Lightning Protection Systems & Shielding Evaluation Methods

Good morning and good afternoon, everyone. Thank you so much for calling into this webinar. We will get started in another minute or two to give more people a chance to jump into the webinar. As people are jumping into this webinar, do note that the GoToWebinar will have a questions entry. So as we're going through this webinar this morning, do feel free to put in any questions that come to mind as we go through the content. We'll make sure to answer that in the question periods if we have time and if not, we'll make sure to respond to you via email or give you a call to make sure the concepts that we're presenting in this webinar make sense and everyone's having a good learning opportunity. And we'll give it another minute or two before we get started with the webinar this morning. I wanna thank everybody for calling in and joining us today or this afternoon, or this morning, depending on your location. Okay. So I think we have, a fair number of people that jumped on to the webinar. Again, thank you everyone for jumping on to this webinar. My name is Dave Lewis. I'm an engineer here at Bentley Systems. And today, I am presenting the lightning protection systems and shielding evaluation methodology. This webinar is meant to be a learning opportunity. So if you are familiar with GoToWebinar or not, there is a place where you can enter in your questions that will allow us to review those questions and provide feedback to you and give a response during this webinar. If we don't get to your question during the webinar, we will make sure to answer that at a later date. So let's go ahead and get started. So the purpose of this webinar is to really provide a basic overview of lightning protection systems and the engineering methodologies for evaluating the protected zones of a lightning protection system. At the end of this presentation, it's really my goal that you'll be able to describe basic concepts of lightning protection lightning and the components of a lightning protection system, be able to explain the evaluation methodologies that engineers are using for evaluating the efficacy of their LPS, and be able to perform some lightning protection system shielding calculations yourself and understand the fundamental concepts behind those. As we get into or how we apply that, we're really gonna be going through a basic overview of lightning, the components of a lightning protection system, and we'll talk about lightning analysis and what engineers may mean when they talk about lightning analysis. What we'll focus on in the major portion of this webinar is really the shielding evaluation methodologies, and I'm using PORTAL because there are multiple evaluation methodologies to determine protected versus unprotected zones. Then we'll go through a couple case studies to really highlight how engineers can, provide these. Before we get into this or before we go into the basics of lightning, we do have a few poll questions that we'd like to better understand the audience so that we can kind of tune this discussion as we go along. So the first question is have you attended training for lightning analysis before now? If you can please respond, definitely appreciate that. Let us know if you are new to the subject, this is your first time seeing these concept presented, if you've attended some training either internal or external, or if you've just simply had some discussions with colleagues. Might be a a dangerous not level of knowledge or well equipped to perform these. Definitely appreciate everybody's vote on this. And we have a really good split this morning. So we have, about a third of the audience is new to the subject. Similarly, we have some that have attended training in the past and others, a fair number or the majority, have had some discussions but not any sort of formal training. That's great to note for us as we go through this. Another one to help us along here is how familiar are you with the lightning related standards? And this is just a couple of standards, so these are more biased towards North America. If you're calling in from other parts of the world, you may be familiar with the IEC. But IEEE standard nine ninety eight, this is related to lightning protection systems for substations. NFPA seven eighty, this is related to general buildings, generic building, lightning protection systems. So we have a idea of what we might see from this based off of the previous poll, but we'll go ahead and share the responses here. So I think there's a good, mix of knowledge here. So I think most people seem to be new to the subject, might have had to some discussions but haven't practically applied those. So we'll make sure to show how an insurer might actually approach these types of analyses. And, there's a number in the audience that are familiar with the NFPA seven eighty. And we have one last poll here, kinda gauging how often you're actually performing these. I think most of the audience will be in this none to one to two one to five category, but I'm sure there's some that are, some technical experts on this call as well. So appreciate your taking the opportunity to fill in these poll questions. And I think we have a quorum here, so I will go ahead and share the responses. So great. Really appreciate everybody answering these polls. I think we really wanna make this a great learning opportunity for everyone, and I wanna highlight that we're really doing a basic overview of light lightning analysis, lightning protection. There are, over five hundred page manuals provided by some vendors that really give a more thorough description of all the instances and all the nuances of lightning protection. But we're just gonna give a basic overview so that people can visualize how engineers are approaching these types of systems. So let's go ahead and talk about the basics of lightning. When we talk about lightning, it's first we wanna be familiar with, the different types of lightning. So I think most people have or have, can visualize what lightning looks like but there are different types that we can call or categorize lightning as either positive stroke or a negative stroke. So there's a polarity associated with that. We can actually have a lightning event within a cloud itself or between clouds. What we're really concerned about when an engineering perspective is not going to be these lightning events that are within a cloud