Editing Substation (section)

{{short description|Part of an electrical transmission, and distribution system}}
{{other uses}}
{{More citations needed|date=May 2025}}
[[File:Electrical substation model (side-view).PNG|thumb|upright=1.5|'''Elements of a substation''' {{olist |list-style-type=upper-alpha
 |Primary power lines' side
 |Secondary power lines' side
}}{{olist
 |Primary power lines
 |Ground wire
 |Overhead lines
 |Potential transformer 
 |Disconnect switch
 |Circuit breaker
 |Current transformer
 |Lightning arrester
 |Main transformer
 |Control building
 |Security fence
 |Secondary power lines
}}]]
[[File:Melbourne Terminal Station.JPG|thumb|A 50&nbsp;Hz electrical substation in [[Melbourne]], [[Australia]], showing three of the five 220&nbsp;kV/66&nbsp;kV transformers, as well as [[high-voltage transformer fire barriers]], each with a capacity of 150 MVA. This substation uses steel lattice structures to support strain bus wires and apparatus.<ref>{{cite web |title=Joint Consultation Paper: Western Metropolitan Melbourne Transmission Connection and Subtransmission Capacity |url=https://jemena.com.au/getattachment/industry/electricity/Network-planning/Western-metropolitan-Melbourne-transmission-connection-and-subtransmission-capacity.pdf.aspx |website=Jemena |publisher=Powercor Australia, Jemena, Australian Energy Market Operator |access-date=4 February 2016}}</ref>]]

[[File:Electrical Substation.JPG|upright=1.3|thumb|A 115&nbsp;kV to 41.6/12.47&nbsp;kV 5&nbsp;MVA 60&nbsp;Hz substation with circuit switcher, regulators, reclosers and control building at [[Warren, Minnesota]]. It shows elements of low-profile construction, with apparatus mounted on individual columns.]]
A '''substation''' is a part of an electrical [[Electricity generation|generation]], [[electric power transmission|transmission]], and [[electric power distribution|distribution]] system. Substations transform [[voltage]] from high to low, or the reverse, or perform any of several other important functions. Between the generating station and the consumer, electric power may flow through several substations at different voltage levels. A substation may include [[transformer]]s to change voltage levels between high transmission voltages and lower distribution voltages, or at the interconnection of two different transmission voltages. They are a common component of the infrastructure. There are 55,000 substations in the United States.<ref>{{cite news |last1=Anguiano |first1=Dani |date=10 December 2022 |title=Attacks on Pacific north-west power stations raise fears for US electric grid |url=https://www.theguardian.com/us-news/2022/dec/09/us-power-grid-pacific-northwest-attacks |work=The Guardian |location=Los Angeles |access-date=10 December 2022 }} </ref> Substations are also occasionally known in some countries as '''switchyards'''.

Substations may be owned and operated by an electrical utility, or may be owned by a large industrial or commercial customer. Generally substations are unattended, relying on [[SCADA]] for remote supervision and control.

The word ''substation'' comes from the days before the distribution system became a [[electric power transmission|grid]]. As central generation stations became larger, smaller generating plants were converted to distribution stations, receiving their energy supply from a larger plant instead of using their own generators. The first substations were connected to only one [[power station]], where the generators were housed, and were subsidiaries of that power station.
[[File:Umspannwerk-Birkenfeld_Transformatoren_220kV-110kV-20kV.jpg|thumb|upright=1.3|220&nbsp;kV/110&nbsp;kV/20&nbsp;kV station in Germany]]