Lightning protection design scheme of network computer room   1. Protection against direct lightning strikes The building where the computer room is located has external lightning protection facilities such as lightning rods and lightning protection strips, and no supplementary design for external lightning protection is required. If there is no direct lightning protection before, it is necessary to make a lightning protection belt or a lightning protection net on the top floor of the computer room. If the computer room is in an open area, a lightning protection rod should be installed depending on the situation.       2. Lightning protection of power system (1) For the protection of the power line of the network integration system, first of all, the power supply line entering the general power distribution room of the system should be laid with metal armored cables, and both ends of the cable armor should be well grounded; if the cable is not armored layer, the cable is buried through the steel pipe, and the two ends of the steel pipe are grounded, and the length of the buried ground should not be less than 15 meters. The power lines from the general power distribution room to the power distribution boxes of each building and the power distribution boxes on the floor of the computer room shall be laid with metal armored cables. This greatly reduces the possibility of induced overvoltage on the power line.   (2) It is an essential protective measure to install a power lightning arrester on the power supply line. According to the requirements of lightning protection zones in the IEC lightning protection specification, the power system is divided into three levels of protection.   ① A first-level power lightning protection box with a circulation capacity of 80KA~100KA can be installed on the low-voltage side of the distribution transformer in the general distribution room of the system.   ② Install secondary power lightning protection boxes with a current capacity of 60KA~80KA in the total distribution box of each building;   ③ Install a three-level power surge arrester with a flow capacity of 20~40KA at the power inlet of the important equipment (such as switches, servers, UPS, etc.) in the computer room; ④ Use socket-type lightning arrester at the power supply of hard disk recorder and TV wall equipment in the control center of the computer room. All lightning arresters should be well grounded. When selecting a lightning arrester, attention should be paid to the form of the interface and the reliability of the grounding. Special grounding wires should be set up in important places. The lightning protection grounding wire and the lightning rod grounding wire should not be connected in parallel, and should be kept as far away as possible and separated into the ground.   3. Lightning protection of signal system (1) The network transmission line mainly uses optical fiber and twisted pair. The optical fiber does not require special lightning protection measures, but if the outdoor optical fiber is overhead, the metal part of the optical fiber needs to be grounded. The shielding effect of the twisted pair is poor, so the possibility of induced lightning strikes is relatively large. Such signal lines should be laid in the shielded wire trough, and the shielded wire trough should be well grounded; it can also be laid through metal pipes, and the metal pipes should be kept on the whole line. Electrical connection, and both ends of the metal pipe should be well grounded.   (2) It is an effective way to install a signal lightning arrester on the signal line to prevent induction lightning. For network integration systems, special signal lightning protection devices can be installed before the network signal lines enter the WAN router; signal lightning protection devices with RJ45 interfaces are installed at the system backbone switch, main server, and signal line entrances of each branch switch and server respectively ( Such as RJ45-E100). The selection of the signal arrester should comprehensively consider the working voltage, transmission rate, interface form, etc. The arrester is mainly connected in series at the interface of the equipment at both ends of the line.   ① Install a single-port RJ45 port signal arrester at the server input port to protect the server.   ② 24-port network switches are connected in series with 24-port RJ45 port signal arresters to avoid damage to the equipment due to lightning strike induction or electromagnetic interference from entering along the twisted pair.   ③ Install a single-port RJ11 port signal arrester on the DDN dedicated line receiving device to protect the equipment on the DDN dedicated line.   ④ Install a coaxial port antenna feeder lightning arrester at the front end of the satellite receiving equipment to protect the receiving equipment.   (3) Lightning protection for monitoring system room ① Install a video signal lightning protection device at the video cable outlet end of the hard disk video recorder or use a rack-mounted video signal lightning protection box, 12 ports are fully protected and easy to install.   ② Install the control signal lightning protection device (DB-RS485/422) at the control line entry end of the matrix and video splitter.   ③ The telephone line of the computer room adopts the audio signal lightning protection device, which is connected in series with the telephone line at the front end of the telephone, which is convenient for installation and maintenance.   ④ Install a control signal lightning protection device at the access point of the signal line at the front end of the alarm device to provide effective lightning protection for the signal line of the alarm device. Note: All lightning protection devices should be well grounded. When selecting lightning protection devices, attention should be paid to the form of the interface and the reliability of the grounding. Special grounding wires should be set up in important places. To keep as far away as possible, separate into the ground.   4. Equipotential connection in the computer room Under the anti-static floor of the equipment room, arrange 40*3 copper bars along the ground to form a closed-loop grounding busbar. Pass the metal shell of the distribution box, the power ground, the arrester ground, the cabinet shell, the metal shielded wire trough, the doors and windows, etc. through the metal parts at the junction of the lightning protection zones and the shell of the system equipment, and the isolation frame under the anti-static floor. The point equipotential grounding goes to the busbar. And use the equipotential bonding wire 4-10mm2 copper core wire bolt fastened wire clip as the connection material. At the same time, find the main steel bar of the building in the computer room, and it is confirmed that it is well connected with the lightning arrester after testing. Use 14mm galvanized round steel to connect the grounding busbar with it through the copper-iron conversion joint. Equipotential is formed. The purpose of using a joint grounding grid is to eliminate the potential difference between the local grids and ensure that the equipment is not damaged by the counterattack of lightning.     5. Grounding grid production and design Grounding is one of the most important aspects of lightning protection technology. Whether it is a direct lightning strike or an induction lightning, the lightning current is eventually introduced into the ground. Therefore, for sensitive data (signal) communication equipment, it is impossible to reliably avoid lightning without a reasonable and good grounding system. Therefore, for the building grounding network with grounding resistance > 1Ω, it is necessary to rectify according to the specification requirements to improve the reliability of the grounding system of the equipment room. According to the specific situation, the effective area of ​​the grounding grid and the structure of the grounding grid are improved by establishing different forms of grounding grids (including horizontal grounding bodies and vertical grounding bodies) along the computer room building.   When using a common grounding device, the common grounding resistance value should not be greater than 1Ω; When a special grounding device is used, its grounding resistance value should not be greater than 4Ω.   The basic requirements are as follows: 1) Make a grounding grid around the building to complete the most effective grounding device with less materials and lower installation costs; 2) Grounding resistance value requirements R ≤ 1Ω; 3) The grounding body should be set about 3~5m away from the main building where the computer room is located; 4) The horizontal and vertical grounding body should be buried about 0.8m underground, the vertical grounding body should be 2.5m long, and a vertical grounding body should be set every 3~5m. The grounding body is 50×5mm hot-dip galvanized flat steel; 5) When the ground mesh is welded, the welding area should be ≥6 times the contact point, and the welding point should be treated with anti-corrosion and anti-rust treatment; 6) The nets in various places should be welded with the steel bars of multiple building columns at 0.6~0.8m below the ground, and treated with anti-corrosion and anti-rust treatment; 7) When the soil conductivity is poor, the method of laying resistance reducing agent shall be adopted to make the grounding resistance ≤1Ω; 8) The backfill must be new clay with better electrical conductivity; 9) Multi-point welding with the building's foundation ground network, and reserve grounding test points. The above is a traditional cheap and practical grounding method. According to the actual situation, the grounding grid material can also use new technical grounding devices, such as maintenance-free electrolytic ion grounding system, low-resistance grounding module, long-term copper-clad steel grounding rod and so on.

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Post time: Aug-10-2022