Bárbara Freitas-Daniels High voltage takes center stage and is brand new season of Hitachi Energy's Power Pulse podcast. We promise to bring you great content from the brightest minds in the business. We'll discuss challenges, opportunities, and all the hot topics any high voltage enthusiasts or anyone interested in sustainability for that matter, is sure to enjoy. In this episode of the podcast, we follow on from the history of the power grid to explain to our listeners some of the main components that make it up.
Bárbara This could easily be a very technical episode, and we want to make sure that anyone from a background out of this realm is able to understand. So we asked Doctor Christian Ohler, who is widely known to have the ability to explain very complex information in terms that are easily accessible. Christian holds a PhD in physics from the University of Aachen.
Bárbara He joined the company 25 years ago and currently heads up the Switchgear Product Group at Hitachi Energy. He will tell you why high voltage is called high voltage. He'll also tell you what switchgear and circuit breakers are, and how the electricity pylons we see scattered across landscapes around work. Sam Dash Welcome back to Power Pulse. I'm your host, Sam Dash, and today I'm speaking with Christian Ohler, head of GPG Switchgear. Hi, Christian. Christian Ohler Hi Sam. Nice to see you.
Sam Nice to see you too. Thanks for coming in. Christian, I hear you're a keen photographer. Has your photography ever crossed paths with your work and expertise in energy? I can sort of imagine some beautiful photos of electrical gear or power lines or something really fascinating.
Christian In fact, it has, but also in a different way than than you are describing now, because we had a celebration at the time. That was the 50 years celebration of the research center where I was part of the team. And then we said, in order to contribute to the celebration, we make photographs of all the employees in there working environment. Christian And that was actually a nice photographic project with a lot of colleagues who also like the photography. Sam Oh, amazing.
Christian Yeah, but as you say, there was also one occasion in my life I was actually doing an article about power equipment, and I wasn't satisfied with the type of photographs that were around. And I was going out myself into the landscape and seeing what type of equipment I could see and make nicer photographs than what I saw was available.
Sam Oh, fantastic. And is there anywhere that people can see those photographs that you took of this docuseries of the employees working in their environment? Christian I mean, we published a book in a self-made way, and it has maybe 100 copies. So it's pretty rare. Sam A limited edition. Maybe people can find it on the internet somewhere.
Christian But it was beautiful. And we also made an exhibition and it actually was great because the nice thing is the interaction as a photographer, if you photograph a person, it's also a very kind of close encounter. Sam Yeah, it’s quite intimate. Christian Yeah. So, actually it's contributed a lot to the spirit of this celebration that we had done this before.
Sam Yeah. So, Christian, let's get a little further into your work life. Can you talk to me about high voltage? What does high voltage as a term refer to and how high is high voltage in this case? What are the differences between high and low voltage and medium voltage? And which is best to use when in what circumstance? Sam I know that's a lot of questions to throw at you.
Christian I try my best, but the term high voltage is there for a reason. So why are we calling all this domain high voltage? Because the fact of having high voltage is the most important in a way. Sam Yeah. Christian Electric power comes with two important properties: the current and the voltage. I think most people still remember this in some way. And the current just means, okay, how many electrons are flowing. Christian More or less. So it’s the quantity of something flowing. Sam Right.
Christian Whereas the voltage is the potential force that these flowing currents can execute. And in order to have a high power, so large amounts of energy in short moment of time, you need both of them. So you need lots of electrons and you need them to have a lot of force, potential force if they are released. Sam Right.
Christian And why is the high voltage so important? Because the losses that we have, they go with the amount of current. So if you if you would put all our kind of things into the current, we would lose a lot during the transport of that but by bringing it to a high voltage, actually, we have very small losses. And this is why all overhead lines need to be so high, why everything needs to be so high.
Christian Because in this way we can transport it over very long distances, hundreds of kilometers, without losing the force of the electricity. Sam So correct me if I'm wrong. It sounds like it's a matter of efficiency. Is that right?
Christian Yes, absolutely. So, only with the invention of high voltage grid, it became possible, actually, to send electricity to a faraway place and to build grids also that really- well, that's where you don't care where the electricity comes from. When you use the plug in your home. Sam So let's get more into that. That brings me to my next question. What is a grid in basic terms?
