In 1750, franklin offered a needle to release the charge in slow and thunder cloudsA lightning rodFor mine protection. Subsequent practice has shown that it cannot “shun mines”, but instead directs them towards itself to protect the equipment around them. This was subsequently argued by russian romonosov in a paper published in 1753 (on atmospheric phenomena due to electricity) after he repeated the famous kite experiment in franklin (with his friend lihman, who died as a result of a direct lightning strike). An important fact that is hardly known is that shortly after franklin published the mine-shield theory, a french engineer set up a mine-shield in accordance with his theory, and a flashing occurred soon. This is the first time that humans have made a proactive effort to change the thunderstorm path, and it is also proof that direct-fire can be protected. The french engineer, as an honest scientist, was pleased to report on the success of the lightning rod in franklin。
The practical application of the detonator must address its scope of protection. This has been progressively quantified over the years in laboratory and practical applications, and its accuracy has largely satisfied the need for engineering design. It is the development of high-voltage transmission and electricity systems in all countries that has contributed to this scientific work。
In 1925-1926, peek was the first to use a shock voltage generator in a laboratory to create an “artificial mine” discharge to the lightning-shield model, to study the relationship between the protective factor and the height of the thunder cloud to the height of the needle (h/h) and to study the impact of the polarity of the thunder cloud on the protective factor. In 1930-1934, countries began to make extensive use of lightning rods to protect power plants and substations. The 230kv grid had been in existence for many years and 287kv ultra-high voltage grid was under construction. For example, the united states gas and electricity corporation (age) began protecting transformer stations with lightning rods and wires in 1934. The scope of protection for lightning escape wires is defined as follows: 0. 3 m higher per protection level when the structure is sufficiently robust, and 0. 3 m higher per protection level; and 0. 6 m higher per protection level when the structure is limited. This is equivalent to an angle of 56° and 64°, respectively. This is close to japan's mine-control norm at 60° in the late 1960s. By the early 1960s (davis, 1963), the early 1970s (u. S.-united states-english) and other countries continued to offer the doctrine of range protection for the protection of lightning lines, i. E., the selection of the scope of protection by considering the size of the current irradiation value of the lightning. A similar approach was proposed by our high-voltage workers (professor jumumi directed comrade wang xiaoyu) in 1962-1964 when they studied the mine-proofing of transmission lines. As for the protection of power plants and transformers, in the 1950s we used only lightning rods for fear that the breakout would affect the entire plant and the whole transformer. By the mid-70s, it was not until the end of the decade that clear-cut wires could be used for the protection of power plants and transformers。
Thunder belts
The mine avoidance belt, which is a geoconductor placed around the ridge and roof of the building, was developed by lightning rods and wires. The author was first informed of this technology by german sources. The mine avoidance net is a perimeter conductor placed in the middle of the belt to protect the middle of the building. For the protection of buildings, the advantage is that it is simple to fit, cheap to build, and the probability of mine diversion is significantly lower than that of a high-profile lightning rod. Moreover, it is usually followed by multiple detours, with relatively low countervailing voltage on indoor equipment. The cage-based mine-proofing approach proposed by our construction and mine-protected workers and widely used throughout the country is a farah cage formed from the steel bars of the building. At the same time, the problem of waiting for power connections was resolved, which greatly improved the reliability of the building. In addition, it facilitates the integration of electricity, telecommunications and electronic facilities (co-location) within cages. Our electricity sector has power plant plants, machine rooms, transformer stations and main control rooms, including electrical equipment for different uses, such as control and signal cables, and has established standards for voltage and grounding since 1952 and 1956. This is more than 40 years earlier than the iec's recent regulation, the reunified location widely publicized by foreign companies and the level connection。
Attempts to use radioactive material on the tip of a needle to increase the impact of a mine and to expand the scope of protection proved ineffective. In the late 1960s and early 1970s, mine-awareness norms for buildings in england and germany clearly reached negative conclusions. In the 1980s, tests conducted by the faculty of electricity sciences of the ministry of water and electricity in the high pressure test chamber also proved that the radiation rods did not differ in their effect in terms of the same size as the ordinary rods. Our standards of insulation and voltage have always been negative to it. Despite international findings, france and some french-speaking countries have continued to use radioactive detonators. Some of the industrial equipment that we have imported from french-speaking countries is also protected by these detonators. This is not only a waste of funds and does not contribute to mine-awareness improvements, but also causes environmental hazards to the human body because of its radioactive materials. It violates all of our national standards for mine-awareness。
The principle of early discharge of lightning rods is to produce an up-to-front lead faster than an ordinary lightning rod. This description is most common in the case of negative subpolar discharges。
How does the unit protect against thunderstorms
1. Units should conduct regular mine-protected inspections of mine-protected facilities by specialized mine-protected companies to assess whether the mine-protected facilities comply with national norms, such as schools, companies, hospitals above district level, hotels above four stars, and high-level buildings above 45 metres in urban areas, which require biennial testing。
2. The unit shall establish persons responsible for the prevention of lightning and electrical hazards, who shall be responsible for mine safety, mine safety, regular detection of mine-protected facilities, post-mine inspection and routine maintenance. In the event of a thunderstorm, the excess protections installed on the power sources and signal lines of electrical equipment, such as telephone exchangers, computers and so forth, should be checked for damage and replaced in a timely manner。
