"7.23" The Wenzhou-Wenzhou Railway has experienced a special major railway accident for nearly 10 days. The relevant authorities said at the conference for concluding the accident confirmation that the cause of this major rear-end collision was caused by a lightning strike that caused a signal device failure. The software design of the data acquisition board in the control center was seriously flawed, which caused the signal light to indicate an error and eventually led to a tragedy of 40 deaths. Whether there are serious defects in the signal equipment design or not, it will have a certain impact on signal transmission in the event of strong lightning weather, but it is only a momentary power outage or a complete difference. The train rear-end accident not only gave the Ministry of Railways a lesson, but also gave the security industry a warning. The problem of lightning protection is not limited to railway signal transmission. In fact, in the security monitoring system, lightning protection design is also very prominent.

In the field of security, many devices of the video surveillance system and the perimeter security system are placed outdoors, and in summer it is a season of frequent lightning. Therefore, the possibility of destruction of the surveillance system equipment due to lightning strikes has greatly increased. The consequence of this may be that the entire monitoring system will fail to operate, causing the economic loss of the equipment and making the system unable to work properly. In order to take effective lightning protection measures for the security monitoring system and ensure the normal and reliable operation of the monitoring system, it is necessary to first understand the main reasons for the lightning damage of the monitoring system and the possible intrusion paths for lightning, especially the outdoor monitoring equipment with serious damage caused by lightning strikes. Based on the analysis of the causes of damage, properly select and use lightning protection devices for monitoring system equipment, and study the layout of signals, power lines, shields, and grounding methods to improve the lightning resistance of the monitoring system. The monitoring system is divided into front-end equipment, transmission equipment and terminal equipment. The lightning protection technology of the monitoring camera itself in the lightning protection design and the method of installation of the entire equipment have become the key elements of lightning protection. Security engineering companies play an important role in optimizing the system's lightning protection level.

According to the division of the product line, the front-end equipment, the video surveillance camera, shall be placed within the effective range of the lightning rod; secondly, in order to prevent the lightning wave from invading the front-end equipment along the line, an appropriate lightning arrester shall be installed on the device. Surge device); again, during the transmission of thunderstorm signal, the cable or cable with shielding layer is laid through the steel pipe to keep the electrical connection of the steel pipe, and at the same time it is also very effective for protection against electromagnetic interference and electromagnetic induction; Finally, in terms of lightning protection of terminal equipment, 80% of lightning high-voltage is invaded from the power line. Therefore, before the video signal transmission line, signal control line, or intrusion alarm signal line enters the front-end equipment, or before entering the center console, corresponding equipment should be installed. Lightning protection device. The example application of Beijing Tianyixun tells us that lightning protection design must place the arrester in the first place. The general manager of Guangzhou Jingdian Electronics stated that they integrated the lightning protection technology into the monitoring equipment to form an all-in-one lightning protection product; in concept, it is different from the conventional lightning protection to release energy. They use energy consumption when they sense When there is lightning and the safe voltage is exceeded, the voltage is weakened by the line loss. Of course, there are certain limitations in the supply of electricity. Because the lightning protection system encounters a phenomenon of “tripping” due to high current, it will have a certain influence on the situation of centralized power supply. In fact, no matter what kind of lightning protection method, the ultimate goal is the same. In the days of thunderstorms, the monitoring equipment is operating normally, and the screens we need can be collected and used as the most powerful evidence for accidents.

The “lightning protection” in the monitoring room is equally important. Lightning protection in the monitoring room is the most easily overlooked place for people. In fact, lightning protection in the monitoring room is the last step in monitoring and lightning protection. The monitoring system transmits the signal to the terminal receiver through the line transmission. The signal will be transmitted from the outside to the room or will pose a certain threat. Therefore, the building where the monitoring room is located should have lightning rods, lightning protection strips or lightning protection nets for direct lightning protection. In order to avoid the damage caused by lightning. The building shall be provided with a pressure equalizing ring, and all the downleads, metal structures and metal objects in the building shall be connected to the pressure equalizing ring.

In the interview process of the writer, I also clearly realized that the lightning protection facilities mentioned above mainly deal with induced lightning. For direct lightning strikes with too much power, only protective measures to reduce damage are currently available. This also requires the joint efforts of mine-prevention and security circles to develop and manufacture lightning protection equipment and measures that are more advanced and more capable of combating attacks. There are more and more types of security surveillance cameras, and lightning protection cameras are also rising stars in the market. We have reason to believe that with the expansion of surveillance applications, lightning protection cameras will surely burst out.