Christian You have lines and you have nodes where the lines actually intersect and touch each other. And the high level of reliability that we have in the supply of electricity. I don't know, you probably don't remember when was the last blackout in your life or something. But so why can it be so reliable? Because you have a multiple paths of the electricity to go from the power plant or the the wind tower, or to your place.
Christian So when one of these paths is compromised, like there is maybe a tree falling. Sam Obstructed in some way.
Christian Yeah, but then it will just take another path. And this is possible because it's a grid, because you have multiple lines that have nodes where they join together. And these nodes, by the way, are the substation where most of our equipment goes. But this is why with a grid you actually achieve the reliability kind of. You have multiple ways to to get from one point to a different point.
Sam So again, correct me if I'm wrong. You know, obviously I don't have the experience that you do. So I'm just sort of wrapping my head around this now. But it seems to me that the grid is sort of aimed at maximizing the opportunity for electricity to get to. Is that fair to say? Christian Absolutely. Like it's almost like a road network. If one road is blocked, you take a detour. Sam Right.
Christian And this is this is actually, as it happens in the power system. So, when you plug you don't know actually, which is the path that is taken by the power that comes to where you need it. Maybe short thing I forgot in the first. Christian Did you ask about the level of the high voltage? And one figure to have in mind is when you are at home and you have a socket, you have roughly 200V. It's the voltage you have.
Sam And is that dependent on where you are in the country or sorry, where you are in the world? Christian A little bit, but not much. So there are countries that are more around 100, 110. United States, for example, or 220 in most other countries. So they are not too many variations. So but the important thing is, is around 200 200. When we talk high voltage, we talk 1000 times or 2000, 3000 times this voltage. So it's a lot higher.
Sam Yeah. There are these high voltage power lines in the grid. But what other equipment is essential to make a power grid work that we might see out in the wild?
Christian The overhead tower. This is the one thing that everybody knows and sees. It's actually also something nice because you can see it's high because of the high voltage. The other equipment. There are really two important components that make it all in a way. The one is the transformer and the other is the switchgear. Okay, maybe first taking the transformer.
Christian Why is the transformer so essential? Because the transformer makes it possible to change the voltage level. So for example, we have the power plant and it's fairly low voltage in your power plant. But in order to transport it far away it needs to go to the very high voltage. And this is the so-called step up transformer that's doing this job. Sam And just to sort of paint an image for us, what does a transformer look like if we saw one out in the world?
Christian Transformer is in a way a chunk of metal So it's kind of, you have the multiple turns of a wire, and inside those wires you have a lot of iron because the current actually produces a magnetic field that is then in the iron. And then with a different number of turns, you bring it to the different voltage. So transformers are very heavy object.
Sam Right. And then what is switchgear? Can you tell us about air insulated switchgear versus gas insulated switchgear which is two different terms I've heard spoken about, but I don't really know the difference.
Christian Yes. So the transformer makes it possible to bring it to different voltage level. But what is also essential is at these nodes where we have the substations, we need to be able to switch on and off certain parts of the electricity. And this is the job of the switchgear. So in the substation we have the switchgear and it comes in two extremely different varieties.
Christian We can say the one is actually people can see when you go around the world with open eyes, once in a while you see the overhead line ending in the yard, let's say, that is about the size of a soccer field. Typically it’s pretty big. And there you have lots of equipment in small pieces and then kind of overhead lines in between this.
Christian And this is the so-called air insulated substation because you need to have all this equipment very far away from the floor and also very far away from each other. This is why it takes a huge amount of space, like a soccer field. Sam And can you say a bit more about why you need to have that equipment so far away from the floor, so far away from each other?
Christian Because if you come close, it will kill you. It's very simple. Like safety and electricity, it's always about keeping away from where it's dangerous to touch. And we know it from home. Never put your fingers into the socket. But when we talk about high voltage, it means don't come ever close than 5 meters or 10 meters from it. Sam Right.