or from cloud to cloud. We're primarily going to be concerned about providing protection for these cloud to ground events. So we can see this illustrated here as a typical lightning event. And another one to be familiar with or another type of lightning event is the, tall structures to cloud where we can actually incite lightning events because of the elevation or the height of a structure, for instance. But for the most part, we're going to keep things below sixty meters and look at a basic cloud to ground application for this instance as we walk through this workshop with the webinar. Do wanna bring up some terms or, terminology that you may not have heard before. One of them is ground flash density. So this is a measure of how frequent a lightning stroke or a flash occurs within a given area. As you can see in the panhandle of Florida, in North America, we have a significant number of brown flashes in these areas as well as in Africa. You may not have measured values for this. In North America, we have a pretty robust measurement system. Some other countries have this as well so that we can actually measure where a measure the stroke current or the energy that was associated with the lightning event as well as where that may be and the time or the instance of when that happened. Other ways to calculate this may be just based off thunderstorm days and how frequent or violent or active those thunderstorms may be in a given area. So there's different approaches but measure is obviously the best. Another term to be familiar with is the step leader. So as illustrated here, when you think of lightning coming down from the cloud, it kind of makes these jagged paths coming down, and these are referred to as the step leaders. So dependent on the energy or the stroke current of that lightning that will, relate to how large of steps this lightning path may be. And as we make our way down from the cloud to the Earth, you'll actually have a step leader, upper leader coming from the Earth, so or the structure that may be about to be struck. The slow motion video captures of this often will show you can have one step leader or you can have multiple step leaders. And another term to be familiar with would be our return stroke, so our return stroke current. So we can see the step leaders coming down from the cloud, and then this bright flash occurs. That bright flash is when we have total ionization path from the earth to the cloud. So we have a significant amount of current. That current can be thirty k a, a hundred k a, three hundred k a. A significant amount of energy can be discharged in this lightning event, and the the magnitude of that first current is referred to as the return stroke current. And, again, that can be either a negative, negative stroke or a positive stroke. And that first stroke is really what we are concerned about causing damage on our infrastructure, whether it's a building or a substation or transmission line. Now when we talk about lightning protection systems, it's good to be familiar with what components are used in that. Air terminals is going to be something for those of you that are familiar with NFPA seven eighty. Here we have an image of a lightning protection system. We can see the conductors running along the edge of our structure and then we have our air terminals extending above the edge of this wall, and that is meant to intercept any lightning. We also have, shield wires, which are very common for transmission lines. For instance, we have a shield wire just above the phase conductors on this transmission line, or we have mass, or again, we could use air terminals. So here we have a bunch of bus work, and above that bus work is our air terminals extending above our equipment to help protect those from any direct strokes. Other parts of the lightning protection system that aren't directly involved in the interception of that lightning event are our down leads. That's going to allow us to pass that current or energy from the lightning event down to Earth. At the Earth, we have our grounding system and it can be something as simple as a copper loop that goes around our structure or a full grounding system that we would see in a substation or a transmission transmission, tower. And this grounding system, depending on how well it's constructed and how it's interacting with the soil, will allow that energy to disperse from that lightning event. Obviously, we're gonna have all of our connections too that are gonna be very important to be able to withstand that significant amount of current on that short duration, as well as from a, I can say, heating perspective, the thermal limits of that material as well as a physical limits because as you have a impulse, a lightning impulse coming through a connection, it's going to have some significant physical or Lorentz forces that are going to try and force that connection apart from any other metallic structures. So the air terminals, shield wires, mass, down leads, grounding con grounding system, the connections to them, they all need to be designed properly, connected properly, and maintained in order to have a functional lightning protection system. So you can't have one leg working without the other two. Now with that, we can kind of segue from our basic understanding of lightning and lightning components into lightning analysis. And I think this is something that is often misunderstood when we talk about lightning analysis. It depends on who you ask, but when you, talk about lightning, there's a risk assessment. So how likely is there to be lightning in your area and lightning of sufficient magnitude that's going to affect the facility that you're trying to protect adversely? Next, we can look at shielding. So if there's a lightning event in our area, once we've gone through this risk analysis, where is that lightning going to strike? Is there a zone that we want to protect? Are there zones that we really don't care about and we can allow that lightning to discharge without any sort of interception? And then finally, what happens when that lightning actually hits a structure, whether it be the intended structure, our lightning protection system, or an inadvertent structure, and that would be a lightning transient analysis. So when engineers refer to their lightning analysis, there needs to be a little more granularity on what exactly they're referring to with that. And to go into this with a little more