The natural weather phenomenon of thunder and lightning since ancient times has caused great impact on the development of human beings. If we do not pay attention to protection, it will cause serious damage to our lives and property. For the lightning protection of radio communication equipment, lightning protection design must be taken as an important task in engineering design. In this article, Zhengzhou Leidi Electronic Engineering Co., Ltd. technical personnel to analyze the radio's lightning protection related information.
The test of all single components in the secondary dispatch (current, voltage, time, differential, balance, negative sequence, distance, power direction, inverse time, frequency, synchronization, reclosing and other relays).
In general, there are four ways for buildings to avoid lightning strikes: 1) Diverting, ie, the earth where the charges in the thunderclouds are eased, thus avoiding direct lightning strikes or inducing lightning currents to flow through protected buildings or equipment. Things or equipment from lightning strikes. 2) Isolation, ie the isolation of lightning signals from the protected object to avoid lightning strikes. 3) Equivalence, that is, equal to the potential of the iron tower, work place, and public land of the building. 4) Dissipation, which releases the charge of the opposite charge and the charge in the thundercloud to neutralize it, thus preventing the formation of lightning. According to the above four lightning protection methods, the lightning protection measures of a radio communication project include the following methods.
1. Installation of Lightning Arrestors or Lightning Arresters Most of the lightning protection facilities for communication equipment are mainly equipped with lightning rods on communication towers. This method is economical and simple, but it must be installed in strict accordance with the following requirements.
a. The lightning rod should be installed a few meters above the tip of the antenna. There should be a certain gap between the lightning rod and the antenna to prevent the radiation pattern of the antenna from being damaged due to the existence of the lightning rod. The general practice is that the lightning rod becomes the main pole of the antenna tower, and the communication antenna is installed outside the outer edge of the lightning rod about 1.5 wavelengths.
b. The resistance requirement of the DC path of the lightning protection ground wire is sufficiently low, generally 10-50Ω. Due to the large lightning surge current, wide spectrum and short duration, it is required to have as small inductance as possible.
c. Flat wire or stranded wire cannot be used for the ground wire because the wire inductance is large, which is not conducive to the discharge of lightning current and is easily corroded. Use solid wires of 3 mm or more as much as possible, and it is the same metal material.
d. In order to increase the relief area of ​​the ground surface, multiple grounding bodies buried at certain intervals may be used and welded to each other. For example, 10 or so copper pipes are buried at an interval of 1 to 2 meters around the building and they are welded together.
Installing a lightning rod on a communications tower is economically simple, but it is difficult to be foolproof. For some important communications projects, consider installing a lightning protection device. The lightning protection device can be said to be one of the most advanced lightning protection devices in the world.
The key part of a radioactive lightning protection device is a radioactive source, which can continuously emit particles on its own and ionize the surrounding air to produce a large amount of electrons. These electrons are constantly accelerating under the action of the lightning electric field. They generate chain-linked multi-stage ionization or avalanche ionization, forming an electron flow proportional to the strength of the electric field. At this time, the ionization conduction from the radiation source to the thundercloud will never occur. Intermittently neutralize and release space charge, eliminate the existing low electric field, reduce the possible high electric field to a low electric field, thus effectively preventing the occurrence of lightning, and play a significant role in eliminating lightning. This kind of radioactive lightning protection device has a large protection area, its radius is about 260 meters, and its safety and reliability are not harmful to people. 2. In addition to installing lightning rods or lightning protection devices on communication towers, it is necessary to pay attention to eliminate lightning induced lightning. In lightning strikes, the usual practice is to install surge arresters in antenna systems.
When installing an arrester in an antenna system, pay attention to the following issues. One is that the grounding end of the arrester must be connected to the ground reliably. The grounding resistance must not exceed 5Ω, otherwise it will affect the lightning protection effect. The second reason is that there is a certain insertion loss in the arrester, which has a certain influence on the intensity of the antenna radiation signal. At the same time, attention must be paid to the change of the standing wave ratio. Generally, the standing wave ratio of the antenna system must be less than or equal to 1.5. The third is when the communication antenna is installed, the antenna struts and the tower are reliably connected, and the connection resistance is equal to 0Ω. The feeders should hang down from the inside of the tower and be fixed with copper wire and iron towers at intervals.