Christian Otherwise you are a dead person. And this is why in the air only has a limited insulation capability. You need a certain distance. So this is why these air insulated substations are so big. And this is why people have invented 80 years ago or something, a very different way to make it. You have kind of the soccer field in a small room. And how you do it? By taking stronger gases that can reduce this distance, that need to be kept. Sam And sort of create more of an obstacle.
Christian More of an obstacle. And of course, we know it from a cable like everybody knows. Okay, I can touch a cable from outside. Why? Because the solid insulation of the cable, it keeps you away enough from the hot part. Sam So you're trying to create a dense enough air that simulates that level of insulation. Is that right?
Christian Correct. And it's not in that case its air, it’s special gases that are really made for the purpose of being good insulators and also being able to switch because the one thing in the switchgear is, okay, you need to be able to give the isolation so the distance from it, but you also need to be able to change it.
Christian One moment you want the electricity to flow that way, so it should be a perfect conductor. Then you want it to stop flowing that way. You need to separate it. And the really the hard job of this equipment is this interruption process. So to change from conducting to the insulating part. And this is really the, let me say, the high art of equipment. Christian It's really this transition between conducting and insulating.
Sam So Christian, I feel like we're talking about this already. But what is a circuit breaker? Is this another name for a kind of switchgear? Christian Exactly. More or less, the circuit breaker is the king of the switchgears. Sam Yeah.
Christian Like, so there are different type of switchgears. For example, at home you have your light switch, which is a kind of a trivial type of switchgear. And we also have this trivial type in high voltage. But the circuit breaker is the one that does the job to interrupt enormous currents at enormous voltage.
Christian So kind of when all the bad things come together and current is flowing into a path that it shouldn't. Like, for example, this example, a tree has fallen on an overhead line and there will be like a lightning strike going from the overhead line to the ground. And we need to interrupt this extremely quickly so that the other grid remain undisturbed. Sam Right.
Christian And this is done by the circuit breaker. So the circuit breaker will first node such high current flowing the wrong way. And then it will open up the contact. And there will be kind of a small explosion inside the circuit breaker because the current refuses to stop. Like as we talked, there is the limitation of insulation. And actually there's a huge force behind all this high voltage.
Christian And now the circuit breaker has the capability to blow out this explosion. It's almost like blowing out a candle just 1 million times more powerful, like an enormous candle. You need to blow out. And this is actually the job of the circuit breaker. And this is why these circuit breakers are really high tech pieces inside. So if you think what is really, the technology wise, the most advanced piece in all the electricity grid, it's the circuit breaker that can interrupt the short circuit current.
Sam So what are the features of design and classification according to voltage rating in terms of the circuit breakers? Christian You have circuit breakers for all voltages and they are always specific for that voltage. You have it for different amounts of short circuit currents or very powerful short circuit currents, or more moderate short circuit current. So there's a whole zoo., let’s say, of devices that need to be tuned to the duty they are supposed to fulfill.
Sam And where does all of this equipment live at various stages, these larger circuit breakers? How are they connected to the electricity pylons and the various towers we see scattered across the landscapes?
Christian All this equipment is in the substation. So more or less the high voltage grid. We have overhead lines and cables that everybody knows and sees once in a while. And then wherever this meets in a node or two lines come together, you have a substation, smaller substation, bigger substation. And inside the substation you have this equipment. For example, in an air insulated substation you can see the line coming.
Christian And then there are these strange objects, and these are actually the circuit breaker and the other switchgear type of equipment. So I just invite you if you now go back with the train or so. Look out of the window and once in a while you see the point where actually the overhead line is ending and you can get some glimpse of this type of equipment how it looks like.
Sam I know, I was just thinking, actually, I will be looking out the window quite differently on these, on these train rides, which, you know, I'm sure many people see out their train windows, all these different bits of equipment scattered across fields and things. Christian Yeah, the train always shows a bit like the back door of the world. It’s different to the road. Do you see the nice face of the house with the train? You see the back face? Yeah.
Sam You're right. I think there's something quite fascinating about taking train rides. So, Christian, most of us have internalized from a young age that electricity can be dangerous and requires safety precautions, like you were saying, sort of keeping one's distance away from electricity. How is the equipment that you specialize in safe? how do you ensure all of us access electricity in a safe way on a daily basis?
