Substation Layout

Electrical Substation

Basic Description of a Substation:
A substation is a high-voltage electric system facility. It is used to switch generators, equipment, and circuits or lines in and out of a system. It also is used to change AC voltages from one level to another, and/or change alternating current to direct current or direct current to alternating current. Some substations are small with little more than a transformer and associated switches. Others are very large with several transformers and dozens of switches and other equipment. There are three aspects to substations:

In Depth Description of a Substation:
An electrical substation can be described as a subsidiary station of an electricity generation, transmission and distribution system.  In a electrical substation the voltage is transformed from high to low or the reverse using transformers. Electrical power is able to flow through several substations from generating plant to consumer. This may change the voltage in several steps.
Looking at a substation that has a step-up transformer increases the voltage while decreasing the current, while a step-down transformer decreases the voltage while increasing the current for domestic and commercial distribution.
The very first substations were connected to only one power station. Here the generator was housed, and were subsidiaries of that power station.

Where does the word substation come from? The days before the distribution system became a grid.

Elements of a substation
Substations generally have:

• switching,
• protection equipment
• control equipment
• one or more transformers.
• Power factor correction capacitors
• Voltage regulators

in larger substations generally to interrupt any overloads or short-circuits that may occur on a network, circuit breakers are used.
This will vary on smaller distribution substations where fuses or recloser circuit breakers for protection of distribution circuits.

Usually substations would not have generators, but you would usually find a substation located nearby a power plant.

Substations can be located in various locations:

• On the surface in fenced enclosures
• Underground
• In special-purpose buildings

Substations may even be located inside high-rise buildings.  Several may even be located inside one building.
In urban areas you will usually find indoor substations to reduce the noise coming from the transformers.  This is also true for aesthetic appearance and to protect the switchgear from pollution or climate conditions.

Proper grounding is used where substations are surrounded by a metallic fence.  This is to protect people from the high voltages that may occur during a fault in the network.  Earth faults at a substation can cause severe electrocution.

Substations are designed to accomplish the following functions, although not all substations have all these functions:

• Change voltage from one level to another
• Regulate voltage to compensate for system voltage changes
• Switch transmission and distribution circuits into and out of the grid system
• Measure electric power qualities flowing in the circuits
• Connect communication signals to the circuits
• Eliminate lightning and other electrical surges from the system
• Connect electric generation plants to the system
• Make interconnections between the electric systems of more than one utility
• Control reactive kilovolt-amperes supplied to and the flow of reactive kilovolt-amperes in the circuits