Lightning Rods, how they work, introduction and follow up. (Chapter I)

The effectiveness of a lightning protection system is one where the principle is to minimize or avoid direct lightning discharge on installations we want to protect, and to avoid all kinds of risks such as human death, accidents or fire caused by voltage differences or surges during the lightning strike.

Introduction

The lightning phenomenon: 

According to the world weather detection system, around 44,000 storms generating more than 8,000,000 lightning strikes happen during every second of every day around the world.

 

This is reference data because the evolution of weather is affecting lightning activity off season and even in winter or during snow storms.

 

A lightning strike is the electrical reaction caused by the saturation of electrostatic charges that have been generated by progressive accumulation of the electrical field between earth and cloud during the start of a typical storm. In a fraction of a second during the lightning discharge, the accumulated electrostatic energy becomes electromagnetic energy (the visible lightning strike and the sound interference), acoustic energy (thunder) and finally heat.

The lightning phenomenon is represented by an atmospheric electrical potential (10/45 kV). It is previously generated between two points of attraction of different polarization and equal potential in order to compensate for the saturation of electrostatic charge.

The lightning’s charge density is proportional to the electrostatic charge saturation of the area. The more density charge in the cloud, the bigger the risk of generating a leader in land and a lightning strike. The intensity in the lightning discharge is variable and will depend upon the critical moment of the air resistance break between the two reference points. The resistance of the exposed materials like land, rock, wood, iron, lightning installations and grounding will influence it, but will not limit the place of the strike, only its intensity. Lightning can transport an electric charge equivalent to 100 million ordinary bulbs in less than a second. The average measured charge per lightning strike is 20GW.

Once the lightning is formed, its trajectory can be chaotic, it will always predominate the power charged environments in the earths natural high voltage field. This electrical phenomenon is represented as an electrical shadow that will determine the elements that will be affected by the exchange of charges inside the natural high tension field.

Studies of the atmospheric electrical field around the earth determine that the charge distribution during the generation of the earth’s high tension field is not static but dynamic, by generating the leader in motion and different geographical points at the same time. The intensity and location of these electrical shadows can change radically and affect the sides and low parts of high buildings or structures.

Once the lightning is formed, the area of impact or the intensity of discharge cannot be guaranteed unless there is adequate protection.

Lightning causes great economic losses. 

According to references from 2002, lightning causes more than 5 billion dollars in economic losses to the United States alone.

Reference values for lightning :

 

• Voltage between cloud and an object on earth 1.               To1.000. KV
• Intensity of discharge                                                      5 a 300 KA
• di/dt                                                                    7.5kA/s to 500kA/s
• Frequency                                                                1 K Hz to 1 M Hz
• Time                                      10 microseconds to 100 milliseconds 
• Temperature higher than                               27,000 degrees Celcius 
• Propagation                                                    340 meters per second
• Electrostatic field/meter of elevation from land               10 kV

This data is only for your information since it is only proportional to the intensity of the cloud’s charge and the intensity of the lightning strike in each geographic zone.

The electrical phenomenon reverberated by a lightning impact, directly or indirectly during its strike, will vary according to the environment or installation that it finds in its path, where variable voltage values will appear depending upon material resistance, structure, situation and humidity of the ground grounding rod dissipation rate, absorption time of the physical land’s mineral compound, electrode’s crystallization state, etc.

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