How to do lightning protection for network cameras?

Network camera is a new camera which combines traditional camera and network technology. It is an important part of the monitoring system. It can transmit the collected audio and video data to users through the network, which is simple and convenient. It is widely used in education, medical care, public affairs and other fields. However, webcams are all installed in the open air and are vulnerable to lightning. So, how to do a good job of lightning protection for webcams? Hejun Electronics will make the following detailed analysis for you.

Firstly, the reason why the network camera was struck by lightning was analyzed.

(A) the main forms of network cameras being struck by lightning

The main forms of lightning strike are direct lightning and induction lightning.

1. Lightning is a direct lightning attack on the webcam, which causes the most serious mechanical damage, but this form rarely appears in reality.

2. Induction lightning

Due to the rapid change of lightning current, a strong electromagnetic field is generated around it, and the network camera and its transmission line in the magnetic field induce a strong electromotive force, that is, electromagnetic induction; At the same time, the webcam and transmission line in the magnetic field will also induce charges opposite to lightning, forming electrostatic induction. Induction lightning will cause great damage to the monitoring system, which is ubiquitous in reality and is the key protection object.

(2) The network camera is the front-end equipment of the security monitoring system, which belongs to weak current equipment, and its sensitive components have low tolerance, and can't withstand the impact of lightning current. At the same time, this kind of equipment is distributed in the open air and becomes an important target of lightning strike. Once struck by lightning, the lightning current will damage the camera and enter the terminal system along the transmission lines such as power supply and signal, causing serious damage to the monitoring center.

(3) The important reason why the network camera is struck by lightning is that the building security system has not yet established effective lightning protection measures, as follows:

1. There are no effective measures to prevent direct lightning in the lightning protection zone PLZOA;

2. The overhead transmission cable has not taken good measures to prevent the invasion of lightning waves;

3. The front end of the network camera is not equipped with a signal surge protector or the surge protector fails;

To sum up, because the network camera is an indispensable part of security monitoring, only the comprehensive lightning protection of the monitoring system can solve the lightning protection problem of the network camera comprehensively, systematically and effectively.

Three, the main measures of lightning protection monitoring system

(1) Lightning protection of front-end acquisition equipment (including network cameras)

1. Protective measures against direct lightning

When the front-end acquisition equipment of the monitoring system (including the network camera) is within the scope of the direct lightning protection zone (LPZOA), the protection measures for direct lightning protection should be taken, specifically, lightning rods should be installed near the network camera, and the protection range should be calculated strictly according to the radius of the sphere.

When the lightning rod is installed on the camera mounting rod, the steel pipe of the mounting rod can be used as the down lead; When installed next to the camera, the distance between the two mounting rods should be more than 3 meters.

2. The connecting cable of the camera should be shielded, that is, the connecting cable should be laid in the steel pipe and placed in the steel pipe of the camera mounting rod;

3. The camera metal mounting rod should be grounded, and the grounding resistance value should not be greater than 4Ω.

4. The front end of the network camera should choose an adaptive monitoring signal surge protector, which is generally a three-in-one surge protector of monitoring, network and power supply KS-E3/24/M. The product features are as follows:

Large discharge current, multi-level protection;

Built-in fast semiconductor protection device, fast response speed and low residual voltage;

Excellent core components and excellent performance;

Energy saving, environmental protection, simple installation, suitable for various standard interface types;

Low insertion loss ensures smooth lines;

Small standing wave coefficient and wide working frequency range.

(2) Lightning protection of transmission cable of monitoring system

The transmission cable of the monitoring system should prevent the invasion of lightning waves, and should be shielded or laid through metal pipes all the way. The shielding layer should be electrically connected, and both ends should be grounded or connected with equipotential respectively. The part crossing the area (LPZOA) shall be buried. If it cannot be laid underground, reinforced concrete poles should be used for overhead laying.

(3) Lightning protection of terminal equipment of monitoring system

1. shielding measures

If the terminal equipment of the monitoring system is a non-metallic shell, shielding measures should be taken, and the distance between it and the external wall structural column should not be less than1m.

2. Equipotential bonding

Terminal equipment shall be equipotentially connected and grounded, and connected with lightning protection grounding and protective grounding and grounding system of buildings.

The exposed conductive part of the electronic equipment and the working grounding of the electronic system shall be connected to the equipotential connection network through wires.

3. Reasonable wiring

The integrated wiring of monitoring system should meet the requirements of technical specifications.

To sum up, network camera lightning protection is a systematic and comprehensive lightning protection project, and only when it is fully carried out can it play a good protective role.