How Do Substations Work? 

As a retired electric utility engineer I can say that this is a great video. Much more info than what is usually presented to the layperson but explained well. One other type of equipment in substations is capacitor or inductor banks. These are used to adjust voltage and reactive power requirements. Reactive power is difficult to explain but briefly it is the additional current that flows beyond current needed to transmit power. It affects the voltage on the power line. As you noted, customer loads are different and some, such as motors draw a lot of reactive power (as well as real power) which creates three problems: 1) it drops the voltage, 2) it results in extra current in the lines which steals from the maximum capability of the line to deliver real (actual) power and 3) increases losses in the lines. Nowadays, capacitors (which inject reactive power) and inductors (which do the opposite) are being replaced by solid state semiconductor devices (thyristors) which can do much finer control and at lightning speed.

Your public works videos are the best!

In August of 2019 my wife was pregnant with our daughter and had been diagnosed with high blood pressure. We were required to monitor it daily and go to the hospital if it was too high. It's 9:30 or so at night and my wife's pressure cuff reads something borderline... like maybe we should go to the hospital maybe not. We decide to wait 10 minutes and read it again. While we’re waiting I put this video on to kill time and learn something. We take another reading and they are the lowest they’ve been all night! Grady, you saved my wife a trip to the ER. Thank you!

I’m a utility protection engineer and I can tell you that you did an outstanding job. Really enjoy your videos.

If your power begins to flickler, start counting. If it goes on and off three times in quick succession it will most probably be out for a while. Automatic resets will reconnect in the hope that the fault was transitory and will clear itself. If the fault doesn't clear then the power line is opened and won't close again until a workman/lineman has been called out and has been able to find and clear the fault. Most power companies don't keep crews on duty 24/7 (excluding on duty power plant workers who aren't lineman) so someone will have to be called from home and then they can begin searching for the problem. That's why when the power goes off it usually stays off for a while. Also there is another type arc suppression breaker which is an Air Blast Breaker. When the electrical contacts separate high pressure air is directed between the two contacts which blows away any ionizing gas and prevents arcing.

Being an electrical engineer who has worked for both electrical distribution and transmission companies, I love that you are covering this topic. Even more so, I love how you are able to keep the technical details while explaining them in ways the lay-person can understand. Thank you!

Having worked at several sub stations, the most amazing thing to see is switching, the noise and the power that is involved is incredible. When we were working on a sector area, which was turned off, we could still feel the power from a neighbouring sector area. Imagine having a constant low current constantly pumping true your body. Electricity is a very interesting power.

For two summers while I was in college, I worked for my city electric utility as part of a 4-person crew (3 laborers and 1 truck driver). Our only job was to visit every one of the several dozen substations the utility owned and dump 50-pound bags of salt into concrete lined holes in the ground scattered throughout the substation. Small substations had just a dozen or so of these holes. The big ones had a hundred or more. The newer substations gave us plenty of room to work, the older ones involved crawling underneath some of the power structures to reach the holes. We were told this action provided some benefit to the underground infrastructure of the substation that Grady mentions in this video. It was a great summer job, lots of exercise and it paid well for a laborer position. Years later I worked for another part of the same city government. I remember telling the then director of the electric utility about my great summer job and he told me that they had stopped doing that work just a few years after I had done it because of concerns about contaminating groundwater.

I have been to a tour through a substation that was under construction. As it was still under construction, it was not connected to the grid yet, so there was no power anywhere in it at the time. It really was a unique chance to see a substation from this close. The guide told us that even when the power is on, there is nothing you can touch that has high voltage (unless you jump with your arms up). They have switches that are designed to disconnect the load, and switches that only are allowed to switch when the power is already off (to connect/disconnect a line to/from the bus). The grid below the ground is also to keep the ground at the same potential, so there is no voltage difference between your legs when making a step. They have concrete walls around the transformers, to suppress fire risk, but also to block noise from reaching the people living near the substation. The one I visited was built in an already existing high voltage power line to split of power to newly developed neighborhoods, and provide redundancy for the lower voltage network, and as a point to connect a future high voltage line.

Electrical grids are unsung heroes of modern world.

07:41 "A Transformer is an extremely simple device" Optimus Prime: "u f'ing wot m8?"