3. The construction unit shall be designed and constructed in such a manner as to be safe and reliable, technologically advanced and economically sound, taking into account geological, soil, meteorological, environmental, protected features, patterns of lightning and electrical activity。
4. Mine-protected equipment, devices, equipment, and avoidance of the use of non-standard mine-protected products and devices shall be used in a manner and of a quality consistent with national standards。
5. Additional construction and installation should be accompanied by the re-engineering and construction of mine-protective systems, such as the re-engineering of computer network lines, the migration of outdoor antennas and the upgrading of facilities。
6. Mine-related disasters should be addressed in a timely manner and measures should be taken to avoid further thunder strikes。
Six o'clock
In response to the damage caused by lightning, we believe that mine protection must be comprehensive. These include, inter alia:
A. Control of thunderpoints (using broad-protected detonators)
B. Securely guide thunder into the grid
C improved low-accessible network
D elimination of ground circuits
E. Power surge shock protection
F transient protection of signals and data lines
Today, as science and technology are developing, although it is impossible for humankind to control stormy thunderstorms completely, a long history of mapping and practice has led to the accumulation of knowledge and experience on mine prevention and to the development of a range of methods and techniques that are effective in mine-prevention, and that are of general relevance to all sectors of society in effectively preventing thunderstorms。
1) flying
The flashing is the release of lightning energy from a certain range into the earth in accordance with the corridors that people design. The safety of ground communication stations depends to a large extent on the ability to capture a certain protected range of lightning discharges using effective flashing devices and to incorporate pre-designed reasonable discharge routes to the ground. The lightning rod is an active flashing device, originally known in english as lightning conductor, intended to be a lightning guide whose function is to channel lightning currents into the earth. The cords and belts are developed on the basis of lightning rods. The introduction of lightning rods is the first and most basic measure of mine prevention。
2) consistency
When the lightning is caught, the line immediately rises to a high level, creating a side-link and raising the level of the conductor at the ground level around the mine-proof system, thereby endangering personnel and equipment. In order to reduce this flash hazard, the simplest approach is to use an average pressure ring that connects a level of power, such as a conductor at a ground level, to a local installation. Metal installations, electrical installations and electronic devices within stations should be connected to mine-protective systems by thicker guidance lines if they do not meet the required safety requirements at a distance from the conductor of the mine-protective system, particularly the flashing device. This means that all the facilities inside the station immediately form an “alternation island”, which ensures that no harmful level differentials are created between conductor parts and that no side flash discharges occur. A well-developed level connection can also prevent counter-attacks resulting from higher ground levels caused by lightning inflows。
3) location
The grounding is the release of lightning energy that has been incorporated into the mine-proof system, so that good grounding can effectively reduce the voltage on the line and avoid counterattacks. In the past, some norms had required electronic equipment to be located separately, with the aim of preventing undispersed currents or temporary currents from disrupting the normal work of the equipment. Prior to the 1990s, the force's communications navigation equipment was dominated by electronic tubes, using analogue communications, which were particularly sensitive to interference and, in order to counter it, used the method of separation of power from communications. Currently, the area of mine protection is not promoting separate sites. Neither iec nor itu-related standards promote separate locations, and us standard ieeestd 1100-1992 states more acutely that no so-called separate, stand-alone, computer-based, electronic or other such incorrect terrestrial interfaces are recommended as a link point for equipment receivers. Grounding is the most basic component of mine-protection systems. The impact of all mine-protective measures cannot be realized as a result of poor terrain. Mine-protected sites are the most basic safety requirements in the acceptance instructions for the installation of ground communications stations。
(4) diversion
Subtracting means connecting and connecting an appropriate shield between all guidance lines from outside the room (including electrical power lines, telephone lines, signal lines, feeders of antennas, etc.) and the ground line. When the percussion waves generated on the direct or sensoral road enter the interior or the equipment along these lines, the lightning shield suddenly drops to a low value, close to a short circuit, and diverts lightning currents into the ground。
Diversion is the focus of the rapid development of modern mine-prevention technology and is a key measure for the protection of electrical and electronic equipment. The new forms of landmines, which have frequently appeared in recent years, almost all require this approach. Since a small proportion of the lightning flow follows the guidance line after diversion, which remains dangerous for high-pressure microelectronic equipment, multi-level diversion of such equipment should take place prior to entry into the shell。
The research and development of mine avoidance devices now goes beyond diversion. Some of the detonators can be linked directly to a signal line or an antenna feeder, which allows a useful signal to pass and block the thunderstorm。
When introducing diversion as a mine-proof measure, particular attention should be paid to the selection of mine-shield performance parameters, since the installation of additional facilities will affect the performance of the system to a greater or lesser extent. For example, access to a signal shield should not affect the rate of transmission of the system; the loss of a sky-resilient shield in the belt should be as low as possible; and the use of a directional device should not result in a location error。
5) block
The shield consists of encircling objects in need of protection with metal nets, tacks, shells, tubes, etc., to prevent the pulsating electromagnetic field from entering from space. Blocking is the most effective way of preventing the impact of lightning electromagnetic pulse radiation on electronic equipment。
