Изоляционная стойка - Insulation rod
Электронный блок - Electronic unit
Диэлектрические держатели - Dielectric holders
Металлическая опора антенны - Metal antenna support
Металлический токоотвод - Metal current collector
To explain the principle of operation of an isolated lightning protection, the antenna system is usually demonstrated with the electronic unit installed on its support. It receives a valid signal or, vice versa, emits the electromagnetic pulse bearing a control command. The electronic unit requires protection against lightning current which, upon the strike into the antenna mast, distributes along its metal structures nearby and sets up a strong magnetic field. There are two ways to reduce the electromagnetic interference to the unit: you should either increase the distance to the current collector or reduce a fraction of the lightning current in the current collector. Isolated lightning protection implies choosing the first option. Its lightning arrester is isolated from the antenna mast, and the current collector is spaced to the maximum possible distance, D, from the protected unit, since the magnetic field is inversely proportional to this parameter.
The effect is restricted by the length of dielectric holders. In real-life structures, it is within one meter. We should make a remark for isolated current collectors. Isolation and a semiconductor layer applied onto the surface of such current collectors are not shields and they do not weaken the magnetic field of the lightning current. In this regard, their use does not provide any advantages.
There is an alternative solution that requires current passage among as many current collectors as possible. This is possible in practice if their role is played by a metal structure of the antenna mast.
For details, read "Which Way Is Better To Protect Telecoms Equipment Installed on Towers from Lightnings: An Insulated Current Collector or Natural Steel Structures?"
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