Electrical Substations: Components, Types, Functions

When power is produced, it must be transported from the production site to the consumer. This power is usually high in voltage. An electrical substation is a high voltage facility where high voltage gets converted into different levels, such as high to low or the reverse. Power apparatus such as generators, circuits, and lines are also switched in and out of the electrical substations system.

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Substations usually contain numerous equipment that functions to ensure there is power supply. If there is any fault on any of these items, the power supply is likely to be interrupted. Below are the main components of an electrical substation:

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Power Transformers

Their main function is to step-up or step-down transmission voltage. 3-phase transformers that are naturally cooled and oil immersed are usually used for a rating of up to 10MVA. Air blast cooled transformers are used for requirements above 10MVA.

Lightning Arrester

This is a very important component of all substations. Lightning arrestors are usually connected between the phase conductor and the ground. They protect components in the substation from passing high voltage to avoid any damage. They also stop the amplitude and the duration of the flow of current.

Circuit-Breaker

Circuit-breakers consist of two moving parts that remain closed under normal conditions. The circuit-breaker works like a switch in conjunction with relays, to open or close whenever an error in the power system arises.

Busbars

These are conductors that collect power from electrical feeders and transmits to outgoing feeders. It can be viewed as an electrical junction where outgoing and incoming electrical currents merge.

Wave Trap

Carrier signals that have a high frequency are prevented from entering the substation side by the wave trap.

Earth Switch

All stray charges that may have been left on the transmission line are discharged by the earth switch to prevent shock.

Isolator

This is an electrical switch that isolates the circuit when there is a disruption on the current flow. Isolators work under no-load conditions.

Current Transformer

An electrical device for stepping down the value of current from high to lower value.

Voltage Transformer

A transformer that steps down voltage value from high to lower value.

Different Types of Substations
Step-up Substation

This substation usually receives power from a nearby facility that produces electric power. A large power generator at the step-up substation then increases the voltage to allow power to be transmitted to distant locations.

Step-down Substation

These types of substations change the transmission voltage to sub-transmission voltage, which is usually 69V. Distribution substations can source power from the converted voltage lines. Step-down substations are situated at the switching locations in a power grid, connecting different grid parts.

Distribution Substation

At the distribution substation, power voltage is reduced to a level appropriate for distribution to end-users. Power is shifted from the transmission system and directed to the distribution system of a specific area.

Primary Substation

Voltage is stepped down to allow for secondary transmission.

Secondary Substation

Voltage is further stepped down to allow for distribution.

Some Functions of Substations:

Eliminate lightning and any other power surge from the grid
Change voltage into different levels
Switch transmission and distribution circuits in and out of the system
Sources of power for customers
Provide linkage between power generation facilities and the power grid

Electrical substations are critical facilities in the power supply. These installations ensure that we receive and safely consume power. Thus, it is important that before making any decision about installing critical units such as electrical substations, you must consult with a licensed professional to get the best recommendations about products, brands, and procedures. Doing so ensures that you pick the best solutions and appropriately understand the industry specifications for safer and sustainable operations!