With the rapid development of communication technology and computer network technology, computers and networks have become more and more deeply embedded in people's lives and work, which also heralds the advent of the digital and information age.
The widespread application of these microelectronic network devices makes the problem of lightning protection more and more important. Because microelectronic equipment has the characteristics of high density, high speed, low voltage, and low power consumption, it is very sensitive to various electromagnetic interferences such as lightning overvoltage, power system operating overvoltage, electrostatic discharge, and electromagnetic radiation. If the protective measures are not effective, major losses may be suffered anytime and anywhere. What is worthy of our attention is that lightning not only damages the system equipment, but more importantly, it interrupts the communication of the system, stops work, and damages its reputation. The indirect losses are immeasurable.
Generally speaking, a network integration system is composed of a main server, a central switch, each branch switch, routers, servers, and a considerable number of terminals. The central switch located in the host room communicates with the outside world through the WAN router, and is connected to each branch switch through optical fiber, and the branch switch is connected to each user terminal through a hub.
Since the network integration system has a wide range of anti-temporal points, in order to protect the building and the various electronic network equipment in the building from lightning damage or minimize lightning damage, the lightning protection plan should be implemented from the perspective of overall lightning protection design. Nowadays, comprehensive lightning protection is adopted. The comprehensive lightning protection design plan should include two aspects: protection from direct lightning and protection from induced lightning. The lack of any aspect is incomplete, defective and potentially dangerous.
1. Protection against direct lightning strikes
If there is no direct lightning protective device, according to the estimation of IEC1312, almost all lightning current flows through the conductor-type lines (power lines, signal lines, etc.) entering and leaving the building. This damage is very serious. Therefore, direct lightning protection is done by induction The prerequisite for lightning protection; direct lightning protection is designed and constructed in accordance with the national standard GB50057 "Code for Design of Lightning Protection for Buildings". It mainly uses lightning rods, nets, wires, belts and a good grounding system, and its purpose is to protect short buildings from lightning strikes. Destroy, to provide a relatively safe environment for people or equipment in the building.
2. Protection of power supply system
Statistics show that more than 80% of lightning accidents in microelectronic network systems are caused by lightning impulse overvoltage induced on the power line connected to the system. Therefore, protecting the power cord is an important part of the overall lightning protection.
For the protection of the power cord of the network integrated system, first, the power inlet into the general power distribution room of the system should be laid with a metal armored cable, and both ends of the cable armor layer should be well grounded; if the cable does not have an armor layer, then The cable shall be buried in the ground through the steel pipe, and the two ends of the steel pipe shall be grounded. The length of the buried ground shall not be less than 15 meters. The power lines from the main power distribution room to the power distribution boxes of each building and the power distribution boxes of the machine room floors shall be laid with metal armored cables. This can greatly reduce the possibility of overvoltage induced by the power line.
Secondly, installing a power surge protector on the power line is an indispensable protective measure. According to the requirements of lightning protection zones in the IEC lightning protection specifications, the power system is divided into three levels of protection. A primary power lightning protection box with a maximum current capacity of 80KA can be installed on the low-voltage side of the distribution transformer of the system’s general power distribution room; a secondary power lightning protection box with a current capacity of 60KA can be installed in the general power distribution box of each building; in the computer room Install a three-level power lightning protection device with a maximum current capacity of 40KA at the power inlet of important equipment (such as switches, servers, UPS, etc.); according to the situation, install a power lightning protection box ZSPDTT20KC in front of the important equipment UPS power supply in the computer room. All lightning protection devices should be well grounded.
3. Protection of signal system
Although lightning protection devices are installed on external incoming lines such as power supply and communication lines, the overvoltage induced on the network line (such as twisted pair) due to lightning strikes will still affect the normal operation of the network and even completely destroy the network system. A huge transient magnetic field is generated during a lightning strike. Metal loops within 1 km, such as network metal connections, will induce extremely strong lightning strikes; in addition, when the lightning voltage is transmitted from the power line or communication line, or the building When the ground wire system of the object discharges a lightning strike, a strong transient current is generated. For the network transmission line, the induced overvoltage is enough to destroy the network at one time. Even if it is not a particularly high overvoltage, the equipment cannot be destroyed at one time, but each overvoltage shock accelerates the aging of the network equipment, affects the transmission and storage of data, and even DOWN the machine until it is completely damaged. Therefore, the lightning protection of the network signal line is a very important link for the overall lightning protection of the network integrated system.
The network transmission line mainly uses optical fiber and twisted pair. The optical fiber does not require special lightning protection measures, but if the armored optical fiber outdoors is overhead, the metal part of the optical fiber needs to be grounded. However, the shielding effect of twisted-pair cable is poor, so the possibility of induced lightning strikes is relatively high. This type of signal line should be laid in a shielded wire trough, and the shielded wire trough should be well grounded; it can also be laid through a metal pipe, and the metal pipe should be kept in the whole line. Electrical connection, and both ends of the metal pipe should be well grounded.
Installing signal lightning protection devices on signal lines is an effective way to prevent induced 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 for interfaces can be installed at the signal line entrances of the system backbone switch, main server, and each branch switch and server. The selection of signal lightning protection device should comprehensively consider the working voltage, transmission rate, interface form, etc. All lightning protection devices should be well grounded.
4. Equipotential connection
The central computer room where the backbone switch of the integrated network system is located should be equipped with a pressure equalizing ring to electrically connect all metal objects in the computer room, including cable shields, metal pipes, metal doors and windows, equipment casings, and all metal pipes entering and leaving the building. Connect to the equalizing ring to equalize the potential.
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