Webinar «International electro technical standard IEC 62305. Protection of structures against damage», page 1

— Good afternoon, dear colleagues! We are happy to greet you at the next webinar on the design of lightning protection and our topic today is "International electrical technical standard IEC 62305" part three - it is protection of structure and human from physical damage of lightning. Our irreplaceable lecturer - Dr. Marek Loboda from Poland will make the report today. Dr. Marek Loboda is the author of over 150 publications on "Lightning protection". He is a member of the Commission on development of IEC 62305, and it means we can address our questions regarding the design and calculation of lightning protection or questions about IEC standard directly to the expert in this field. My name is Alexey Korytko, I am an administrator of this webinar. And first of all, a few words about the order of our event, how it will be held. The webinar is 90 minutes and consists of 4 blocks and pauses between them. The pauses are to answer your questions. You can send your questions to the lecturer or questions on how to adjust sound in the chat on the bottom left of the screen. The webinar will be held in English with simultaneous interpretation. To hear everything well, you need to adjust the level of volume of the hosts. When the interpreter turns the mic on, you can point at the icon on the left and you will see a volume regulator.

— On the slide in the central part of the screen, you can see how to adjust it. We recommend you to set the interpreter's volume level to maximum - 80 or 100 to hear Russian speach well, and the level of Marek's volume - to 50 or lower. You can do it in real time mode to hear everybody well. If you have any questions on connection, adjustment of sound, you can send them to the chat and I will answer them. If there are no questions, we can start the main part. Marek, I give you the floor.

— Today we will work on the third part. We will talk about protective measures, which mostly relate to external lightning protection. And here you see correlations between the series of lightning protection standards 62305 in this chart. Let's start with the first part. There is a plan to work on the fourth part, which will be presented at our next webinar. It will refer to protective measures on electronic, electric systems in the buildings.

— The third part of the standards - general view on this part shows us the requirements on the protection of buildings from physical damages and protection from injuries of human and living beings, which they can get due to step and touch voltage near lightning protection systems outside the building. Of course people can be subject to lightning strike inside the buildings themselves.

— On this slide we see the diagram of the process of lightning protection system design. Usually everything starts with the characteristics of the protected building. Of course, we need to understand what is this building? What does it consist of? What is it made of: wood, brick or concrete? Where is it located? What are its sizes? What is its structure type? What systems will be inside? And on the electronic, electric equipment inside it. Before designing lightning protection system, it is necessary to collect a lot of information. The next step - determination of lightning strike risk. Heat risk, necessary protection level which should be defined for each building. If we are talking about lightning protection, we of course mean external systems - lightning rods, lightning arresters and grounding systems. There are different possibilities of these parameters choice: type of material, determination of protective component parameters, and also use of natural components. In fact the use of natural components is very welcome - these are metal elements of building construction, they can help in lightning protection systems. And finally, design of internal lightning protection system.

— Now I'd like to start with the description of lightning rod system. Usually they consist of lightning rods, include free-standing masts of lightning arresters, catenary wires and meshed conductors or celled conductors. These are general types of lightning rod systems. It is very important, that real physical sizes of metal systems of lightning rods must be used to define the spatial volume to be protected from lightning strikes. Many years ago, radioactive lightning rods were used in many countries of the world. It was thought that their efficiency was higher, but now their use is forbidden. There are still more than hundred thousand radioactive lightning rods all over the world. It is quite a big problem what to do with them, but it is prohibited to use them. Today there are three safe methods to define lightning rods location - protection angle method; it usually fits for buildings of a simple shape and small size. The second is rolling sphere radius, the most recommended method based on the electrical geometrical model and is suitable for all cases. I want to say a few more words about this model. Maybe this information will be interesting for you.

— Here you see the recommended data of rolling sphere method, which are based on electric geometric model. It was intended, was developed by many professors, in particular a professor from Krakow and from many universities, I know them personally and they developed thee recommended regulations. Well, the system of lightning protection includes protection from a downward lightning strike or lightning "leader» that is from cloud to the ground. If we analyze this phenomenon, we will see, that there is a distance of a possible strike on a certain level above the ground; it is orientation of the downward strike to the place where lightning will hit or object which is located on the ground surface. It is a distance of a possible strike and it strictly depends on the values of lightning parameters.

— That is why, different lightning protection level types, mainly depend on the rolling sphere radius and on the building height. Here you see the number of meters of the building height 20, 30, 45, 60. And on the protection angle. On this picture, we see the comparison of square of equal surfaces, protection angle method, lightning rod and rolling sphere method use. Usually we see that the surfaces are almost equal. The surface of the zone, which should be protected, depends on the protection level and angle and building height. In green we see the unprotected zone, which appears if we use right angle protection method. And in red - it is what is protected by rolling sphere method. In fact, rolling sphere method is quite conservative in comparison to protection angle method. But there is an agreement between the experts in accordance with the European standards, that all these standards may be examined.

— And on the examples, on the left picture you see a cone-shaped protection, in the middle there is a lightning rod and the sizes of the building under protection, we see that it is straight in the protection cone. Here we only see twist-and-steer wires on the second picture and divided lightning protection systems.

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