Editing Substation (section)

===Distribution substation===
[[File:Turmstation.jpg|thumb|upright|Transformer tower in Germany. Medium voltage supply at the front, low voltage output on the side.]]
[[File:SubstationHouseScarborough.jpg|thumb|A distribution substation in [[Toronto]], Canada, disguised as a house, complete with a driveway, front walk and a mown lawn and shrubs in the front yard. A warning notice can be clearly seen on the "front door". Disguises for substations are common in many cities.<ref>{{cite web |last=Steinberg |first=Neil |title=Lights On but Nobody Home: Behind the Fake Buildings that Power Chicago |date=13 December 2013 |url=http://www.messynessychic.com/2013/12/13/lights-on-but-nobody-home-behind-the-fake-buildings-that-power-chicago/ |access-date=14 December 2013}}</ref> ]]
A ''distribution substation'' transfers power from the transmission system to the distribution system of an area.<ref name="Design Guide for Rural Substations">{{cite web |last1=Stockton |first1=Blaine |title=Design Guide for Rural Substations |url=http://www.rd.usda.gov/files/UEP_Bulletin_1724E-300.pdf |website=USDA Rural Development |publisher=United States Department of Agriculture |access-date=4 February 2016}}</ref> It is uneconomical to directly connect electricity consumers to the main transmission network, unless they use large amounts of power, so the distribution station reduces voltage to a level suitable for local distribution.

The input for a distribution substation is typically at least two transmission or sub-transmission lines. Input voltage may be, for example, 115&nbsp;kV, or whatever is common in the area. The output is a number of feeders. Distribution voltages are typically medium voltage, between 2.4&nbsp;kV and 33&nbsp;kV, depending on the size of the area served and the practices of the local utility. The feeders run along streets overhead (or underground, in some cases) and power the distribution transformers at or near the customer premises.

In addition to transforming voltage, distribution substations also isolate faults in either the transmission or distribution systems. Distribution substations are typically the points of [[voltage regulation]], although on long distribution circuits (of several miles/kilometers), voltage regulation equipment may also be installed along the line.

The downtown areas of large cities feature complicated distribution substations, with high-voltage switching, and switching and backup systems on the low-voltage side. More typical distribution substations have a switch, one transformer, and minimal facilities on the low-voltage side.