A lightning strike discharges an enormous amount of energy in a short period of time. This can hit the buildings or electrical systems in an area resulting in unpredictable damage. In order to protect these structures and electrical systems, we have Lightning Arresters installed on top of such structures. In this blog, we have explained the Lightning Arrester’s Coverage Area calculation, which is essential for installation.
What is a Lightning Arrester?
A Lightning Arrester is the primary part of the Lightning Protection System. It protects the power system by directing the charges from lightning strikes to the ground through a low resistance path. Thus, the charges get grounded saving the electrical systems from any damage caused by lightning.
There are mainly two types of Lightning Arresters in use:
Lightning Arrester Coverage Area Calculation:
The coverage area calculation shall be as per the relevant standards in practice and shall follow the guidelines mentioned below:
Lightning and Surge Protection: IEC 62305/ BIS 62305 (IS-2309 Obsolete)
The Lightning Threat – IEC62305- Part-1
Lightning Risk management – IEC 62305- Part-2
External Lightning Protection – IEC 62305- Part-3
Electrical and Electronics Protection – IEC 62305- Part-4
National Electric Code – IS 3043
Lightning Arrester Coverage Area Calculation Formula:
Formula = [(L*W) +2*(L*H) + 2*(W*H) + (3.14*H2 )] Sq. m
Base Area of Structure/Building (Ab) = L*W m2 (Check for Base Area > 100 Sq.m)
Perimeter of Structure (P) = 2*(L+W) meter
Where L – Length of the Building/Structure; W – Width of the Building/ Structure; H – Height of the
Building / Structure.
Factors for Calculating Lightning Flash Density:
Probable No. of strikes to Building/Year (P) = [Coverage Area (Ac)* Lightning Flash Density (Ng) * 10^(-6) ]
Overall Multiplying Factor (M) = [A*B*C*D*E]
Overall Risk Factor Calculated (XC) = P *M
When the overall risk factor calculated is greater than Maximum Acceptable Overall Risk Factor determines the requirement of Lighting Protection.
Conventional Lightning Arresters
The Conventional Lightning Arrester use Franklin Rods or mesh. The Franklin Rods/mesh is located at critical points on a building/structure with a Down Conductor and Earthing System. To protect Electrical and Electronic systems within the structure Surge Protection Devices are necessary.
Size: Single to Five Spikes
Specification: Solid Copper/Gi air terminal lightning protection spike of 300mm long and 25mm dia should be internally assembled with 100mm dia Copper Ball fitted with side flash protection spikes with Air Gap Technology. Also, Conventional Lightning Arresters are maintenance-free, have excellent earthing stability and maintain low resistance for a very long period.
Early Streamer Emission (ESE) Lightning Arrester
ESE Lightning Protection Systems is a relatively new approach to the problem of lightning hazards, according to (NFC 17-102, UNE 21186) standards, it is the most effective protection against lightning.
ESE terminals are equipped with a discharge-triggering device to initiate streamers and increase the probability of connecting to a downward leader. Advance lightning arrester works on early streamer emission, where it starts to emit accumulated charges to the atmosphere before the lightning strikes objects. The ESE system at the level of protection 1 is connected to the metal structure or reinforced bars of the building in addition to the Down Conductors included in the ESE system at the roof level and ground level. When down conductors are not interconnected at roof level, a ring conductor located above the roof can be used to achieve this requirement.
Other materials required for Installation of ESE
Lightning Event Counter (6 digits) mounted on the down conductor in IP 67 enclosure with minimum sensitivity 1 kA for 8/20 μs pulse.
Supporting Mast Fabricated from GI pipe of 50 mm dia, 3-meter length class “B” providing, all necessary hardware for mounting arrangement for the down conductor.
Copper Cable as Down Conductor with all accessories for connecting ESE Lightning Device with the Earth Pit from top to bottom.
Maintenance-free Chemical Earthing with Earth Pit cover shall be provided.
Advantages of ESE Lightning Arrester
Easy Installation and Wider Coverage Area: Easy to assemble and install, one can quickly set it up and start using it without much hassle. Additionally, the wider coverage area means that this product can be used in larger spaces, making it a great option for those who need to cover a lot of ground.
Highly Resistant to Corrosion: Corrosion can be a big problem for outdoor products. However, ESE Arresters are highly resistant to corrosion and can hold up well even in harsh environments. This can be particularly important for those who live in coastal areas or other places where the air is salty or humid.
Works in All Weather Conditions: The ability to work in all weather conditions is a major advantage. These arresters perform consistently irrespective of the weather.
Conventional Lightning Arresters VS ESE
Early inception of the connecting leader from an ESE terminal in comparison to a normal Franklin Rod would provide a possibility of interception at a longer distance in comparison to that from a Franklin rod. Consequently, it is claimed that under similar circumstances an ESE terminal will have a larger protection area than a Franklin rod of similar dimensions. You can watch a detailed video on the comparison of both the arresters here.