detail, well, we'd refer to a lightning analysis. Typically, this can be something that's calculated based off guidance from NFPA seven eighty, the IEC sixty two three zero five, IEEE nine ninety eight has guidance as well, but fundamentally, they are following the same types of methodology or concepts. We have an area that our structure is located within. And then some distance away from that structure, we can associate that with a possibility that a lightning event within this area can affect our system. So we will calculate a given area associated with our infrastructure that we want to protect, typically based off of the height of that object and some, calculation of a distance off of that height, then we can calculate the ground flash density. And based off of the area that we consume compared to the ground flash density, that gives us a rate of lightning events in our area or within a place that we are trying to protect. These will often consider the cost of damage so if a non important structure is hit and easily replaceable, then we may not provide lightning protection systems. If it's something that's critical to operations, so obviously substations are critical infrastructure as that is going to feed into all sorts of businesses, industrial complexes. Databases are critical infrastructure as they house a lot of our data. The hospitals, these other things that are going to provide, very critical services for, our infrastructure and personnel, that is going to be a significant factor in your risk assessment. If it's important, we wanna protect that even if the risk is low because the hazards associated with the failure to protect are significant. Next, we'll talk about lightning shielding, and we're going to focus on this as the tail end of our webinar so we can really, hone in on shielding methodologies. So shielding analysis is really to determine what areas are going to be struck in a lightning event and what areas may not be. And I will note that lightning is, probabilistic in its nature. So we may have a lightning protection system that can provide ninety nine percent likelihood of coverage, but there's still a chance that we can have a bypass or some sort of, unintended strike. Now here we see a structure, just a simple illustration of one, and the lightning protection system, you can see the mass extending above that, but there are multiple parts along the edge that we have not protected sufficiently. So that would be a, unprotected structure in this instance. And this is where we're gonna focus on in our webinar in the second half, so we'll we'll come back to this. Now the lightning analysis or lightning transient analysis, this tells us what happens when lightning strikes, And as you can imagine, lightning is an impulse. It's not a sinusoidal frequency like our power system. It is going to be a steep, rise in current. It could be in the microseconds, a couple microseconds. You can go from zero to one hundred kA and we need to understand the, conductive effects of that, the inductive effects of that, and the capacitive coupling associated with that as well. So we can model such things like a transmission line, see the stroke current propagating down from our shield wire as it goes down to the earth. And this, this little illustration indicates the ground potential rise that we see or the Earth's surface potential as the ground rods around that lattice tower are dispersing that current into the Earth. And what we are concerned about is this peak voltage along all of our components of this lattice tower. If your insulators supporting your base conductors is not sufficient, you can have this peak current actually exceed that insulator, and you could have a flashover and then have an outage of that line. You can also have a poor grounding system. And instead of this peak current going up and reflecting back down, it can go up and similar to a wave, start to go down before it bounces back and increases again. So these lightning transient analysis can get very detailed to determine the likely or exactly what's going to happen as the current's propagating through this metallic structure. And this could be applied to critical buildings in order to see if there's going to be a side flash, transmission lines and substations. All these are, more critical infrastructure that you can evaluate with higher detail. Now let's get to the focus of this webinar, which is really how engineers are evaluating the efficacy of their lightning protection system or the shielding evaluation of their lightning protection system. Typically, I guess, for those that have attended any sort of external training, you'll typically walk through the more simplified methodologies and then walk into a more complex method. I kinda like to think of it as a, take the opposite approach in explaining this because I think, the volume sphere methodology and the electrogeometric methods really do a good job in explaining the fundamental characteristics of how lightning makes connection with structures. So rolling sphere methodology, some of you I'm sure have heard of this term. This is a electrogeometric method and the as you have your step leaders coming down from the cloud, the distance, the strike distance associated with this is going to be related to the energy or the stroke current of that lightning event. Now you can relate that to a sphere size from your lightning as it comes down. And you can kind of see this illustrated here, this little circle represents the striking distance off of our the end of our downward leader and it's within the upward leader, so you're anticipating the next step will be this strike, and then you have a return stroke current. Now depending on your standard or what you're looking at, you may have a specific sphere size, so an FPA seven eighty. Ordinary structures, it's going to refer to a forty five meter sphere radius or more critical infrastructure or things that may have some explosive nature to them could use a thirty meter radius. Depends on the application what is most applicable for your site. The thirty meter radius is going to be a more stringent application and we'll get into that as we talk about IEEE standard nine ninety eight. So IEEE standard nine ninety eight is the standard that discusses in more detail how those rolling sphere methods were developed, the different variants of that rolling sphere methodology since there are a little bit different electrogene methods, but