Electrical Substations

July 2, 2014

What are Electrical Substations?

Substations are the connectors in an electrical distribution system between long distance and short distance of electrical transmission.

Electricity traveling long distance is stepped up to higher voltage to minimize energy losses along the way. When it’s time to “exit the highway” so to speak, it enters a substation where the voltage is stepped down to be distributed to the end user – the consumer. Likewise, it might be stepped up if it is traveling in the opposite direction.

In addition, electrical substations provide a sort of checks and balances to the grid providing a place to shut off electricity when needed.

Above or Under Ground?

Power lines entering and exiting the substation might be overhead or buried, depending on a variety of factors. Overhead lines tend to be less expensive to construct, but tend to have more power outages due to weather incidents. The substations they serve may also be above ground behind a fence, or underground.

Substations in urban areas tend to be underground or in buildings, while they are more likely to be above ground in more rural areas

Types of Substations:

• Transmission: Connects two or more transmission lines.
• Distribution: Transfers lines between distribution and transmission, which would involve stepping up or down the voltage.
• Collector: Works in concert with renewable energies, collects energy, steps up voltage and sends to the transmission lines.
• Converter: Converts the frequency of the currents.

Two Types of Switchgear Protect Circuits

• Air insulated switchgear: Circuits are protected/insulated by a layer of air and are only outdoors because they require space and higher voltage.
• Gas insulated switchgear: This is now becoming more common. Although it is more expensive to construct, it is generally considered safer and is more cost effective in the long run, because it requires less maintenance and space.

What is in a Substation?

Substations are comprised of transformers, switching protection, and control equipment such as circuit breakers and disconnectors. Control mechanisms are installed which protect and measure activity. Transformers transform the voltage up or down depending on which direction it is headed. Circuit breakers and disconnectors allow a portion of the system to be instantaneously shut down, or limited if there is a problem.

Who Owns the Substation?

Ownership of the substation might be the utility company, the municipality, or a commercial customer.

Why is it Called a Substation?

Actually, the name came before the electrical system was a grid. These substations were smaller plants that were no longer being used because of the construction of larger generation plants. They received their energy from these larger plants and then distributed; thus the name “substation”.
*Source: Wikipedia.