Lightning protection-system lightning protection is a systematic project, which mainly includes:
1, direct lightning protection (lightning arrester, down conductor, grounding device);
2. Induction lightning protection (power arrester, signal arrester, etc. );
3. Grounding devices (vertical grounding body and horizontal grounding body);
4, equipotential connection (electrical equipment, metal shell, bus, grounding bus and other reliable connections);
5, electromagnetic shielding (set of metal shielding tube);
6, reasonable wiring (power lines and signal lines laid separately, etc.). ). Lightning protection-engineering lightning protection engineering refers to all projects involved in lightning protection.
Lightning protection works include: external lightning protection and internal lightning protection.
Generally speaking, external wall lightning protection is direct lightning protection; Internal lightning protection refers to preventing induction lightning.
The most direct purpose of external lightning protection is to protect life safety, while internal lightning protection is to protect equipment from lightning strike. Lightning protection-lightning protection devices can be roughly divided into: power supply lightning protection device, power supply protection socket, antenna feeder protector, signal lightning protection device, lightning protection test tool, lightning protection device of measurement and control system and grounding electrode protector. A complete lightning protection device includes lightning receptor, down conductor and grounding device. The above needles, wires, nets and belts are only lightning arresters, which are special lightning protection devices. The sum of lightning arrester, down conductor, grounding device, surge protector and other connecting conductors. Lightning arrester lightning rod, lightning wire, lightning protection network and lightning protection belt are all lightning arresters. They all use their prominent position above the protected object to lead the lightning to themselves, and then drain the lightning current into the earth through the down conductor and grounding device, thus protecting the protected object from lightning strike. The materials used for lightning arresters should meet the requirements of mechanical strength and corrosion resistance, and also have sufficient thermal stability to withstand the thermal damage caused by lightning current. The function of lightning arrester is to protect all kinds of electrical equipment in power system from lightning overvoltage, operating overvoltage and power frequency transient overvoltage. The types of lightning arresters mainly include protective gap, valve arrester and zinc oxide arrester. Protection gap is mainly used to limit atmospheric overvoltage, and is generally used for the protection of distribution systems, lines and substations. Valve arrester and zinc oxide arrester are used to protect substations and power plants. In systems below 500KV, they are mainly used to limit atmospheric overvoltage. In the EHV system, the backup protection lightning arrester used to limit or make internal overvoltage is connected in parallel to the protected equipment or facilities. Usually, the equipment is insulated from the ground. When lightning overvoltage occurs, the equipment and the earth turn from insulation to conduction, which leads to breakdown discharge, and lightning current or overvoltage is introduced into the earth to play a protective role. After the overvoltage was terminated, the arrester quickly returned to the impassable state and resumed normal work. Lightning arrester is mainly used to protect power equipment and power lines, and also as a safety measure to prevent high voltage from invading the room. Lightning arrester includes protective gap, tube arrester, valve arrester and zinc oxide arrester. The down lead of lightning protection device for down lead shall meet the requirements of mechanical strength, corrosion resistance and thermal stability. Flow chart of lightning protection engineering of power arrester Power arrester is to prevent lightning and other internal overvoltage from invading equipment. Starting from the comprehensive lightning protection scheme combining outdoor lightning protection with line lightning protection, this paper introduces the concepts of external lightning protection and internal lightning protection, protection zone and lightning protection equipotential connection. The working principle of lightning protection for power supply is analyzed. Lightning protection of power supply can release a large number of pulse energy short circuits induced by lightning on the circuit to the earth in the shortest time, and reduce the potential difference between equipment interfaces, thus protecting the equipment on the circuit. Power arresters are divided into three grades: B, C and D. According to the theory of IEC (International Electrotechnical Commission) standard, Class B lightning protection belongs to the first-class lightning protection device, which can be applied to the main distribution cabinet in buildings. Class C belongs to Class II lightning arrester, which is used in the shunt distribution cabinet of buildings; Class D is a three-level lightning arrester, which is used in the front end of important equipment to protect the equipment finely. If the lightning arrester is installed correctly, the probability of power damage caused by lightning strike can be reduced to near zero, which can avoid the cost of replacing equipment and ensure the uninterrupted and continuous operation of the system. It can also reduce the probability of electric fire caused by lightning strike of buildings and ensure the safety of people and other property. According to the requirements of IEC 6 1644, the signal arrester is divided into three grades: B, C and F. B (basic protection) basic protection level (coarse protection level), C (combined protection) comprehensive protection level, F (medium &; Fine protection) in&; Fine protection level. Professional lightning protection equipment for network, communication, optical cable, broadcasting, television, monitoring, video and other equipment. Video arrester, also known as coaxial cable surge protector, has two impedances, one is 75 ohms and the other is 50 ohms. Among them, 50 ohms are used for outdoor cable transmission protection of cable TV, and 75 ohms are used for video transmission, such as closed-circuit TV monitoring system transmission, commonly known as video arrester. Video arrester is installed at two sections (front end and back end) of video transmission line, which can effectively protect camera, ball machine, matrix, digital video recorder and monitor from lightning damage. The complete internal structure of video arrester can generally be divided into three parts: discharge part, current stabilizing part and voltage stabilizing part; In the video arrester with good performance, a circuit that can increase the transmission frequency of the signal arrester is added to reduce the loss caused by the interface. Lightning protection grounding device Lightning protection control flow chart Grounding device is an important part of lightning protection device. The grounding device releases lightning current to the earth to limit the lightning protection device's voltage to the earth to be too high. Lightning protection grounding devices can be used in conjunction with other grounding devices except independent lightning rods, provided that the grounding resistance meets the requirements. Grounding for the purpose of lightning protection and stopping lightning damage is called lightning protection grounding. The grounding protection device includes the following parts:
1. Lightning receiving device: metal rod (lightning receptor) that directly or indirectly receives lightning, such as lightning rod, lightning belt (net), overhead ground wire, lightning arrester, etc.