Great video. I’m actually a substation engineer. That’s actually my job title haha. I design and plan out everything inside the fence line, and your video did a good job giving us a basic overview of some of the components. Some things that you didn’t cover were the control house, metering, relays, networks, communications, and capacitor banks. Relays are really the second most important part of a substation because they are the brains behind everything and control all safety aspects inside the substation. These relays can all be programmed differently and actually tell the breaker when to trip, the breaker doesn’t know when to trip itself. The ground grid is the most important part of a substation and is designed to be the last component to fail.

As a substation operator this is an absolutely fantastic and accurate description of how they work. I would like to add just a few things, the interruption mediums for CB’s now include SF-6 sulfur hexa flouride, vacuum breakers are used on lower voltage cb’s and the higher voltage cb’s oil breakers are being replaced by sf-6 gas cb’s, better for the environment and also if there is a catastrophic fault where an oil cb is compromised, you will not get a river of burning mineral oil everywhere, but even sf-6 gas breakers are being replaced by vacuum cb’s. The cb’s trip and recloser algorithm is different for each line, some lines are 100% underground and are difficult to patrol , and others go into high fire areas which require extra scrutiny during hot dry windy days, but for the most part relay coordination are setup for a transient fault, birds tree branches etc and will test on their own after 15-30 seconds, giving the branch time to clear itself, if wires are still down or tangled up it will lock out till crews can access and repair, be patient with port outages folks , they are there for grid and public protection, during a storm whole pole lines or equipment can be damaged and take time to repair safely

I legitimately can't wait to walk past my local substation tomorrow. Another great video explaining something I've always wondered about!

As a layman, I must say that I found this video so incredibly helpful! I have always had an interest in and fascination with how electricity works. I pass, everyday, a major coal powerplant here in the U.S. and your videos bring a new understanding to the engineering marvel that is witnessed by my eyes. I thank you, sir, for your dedication to explaining how this amazing science works.

This video came out the night before my job interview with a power distribution company... Just heard back today that I got the job. Thanks for the help!

Great video, a few minor comments (yea, I'm going to be that guy) 1. The purpose of the Switch at the substation is often not for breaking load and faults. Most switches in the US are used simply as a "visible break". A worker can look at a switch and visually tell that downstream conductors and equipment won't be energized. This is important because often you can't tell if a breaker is open at a glance because the breaking mechanism is internal. The breaker's job is to stop the power flow. The switch's job (most of the time) is to visually show that the line is dead. Open breaker first, then the switch. 2. Instrument transformers often don't energize the monitoring equipment anymore. Microprocessor relays are powered by a giant substation battery bank. All intelligence and monitoring in modern substations are powered by the substations batteries. The batteries are powered by the distribution side of the substation via a service transformer. 3. "Recloser" is mostly a distribution term and a distribution equipment. Substation breakers can be set to reclose but are not often referred to as a recloser. 4. Substations are already "smart". "Smart Grid" (a terrible term) often refers to adding intelligence and flexibility to the distribution system.

its simply stunning how the basic needs of our daily life are ensured and how little we know or care about it... you videos really are easy to understand, easy to follow and give us so much insight about stuff most of us dont really care about in our daily life, but its something that we should appreciate instead of taking for absolutely granted. and thank you Grady for all the work you put into your videos and presentations!

8:27 That dial is just so happy to see them!

@3:48 That was always the best day of switch yard training. Watching the arc and the face of the person cranking the handle. "Don't stop. Keep going" 👍

Where I work transmission voltage is stepped down usually 3 times. When a transmission line enters the first station, its stepped down from 238kv to 34.5kv that's a receiving station or RS. From there it goes to multiple smaller stations called distribution stations or DS's. From there it can go to large transformers on customers properties called industrial stations or IS's which can step it down to what the customer needs, normally 277/480 or it leaves as stepped down voltage from the DS at 7.5kv and will travel around to neighborhoods to the transformers you normally see on poles or underground, the transformers are calls customer stations or CS's at that point its stepped down to usuable voltages for the customer which can be 277/480 wye or 120/208/240 for delta or 120/208 if wye

As a substation commissioning engineer, I gotta say Grady, you did a great job making this seem understandable to the average person. Might have to make my mom watch this so she’ll stop calling me an electrician lol.

I worked as an Apprentice Transmission lineman for a couple of years; the job wasn't for me, but it definitely made me appreciate all that goes into getting power to the people.

