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Surge Protection Application in CCTV System

In generally, video surveillance system consists of three parts, including Front part: Camera, lens, pan, protective cover, frame and other components. Transmission part: Using coaxial cable, CAT-5, power lines or grounding to transmit video, audio or control signals etc. End part: The Quad, monitor, control equipments and other components.

In CCTV system, we know there is much lightening and overvoltage, which can destroy the video surveillance equipments such as cameras, DVR, monitor, Quad etc. When CCTV system is struck by lightning, there are some following ways to cause damage to the system.

Direct Lightning Strike:

Direct lightning strike can damage the outside cameras. Cameras poles has no making surge protection, basically they are damaged by lightning every time. Parts of outdoor poles are mounted on the lightning rod. And the poles body is as vertical deflectors. In the process triggered lightning, lightning current conducting on the rod body connect with the cameras housing, the cameras still can be damaged.

Lightning Wave Invasion:

When power lines, signal transmission cable, video cables are induced by lightning, the lightning wave along the metal wire invade the devices, causing voltage difference, which can damage equipments. Electromagnetic induction and electrostatic is called induction lightning, also known as secondary lightning. Its damage are smaller than direct lightning. But they are much greater than the probability of occurrence of direct lightning strike.

In order to guarantee the CCTV system stable and reduce economic losses, surge protection on electric equipments become more and more popular now. According to the structure of CCTV system and the possible invasion pathways of lightning, now we offer the following surge protection solution.

● Outdoor Cameras Surge Protection

The lightning and anti-surge designs of outdoor video surveillance equipments play the key role in the entire security equipment systems. In particular, the failure rate of outdoor cameras on the pole on both sides of the road is greater than normal outdoor cameras around the building. The reason is mainly outdoor direct lightning and lightning electromagnetic induction occurs largely, broader, higher level due to lightning protection zone.

The core components of surveillance equipments and supply voltage are very sensitive to for inrush current. Installing suitable surge protectors on IN and OUT terminal of the devices can solve this problem. For example, we need to build one suitable grounding device near equipment box before installation. Then we make piping layout and install outdoor equipment box. Please make sure that the input terminal of cables must be separated.

The devices can not be powered before installation. Besides, please check the devices' whether they is qualified or not. At last, we need to install surge protection devices for important devices such as outdoor cameras etc and connect the grounding cables to the grounding centralized metal devices. The following are outdoor cameras surge protection installation diagram:

● Control Room Surge Protection

In video surveillance system, surge protector in control room is most important such as direct lightning protection, lightning surge intrusion, equipotential connection and surge protection. The building of control room should contain lightning rod for preventing direct lightning, lightning protection zone or lightning network.

And the variety of metal pipes entering into the control room shall be connected to the grounding device for anti-lightning. When the cables are directly pulled into, the surge protector devices should be installed before entering house and connect the metal outer sheath of cables to the grounding device. Because 80% lightning high voltage invade from the power line. In general, power supply should be set on three levels lightning protection (surge protection module) in order to ensure the safety of equipments. The maximum flow capacity of surge protection modules are about 20 ~ 60KA.

Besides, the control room should have the separate grounding network. And grounding resistance should be less 4Ω. The grounding copper bars or ring metal bands should be pre-laid under indoors static flooring. Indoor equipments should be done professional equipotential bonding devices to prevent electrostatic electromagnetic induction and voltage difference damaging equipments and people.

Through making the comprehensive lightning protection in video surveillance system, direct lightning, inductive lightning and overvoltage can be effectively held back and guided. The lines can also absorb and divert surge current. The damage rate of lightning can be reduced more than 85%.

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