the most common one we'll talk about here. And what we're looking for is to calculate the minimum stroke current that can cause us significant damage. So when we look at this from a substation application, we have our sphere that we are imagining rolling over our system. And as that rolls over the fence line, some of our support structures or our mass, that these mass are going to provide a zone of protection below them in an area where there's unprotected from lightning above them. So here we can see this rolling spear can roll and this piece of equipment may be susceptible to a direct lightning stroke while this one is protected from that. Now that I mentioned, we're looking for the minimum stroke current and the reason is the the smaller your stroke current is, that correlates to a smaller sphere. And you can imagine if we were to shrink this sphere down to half the size, that sphere would be able to roll over this mass and roll down, roll over this mass to roll down, and now this transformer is no longer protected. If that sphere was of, insufficient magnitude or the return stroke current was insignificant magnitude to cause a outage, we don't have a problem. However, if it is significant enough that it exceeds our insulation levels at our utility substation, we could have an outage at that substation and could be a critical issue for us as we're trying to maintain power for users in a storm environment. Now another method that we are going to talk about or be familiar with is the fixed angle method. This, is easy to understand when you think about that rolling sphere. So based off of the height of our mass or our air terminals, we can calculate the fixed angle that we may assume some protection to other components or equipment or a structure. So depending on the height of our mast for substation application using IEEE standard nine ninety eight, your fixed angle may be a thirty degree angle off of the mast or a forty five degree angle depending on how high this mast is relative to the plus work or the transformer that you're trying to protect. Similar concept for NFPA seven eighty, a little bit different angles, but if you have a structure that maybe has a roof line difference of twenty five feet from one roof to another, you may be able to use a sixty degree angle of protection indicating that air terminals on the edge of your upper roof line may provide some extended protection to the roof line or the lower roof line below. And, again, that angle is going to vary based off of the relative height difference from your air terminals or mass to whatever you're trying to protect. And if you think about this, we're really going back. If you look at the rolling sphere, which has this little curve, if the sphere is large enough, that rolling curve starts to look like a straight angle. So it makes it nice and easy to understand the relationship or how these fixed angle methods come about. Another methodology is more of a prescriptive approach. So NFPA seven eighty is really a guide for how you install these systems and is meant to install them properly so that you are having you have a protected system. And this is going to describe how frequently you space these air terminals represented with the blue lines, the connections to your conductors to down leads, how frequently those need to be done to the earth connection or ground connection, as well as any sort of internal connections across the roofline if it's a significantly large roof. You may need to make connections every fifty feet or run a cross lead every one hundred and fifty feet depending on your structure geometry. There's also another methodology described in the IEC, which is the mesh methodology as well. And as you can imagine, both of these are more prescriptive. They are not telling you that you're or you're not giving an analysis that you've met the, you've created this land of protection zone. However, properly following these methodologies, you should create that. However, challenges that you need to also commonly prove that your design is actually meeting your intended goals. So that's where we're going to use, the fixed angle methodologies or the rolling experiment method in order to show our clients or be able to prove to our, leadership that we have a protected system against lightning. So let's go ahead and apply the rolling spirit methodology. I think the rolling spirit methodology tends to be one of the most commonly, utilized in industry. And I think it's best to do this first by going into the source document, which is IEEE standard nine ninety eight. This is the one that helps us calculate how we get a sphere size or how we get that calculate that return stroke current that's going to cause damage to our structures. So we have, a few calculations we need to do. So this z s calculation, this is the surge impedance that a lightning stroke current will see when it hits our structure. And this is calculated by multiplying sixty times the square root of the natural log of two h over r c, natural log two h over r. The r or the h value, I guess, is the height of whatever conductors you're trying to protect. Those phase conductors of a substation is what this calculation methodology is considering, but same concepts would apply to another type of structure such as a structure that is housing explosive materials. You can use the same type of calculation to make sure that you have a correct protection zone. Your r value is the conductor radius, that's pretty understandable, but this corona radius, this r c value, is actually another series of equations that you can look up in the annex of IEEE nine ninety eight. So part of that, we'll have a figure lookup to determine the corona radius where you can create some calculations in Excel or use the software in order to calculate that, but this would be kind of our first step in our calculation methodology, just determining that surge impedance. Next, we can use that surge impedance to calculate the minimum stroke current that exceeds our BIL. So this IS will equal BIL which could be described as the basic impulse insulation level. You You may see this described as the basic impulse level, basic insulation level. Really, we're all referring to the same thing. It's the peak voltage that your equipment or your insulation equipment is able to withstand without a flashover. Another term you may have heard of is the critical flashover. That's really a value associated