My experiences with substations are few. Once I tripped a substation breaker before the power company opened the air switches. The trip switch was in a steel booth about the size of a phone booth (if anyone remembers those), but it was made of 3/8” steel. I was a little nervous pushing the button even though I was wearing a protective suit and closed inside the kiosk. My other substation related experience involved a squirrel in a substation transformer. The resulting brownout caused a malfunction with a 1200 horsepower, 4000v motor a few miles away and the motor exploded. The top portion (about the size of a minivan was flipped launched about 15 feet away. I was dealing with the motor, but it’s amazing that one squirrel caused such a catastrophic failure. Now there were maintenance issues involved with the motor that also contributed to the motor failure.

Great little overview! The thorough grounding underneath substations is also for protection against lightning strikes. It's connected to lightning rods and conductors that can "catch" lightning strikes so they don't hit the active devices too badly.

Trained and working in electricity and electronics for many years, I was amazed at the clarity and simplicity (and accuracy!) of your presentation. I've never seen anything else as good; congratulations!

Video is made for ordinary non technical people, but comments are mostly from Electrical Engineers! I am too studying Electrical Engineering third year! Best wishes dude 🙏!

I’m a retired Senior Reactor Operator. In your example of how a transformer steps down voltage, in your example to drop voltage to 1/10 of the incoming voltage please remember that at the same time amps increase 10 times the incoming amps. Power plants do not have a “substation” they have what is called a “switch yard” this is for feeding power out to several transmission lines. The stepping up of the generator output voltage is done in what is called a “Main Transformer” before entering the “switch yard”. My plant had 2 nuclear power plants and 2 fossil fuel plants while I was there, it’s different now.

The aftermath of a 33 KV oil filled circuit breaker failing is something to behold, I've seen a 4 x 4 metre hole blown threw a 4 layer thick brick wall from just 1 of them the size of a household washing machine exploding under load.

@10:49 Wait a minute, is that a real substation with giant metalwork human figures looking like they're playing chess with the substation pieces?

I'm a lay person, but I find this stuff fascinating. There's no telling how many people passing by in cars who have said, "Look at that crazy person," as I was walking down the sidewalk gawking up at the power lines and transformers.

My father was a lineman. He constructed high lines and substations. Thank you for the detailed info on how a substation really works.

I am a Final year electrical engineering student and I have done my training at 400kv Grid Sub Station

Just a note on CB dielectric. There are several types of dielectric. From oil, sf6, and vacuum to name a few all of which are used in voltages ranging from 10kv upwards to 400kv+. Most high voltage CB are sf6 but that varies depending on the country

I'm an electrical engineer and I approve this video.

As an electrician and fellow life long learner, I love all your public works videos. Please keep them coming.

Cool video. I'm a electrical engineer for a power company and that was a great and informative video to help people understand our types of systems. I'd say they only thing I can say is a bit off is the breaker on the right side of the transformer is the one that would operate before the one on the left since that would have fewer people out of power and also protects the investment of the transformer by no allowing dangerous amounts of current to flow into it ( I know for a general population isn't going to know the difference and it is a minor thing ). Thanks for the video and I look forward to more of your videos. Have a great day!

Good video capture of an arcing disconnect switch. I retired from power engineering and substations kept my mortgage payments going. I salute those who work in this very challenging but rewarding industry. High voltage disconnect switches are not designed to interrupt load current, but they can interrupt charging current. Some high voltage switches have vacuum/gas bottles that provide interrupting contacts that allow interruption of some load current. I have attempted to switch line switches where the bottles were faulty and the resulting arc and heat generation made me almost evacuate my bowels. Very unpleasant. When a breaker is tripped and when one switches the isolating disconnect switches, at times the charging current can be very intimidating. Rookies will try and drop the switch blades back closed because they panic, while veterans will keep cranking to open the switch while enduring the arcing and sparking. With the breaker open, it's only charging current, but it's noisy and scary. Your video was a very good summary of substations. P.S. I noticed some personnel at a substation wearing high heels and others wearing low profile shoes. We would prohibit that as it could lead to tripping and injury. The power industry's safety practices have been developed and "written in blood' so to speak. We have adapted out safety practices based on previous accidents and fatalities. Very dangerous industry, but the danger is very manageable. I like you section on the buried conductor ground grid. We have had many injuries and some fatalities based on improper bonding and grounding practices. Great video.

