Webinar «Methods of active influence on lightning strike. How ESE lightning rods are effective and feasible?», page 1

— Good afternoon, dear colleagues! I am sitting in front of a web camera and talking to you for the eighth time already. This time, however, we intend to talk about ESE lightning rods. And as usually, in this case, my dear assistance Nadezhda will help me to communicate with you.

— Good afternoon, dear colleagues! ZANDZ project with its next webinar is greeting you. Please write in the chat how well you can hear and see us and I am giving the floor to our dear Eduard Meerovich.

— You know, the preparation to this seminar was very hard, I even asked the organizers for a double term, because I had so many doubts. The doubts of two kinds. The first one - if I have the right to hold such a seminar. The matter is as follows. I was not very much concerned about the professional preparation, because I've been sitting in an experimental laboratory for 25 years and working on a long and rapid lightning. Almost for the same time period, I've been working with the theoretical research of lighting, practical lightning protection and that's why I am well familiar with the material. But one circumstance left me perplexed. I've always considered and remain to consider myself an active opponent of ESE lightning rods. And I had a doubt if I have a right to tell you what I think, because my personal opinion is to some extent biased. However, I decided to hold this seminar for you to hear the argumentation which the opponents of ESE lightning rods have. And I also decided to make it, because the organizers of the seminar, as I know, made an agreement with one of companies producing and selling ESE lightning rods and they are ready to give their ideas too. So there should a very interesting discussion I guess. I have a request to you. Please, give me the chance to answer all questions in the end, so I don't interrupt a report which is very difficult for me. But if the question is very critical, Nadezhda will catch it and interrupt me. So, I begin.

The use of ESE lightning rods is not envisaged in the Russian regulatory framework, like in IEC 62305 standard and also in the regulatory bases of the majority of technically developed countries.

Why?

The question is different. Is it possible to manage lightning for the sake of mass lightning protection?

Бесстримерная корона – streamerless corona

Переход короны в стримерную форму – transition of corona into a streamer form

Инициирование встречного лидера – initiation of the counter leader

Обеспечение устойчивого развития встречного лидера – provision of a stable development of a counter leader

The problem is to make a device applicable for practical lightning protection. And what to start with in this device? We need to start with money, because today the cost of external lightning protection is the share % of the protected object cost. And nobody wants to pay more. And the first question if we can make a cheap managing device? This is a very serious question. The second question which we have to discuss is as follows. If we make such devices, will they have the same reliability which is required for a modern lightning protection? Modern lightning protection is operated by the reliability at the level of 0,999. So will our managing devices function with the reliability of 0,999? This is a new question. Next question. If we make these devices and are ready to deliver them. Will there be any operating costs? And do we have to think about operating costs of these managing devices? If their management is quite serious, then it is quite possible to hope for their mass application. And then the final thing which is not always discussed. We are talking about rapid response of devices. Because the device that controls lightning should be rapid. Is there a problem? The problem is easy. The thing is that today data about lighting discharges, which are present in the world are known and summarized by the IEC on large electric networks CIGRE.

This commission made a report, which was modestly called a brochure. The brochure contained summarized data on lightning. And if you read through it, you will see, that about 70% of all lightning strikes are multi-component. It means there can be several electric discharges in one lightning flash. Averagely 3-5, but the thing is that half of these discharges doesn't repeat the trajectory of the first one. The discharges go along other trajectories. They are different by the trajectories. And from the lightning protection view, each such component is a new lightning flash. They should be all intercepted. It means, the device must be ready for a repeated work of each next component, which go with a pitch of less than 1/10 seconds. All this together makes lightning protection specialists to think if it is possible to make ESE lightning protection? Let's see what is being sold at the lightning protection market. It is an important moment and I want to study it from the following positions. What gives a start to a counter discharge? A counter discharge starts with corona, which the Western people like to call glucorona. We call it avalanche corona, streamerless corona. It's not important how it is called; it is important what this device is. It's a weak glow at the top of a lightning rod or object, which doesn't grow and doesn't turn into a channel intercepting lightning. It doesn't happen for such a reason. For the channel to grow, it is necessary for this corona, which appears in an electric field, which is defined by the formula, it is somewhere at the level of 30 kV per cm. So this corona can heat the air in its volume, because only a hot channel which keeps high conductivity can grow. And for the channel to keep high conductivity, it is necessary for the electrons to exist. And electrons, formed in the result of ionization die in a normal, not heated air, in 1/10 seconds. It is necessary to heat ionization zone, and in order to heat it, it is necessary to switch from this streamerless corona to the next development shape - the so-called streamer discharge, which presents itself an unfolded brush of thin ionized channels. These are the thinnest channels, which cannot be heat up, because there is not enough energy, but they can't heat up their base - the so-called stem. And for this heat to happen, corona must be powerful enough. Streamer flash should use voltage at the level of about 500 000 V. Only after that a growing channel can develop in the channel. This is the complex sequence of events.

Длина канала, м - channel length, m

Стержневой молниеотвод – rod  lightning rod

Остановка лидера – leader stop

Время, мкс – time, ms

Поле атмосферы – atmosphere field

Внешний источник подает на вершину импульс напряжения длительностью 500 мкс – Exterior source gets on the top of the voltage pulse with the duration 500 ms

Increase of the top potential even to 300 kV does not provide the sustainable leader

But let us not rush with the estimation of ESE lightning rods. We've been working a lot on what will happen if I start a counter leader. What will happen to it? Will it be able to develop towards lightning or will it cease its development in a short distance. A very serious simulation model was made for this purpose. Dozens, hundreds of different variants and typical examples of such calculations as I want to show you were calculated on this simulation model. I will again operate by a very high lightning rod, which is 50 meters high and I will again think that the electric field in the atmosphere is great, because the average value is twice larger the one I am working with. I will think that my leader has been started and that this counter leader is supported by the pulse voltage of a great duration of 500 ms. Now I will see that is connected to the control impact? Control impact of 100 kV, the leader grew up to 2 meters and stopped its development. Not a lot of sense from such a leader. Lightning won't even feel such an increase of lightning rod height. I increased it twice - 200 kV, now the leader grew to 3,5 meters and stopped its development again. I took 300 kV, the leader grew to 5 meters and again stopped its development. There is not enough energy.

Длина канала, м – channel length, m

Время, мкс – time, ms

Ток. А – current, A

Ток лидера  - leader current

При времени – at time equal to

Потребляемый заряд – consumed charge

Отсюда- заряд на выходной емкости источника – It means the charge at the output capacity of the source

Let's see what source it should be? What electro-technical characteristics should it possess? What feeds this source? It feeds the leader channel. What current flows inside the leader channel? At the initial development part, the current flows at the level of Ampere shares, roughly speaking 0,5 A. If such a channel will grow with the current of 0,5 A during 600 ms, it will use the charge, which is at the level of 0,3 mCl. That means, we need to have such a charge at the capacity, but I need to keep the pulse duration. I estimate the pulse duration at the level of 0,5. It means during this time, the reserve capacity, which feeds the channel, should have twice a larger charge. I took this twice larger charge. Now if I divide this charge to the voltage I am working with, and I am working with 500 kV, it will mean the source capacity will be 1000 pF. Now the specialists, and I am sure there are specialists at the seminar. The specialists know how the capacity of 1000 pF looks at the voltage of 500 kV. What are the sizes of this capacity? And now remember and compare these sizes with the sizes of the devices that are being sold. The capacity of 500 pF, of 1000 pF with the voltage of 500 kV won't fit into any ESE lightning rod under no circumstances.