For important communication projects, besides installation of lightning arresters in antenna systems, attention must be paid to lightning protection of the power supply system. The general practice is to install lightning protection devices in transformers and power distribution rooms. All the above content is the experience summarized by experts of Zhengzhou Leidi Electronic Engineering Co., Ltd. If you need more information, please contact us directly.
The test of all single components in the secondary dispatch (current, voltage, time, differential, balance, negative sequence, distance, power direction, inverse time, frequency, synchronization, reclosing and other relays).
In general, there are four ways for buildings to avoid lightning strikes: 1) Diverting, ie, the earth where the charges in the thunderclouds are eased, thus avoiding direct lightning strikes or inducing lightning currents to flow through protected buildings or equipment. Things or equipment from lightning strikes. 2) Isolation, ie the isolation of lightning signals from the protected object to avoid lightning strikes. 3) Equivalence, that is, equal to the potential of the iron tower, work place, and public land of the building. 4) Dissipation, which releases the charge of the opposite charge and the charge in the thundercloud to neutralize it, thus preventing the formation of lightning. According to the above four lightning protection methods, the lightning protection measures of a radio communication project include the following methods.
1. Installation of Lightning Arrestors or Lightning Arresters Most of the lightning protection facilities for communication equipment are mainly equipped with lightning rods on communication towers. This method is economical and simple, but it must be installed in strict accordance with the following requirements.
a. The lightning rod should be installed a few meters above the tip of the antenna. There should be a certain gap between the lightning rod and the antenna to prevent the radiation pattern of the antenna from being damaged due to the existence of the lightning rod. The general practice is that the lightning rod becomes the main pole of the antenna tower, and the communication antenna is installed outside the outer edge of the lightning rod about 1.5 wavelengths.
b. The resistance requirement of the DC path of the lightning protection ground wire is sufficiently low, generally 10-50Ω. Due to the large lightning surge current, wide spectrum and short duration, it is required to have as small inductance as possible.
c. Flat wire or stranded wire cannot be used for the ground wire because the wire inductance is large, which is not conducive to the discharge of lightning current and is easily corroded. Use solid wires of 3 mm or more as much as possible, and it is the same metal material.
d. In order to increase the relief area of ​​the ground surface, multiple grounding bodies buried at certain intervals may be used and welded to each other. For example, 10 or so copper pipes are buried at an interval of 1 to 2 meters around the building and they are welded together.
Installing a lightning rod on a communications tower is economically simple, but it is difficult to be foolproof. For some important communications projects, consider installing a lightning protection device. The lightning protection device can be said to be one of the most advanced lightning protection devices in the world.
The key part of a radioactive lightning protection device is a radioactive source, which can continuously emit particles on its own and ionize the surrounding air to produce a large amount of electrons. These electrons are constantly accelerating under the action of the lightning electric field. They generate chain-linked multi-stage ionization or avalanche ionization, forming an electron flow proportional to the strength of the electric field. At this time, the ionization conduction from the radiation source to the thundercloud will never occur. Intermittently neutralize and release space charge, eliminate the existing low electric field, reduce the possible high electric field to a low electric field, thus effectively preventing the occurrence of lightning, and play a significant role in eliminating lightning. This kind of radioactive lightning protection device has a large protection area, its radius is about 260 meters, and its safety and reliability are not harmful to people. 2. In addition to installing lightning rods or lightning protection devices on communication towers, it is necessary to pay attention to eliminate lightning induced lightning. In lightning strikes, the usual practice is to install surge arresters in antenna systems.
When installing an arrester in an antenna system, pay attention to the following issues. One is that the grounding end of the arrester must be connected to the ground reliably. The grounding resistance must not exceed 5Ω, otherwise it will affect the lightning protection effect. The second reason is that there is a certain insertion loss in the arrester, which has a certain influence on the intensity of the antenna radiation signal. At the same time, attention must be paid to the change of the standing wave ratio. Generally, the standing wave ratio of the antenna system must be less than or equal to 1.5. The third is when the communication antenna is installed, the antenna struts and the tower are reliably connected, and the connection resistance is equal to 0Ω. The feeders should hang down from the inside of the tower and be fixed with copper wire and iron towers at intervals.
For important communication projects, besides installation of lightning arresters in antenna systems, attention must be paid to lightning protection of the power supply system. The general practice is to install lightning protection devices in transformers and power distribution rooms. All the above content is the experience summarized by experts of Zhengzhou Leidi Electronic Engineering Co., Ltd. If you need more information, please contact us directly.
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