IP CCTV

Integrated network system overall lightning protection solution

2016/03/04

With the rapid development of communication technology and computer network technology, computers and networks have become more and more deeply involved in people's lives and work, and they also indicate the advent of the digital and information age.

      The widespread use of these microelectronic network devices makes the issue of lightning protection increasingly important. Due to the high density, high speed, low voltage, and low power consumption of microelectronic devices, it is very sensitive to various electromagnetic interferences such as lightning overvoltage, power system operating overvoltage, electrostatic discharge, electromagnetic radiation and the like. If the protective measures are not effective, you may suffer significant losses anytime, anywhere. What deserves our attention is that lightning not only destroys system equipment, but more importantly, it causes system communication interruption, work stoppage, reputation damage, and its indirect loss cannot be estimated.

Generally, a network integrated system is composed of a primary server and a central switch and each branch switch, as well as a router, a server, 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 the optical fiber. The branch switch is connected to each user terminal through the hub.

Since the network integrated system has many anti-temple points, in order to protect the electronic network equipment in buildings and buildings from lightning damage or to minimize lightning damage, the lightning protection scheme should be implemented from the perspective of overall lightning protection. design. Comprehensive lightning protection is now adopted. The integrated lightning protection design plan should include two aspects: direct lightning protection and inductive lightning protection. Any lack of one aspect is incomplete, defective and potentially dangerous.

1, direct lightning protection

      If there is no direct lightning protection, according to IEC1312, almost all lightning current flows through the conductor type lines (power lines, signal lines, etc.) entering and exiting the building. The damage is very serious. Therefore, direct lightning protection is used for induction. The premise of lightning protection; direct lightning protection is designed and constructed in accordance with GB50057 "Lightning Protection Design Code for Buildings", mainly using lightning rods, nets, wires, belts and good grounding system. The purpose is to protect the building from lightning strikes. Destruction provides a relatively safe environment for people or equipment within a building.

2, the protection of the power system

      Statistics show that more than 80% of lightning accidents in microelectronic network systems are caused by lightning surges induced on the power lines connected to the system. Therefore, the protection of the power cord is a part of the overall lightning protection that cannot be ignored.

For the power line protection of the network integrated system, first of all, the power incoming line entering the total power distribution room of the system should be laid with metal armored cable, and both ends of the cable armor layer should be well grounded; if the cable has no armor layer, then The cable is buried in the steel pipe, and the steel pipe is grounded at both ends. The length of the buried ground should be no less than 15 meters. The power distribution lines from the main power distribution room to the distribution boxes of each building and the power distribution box of the equipment room floor should be laid with metal armored cables. This greatly reduces the possibility of overvoltage induced by the power line.

      Secondly, installing a power surge protector on the power line is an essential protective measure. According to the requirements of the lightning protection zone in the IEC lightning protection specification, the power system is divided into three levels of protection. A primary power lightning protection box with a maximum circulating capacity of 80 kA can be installed on the low-voltage side of the distribution transformer of the system main power distribution room; a secondary power lightning protection box with a flow capacity of 60 kA is installed in the main distribution box of each building; Install the power supply lightning protection box ZSPDTT20KC in front of the important equipment UPS power supply in the equipment room. All lightning arresters should be well grounded.

3. Protection of the signal system

      Although lightning protection devices are installed on external incoming lines such as power and communication lines, the overvoltage generated by lightning strikes on network lines (such as twisted pairs) can affect the normal operation of the network and even completely damage the network system. A huge transient magnetic field is generated during lightning strikes. Metal loops within 1 km, such as network metal connections, can induce extremely strong inductive lightning strikes. In addition, when power lines or communication lines transmit lightning voltage, or buildings The grounding system of the object generates a powerful transient current when the lightning strikes, and the induced overvoltage is sufficient to damage the network at one time for the network transmission line. Even if it is not a particularly high overvoltage, it can not damage the device at one time, but each overvoltage shock accelerates the aging of the network equipment, affecting the transmission and storage of data, and even the DOWN 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 fibers and twisted pairs. The fiber does not require special lightning protection measures, but if the outdoor braided fiber is overhead, the metal part of the fiber needs to be grounded. The twisted pair shielding effect is poor, so the possibility of inductive lightning strike is relatively large. Such signal lines should be laid in the shielded wire trough, the shielded trough should be well grounded, or the metal pipe should be laid, and the metal pipe should be kept in the whole line. Electrically connected, and the ends of the metal tube should be well grounded.

Installing a signal lightning arrester on the signal line is an effective way to prevent lightning. For the network integrated system, the dedicated signal lightning protector can be installed before the network signal line enters the WAN router; the signal lightning protection device of the interface is installed at the signal line entrance of the system trunk switch, the main server, and each branch switch and server. The selection of the signal lightning protection device should consider the working voltage, transmission rate and interface form. All lightning arresters should be well grounded.

4, equipotential bonding

      The central computer room where the integrated network system backbone switch is located shall be provided with a voltage equalizing ring to electrically connect all metal objects in the equipment room, including cable shielding layers, metal pipes, metal doors and windows, equipment casings, and all metal components such as metal pipes entering and leaving the building. Connect to the equalizing ring to equalize the potential.


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