Some common and effective lightning protection measures.
1. Distinguish different types of lightning such as direct lightning, indirect lightning, lightning induction .
– Direct lightning strike is a lightning strike directly on a building’s house or on a metal water tank or antenna post located on the building, hitting a tree, hitting a moving person while there are thunderstorms … This is the most dangerous type of lightning because it can cause severe damage to the building or cause death.
– Indirect lightning strike is a lightning strike on a telephone line, a high-voltage or low-voltage transmission line in a certain place and then along a transmission line into the project, damaging the electric equipment being used. We often see the phenomenon of light bulbs, phones, TVs, refrigerators … burning or people calling are shocked after a thunderstorm all due to the effects of this type of lightning. Induction includes electrostatic induction and electromagnetic induction. Electrostatic precipitates are usually only dangerous for structures containing flammable substances such as petrol and gas due to the impact of secondary discharges while electromagnetic induction lightning is only dangerous for modern equipment used. electronic components sensitive to electrical impulses in post, telecommunications and broadcasting projects.
– A complete lightning protection system must fully show the above lightning protection content, but for most households people are usually only interested in direct lightning protection.
– There are many technical measures for lightning protection, but so far no equipment or system of lightning protection has achieved absolute efficiency. A common lightning protection model that has been recognized as effective in a limited range that is still widely used in many parts of the world is the classic Franklin lightning collecting system because it has proven Intelligent protection with an allowable reliability has existed for hundreds of years.
– Franklin lightning rod is a metal rod with a tip about 3m long, installed at the highest point in the area to be protected, it operates according to the principle of point discharge, that is, in the atmospheric electric field of a thunderstorm, This lightning rod will continuously release charge into the space so that around the air-termination end there will be a strong local electric field compared to the surrounding points and form a priming spark (bait line) so it is easy Attracting the downstream lightning current from the clouds, this lightning current will be transmitted from the needle through the wiring system to the ground and dissipate quickly in the soil by the grounding grounding. Thus, the lightning protection system will create a safe range for the works that it protects. However, in reality, there are still lightning strikes in buildings that have anti-lightning systems, which are called ring lightning, so to ensure safety, we should not install the lightning protection system by ourselves, but thanks to go to the technician to design and calculate the system so that the system ensures specifications such as protection range, lightning dissipation resistance, lightning strike capability, secondary discharge capability, etc. so the new lightning protection system fulfills its duty. In the opposite case, the system itself is the cause of the disaster for the building and the people living in it.
2. Select lightning arreste:
a/ Early discharge type: These are lightning collecting needles which have a characteristic of emitting a relatively early primer line when the atmospheric electric field has not reached the critical value, which means that it actively catches lightning discharge current at some point in the space away from the structure it protects. We can imagine that when operating, the lightning collective needle stretches tens of times their actual length, this segment is called the virtual height of the lightning collective needle and thus they have a scope. The protection is much bigger than the classical lightning collecting needle at the same height.
b/ Type of charge dispersion: These types of lightning collecting needles have the characteristic of creating a positively charged layer of space in the atmosphere above the tip of the needle based on the principle of point discharge. the more powerful and spatially charged, the more it acts as an electrostatic screen that weakens the electric field between the thundercloud and the soil, eliminating the risk of lightning discharges.
There is also a combination of the two types to create another lightning protection system called a kind of delayed discharge. This type has the advantage of increasing the protection scope but is very expensive compared to the two types above.
– For nearly 20 years, we have studied the specifications of over 20 different types of lightning collecting needles, including those not yet available in Vietnam market and also designed and constructed hundreds of lightning protection systems. For many different types of buildings, in general, the working principles are much more effective than the classical lightning collecting needles and each has different advantages and disadvantages. Moreover, since active lightning collecting needles have only developed strongly in Vietnam in the past 5 years, more time is needed to monitor and evaluate which ones meet the quality and level requirements. durable and effective in protecting the building in tropical climates like our country, in addition to the price is also a factor of concern because they are not very suitable for the majority of households who want to install a Own lightning protection system for your home.
– In summary, as mentioned above, a lightning protection system in addition to the lightning collecting needle also has a guide for lightning and a ground for dissipating lightning current in the soil which is not easy to install, especially for public buildings. Process of urban areas. The down-conductor has the effect of easily conveying the lightning current to the ground, it must withstand local heating temperatures so as not to deform. The grounding ground is responsible for quickly dissipating the lightning current in the ground to avoid the high voltage existing on the lightning protection system, which is to prevent secondary discharges and the effects of step voltages, which are dangerous factors. can damage the structure and cause death. Therefore we see that once the lightning protection system is not up to technical quality, it is a disaster for us to have lightning strikes on the building. So if you require installation of a lightning protection system, you can contact us for specific instructions by relying on the actual characteristics of your building such as soil resistivity, geographic characteristics. management of the area, installation site and ground structure, safe distance in air and in the earth … in order to achieve a lightning protection system that maximizes their ability to protect safety for the building and the people living in it.