Ah, man, great video as always. Well done. I am a retired EE ( little 'E' - component level voltages ) and software engineer, and am glad to read the comments from electrical and utility engineers. However, you had me right up to the point you dropped the "hopefully continue to replace fossil fuel generation ....". As a person whose family ( grandfather before Standard Oil became Mobil oil, father and two uncles that retired with 120 years of service ( exploration, production, transportation ) with Mobil Oil ), I don't buy into the global warming narrative that is being pushed, or "we will run out of fossil fuel", or coal and oil burning facilities are bad, bad, bad. They may be when you compare how China pollutes and how the US pollutes. I am old enough to remember the times before the catalytic converters, carbureted ( vs computer controlled fuel injection systems ) engines, and driving through Los Angeles. For example, solar panels/cells like sunlight as does the food needing to be farmed. It's difficult to have both in the same space. Very, very, very few ( if any ) solar powered systems are optimized (sun trackers) - which lose credibility when they are being pushed/crammed down our throat. Ok, done with my rant. Great video.

as a protection and control engineer working on these systems, id have to say you did an amazing job describing the inner workings of the Grid. Congrats and keep up the great work!! Tasmania, australia!

Couldn’t explain it better myself. I worked in substations and power systems for over forty years. There are two other type of stations that look very similar to substations. They are called switching stations and capacitor stations.

Dielectric, easy enough to remember :) Been apprenticing for the past 5 years or so and still learning new things everyday about the technology. Thank God for the internet! 🤯👏

When I first watched this, I was working at McDonalds, now a year later I work in a sub station. They are pretty similar here in New Zealand. Its fascinating to learn how the grid works. Thanks for making the video! :)

This covers everything I learned in 3 months of internship. Awesome job!

I always take time to admire the hum of the transformers and the buzz of the transmission lines as I bike past my local substation. Now I'll enjoy it even more!

As an engineer that is frequently asked to repair older insulators and bushings, your videos are extremely informative and well presented. Please keep up this important work.

Great video. I work at PG&E Substations and the precautions we take are extremely necessary

The timing of this new series is really weird and convenient.n I'm a Civil Engineer and started my career four years ago in bridges (lots of coordination with hydraulics/soils) and now I moved over to working for an electric utility. Thanks for the quality content! :)

I am an electrical engineering student and have learned a lot of powerline contraction basics from you ,Thank you and keep on sharing your knowledge with us

I am a Civil engineer working in substation construction i really learn every day new things about substation.

Funnily enough a mear 10mins after watching your video. A strong gust of wind came over my town and I watched the green flash of power lines hitting a tree followed by the power fluctuating three times before going out completely. Just like I just learned from the circuit breaker portion of your video!

Hello your videos are really well done although I do not speak English I still manage to understand the concepts and theories thanks to your schemas very well explained ... thank you

Great vid! Learned a lot, I’ve always looked at substations whenever I pass by them and think about how each equipment works.

Studying for NERC exam. Your videos are so much easier to watch and understand compared to the “prep” course.

Finally, someone that understands! I am utterly fascinated by utility infrastructure. I'm a project manager in wireless deployment, having built towers and currently managing a 5G deployment project. These videos are *exactly* what I have been looking for. Will watch all of them. :)

Very nice video. Thanks for the information, didn't know about the ground rods in substations but it makes so much sense!

I'm an apprentice electrician and I've been searching for a video explaining detailed operations of power grids. This presentation is the best one I've seen yet! Thank you for this! It definitely aids in my understanding!

Thanking you these are great places to see what goes into engineering outdoors dealing with the environment we lived close to the substation long ago not know they are really neat as we utilize 3-phase power for our machinery, we are still within only a few thousand yards from a local substation. The sub-stations here in the California high-desert are not as big as many you shared those are well really large we bet you love visiting them. We get lightening strikes as there are no other structures here in the desert near these. Thank you so much for making this learning easier for us that want to know but are not electrical engineers. Lance & Patrick.

Another great presentation! I may just want to note that (3:34) it is not interrupting high voltages that cause arcing, interrupting high CURRENT does. That's why a switch's most important rating is its interrupting current capacity. You can switch off a high voltage line that has minimal or no current (or no load) relatively safe with either a disconnect switch or a breaker. But if it has current flowing through it, better do it with a breaker which has internal mechanisms to extinguish arcing. Of course switches/breakers has voltage rating also but this more relates to their static insulation properties rather than an in relation to operating/switching condition.

