Webinar "Origin of Lightning Protection Zones, Their Actual Capabilities, and Negative Impact on External Lightning Protection Optimization". Page 1

The nineteenth webinar of "Earthing and Lightning Protection: Design Issues and Problems" series.

(held on November 22, 2017 at 11:00)
 

Webinar text. Page 1

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Approximate reading time: 1 hour 02 minutes.

Origin of lightning protection zones

– Good afternoon, dear colleagues! Good afternoon, Eduard Meerovich!

– Good afternoon!

– Let's begin. We are happy to greet you during our next webinar with the participation of professor Eduard Meerovich Bazelyan, the well-known expert in lightning protection and earthing. Our current webinar is titled: "Origin of Lightning Protection Zones, Their Actual Capabilities, and Negative Impact on External Lightning Protection Optimization". Here are some organizational aspects: the webinar will take about 90 minutes, including 60 minutes for the report of Eduard Meerovich, and about 30 minutes for your questions. The questions will be answered at the end of the webinar. I ask you to send your questions eagerly and leave comments in the chat. Moreover, I recommend that, when asking a question, you specify the professor's slide or phrase it relates to, so that it would be easier to understand and to answer it more specifically. In addition to your questions related to this webinar, write subjects and questions you are interested in, in the chat. On their basis, we will schedule and hold our next webinars. Follow this link to get information on the forthcoming webinars. Moreover, you may get information on new events in our social media groups. Join our social media groups or register at the website so that not to miss the relevant events. Dear colleagues! I have finished the introductory word and give my turn to the speaker. Eduard Meerovich, good afternoon!

– Good afternoon, dear colleagues! I am very pleased to see so many participants. I am grateful to the webinar administrators for this subject because I have felt myself an archaeologist for two weeks and have dug into the old books to understand how these protection zones had appeared. Probably I will not start from the ancient times and I will not tell you about the seal skin that the ancient Romans considered to be an excellent means to protect against lightnings.

Protection against the lightning current interference

– It was in the past. And now, we have returned to this issue for the following reason: today, we have got a special relationship with the lightning arresters. Few of us bother about the direct lightning strike into a building, but today, the people are more concerned about the electromagnetic impact this lightning induces. And even if the lightning was caught by the lightning arrester, such electromagnetic impact does not disappear. And if we want to protect the facilities through using lightning arresters with a significant height, we will do the following: we will attract those lightnings to the facility to be protected, and their electromagnetic impact may be much more dangerous than the effects from its direct strike. For this reason, today we have returned to the issues of protective action of lightning arresters and to the protection zones. I must admit that I am a vociferous opponent of using the protection zones during the design, and the words I will say today are, to some extent, an effort to show you the imperfection of a protection zone, and what it all results in.

Remote methods for recording the lightning strike point

– Let's start with the end. I am imagining now that all of us have decided that the protection zones being used today are not very reliable, and we need to design them from the very beginning. What can we do in this case? The answer is simple: let's install a facility or a facility model in an open field, install the lightning arrester thereon and see, how many lightnings are caught by the lightning arrester and what percent of them is got into the facility. Let's hope that we will define the zone with a reliability of 0.999. What can we do for that? To generate a zone with 0.999, you need to have at least one thousand discharges, and out of them, one may get into the facility. To understand, how much of them will break through the protection, there must be 10,000 discharges. If we have got a facility of 30 meters high, and the lightning arrester will have about the same height, then, on average, in Russia, the strike will happen once in 10 years. It means that after 100,000 years, we will have the required statistics. Myself and most of you will not live enough to do this. Therefore, we can do it another way: we can increase the number of facilities to be observed simultaneously. If we have got one thousand facilities, then our experiment will take 100 years, and with 10,000 facilities, we will need 10 years. Generally, it is very expensive. These experiments have not been conducted ever, and, I think, they will never be. You can say: "Dear Eduard, you have forgotten that today we have got remote methods available for recording the lightning strike point, and there are several global companies that sell these systems. You must buy and install them". But it will work out, and the reason is: I contacted such companies many times. We discussed the issue of buying such systems for Russia more than once. But the point is that the accuracy for determining the lightning strike point in the major portion of such systems is about 200 meters. It means that the system cannot differentiate the lightning arrester and the facility. It means that, unfortunately, we cannot rely on the direct experiment on determining the protection reliability.

What was the originators way of thinking?

– From then onward, let's see into what protection zone is and what we can do with it. You understand that we have to start with Franklin and Lomonosov. Franklin was the first who determined that lightning is an electric charge accumulated in the clouds. He invented a lightning arrester, but he did it from the other end. In general, you know that he wanted to install lightning arresters not to attract the lightning, but he thought that the electric charge that would develop from the lightning arrester would go to the cloud and neutralize the cloud charge, and the lightnings would disappear. To the contrast, the Franklin's system did not work. After some time, it became obvious that the direct function of the lightning arrester is to attract the lightning discharge while taking it away from the facility to be protected. This idea was so brilliant that Lomonosov wrote an ode addressed to Count Shuvalov describing how efficiently the Franklin's lightning arresters were operating.

Lightning arrester protection radius

конус    cone
– From this moment on, the second question is arising: if I install a lightning arrester of 10, 20, 30, 100 meters high, what will be its protection zone? From what distance will it attract lightnings? The table you can see is borrowed from the excellent book of my teacher, professor Ilya Stekolnikov, titled "Lightning and Lightning Protection". Please note that it was published in 1942.

Research of I.S. Stekolnikov

– I want to show you one more picture taken from this book. Here is a circle protected by the lightning arrester, and there are the strike points outside the circle. It is interesting what kind of lightning arrester was used there. The lightning arrester was 900 meters high and was installed in the Moscow Region. What do you think, what kind of lightning arrester was it? The lightning arrester was made as air balloons to protect against the German bombers that were flying near Moscow. The researchers observed the protective action of these air balloons and tried to determine the protection zone in such a way. But frankly, it is impossible to make observations without any devices within the radius of about several kilometers. Certainly, it was a speculative research rather than a serious one, but on this basis, they tried to determine the protective action of lightning arresters.

Preceding lightning arresters

– I have provided this extract from the book to show that, more than 50 years ago, active lightning arresters were proposed, and it was suggested to protect the facilities by placing them into the isolated bin made of concrete, which should have had to protect them from the direct lightning strikes. Surely, such protection as well as currently available active lightning arresters do not operate, but there were such proposals.

First protection zones

– When did their use begin? It began in the moment when the high-voltage sources appeared. When pulse generators appeared that could provide a voltage of at least one million volt, and when we could break through the distance of 1 to 2 meters by applying this voltage. From this moment on, the following idea occurred: "Let's install a model of a lightning arrester and a model of a facility in the laboratory. Instead of lightning, we will have a spark of 1–2 meters, and we will see how this spark will strike the facility". The first experiments of this kind began in the Soviet Union in the 1930s. In the beginning of the 30s, the protection zone was invented which was then represented as a cone starting from the lightning arrester top, and the sides of such cone were angled at 90º. When I tried to understand why the angle of 90º was used, I could not find any explanation except for one: 100 is already used because it is the water boiling point, and 90 is not used, so they took 90º. It was the first protection zone. And the protection zones are based on such "serious" grounds.

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