction of new infrastructure.

In addition to these main components, substations may also include a variety of auxiliary equipment, such as generators, batteries and cooling systems. This auxiliary equipment is used to provide back-up power in the event of grid failures and to keep the main components in good working order.