Lightning protection of weak current system

 Multi-level classification (class) protection principle
According to the different functions of electrical and microelectronic equipment, different protected programs and their protective layers, the protection points are determined for classified protection; according to the electrical path that lightning hazards may invade, various systems are implemented from power lines to data communication lines, etc. Multi-level protection.
External passive protection
Passive protection is performed in the 0-level protection zone, that is, the outside, mainly including lightning rods (net, wire, belt) and grounding devices (ground wire, ground electrode). Protection principle: When the thundercloud discharge approaches the ground, it distort the ground electric field. On the top of the lightning rod (line), an inter-regional electric field strength distortion is formed to affect the development direction of the lightning pilot discharge, guide the lightning to discharge to the lightning rod (line), and then lead the line through the ground. The grounding device introduces the lightning current into the earth, so that Protect objects from lightning strikes.
Internal protection
Power supply protection, lightning damage is mainly through power supply lines. "Power lightning arrester" is connected to the power line in parallel, which can curb transient overvoltage and release surge current. Three levels of protection are usually configured from the main incoming line to the end of the electrical equipment. After step-by-step voltage limiting and discharge, the lightning energy is gradually eliminated to ensure the safety of the electrical equipment. Overvoltage protection should be divided into three parts according to national regulations: It is recommended to add lightning arresters at both ends of the inner core of the cable between the back end of the high-voltage transformer to the building's main switchboard, as the first level protection; Lightning arresters should be installed at the two ends of the inner core of the cable as the second-level protection; lightning arresters should be installed at the front end of all important and precise equipment and the UPS as the third-level protection.
Signal protection, for various signal systems, it should be divided into coarse protection and fine protection. The magnitude of the coarse protection is determined according to the level of the protected area, and the fine protection is determined according to the sensitivity of the electronic equipment. After the "signal lightning arrester" is connected to the signal line, on the one hand, it must be able to cut off the path of lightning into the equipment, and at the same time, it must be able to quickly discharge to ground. Damage to make the equipment work properly.
By place
In the construction of computer rooms and various types of weak motor rooms, a good grounding system must be required, because all lightning protection equipment needs to discharge the lightning current into the ground through the grounding system to protect equipment and personal safety. If the grounding system of the computer room is not well done, it will not only cause equipment failure, burn out components, but also seriously endanger the life of workers. In addition, there are anti-interference shielding problems and anti-static problems, which need to be solved by establishing a good grounding system.

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Mar. 09, 2020