with that. You know, at a certain peak voltage, there's a fifty percent chance that you could have a flashover, and those are interrelated to each other. And then we have now that we have the calculation for the minimum stroke current, we can take that value and now put this into our sphere radius or our striking distance. So we have this s will equal eight times the k coefficient. This is related to what type of equipment you're using or lightning protection system you're using to protect your system, whether that's a lightning mast or a shield wire, they can have, a mast would have a coefficient of one point two, a wire would have a coefficient of one, and then that is multiplied times your minimum stroke current to the point six five. So if we do this calculation, let's say we have a one fifteen kV, switchyard that has a four hundred kV VIL design. And based off of our calculations for ZS, we determined a surge impedance of four hundred and fifty ohms. So that will feed into our minimum stroke current, which would be two point approximately two point five k a in this instance, which then feeds into our minimum sphere size, which is seventeen point three meters, over, let's see that, three times, otherwise known as fifty five feet. So that is going to give us our sphere. Now if we're following along with IEEE nine ninety eight's methodologies, we can do a lot of hand calculations and mathematical equations in order to determine based off of the height of this mast, we can determine at what point the sphere will make contact with that. And fortunately for us, this is going to create multiple right triangles and we get to use one of our favorite equations, the Pythagorean theorem, in order to calculate. We know this this, distance from one the origin of our sphere to maybe the top of our mass, and that can tell us based off the top of the mass, the height that our, sphere will make contact with that. And then we have our s minus a, a being either the mass height or the base conductor's height, and we can just create multiple right triangles in order to calculate our striking distance, in order to calculate how far away we can put these mass in order to prevent the sphere from rolling through this and making contact with our base conductors of our substation. Now this will end up with a lot of math calculations, and it walks through multiple different methodologies for that. If you have a relatively standardized design, this may be an applicable approach. More often, what we'll see, though, engineers doing or designers doing is we're going to take that concept and then just put it into some sort of software or CAD tool in order to help us evaluate that. One of the simplest ways is if we have, let's say, MicroStation, for instance. Already have a very simple illustration here, so I will rotate my view. You can see this is just a wireframe of a simple building. And if I rotate to from the right, I have a sphere size. And this one is, hundred fifty feet across or hundred fifty feet as the radius, so it's the, forty five meter across NFPA value. And what I can do with this and I'm just gonna copy this value, and I can look to see as I move my sphere across my system, you can see if it's making contact with the structure, it wouldn't do that because I actually have air terminals that will prevent that, and the air terminals are illustrated in orange here. Now I have my view from the right. We'll have to replicate this as we look from the front view of the system, and we'll let's be over this way. This is one methodology that is relatively common in the industry, but there's a little bit of a concern is that we're looking at a sphere that's a three-dimensional object. We're trying to protect a structure that is a three-dimensional object, and if we're evaluating it as a two dimensional views, we can have holes in our analysis. So what I mean by that, we can really illustrate if we go through a case example. So we can go to more complex software. So we have the shield module here that we can use to do this, and I'm just going to import that cad file. I'm going to navigate to the structure that I want to import. I just need to call out the scale of the structure and then I will pull in the binding protection system. I'll note that as a shielding system, then I will pull in the structure that we want to try to protect, apply this, and then with my scale correctly here, I can import this and then we're going to see an illustration of the lightning protection or the, the structure with its lightning protection system on it as we see here, and now we have a three d environment that we can actually analyze this. And I want to specify the striking distance of one hundred and fifty feet, and we'll make sure that we're referencing the shielding before we go into debug and compute this. And as this is analyzing, we'll see a little load bar in the bottom right, but essentially, this is rolling the sphere three dimensionally across our system. And when we look at the system, what you may have determined to be a compliant system from a two d perspective, is pretty easily highlighted to show is not protected from a three three-dimensional perspective. Because if we look here, we can see this sphere actually rolls over the top of the structure, and then we have a little gap that we may have missed in their terminal. And this would highlight for us as the designers, as the engineers that we didn't properly apply an FPA seven eighty, for instance, and we need to go back and mitigate that, which is simple to do. You just go back in, and we'll put in some more shielding here. We'll call this an LPS. I'm going to rotate my view so I can see this more easily. And we will need to reanalyze this but we'll just put in a couple air terminals in order to protect this. I do want to make sure this is, described as shielding so it works as that. And I'm gonna put in another air terminal at this edge because we did see some issues there as well as on this point right here. So now we have, more air terminals that we've added based off of our calculations, and we'll just rerun that analysis so that we can get to a point where we're saying the site is proven to have, a protected zone so that any direct strokes will not directly hit our structure. And what we'll do is provide a view of this. So now we can see this is protected zone. We can do kind of a top down view of this system, take a snap of that, and do the same