Sấm sét là hoạt động thường xuyên xuất hiện trong những cơn mưa giông do các đám mây tích điện gây ra. Khi gặp điều kiện thuận lợi sẽ truyền xuống mặt đất bằng con đường đánh thẳng hoặc đánh lan truyền.
Lightning currents can reach several thousand amperes with tremendous power. Lightning, when struck directly, often kills people and destroys buildings, and explodes houses. Electromagnetic waves from lightning also cause damage from a distance to electrical circuits, called inductive lightning strikes. This is the cause of damage to electrical and electronic equipment such as televisions, computers, technical equipment, machinery, radios in residential areas, etc. Therefore, lightning is one of nature's hazards. Disasters are extremely dangerous to human life and cause great damage to material property.
To protect buildings and construction sites from being struck by lightning, people often install lightning rods. Lightning rods were invented in 1752 by an American scientist named Franklin with the advantage of taking advantage of their high position to capture lightning and transmit it to the ground, bringing safety to people and other objects.
Cột thu sét được cấu thành bởi ba bộ phận là kim thu sét trực tiếp (bao đế và trụ đỡ kim thu sét…), dây dẫn sét và thiết bị tiếp đất chống sét. Mỗi bộ phận đều phải có điện trở rất nhỏ, mặt cắt phải đạt tới mức độ nhất định để chịu được dòng điện cực lớn khi sét đánh qua.
– Lightning rod supports are usually made of zinc-coated clay with a diameter of 60 mm and are more than 2 m long, installed on the roofs of high-rise buildings or on top of chimneys.
– Lightning conductors connected from the lightning protection pole to the ground are made from bare copper wire or anti-interference lightning cables (ERICORE cable of ERICO company).
– The grounding device must be buried at a certain depth underground and must be in good contact with the ground to conduct electricity when struck by lightning.
The lightning protection system (including the lightning rod, lightning conductor, and grounding element) has the effect of protecting the building, that is, when lightning strikes, the lightning protection system has the effect of transferring the lightning current quickly down to the ground.
Lightning poles are usually installed in high positions (the higher the installation, the larger the protection scope of the work). However, it is also not recommended to install the air-termination pole too high, because if it is installed too high, the certainty will not be guaranteed, and when encountering high winds, the air-termination pole may be tilted or toppled, making it ineffective, lighting. In open places where lightning strikes often occur, lightning rods must be planted to ensure the safety of people working in this area.