In order to obtain better communication effect, the communication base station is usually higher than the surrounding environment when selecting the site, the climatic conditions are harsh, the risk of lightning disaster is higher in the summer communication and computer room equipment and the transmission tower, and the modern telecommunication equipment is more sensitive to lightning, so that the problem of lightning damage is increasingly prominent, if the protection is not effective, it may suffer major losses at any time.
First, according to the standard
The communication base station is generally composed of transmission system (SDH equipment, optical cable, etc.), power system (storage battery, mains, etc.), antenna feeder system, base station transceiver BTS, dynamic environment monitoring system and other auxiliary equipment. In order to suppress the lightning hazard to the greatest extent, the lightning protection of the communication base station can be designed according to the Chinese communication enterprise standard QB-W-011-2007 "Technical Specification for Lightning Protection and Grounding of Base Station", YD T 5098-2005 "Code for Lightning Protection and Grounding Engineering Design of Communication Bureau (Station)" issued by the Ministry of Information Industry, IEC61312 "Protection of Lightning Electromagnetic Pulse", GB50057-94 "Code for Lightning Protection of Buildings" and other standards.
2. Direct mine protection
The external lightning protection of the communication base station can be divided into three parts: lightning rod, down conductor and grounding network, all of which are indispensable and constitute a complete electrical path. The communication lines, antenna feeder systems, and computer room buildings in the communication base station will be threatened by direct lightning strikes, and it is very important to absorb the lightning current through the lightning rod and quickly and safely input it back to the ground through a good grounding device.
1.Flash Receiver:The tower itself can be used as the best lightning device in the computer room, and the top of the tower should be equipped with a current limiting flash receiver (lightning rod), and the antenna should be within the protection radius of the lightning receiver. If the tower is near the communication station, a lightning protection belt can be set up on the top of the building, and the protection range of the joint lightning protection of the tower and the lightning protection belt shall be checked. If there is no tower near the base station, the lightning protection net should be preferentially used as the lightning receiver of the building, and the grid size of the lightning protection net should not be greater than 10m*10m, and the lightning rod should be reliably connected with the lightning protection network.
2.Down Lead:The function is to safely lead the lightning current of the lightning receiver to the ground, and the down conductor shall not be less than two, and should be symmetrically and evenly arranged along the surrounding of the building, the spacing of the down conductor shall not be more than 18 meters, and the spacing of the down conductor of the important communication bureau and the telecommunications building of 100 meters and above shall not be more than 12 meters. The length of the down lead wire must be welded, and the down lead wire should be welded with the equalizing ring of each layer, and the down lead wire should be made of 10mm round steel or flat steel of the same area. For buildings with frame structures, the down conductor should utilize the steel bars in the building as lightning protection down conductors.
3.Grounding Grid:YD5098-2005 in 61.Article 1 stipulates that the base station uses joint grounding, and the ground network of the communication base station shall be composed of the ground network of the computer room, the ground network of the tower, or the ground network of the computer room, the ground network of the tower and the ground network of the transformer. When the power transformer is installed in the equipment room, the ground network of the equipment room can be sharedWhen the tower is built on the roof of the machine room, the ground network of the tower and the ground network of the machine room are combined into one ground network.
a.Iron tower ground grid: 40mm*4mm hot-dip galvanized flat steel should be used to weld and connect the metal components in the four corners of the tower, and the grid size of the tower ground grid should not be greater than 3m*3m;
b.Transformer ground grid: When the power transformer is set within 30m from the edge of the ground grid of the computer room, the transformer ground grid and the ground grid of the computer room or the tower ground grid should be welded and connected with each other every 3 5m (at least two places are connected) to form a perimeter closed ground network with each other.
c.The ground network of the computer room is composed of the foundation grounding body (including the ground pile) and the peripheral annular grounding body. The annular grounding body should be laid along the outside of the scattered water point of the machine room building, and welded and communicated with more than two main steel bars in the horizontal and vertical beams of the grounding body of the foundation grounding body of the machine room. When there is a ground pile in the grounding body of the foundation of the machine room, the main reinforcement of the ground pile should be welded and communicated with the annular grounding body.
3. Induction lightning protection
Induction lightning invades the communication station through power cables, communication cables, optical fibers and antenna feeders, and the induction lightning hazards intrusion by power supply are very prominent because of the long distance of power cables and the small transmission loss of lightning waves. In addition, induction lightning can also penetrate the internal wiring of the communication station through spatial sensing, which can also cause equipment failure if not handled properly.
1.Power Protection:According to the YD T 5098-2005 lightning protection standard issued by the Ministry of Information Industry, specific requirements are put forward for the power lightning protection of various base stations, mainly two: one is that the power cable should have a metal shield, and must be buried in and out of the communication station. The second is to install power arresters on the power supply step by step to achieve multi-level protection. That is, a high-voltage arrester is installed at the high-voltage end of the transformer, a low-voltage arrester is installed on the low-voltage side, and AC and DC arresters are installed on the AC distribution panel and DC distribution panel respectively.
2.Transmission Line Protection:Communication base station optical fiber lightning protection is mainly for its metal skin and metal core, from the requirements of line protection these metals should be grounded, it is best to be connected to the ground docking row on the ground floor when burying the ground. The lightning protection of the antenna feeder is mainly for the coaxial cable, the antenna feeder of the coaxial cable should be equipped with the corresponding high-frequency lightning arrester, and the ground wire of the arrester should be connected to the grounding junction of the computer room nearby. Coaxial cables should be used for PCM and DDF cables connected to mobile communication equipment and optical transceivers, microwaves, and switches, and corresponding lightning arresters can be installed. The data transmission line of the monitoring signal can be equipped with a corresponding data arrester. All communication transmission cables entering and exiting the communication station shall be buried in and out of the cable with a metal shield, and the shielding layer shall be grounded near the station.
3.Joint Geonet:The grounding electrodes of the communication station room, substation room and tower should be connected to form a joint ground network, if it is a frame structure of the computer room, the foundation steel bar of the building is an excellent annular grounding network, and the joint ground network is a grounding device shared by all equipment in the communication station.
4.Device Grounding:The metal shell of all equipment in the communication station should be grounded, and metal objects such as metal wiring frames and water pipes must also be grounded. Good grounding of metal objects in the station is not only a requirement for electrical safety, but also an important measure to shield lightning induction and balance the potential of equipment.
5.Arrangement of the grounding collection line:The grounding collection line (busbar) should be arranged close to the arrester, so that the grounding connection line of the arrester is the shortest, and the distribution line of each floor should be directly connected with the total collection line at the bottom of the floor, so as to ensure the realization of a single-point grounding mode, when the floor is higher than 30 meters, the distribution line of the part higher than 30 meters should be connected with the building equalization ring to prevent side strikes.
Nowadays, the communication industry is still developing, and all kinds of equipment of communication base stations are also constantly innovating, and lightning protection measures for communication base stations should be implemented according to the actual situation. TOWE has 22 years of professional experience in lightning protection design and construction, and has obtained the professional design and construction Class A qualification issued by the China Meteorological Administration, and has a group of professional teams engaged in lightning protection design and construction. TOWE lightning protection products and services can provide a reasonable lightning protection solution for customers in the communication industry, and put forward lightning protection measures for mobile base stations to avoid or minimize the threat and damage of lightning strikes to the equipment and personnel of the base station in the future.