type of illustrations that we would with the two d perspective, but have a little more confidence that this is actually protected. We'll do the same thing on this the right side, and we can show a little bit of the interior of our structure so that the clients or our leadership can see that we've actually, as an engineer or designer, have protected the system. And, of course, we need to create some sort of report to illustrate that. So here would be just a quick simple we have a shielding system and a lightning protection system, and our striking distance is following the NFPA seven eighty, with a hundred fifty meter sphere or striking distance and our protected zones as illustrated here. Now this is one approach for that, or a couple different software for doing this. You may see, like, an open substation. There's other lightning protection system, approach or analysis. But we did we do wanna make sure that if you're applying the rolling spirit that you're aware of the fundamental hazards of using a two dimensional approach for evaluating a three-dimensional problem, and also highlight that could be really advantageous to prove to yourself that you've applied NFPA seven eighty properly. Another application is, you know, if you have a more complex structure, so we see this illustrated here, or I've actually done one where it's, a building in Revit or open buildings here. We can see this analysis, which show if we look at a more complex system. When we look at the results of this, we're really concerned about the upper floor and making sure that we've provided air terminals on all those spots. As a designer, we may have missed a spot, meaning we may have not included air terminals on a secondary level or lower level that didn't catch our attention because we are focused on the roofline, for instance. So this is just little ways that we can help improve our design and analysis approach to help keep our infrastructure protected from the hazards of lightning. Now getting back to the presentation here. When we talk about lightning protection systems, really, we were just giving a basic overview of some of the components and approaches this. For this, there is a much greater depth of knowledge that you can look into for understanding how our various approaches for lightning analysis, lightning shielding, lightning risk. How you approach these could be a bonded or isolated system. So you may have a lightning protection system that is, bonded to all the other metallic components of your structure or, you may have one that's isolated. This would be really important to have in areas where you have combustibles or explosives. You would want to have an isolated system to make sure that you maintain separation measure of sparks in in an area that could cause a significantly worse hazard. With that, we need to be cognizant that there is a separation distance to be aware of. So as you're installing your down leads or your air terminals, if it's running right next to a venting system, you may be able to have a side flash occur because you are not maintaining sufficient separation for that. In those instances, you may, as a designer, need to change the path of that down lead or the air terminal. You may need to create some bonding to that. Bonding could be a positive effect or it could be a negative effect because you may, by bonding, expose your structure to a portion of that lightning current. So it's something that as an engineer or a designer you need to be cognizant of, what may be best for protecting a specific type of facility. Other things are surge protection. So if you have your, lightning protection system developed, it's going to try and discharge into the earth and through that grounding system. You may have, opportunities for induced voltages on your power system, and you may need to mitigate that with some surge protection devices. Especially for sensitive electronics, that's a a good way to help provide an external lightning protection as well as protect the electronics of your system. And maintenance techniques or maintenance practices. Many times, we need to be cognizant that this is, generally a passive system until it's required to operate. So the lightning storm or thunderstorm as it's coming in, you will see some current being developed on your air terminals, on your your your ground grid, and all of those effects can lead to some damages. You will most likely want to have some sort of maintenance steps every three to five years at a minimum. Obviously, it's good to provide some sort of inspection of the air terminals, the down leads, the connections, and the earth, the grounding grid, after storms to verify that if there was a strike that you are able to identify any damage and provide a replacement for that equipment. Also, damaging events. This can be something that's like a high wind storm, corrosion, or simply theft. If that's something that comes up in your facilities, you need to be cognizant to do sufficient maintenance and inspections to verify that you have the protection installed even when others may be walking away with some portions of that. Now in conclusion, I really want to highlight that when we talk about lining analysis as an engineering or designer, we're really talking about a few different things under the same umbrella. This can be a risk assessment or it could be a shielding design to determine the protected zones versus unprotected zones. It may be a detailed analysis or a lightning transit analysis to determine how that stroke current is going to propagate through our facility and our lightning protection system. We wanna make sure that you know that there are multiple methods in order to evaluate the the protected zones and verify that your lightning protection design is actually providing that, protection from your structure or your facility. At this point, I think it's a good time to open up for any questions that you may have as we walk through this webinar. Again, this is really meant to be an introductory introductory webinar. I think it's good for much of the audience here that were new to the subject and learning this. If you have any questions, do feel free to place that into the GoToWebinar questions chat box, and that'll give us a chance to answer those. I'm I'm gonna go ahead and look over to the questions. One question that came up is if this slide deck will be provided or if this session is being recorded. Yes. This is a session