All outdoor electronic products must consider the issue of lightning protection, especially special surveillance such as explosion-proof infrared cameras, which must be foolproof, so they must have lightning protection functions outdoors. So how do we do a good job in lightning protection?

Whether it is in a hydroelectric power plant, a thermal power plant, a wind power plant, or even a petrochemical or nuclear power plant, in order to meet the need for large surveillance coverage, the surveillance system will set up cameras at certain commanding heights or in open areas. A lightning strike creates an unavoidable risk.

In the energy industry security monitoring system, there are generally two lightning protection methods, one is grounding, and the other is lightning protection. Grounding is an important measure to protect the safety of people, equipment and power supply, and is an indispensable security measure. Lightning protection is determined based on the environment and needs of the video surveillance system installation. Although it is not necessary, grounding and lightning protection are mutually cooperative mechanisms, so their importance in the security monitoring system of the energy industry cannot be ignored.

Monitor front-end grounding and lightning protection measures
1. Outdoor cameras should be equipped with lightning rods and independent grounding pipelines to isolate the power and image signals of the monitoring equipment to avoid interference with current and damage to the lines. The lightning rod should be installed higher than the camera. The virtual three-dimensional cone range 45-60 degrees downward from the lightning rod tip is the safe range of the camera. When the lightning rod is installed, it should be insulated and isolated from the steel structure that fixes the camera.

2. The grounding of the camera front-end equipment should be concentrated on a ground bus in the terminal part, so that the grounding of the entire monitoring front-end equipment meets the requirement of no potential difference to the ground. Otherwise, a potential difference may be generated in the ground loop and the equipment may be burned.

3. The indoor front-end camera should be grounded to the ground terminal of the shared end. A no-fuse circuit breaker and a leakage circuit breaker with suitable capacity should be installed on the power end of the front-end equipment. At the same time, if funding permits, a lightning arrester with a capacity of 3000KV should be installed. Avoid equipment being damaged by induced lightning or conducted lightning.

4. After the outdoor camera grounding is completed, the grounding resistance shall be tested to be less than 10Ω, and the grounding rod installation shall be conducted according to the standard for a three-point impedance test.

Grounding and lightning protection of transmission parts

1. Since some monitoring signals in the energy industry have long transmission distances and low voltage resistance, they are easily invaded by induced lightning and conducted lightning current and damage the equipment. In order to conduct the lightning current from the signal transmission line to the ground, the cables should be equipped with surge protection. Protector, when designing image signal transmission cables, the signal transmission rate and voltage balance and grounding must be considered to avoid induced lightning intrusion.

2. Outdoor transmission and cables should be well grounded, and the grounding resistance must be less than 10Ω.

3. For overhead self-sustaining signal or power cables, the self-sustaining steel cable should be connected to the earth with a grounding wire at a fixed section.

4. The control signal transmission line uses cables with isolation and shielding functions.

5. The cables in the transmission part should be buried as much as possible during line erection. When environmental conditions do not permit it, the shortest spacing can be used to avoid the reduction of voltage resistance and the intrusion of induced lightning.

Monitoring terminal grounding and lightning protection
1. In the security monitoring system, lightning protection measures at the monitoring end should be cautious, and protection measures such as various possible types of lightning intrusion, ground loop potential differences, and power supply surges should be considered.

2. The building where the monitoring terminal is located should have a lightning protection system, grounding grid and grounding terminals.

3. Various metal pipelines at the monitoring terminal should be grounded and connected to the grounding device together. When the cable enters the terminal room, the metal outer sheath of the cable and the steel cable part of the self-sustaining cable should be connected to the ground terminal.

4. Indoor terminal transmission and cables should be better grounded. The grounding resistance must be less than 10Ω, but the lower the impedance to ground, the better.

The above are the basic effective methods for grounding and lightning protection of monitoring systems in the energy industry. Although they are not as strict as national regulations or standards, if the construction details of grounding and lightning protection are carefully handled, it should be regarded as an effective method of lightning protection.

When the explosion-proof camera is installed independently, in order to prevent transient high potential on the lightning rod and down conductor, it is best to keep the lightning rod 3-4 meters away from the explosion-proof camera. In addition, in order to prevent electromagnetic induction, the explosion-proof camera power cords and signal lines leading along the telephone poles should also be worn in metal pipes to achieve a shielding effect, and both ends of the shielded metal pipes should be grounded. The cables in the transmission part should be buried as much as possible during line erection. If the environmental conditions do not permit it, try to use the shortest spacing erection method to avoid reduced voltage resistance and lead to induction lightning intrusion. In terms of direct lightning protection, the building where the monitoring center is located should have lightning rods, lightning protection belts or lightning protection nets to protect against direct lightning strikes. To put it simply, the lightning protection of the monitoring center should be carried out from the aspects of direct lightning protection, lightning wave intrusion, equipotential connection and surge protection.

All in all, there are more thunderstorms across the country in summer, and most chemical industries, power plants, and factories are built in open areas. Therefore, the monitoring center and front-end monitoring and collection cameras must take lightning protection measures. Lightning protection is a basic measure that an open-air equipment should have. The monitoring system must be designed as a system for lightning protection, including lightning protection measures for the transmission module. Do it well. In this way, we can no longer worry about our camera being damaged when thunderstorms come!