Substation Foundation - The who, what, where, when, and why of substations!

3 October 2019


Are you down for a quick game of guess who? Yes, of course you are. You might see me on the side of the road when you’re driving to work. Or maybe, you’ve seen me on a trail when you’re taking your afternoon bike ride. Perhaps, you can even see me from your house – lucky you! Who am I? You guessed it (or you read the title of this blog) – a substation! I mean come on, is there anything more beautiful? Just check out that picture below. Absolutely, lovely.



Okay, we are kidding. But, aren’t you just a little curious about what’s going on in that mess of electrical equipment? We know you are.

So, what’s a substation?

A substation is a high-voltage electric system facility, used to communicate and connect the distribution power grid to transmission systems by switching generators, circuits, lines, and other equipment in and out. By the way, the distribution grid is the final component in the electric grid that helps get electricity to our homes and workplaces by reducing electric power to safe, human-friendly levels.

A substation will “step” AC voltage from one level to the next, so it can be used throughout the electric grid. It can also switch between AC (alternating current) and DC (direct current). Fancy! Substations are typically fenced off to give the electrical equipment some much need privacy, or perhaps, it’s to protect all of us from high voltages. Not sure about that one – the jury is still out.

Equipped with circuit breakers, substations act as the distribution system’s body guard – protecting against voltage fluctuations, increased load, and monitoring the flow of current. They can vary in size as well, having as few as one transformer for smaller substations and dozens of switches, transformers, and other equipment for the big ones.


Tell me a little bit about all that equipment, please.

Well, transformers, circuit breakers, and switches are going to be the biggest players here. Let’s start with transformers. These guys are going to take extremely high voltages and break it down to lower, more manageable voltage (say 10,000 volts), so it can be used in the distribution system for all of us needy humans. Circuit breakers and switches go hand-in-hand, allowing the substation to control and isolate certain components of the distribution system directly.

There’s more though. Usually, substations are built with a bus (not the yellow kind). In our case, a bus is a steel structure of switches used to move power out of the system by splitting current in many directions. If you have the unique pleasure of touring a substation, you might also see a capacitor working hard to even out the voltage output.

And the buck does not stop here, everyone. (We’re pretty sure that’s not how you are supposed to use that phrase, but it sounds cool. Right?) There are more components. These may include (but are certainly not limited to): batteries, meters, resistors, wires, cable, condensers, reactors, and relays. This list is just the beginning. It doesn’t even begin to capture the mammoth list of equipment found in a substation. If you’re truly curious in learning more about these components, head over here.  

Are all substations the same?

Nope. Substations can be divided into three categories – step-up, step-down, and distribution. We are starting to sound like step aerobics instructors over here!

Anyways, let’s start with a step-up transmission substation. The name says it all. A step-up transmission substation takes electric power from a nearby generating plant, cranks up the voltage using a transformer, and sends it on its merry way. This variety of substation utilizes a transmission bus (that thing we mentioned earlier) to distribute power between transmission line. Step-up substations are particularly appreciated, since the higher the voltage, the more efficiently power can be transferred.  

Next, we have our step-down transmission substations. These are used to connect components of the electric grid and are usually located at switching points. Again, like the name implies, a step-down substation will lower the voltage from transmission levels to substransmission voltage, which can be useful for industrial applications. Subtransmission voltage lines can then source power to industrial facilities or distribution substations.

Ah, now we’ve mentioned the final type of substation – distribution. You probably don’t even know it, but these are the ones you are most familiar with. Distribution substations are found near our homes and offices (or anywhere where an end-user may reside). These substations will take transmission or subtransmission voltage down even further, so power can be delivered to all of us, safely. Sometimes, distribution substations are even located underground. So, you probably don’t see those ones on a daily basis.


-Meredith Kenton, Digital Marketing Assistant, Megger – Valley Forge