What goes on at these electric power utility facilities?

Question

We all know power comes from power plants, massive structures, usually on the outskirts of town, etc. Occassionally though, I'll be driving through my fairly large city, and on a corner let behind a chain link fence within an area of land about one or two residential lots there will be an obvious electrictal structure of some sort. A lot of powerlines will meet there. There will be lots of serious looking electrical equipment and usually one tiny building. What goes on at these sites? Are they just a place for lines to meet, or are they some sort of electrical booster?

Answer 1

What you're describing is a substation.  The power comes in at a very high transmission voltage (138 kV or higher) and is stepped down to lower distribution voltages such as 12 kV.

The 12 kV circuits are known as distribution "feeders" and are the lines that run up and down the streets on wood poles or underground throughout your subdivision.  The transformer that serves your home steps the 12 kV down to the proper voltage for your electric service.  (in the US it's 120/240 V)

12 kV is one of the most common distribution voltages in the US.  The actual distribution feeder voltage can range from 4 kV up to 34 kV depending on the electric utility.

The high voltage coming into the substation is typically 138 kV to 230 kV.  Substations on the outskirts of town can have higher voltages -- as high as 765 kV.