Wonderfully produced, some really beautiful images used as well. Love this series! Keep up the great work. I appreciate you passion sir.

I find this kind of topic to be fascinating. I often walk around my neighborhood and look at all the overhead wiring, transformers, single or 3 phase circuits. There's a substation nearby that I love to walk past as well. Would love more technical details.

Thanks for explaining the complex engineering in the easiest way.

As a SCADA Engineer who works in Control room and perform end to end test without visiting the substation, I really impressed with video.

I'm really diggin' these public works videos, enjoy all your videos!

They're pretty obsessive with substation maintenance, in general. They called me out to check a T1 connection in one today that they'd already confirmed was a LEC problem, "just to be sure."

It’s amazing how quick it gets transformed to HV in a power station switchyard, I worked at an underground hydro station, the bellows wouldent have been more than 20 meters at 13’800V before it’s fed into a giant wilson transformer with an output of 220kv for transmission, from there’s it’s gradually stepped down 220Kv/110Kv, 33Kv - 22/11Kv and 6.6Kv in some rural areas A lot of substations will have a ripple control system to switch hot water off of peak times

Even though I have built many substations I enjoyed the video. Here, in the UK, it is slightly different as we work at different voltages (400kv for the grid and 275kv to cities down to 11kv for inner city power) and a slightly different system. We have many types of substation but they mainly do the same job, take power in and put power out. In towns and cities they are either contained in a fenced area or in some places in a dedicated building, or in one historic location within an old house so it wouldn't be seen in movies like the Avengers. Mainline power distribution substations take power from many locations then synchronise them and sent them out at various voltages to distribution subs for power to towns and cities. The only problem with substations are the amount of tools you need for the international equipment we use, I had to have one toolkit dedicated to the S&C equipment as they were all US Imperial whereas the majority of the rest of the equipment was Metric.

Very nice video! I know it won't be a priority, since it is not that common today, but can you make a video about the different types of mass energy storage? Like Flywheels, Pumped Hydro, Batteries and more? Would love to see that.

You have no idea how many of my fifty year old 'mamma hows that work' questions this channel has answered. I'm probably just an odd one but, I've always marveled at the Substations and the humming sound that raw energy seems to produce.

I work in power utilities as a Lineman, and your video is very well done.

Fascinating stuff for all us folks who always wonder what the gray boxes behind the fence are for! Thanks!!

I love your videos. Short, to the point, and easy to understand. It is easy to tell that you actually understand the topics you are presenting on, thank you! Topic suggestion: The types of renewable energy generation and the challenges of converting to them.

Would you please do a comparison between the grid in the US an elsewhere in the world- specifically about why 3 phase power distribution is extremely expensive to get in the US, but common elsewhere (e.g. Germany)? Also, thanks Grady. Every video I learn something new!

Thank you so much! I am an EE student that is currently talking to a company that makes grid protection products. They wanted me to watch some of their online seminars, but I didnt understand much of the material. This definitely helped to fill my knowledge gaps.

I worked for GE for many years as a switchgear test and inspect tech. We also performed Doble testing on substation transformers. It was a very satisfying career and I enjoyed it. I've been retired for about 11 years now, but I think about that line of work every time I pass a substation or power station

Air is a dielectric too, hence the clip of contact arcing at the substation. The good thing though is that air has a relatively high dielectric constant.

A big thank you to all the electric grid workers out there! ❤️

My husband bought me your book for CHristmas! It was near the top of my wish list, so he bought it for me. I'm happy to learn the names and purposes of all the technology around me. This book should be given to every middle-school library in the country, but I don't know anybody that has that much money. It really makes me happy to look into that book.

Quite precise and easy to understand! Greetings from a Brasilian electrical engineer =)

Awesome video Grady! I will be passing this along to future interns in the Substation Engineering department I work in.

