Installation of lightning protection in video surveillance systems

The summer of 2018 turned out to be rich in thunderstorms. And at one of the company’s facilities, due to a lightning discharge, the radio bridge transmitting the image from the surveillance cameras failed. As a rule, radio bridges are located at a sufficient height above the ground. In addition, this particular radio bridge also had a long, about 70 meters, cable line.

And since the company in this area uses quite a lot of expensive radio bridges and robotic cameras with long cable lines installed on towers and masts, it was decided to install a special video surveillance system component that is especially important and subject to the effects of a thunderstorm.

And now a little theory:

During a thunderstorm, a phenomenon called electromagnetic thunder lightning occurs. It is this factor that causes the failure of all kinds of electrical equipment. From the school course of physics, we know the phenomenon of electromagnetic induction. In particular, if in one closed loop the value and / or direction of the electric current changes, then in another closed loop under the influence of this current there will be an electromotive force (EMF induction). Only in the case of a thunderstorm, all this has gigantic proportions. A lightning channel up to several kilometers long, in which the current for several tens of microseconds varies from zero to several thousand amperes, is the primary circuit of a giant air transformer. Under the influence of this discharge in all secondary circuits, starting from the wedding ring on your hand, and ending with hundreds of kilometers long high-voltage power lines, induction emf is induced.

There are two ways to protect against unwanted voltages – short circuit and insulation.

Isulation – installation of devices having high insulation resistance in the frequency range of electromagnetic interference and low resistance in the operating frequency range of video surveillance equipment.

Short circuit – creating a path for electromagnetic current bypassing data transmission equipment.

We selected and purchased lightning protection combining 1 and 2 methods of protection.

For the effective operation of this lightning protection, it is necessary to have a grounding circuit along which the potential induced by the thunder will go into the ground.

It should be understood that the cost of lightning protection, together with its installation, is incommensurably less than the cost of equipment that failed due to a lightning discharge.

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