Christian Of course. As you already said, the one thing in these air-insulated substations is to keep people away. So you have a fence, and all this is high in the air, so nobody can even come close to it. Sam Yeah.
Christian In the gas-insulated type, it's safe because of the high quality of those gases that are the insulator. And of course there are a number of protocols to follow who can actually go there; what this person is allowed to do; how the person needs to get clearance from the overall control of the grid before doing anything. So there are very narrow procedures whenever you do any change to any of the components that is in the grid.
Sam Right. And can you share some of those safety protocols you follow within the industry for people who are working with this equipment on a daily basis. Christian One of the things that is typical for this type of equipment is that before it's actually commissioned and installed in the place, it goes to tests that are much harsher than anything it will ever see in the life.
Sam Right. Christian So, for example, there are the so-called type test and the factory acceptance tests that create conditions that are much more severe than anything that then will happen in the real life. Christian This means that the likelihood of this equipment to fail is super low, like it's extremely low. This is, I think, one of the main philosophies that lead to the high reliability of the power grid overall, together with the fact that it's a grid.
Sam Sort of to create an analogy, it’s as if you are testing a raincoat and you want to make sure that it's going to be waterproof, so you put it in a room with a torrential rain storm to sort of give it the most, extreme weather that it might possibly encounter. Is that right?
Christian Absolutely. And this is why, in the end, we create or we, develop the raincoat always for the storm like the test. The art of creating this equipment is really to make it passing those tests that are so strong that they will never be reached in the real life.
Sam Right. That's reassuring. So, Christian, we've become pretty accustomed to a grid that works at the drop of a hat with minor outages, as you were saying, happening very rarely in more industrialized, wealthier countries. But this grid needs to be made more sustainable, from what I understand for everyone. Can this be done?
Christian It can be done. And, but first it needs to be done. Why does it need to be done? Because with the so-called energy transition, we are changing the way we produce the electricity; traditional way we have a power plant maybe ten miles from the city center. So electricity had to travel only a relatively small distance to reach the load center.
Christian These days we are producing electricity and we want more of it by wind farms very far away from the big cities. So electricity has to travel much longer, which means we need more lines, more substations. It's not a factor of ten, it's more like a factor of 2 to 3. But it shows that it's imperative actually to reduce the amount of materials and the amount of equipment that we need.
Christian And this is why in each product that we develop, we absolutely minimize the amount of material. So we go to the technical possible minimum of materials that need to be used in order to have this switchgear or this transformer or the equipment that we need. And there is also the special topic; before we talked about this insulation gases that need to be very strong to enable to have the soccer field in a room.
Sam Right. Christian The special type of substation that is very compact and can be in a big city, for example. Sam Used in the switchgear, right? Christian In the switchgear, and there is the traditional insulation and interruption gas, sulfur hexafluoride, which is excellent from all the technical point of view. But unfortunately when there are small leakages of it, it contributes to the global warming effect. And it's a greenhouse gas.
Sam It's a greenhouse gas, right. And sulfur hexafluoride, that's SF6, is that right? Christian Yes. Correct. And now the, really the new thing that will change our industry to a big extent is to get rid of SF6 and to replace it with gases that are good for the environment. And this is actually a lot of what we are currently working on is to create all these products that already exist with SF6 to create them without, free of SF6. And that's the future.
Sam Yeah, yeah. Christian, it has been a pleasure speaking with someone who is so passionate about energy and really seems to be quite an expert; learning about your photography and seeing you take these different perspectives on how you look at the equipment to talking about what the grid really does and what we're aiming for down the line. Sam So thank you. Thanks for tuning in to this episode of Power Pulse. Until next time.
Bárbara And that's it for today. We'll be back soon with some more great content. But before you go, remember to give us a follow so you don't miss an episode. Thanks for tuning in. See you soon! This episode was brought to you by Hitachi Energy, created and introduced by Barbara Freitas-Daniels. Content and script writing by Cassandra Inay. Bárbara Guest speaker, Dr. Christian Ohler. Hosted by Sam Dash. Produced and edited by Creative Chimps.