that we are recording, and we will be putting this onto our website. I believe attendees and those that have registered will receive a notification once that recording is available. So you'll be able to refer to this later. Another question is, do we have any materials related to the risk analysis in more detail? For this webinar, we don't have them at this moment, but just wanted to present the general concepts. If you're looking at NFPA seven eighty, I can't recall the exact annex, same with I triple e nine nine eight. Both of those have, detailed guidance on what factors you may consider in your risk assessment and the probability of a lightning event occurring and the damage that that would occur incur for that. And often what these will come come up with is a, risk or a cost of damage per year and that you can use that in order to justify the expense of a lightning protection system. And I didn't mention this in the webinar, previously, but, it can be a significant benefit to have a lightning protection system just for reducing your insurance costs as well. So that can be something that's packed into your risk assessment is that you can have a reduction in insurance rates as well. Another question is when should one use the, fixed angle method versus the rolling sphere methodology? It really depends on the engineer and the application. From my perspective, you'll see the fixed angle method used very frequently in transmission line applications because there's a relatively fixed space or height difference between your base conductors that you're trying to protect and the shield wire that you're using to protect those base conductors. So that makes it a relatively simple application to use that fixed angle method. Some structures are, more easily evaluated with that simplified fixed angle approach. Typically, though, if you have the software, if you had a CAD package, you can have easy access to do a more robust rolling experiment methodology. And usually in buildings, like, if you're designing something in open open buildings or Revit, that can be a more critical building that you would want to design more. Design and evaluate more robustly with the rolling experiment methodology. One question is, are there any documents or drawings that EasePower might have on lightning protection is typically connected to a ground grid at a plant? I'll say yes and no. So if you download XGSLab, if you're a user of XGSLab, then there are multiple tutorial documents and there's a couple generation facilities in the tutorial documents. So that provides just a brief example of one application of that, but I wouldn't use that as the guide for how to, design these systems. You know? There's a few vendors that have really good documentation. Dane is one that has a, I think, is a five hundred page manual on the concepts and design application for lightning protection systems and how to evaluate them. So that would there's, many resources online that you might be able to look into as well as, of course, the standard documents. They're meant to provide guidance for how engineers and designers should approach protecting our critical infrastructure. Another question is, if maintenance is recommended after a storm, how do we make a judgment call if we need maintenance, or how do we evaluate the, intensity of that storm that may need some maintenance or visual inspection? There's two cup there's a couple different ways I can think of this. One is obviously categories of, tornadoes or high winds, that can launch material in the air, and then that can make contact with your air terminals and, your down leads and all of your protective equipment. That could be one example of a, a case where you may want to look into a, maintenance procedure for reevaluating your LPS. Another is, if you are getting lightning measurement data. So there are terminals throughout the US that is actually measuring the stroke current magnitude, the exact time of the stroke, and then the general, as best they can, try to locate where that may have occurred. If you're receiving that information or purchasing that information, you may be able to look to see if one of those strokes was within your was in proximity of your equipment, whether it's a substation or a power plant, and that may kick off a evaluation. And, of course, if you had an outage during a thunderstorm, that would be a very good case to look into some sort of maintenance procedures and inspection. So another question is how what can be applied as a mobile structure, like a container? And there again, I would point towards NFPA does have guidance for things like ships as well. IAC does as well have guidance for, what we call mobile systems. If you're just moving a mobile system around, you have and I'm not going to discuss the ship application right now, but, let's say you're moving a container from one location to another, you need to have all three components of that lightning protection system installed. So that'll be the air terminal, the down lead, and the ground grid in order to disperse that energy. It should be noted as well that there are some structures that would be, self protecting because of the thickness of the material of it. It can withstand a significant amount amount of, current that it can withstand the thermal limits as well as the physical limitations of that stroke current. The question is, does this offer offer comparison of the lightning protection performance with surface corrosion conductors to ideal conditions? The corrosion aspect and more detailed analysis so that I guess we'll we'll kinda I wanna break this up in a couple of different ways. But, when I think about your analysis in more detail, we're really looking at your grounding system performance and making sure as your down blades or your terminals are providing that path to ground, that they're not going to induce enough current on some other object or create a significant voltage difference that you'll have some side flash. So for those, you'll typically have very high voltage values or magnitudes and that can often go through any sort of corrosion that may have formed or thin thermal corrosion. So that corrosion typically doesn't have the dielectric strength in order to prevent that. I do want to highlight though that your dial there if you have a significant corrosion risk, that can play into your maintenance issues because your connection that you thought was robust will pull off