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SPDA – Protection System Atmospheric Discharge

It's the complete system to protect a structure against the effects of lightning. The first Stop Rays have knowledge was developed in 1752 by Benjamin Franklin who also discovered that lightning was a physical / electrical phenomenon.
The Protection Systems Lightning (Stop rays) are made up of Franklin captors type or air captors mesh captor (Faraday cage) and are installed according to the NBR-5419/01 ABNT (Brazilian Technical Standards Association) .

The Rays can cause:

  • Loss of life;
  • electric Choqui when talking on the phone;
  • Burning appliances and antennas;
  • Computer problems;
  • Faulty electrical network and telephony;
  • etc.

Contrary to what many think, the Stop Rays do not attract lightning on a stormy day. Its purpose is to convey to the highest points of the buildings, the same ionic potential we find in the earth, causing the ray search for the captors to discharge instead of the structures around the captors or the soil itself lying at lower levels in relation to the sensors.
The ground must have low potential so as not to present resistance to lightning discharge (electric current). In the measurement of a grounding, the ideal is that it has a ohmic resistance of ten (10) ohms tending to zero.
First of all it is worth remembering that nothing can be done to prevent a lightning strike in a specific place or structure. In general, higher and higher exposure area points are the favorite radius. As good as the installed system, this will never be 100% efficient, varying according to the level of protection, since we are dealing with a phenomenon of completely unpredictable and random nature.
The captors type in Franklin poles form a cone of coverage that protect structures located in a certain radius of action.
The cordage and ground rods are made of copper or copper-plated materials, which have low resistance to the passage of electricity.
The Fire Department through the Security Code Fire and Panic (COSCIP - Decree No. 897 of September 21, 1976), defines buildings that must have the Rays Stop system are:

  • Building and industrial or commercial establishments with more than 1,500 square meters in building area;
  • Any building with more than thirty (30) meters high;
  • Building and industrial or commercial establishments with more than 1,500 square meters in building area;
  • Any building with more than thirty (30) meters high;
  • Areas used in explosives or flammable deposits;
  • At the discretion of the Fire Department when the characteristics and the danger of the buildings so require;

PROTECTION METHODS:
There are some ways to prepare adequate lightning protection. Among the most common found:

1) METHOD FRANKLIN - protection theory consists in the rotation of the tangent of a triangle around an axis (generatrix), whose opening angle is determined by a specific table, varying depending on the level of protection of the building and the building height.

1 - Captor type Franklin
2 - galvanized mast
3 - Supports insulators for masts
4 - Mounting base and contraventagem
5 - descent conductor (bare copper wire)
6 - Supports insulators for lowering driver
7 - Protection tube
8 - Ground Loop

2) METHOD OF FARADAY CAGE - is to launch horizontal cables on the roof of the building, modulated according to the level of protection. This system acts as an electrostatic shield, trying to keep the radius can pierce the armor and hit the building and also reducing the electric fields within it.

1 - Captor type finish air
2 - Cable bare copper>
3 - insulators Supports
4 - Protection tube
5 - Ground loop
6 - Measuring Connector

NOTE:. Other metal structures of the building to be protected against lightning can be used as natural captors or descent conductors such as: roofs, pillars, trusses, gutters, pipes, etc.
IMPORTANT: Stops Rays systems should not run (installed) without the prior achievement of specific project by engineer authorized by the competent body

.

The manufacture and marketing of radioactive captors is prohibited since 1989 by Resolution 04/89 of the CNEN (National Nuclear Energy Commission) published on 09/05/1989, because manufacturers have failed to prove its efficiency with the use of radioactive material. This type of sensor must be replaced, and after that the installation must be adapted to the ABNT 5419/93 leave that offers a minimum of security in order to minimize exposure to risks arising from a lightning strike.

RAY one of the impulses of a lightning strike to the earth. Captor -. Of the outer SPDA designed to intercept lightning
CAPTOR part of the external LPS intended to intercept lightning.
DOWN DRIVER part of the SPDA designed to lead the lightning current from the sensor to the grounding system.
GROUND SYSTEM part of the external LPS intended to conduct and disperse the lightning current in the ground.
TABLE FOR PROTECTION LEVEL SELECTION
TYPE OF CONSTRUCTION
PROTECTION LEVEL
Building of explosives, flammable, industrial, chemical, nuclear, biochemical laboratories, factories of ammunition and fireworks, telecommunications stations, power plants, industrial heat with risk of fire, refineries, etc.
I
Residential buildings, industries, residential houses, agricultural establishments and farms with wooden structure.
II
Residential buildings, industries, residential houses, agricultural establishments and farms with wooden structure.
III
junk sheds or negligible content farms and agricultural establishments wooden structure;

“If I made valuable discoveries, but was to have patience than any other talent.” - Isaac Newton

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