The destructive nature of bad weather often makes security monitoring equipment unprepared, how to make security monitoring equipment to maintain good conditions in extreme weather?
How to waterproof camera surveillance?
In the application of video surveillance systems, outdoor surveillance occupies a large proportion. Due to the interference of various weather factors, outdoor surveillance often has infrared night vision, waterproof, anti-fog, anti-rain and snow functions. In the event of heavy rain, it is particularly important that monitoring equipment do a good job of defense in advance.
When the camera is working, the temperature changes greatly and it is prone to fogging. Especially in the rainy season, the formation of fog and frost is caused by the condensation of saturated steam in the air. And fog. The camera works under the environment of high humidity and dust, the window glass of the protective cover is prone to dirt, and the light entering the camera is blocked, resulting in the camera failing to capture objects and directly affecting the monitoring effect.
How to solve the fog and dirt on the camera? There are two main ways to solve this problem:
1. Add a wiper to the protective cover and clean the glass by controlling the wiper.
2. Compared with ordinary window glass, the invisible wiper window glass has the properties of repelling water, dust and the like. Use invisible wiper window glass to reduce dirt.
At this stage, there are certain technical problems in the sealing performance of China's surveillance cameras, such as the design of the housing, where joints and screw joints and other places are prone to leakage.
How to make the seal better? You can add a waterproof rubber sleeve, add water pad at the interface, the effect is more ideal; in the connection screw mouth waterproof glue, can enhance the waterproof; infrared waterproof camera is open to use aluminum alloy shell, Improve the accuracy of the interface, and the use of high-quality silicone material, the effect is also more ideal.
Security equipment how to effectively mine?
Heavy rain is often accompanied by lightning. Modern security systems and equipment are basically electronic products. They are very sensitive to lightning overvoltage, electrostatic discharge, electromagnetic radiation and other hazards, and are vulnerable to damage. Video surveillance systems are often susceptible to "injury" during thunderstorms. According to data from the Beijing-based Safety Monitoring Center, in recent lightning disasters, more than 80% of internal lightning, including electrical appliances, video surveillance systems, and probes have been damaged.
Generally speaking, the front-end cameras of video surveillance systems are mostly installed outdoors, in relatively open areas, and have a relatively high risk of lightning strikes. They are very sensitive to lightning overvoltages, transient overvoltages of power systems, and electrostatic discharges, making video surveillance extremely difficult. System equipment is easily damaged by lightning overvoltage, causing the entire closed-circuit television video surveillance system to paralyze. In some residential areas, video surveillance probes, intercom systems, and other facilities have not been designed for lightning protection. Inductive lightning is easy to take advantage of, and destroy the system.
There are many reasons why lightning protection cannot be popularized in practical applications. On the one hand, many Party A's lack of understanding of system lightning protection and awareness of the importance of lightning protection design to the entire system are limited to project cost; on the other hand, some engineering companies do not attach importance to system lightning protection, because if Considering this requirement will increase the project price and affect the price advantage when bidding; therefore, the safety and effectiveness of the system will have great potential risks.
Not only is the outdoor camera damaged by lightning, but the equipment in the video surveillance center room is also “damaged†due to lightning strikes. So, how does the security monitoring equipment prevent lightning? In general, the video surveillance system is divided into front-end camera, intermediate transmission, and back-end video monitoring center.
Video surveillance system lightning protection can start from three places
1. Lightning protection of front-end equipment
The installation position of the front-end camera is often divided into indoor and outdoor, and the camera installed in the room is generally not subject to direct lightning strikes. However, lightning overvoltage may also cause infringement on the camera, and outdoor equipment needs to be considered to prevent direct lightning strikes. Faced with this situation, how to carry out lightning protection?
Usually the front-end device such as the camera is placed within the effective protection range of the lightning receptor (lightning rod or other lightning conductor). When the camera is set up independently, in order to prevent the transient high potential of the lightning rod and the deflector, the lightning rod is preferably 3-4 meters away from the camera.
In addition, in order to prevent electromagnetic induction, the camera power cord and signal line led along the telephone pole should be put in the metal tube to achieve the shielding effect, and both ends of the shielding metal tube should be grounded.
The cable lightning induced electromotive force is a high-frequency alternating voltage, and the position is equivalent to the middle of the cable. According to this characteristic, the basic practice of the protection of the induced lightning is to set a “voltage limiting protection circuit†for the input and output ports of the equipment.
2. Lightning protection of transmission lines
For analog systems, the lines are mainly transmission signal lines and power lines. The power of the outdoor camera can be introduced from the terminal device or from the power source near the monitoring point. The control signal transmission line and the alarm signal transmission line are generally selected from reinforced core shielded soft wires, which are erected (or laid) between the front end and the terminal, and both the reinforcing core and the shielding layer should be well grounded.
According to regulations, when the transmission line is laid in the suburbs and villages of the city, it can be laid directly. When the conditions are not allowed, communication channels or overhead can be used. From the point of view of lightning protection, the direct burial laying method has the best lightning protection effect, and the overhead line is most vulnerable to lightning strikes, and is destructive and has a wide spread range. To avoid damage to the head and tail end equipment, the overhead transmission line should be on each pole. Ground handling is required. The overhead cable overhead line and overhead line cable should be grounded.
In addition, the laying of transmission lines does not prevent the occurrence of lightning strikes. A large number of facts show that the lightning damage caused by buried cables accounts for about 30% of the total failures. Even if lightning strikes a long distance, there are still some lightning currents flowing in. cable.
Therefore, if a shielded cable or cable is laid through a buried steel pipe, the electrical continuity of the steel pipe must be maintained. This is very effective in protecting electromagnetic interference and electromagnetic induction. This is mainly due to the shielding effect of the metal pipe and lightning current. Skin effect. Of course, if the cable is difficult to pass through the metal pipe, it can be introduced before the cable enters the terminal and the front-end equipment. However, the length of the buried shall not be less than 15 meters. The metal sheathing of the cable and the steel pipe shall be grounded to the lightning protection at the entrance end. The device is connected.
3, lightning protection of video surveillance center
In video surveillance systems, video surveillance centers are often the place to handle video surveillance video, so their lightning protection is especially important. In simple terms, the lightning protection of the video surveillance center shall be protected from direct lightning strikes, lightning surges, and “voltage limiting protection circuits†at the input and output ports of the equipment.
As far as direct lightning protection is concerned, the building where the video surveillance center is located should have lightning rods, lightning protection strips or lightning protection nets for direct lightning protection. When an overhead cable line is directly introduced, an arrester should be installed at the entrance to the house and a “voltage limiting protection circuit†should be installed.
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