6:22 This circuit breaker is not able to disconnect the electric line during a lightning strike, because the lightning strike is too fast, and the lightning voltage is too large for the breaker to withstand it. To reduce the effects of a lightning strike, special devices are used. This is called an surge arrester When lightning strikes a line, a lot of voltage breaks through it towards to the ground and saves the line and equipment. en.m.wikipedia.org/wiki/Surge_arrester

Thank you, having worked for several years as power system electrician this saves me a great deal of trying to explain what the job was. I do miss the work I did it all from 4160 up to 240kv; breakers switches xformers grounding metering and communication testing and commissioning. the dangers are real I have seen a p/u truck cut in half by flying glass/ ceramics when a breaker blew.

Apprentice sparky here, starting on my first substation Monday, this video got me so stoked.

Awesome video, as always. Would love if you would go one step deeper. A full video of how different switches work or a whole video of transforms would be really cool. People will miss/forget things so going a little more in depth will help them retain at least the important stuff. I love the production quality of these videos, it shows how much effort you put into them, but occasionally just having a 5 min video of you talking to an EE pointing out the parts of a high voltage switch and how it works would be cool to get more information out to the public with less effort.

Please point out that all elevated electrical lines are not insulated due to weight issues, so be careful if you see one down. Great video!

Pretty good info, couple things are a bit off as per current standards.... Or well from late 80's-early 90's for that matter. One quick thing that I have to say is that a recloser is not a type of breaker, it is a relay that does the operations sending reclose impulses at timed intervals. This is an 81 relay typically although with newer ied type relays it's built into the package along with your other common elements like 50 and 51. Also typically your "instrument transformers" typically called CT's (current transformers) for current, or PT (potential transformers) or CCVT's or etc for voltage.... Your CT's are typically inside of the bushings of your breakers and transformers where as the PT's are generally outside and usually only connected to the bus. Your tap changers for transformer voltage regulation are generally built inside of the transformer itself instead of having an exterior secondary transformer just for voltage control. Another cool thing are capacitors and reactors to deal with voltage and current stabilization. Not a student or something like so many others, I actually work in substations for a living doing relay and control work. It's an extremely cool field, and I understand you have to draw the line somewhere... And I doubt you'll ever even read this. Yeah all in all great high level overview, and the only wrong thing was the recloser breaker.

Handling the instantaneous nature of the supply and demand without the benefit of any real storage capacity never ceases to amaze me.

Great video, Grady.

I'm a professional engineer who has worked building infrastructure for 34 years. I love this channel

When you can hear 60 cycle hum 50 feet away, you know you are dealing with high energy that can be fatal. To most people, the only thing they know about power is when there is an outage. Big salute to power company workers who keep our lights on.

You really know that you study electrical engineering when this great video doesnt tell you anything new. Im really proud of myself. :D Thanks for this awesome video.

Sir, how did you know!!! Every time I'm looking at the substation I'm just standing there and admiring. My heart is in love.

Great video, will the next one go into protective relaying al all? ie transformer differential, overcurrent, line relaying, etc. I work in substations every day and it’s great how you break complex concepts down so they’re easy to understand

This is amazing, thank you for this video and all of the wonderful education content on your channel! Many generations will benefit from this readily accessible information!!!

My grandfather used to work on substations. He never really got into the weeds of it, but he would tell us about which substations he parked at in downtown Cincinnati to avoid paying for parking. What a guy.

My Grandfather worked at plant Bowen in 1986 and he still remembers it plus they gave him belt buckles and hats tons of other little things for their increased capacity or efficiency something like that.

Need one on natural gas. Come visit WV and I'll shown you around from well head to burner tip and everything in between.

Please do a video on the different types of water treatment plants!

My engineers, based out of Denver were responsible for the programming, equipment selection and generator controls here. And for many years I over saw (HMFIC)., the engineers who performed the routine and non routine troubleshooting and diagnostics for the balance of plant and large powertrain and subsystem equipment testing. Grand Coulee was one of maybe 42 power plants we were worked on with a laboratory of 11.5K feet and a couple million or three of lab gear. Great techs at some of these plants and great engineers who keep the western half of this country's power grid from going dark...that's a good thing. And best of all, those I have trained have assumed my position and do the work I once did. I retired and those who replaced me are the best engineers/managers this nation could ask for.

man... sometimes, you listen to stuff like this, and the many, many, MANY other challenges civil and electrical engineers deal with. and you're just taken aback by how insanely COMPLEX the systems we take for granted are, and how long they took to get established and standardized across the country. first world society is absolutely insane.