2. Grounding wire (down lead): a metal conductor used to connect the lightning receiving device and the grounding device.
3. Grounding device: the sum of grounding wire and grounding body. Measurement and control devices are widely used, such as factories, building management, heating systems, alarm devices and so on. Overvoltage caused by lightning or other reasons will not only damage the control system, but also damage expensive converters and sensors. Control system failure usually leads to product loss and affects production. Measurement and control units are usually more sensitive to surge overvoltage than power supply systems. Lightning protection 1. If possible, power surge arresters should be installed at the power supply entrance, and signal surge arresters should be installed at the cable TV antenna, telephone, fax machine, computer modem entrance and satellite TV cable interface. But when installing, you should have a good grounding wire and a good grounding network.
2. Listen to the weather forecast every day. When you know that there is a thunderstorm that day, unplug the power plug and signal plug of household appliances before going to work, and don't forget to close the doors and windows when you go out to prevent the intrusion of rolling thunder. Lightning protection-specification 1, lightning protection specification
Code for lightning protection design of buildings
Code for lightning protection design of building electronic information system
2, lightning protection qualification
Construction qualification of lightning protection engineering specialty (Grade A, Grade B and Grade C)
Lightning protection engineering design qualification (Grade A, Grade B and Grade C) General lightning protection implementation standard-standard lightning arrester (different requirements in different countries): UL IEC6 1643- 1, GB 18802. 1-2002, UL/KLOC-0.
The current lightning protection system in China was formulated by People's Republic of China (PRC) and the Ministry of Construction on March 1 2004: GB50343—2004 Technical Specification for Lightning Protection of Building Electronic Information System and GB 50057-94 formulated by People's Republic of China (PRC) and the Ministry of Construction on June 1 2000.
At present, the more common lightning arresters on the market are ERICO OBO DEHN and so on. Lightning protection-developing a new generation of lightning protection technology, known as "intelligent lightning protection technology", was put forward for the first time in the world by a researcher of China Academy of Sciences and an academician of the International Academy of Astronautics, aiming at eliminating the harm of lightning strikes. After more than ten years of painstaking research and development, the technology is proved to be reasonable and feasible from various angles and methods such as theoretical analysis, simulation calculation, experimental test, model experiment, practical engineering research and field test. During the period, it was appraised and evaluated by many expert meetings, and it was fully affirmed, and it was known as "the dawn of lightning protection in 2 1 century". In 2002, the United Nations Invention Association awarded the world invention. Intelligent lightning protection technology won the gold medal at the same time, it won the only special gold medal in China, and was praised as "the best invention of human survival and protection" by the United Nations international expert group. Passed the test of the test center of the National Meteorological Administration. Passed the temperature, vibration, impact and electromagnetic compatibility tests required by the national military standard. Included in the national torch plan. Obtain environmental certification. Enterprise standards have been registered by the Quality Supervision Bureau. Obtained China patent certificate. Obtain a US patent certificate. Declare international patents, and declare patents in the United States, Japan, Germany, Britain, Italy, Spain, Russia and other countries. Intelligent lightning protection technology is the only new environmental protection lightning protection technology in the world, which can keep out lightning damage and escort modernization and informatization. It can not only make up for the shortcomings of traditional lightning protection methods that can not protect information equipment, but also be especially suitable for places that are difficult to be grounded such as mountain radar stations and moving targets such as cars, ships, planes and missiles that cannot be grounded. The implementation of this project is not only of great significance to improve the combat effectiveness of our army, but also is expected to be included in international standards, becoming the second popular lightning protection method after Franklin, and realizing the innovation in the history of human lightning protection technology. Lightning protection-prompt lightning protection 1, stay indoors and close the doors and windows; People who work outdoors should hide in buildings.
2. TV, audio and other electrical appliances without lightning protection measures or insufficient lightning protection measures should not be used, and faucets should not be used.
3. Don't touch antennas, water pipes, barbed wire, metal doors and windows, external walls of buildings, and stay away from live equipment such as wires or other similar metal devices.
4. Reduce the use of telephones and mobile phones.
5. Don't swim or engage in other water sports. Outdoor ball games are not suitable. Leave the water and other open spaces and find a place to hide.
6, don't stand on the top of the mountain, the roof or other objects close to high conductivity.
7. Don't handle flammable items in open containers.
8. Stay away from trees and masts when you can't hide in lightning-proof buildings in the wilderness.
9. It is not advisable to take an umbrella in an open place, and it is not advisable to carry badminton and golf clubs on your shoulders.
10, not suitable for driving a motorcycle or riding a bike.
1 1. When there is a gap of about one minute between two lightning strikes, you should hide in a protected place as much as possible. If the above conditions are not met, you should kneel down immediately, bend forward and tuck your knees in your hands.
12, you can also rely on tall trees for lightning protection in the wild, but remember to stay at least two meters away from the trunk and leaves. By analogy, it is not suitable to stay under isolated chimneys, beside tall metal objects and under telephone poles. Besides, it's not safe to stand under the eaves. It's better to go into the building at once.
13. If you hold metal umbrellas, golf clubs, axes and other things in a thunderstorm, you must throw them away or let them be lower than your body. There are some so-called insulators, such as hoes, which are not insulated in thunderstorm weather.
14, thunderstorm weather, avoid standing under the lamp holder line when turning on the light indoors.
15, shower is not suitable. Because the water pipe is connected with lightning protection grounding, lightning current can be conducted by water flow, causing casualties.