in the event as it's happening, and so that can lead to unintended damages elsewhere. One question. Another question is, is there a way to model a metal railing as a strike terminal in the software, and is that allowed for NFPA seven eighty? Yes. So NFPA seven eighty does allow for you to take advantage of your system design. If you are, again, having all three components of that system, it's a it can serve A railing can serve as a air terminal, and you need to have down lead from it or some sort of continuity to your ground grid in order to disperse that energy. And that's something that's mentioned in in f p a seven eighty. And you can in XSLab software, it's a pretty flexible tool. So what we will do is, be able to import whatever your structure may be. We are going to import the and this import process, I kinda showed it in the simplified view, but we can pull pull in several of the layers from whatever CAD package you're using in order to do this design. And then we just want to make sure that we denote for the software what parts of our our system are the structure that we want to protect, whether that is, a building or our base conductors of the substation, whatever it may be. We just need to note that as a structure type, and then we have to know what things are a lightning protection element. And I didn't show this in this calculation either, but if we go to, the, axial slab analysis again, we just use this striking distance of one hundred and fifty feet. The calculation can be determined in the software so you can calculate the stroke current and it kind of gives you a nice little guide of all the parameters that you would need to enter in in order to calculate that surge impedance and then that corresponding stroke current and then of course our final goal of that sphere size. Another question is, can we look at installing a a catenary system? So this is pretty common, especially for explosive areas, we would install a catenary system. So if I go to my let's do my simplified building here, that way it can run relatively easily. Let's say I wanna put a catenary wire going across some portion of this building. Let me place this in here. I'm gonna make sure I know the height of this facility before I design this. So the conductor is the top edge of this building is, fifty feet in the air. So let's say we're just going to put our, counterpoise or air terminal seventy feet in the air. And so I want to make sure this is designated as an LPS and I'll call this my catenary. So I can put in this conductor and right now, just a nice straight line, and what I want to do is actually make this something that's curved and so I want to know, the approximate length of this conductor is hundred and eight feet. So this catenary tool is a way for me in my software to add that later on. If you design that catenary in your CAD package, obviously, Existat would import that and analyze that. So we have our starting point is zero. Our elevation is seventy feet. Let's say at fifty feet, we drop down to sixty five feet in elevation, and then we go to the end location, which is a hundred feet, and then we have this z e, lower back up to seventy feet where our masts are supporting that catenary wire, and this will calculate a a parameter, a catenary constant, and then this is something that I can take into my model and then I'll select this conductor, my shield wire. In my layout, we have the catenary parameter and once I apply that then we can see that sat characteristic. And with this, if you're in an area that you want to avoid any strike, any, side flash or side strike, you will want to make sure the elevation of this is sufficient between the structure you're protecting and the location of that catenary curve. And I'm gonna run this as I look into the next question, so, we'll be able to take a look at the results from that. Another question is just related to the video. So I do wanna clarify. The video, we are recording this session, and we will have this on our website. So you will be able to see a recording of this presentation on our website. Anyone that's registered or attended this webinar will be able to see that after the fact. I just want to illustrate here. Now you can see that catenary curve is that catenary shield wire is providing some protection for our structure down below. And I do want to highlight, as we are at the top of that where I'm sure people will need to drop off, If you have any questions, feel free to reach out to me at dave dot lewis at valley dot com. You can reach us at, easy power or HSLAB support. Especially if you're a user, feel free to ask any questions that may come up. But very much appreciate everybody jumping on the webinar. If you have other questions, I will stay on for another couple minutes here to answer those as they're coming up. I don't know if I didn't get your question here, if I accidentally missed it, I will make sure to answer that. If you can, do provide comments on the exit survey. Really appreciate any information as you, attend to this webinar and things that we could do better or things that you'd like us to explore in more detail. Again, thank you everyone for attending this webinar today. I think this might be our final question. So are we able to link this software? So the ExisLab software is what we're using in, analysis here for the rolling sphere. So are we using are we able to link the ExisLab shield software with others like Revit to import structures? Absolutely. So here, just to show you, this is the Revit file that I started with for my analysis. And so I'm just exporting this out to a readable format for XGS lab, which is just really, DWG, TXF file from them. Similar concept applies when you're using a MicroStation or OpenBuildings. You'll be able to export from whatever CAD package you're using into a readable format with XGS Lab in order to do these types of analyses relatively efficiently. And here, just want to highlight again, when you're using XS Lab I can import the layers or the levels that I want to bring in. It illustrates the, building as you can see here, and then we're going to evaluate the lightning protection system and how the terminals are hopefully preventing any lightning strike from hitting our structure directly. Good. Thank you everyone for attending this. I'm gonna go ahead and, close our webinar, and do please, enter your comments for the end survey. We really appreciate everybody calling in today.