Lightning and Surge Protection Now in Bangladesh
ESE Air-terminal creates an upward propagating streamer faster than a Franklin passive rod. In the case of passive rods, the upward tracer propagates only after a period of charge reorganization. The time difference Δt is the ESE advantage, called “early emission” (μs).
The reduced initiation time allows for the streamer to connect with the downward leader at a strike point situated high above the tip of the ESE rod.
This increases the protected volume, facilitates the protection of large areas and simplifies and reduces material and installation costs
Without Lightning Protection System
With Lightning Protection System
Lightning discharges contain awesome amounts of electrical energy. It has been measured from several thousand amps to over 200,000 amps – enough to light half a million 100 watt bulbs! Even though a lightning discharge is of a very short duration (typically 200 microseconds) it is a very real cause of damage and destruction. The function of an external lightning protection system is to intercept, conduct and disperse a lightning strike safely to earth. Without such a system a building’s structure, electronic systems and the people working around or within it are all at risk.
During a storm, when the propagation field conditions are favourable, the air terminal first generates an upward leader. This leader from the tip propagates towards the downward leader from the cloud at an average speed of 1 m/μs.
The triggering time ΔT (μs) is defined as the mean gain at the sparkover instant (continuous propagation of the upward leader) obtained with an ESE air terminal compared with a single rod air terminal exposed to the same conditions. ΔT is measured in the high-voltage laboratory, all tests are defined in appendix C of the French standard NF C 17-102.
ESE air terminals are especially effective for the protection of classified industrial sites, administrative or public buildings, historical monuments and open-air sites such as sports grounds.
Air Terminal: As a general rule, the lightning air terminal should culminate at least two meters above the highest points of the building(s) to be protected. Its location should therefore be determined relative to building superstructures: chimneys, machine and equipment rooms, flagpoles, pylons or aerials. Ideally, these vulnerable points should be selected for lightning air terminal installation. The lightning air terminal may be raised by an extension mast.
Down-Conductor: The Down-Conductor is that part of the external Lightning Protection System (LPS) that conducts lightning current from the Air Terminal system to the Earth Termination system. The Down Conductor must be installed straight and vertically in order to provide the shortest and most direct path to earth.
Earth Rods: In a lightning protection system, a earth rod is a single component of the system. The earth rod requires a connection to earth to perform its protective function.
Bangladesh National Building Code (BNBC) gives clear regulations for setting up “Lightning Arrestor” recommended for buildings over 22m high and mandatory for buildings more than 33m high. It is obligatory to take the NOC (No Objection Certificate) for all realtors which comply with BNBC code.
International organizations working in Bangladesh like Accord Bangladesh, Alliance, ILO, Nirapon etc. has made LPS mandatory for every industry to get enlisted with them.
Fire Service and Civil Defense department and, Public Works Dept. (PWD) of Bangladesh government are working relentlessly in lightning awareness and protection in common people.
Rods and protection systems don’t attract lightning, nor do they influence where lightning will strike. They also do not and cannot prevent lightning, nor can they ‘discharge’ thunderstorms.
Lightning protection systems (including placement of rods, cables, and groundings) are custom-designed for individual structures and require complex engineering to function properly. They should only be installed by qualified contractors.
Globally 44,000 thunder storms per day
100 lightning strokes every second
Voltages 1,00,000 kV and peak current 30 kA
Total energy released can reach up to 40 GJ
Lightning hits nearby air at about 10,000°C
Temperature can rise up to 50,000 °C
Lightning strokes ranges from 100 m–8 km in length
Lightning can travel at speed of 60,000 m/sec
Lightning kills 2 in Hobiganj, 28 April, 2019
2 killed, 4 injured in separate lightning strikes in Pabna, 30 March, 2019
Lightning kills 5 in Gazipur, Brahmanbaria, 25 September, 2018
Farmer killed by lightning in Naogaon, 13 September, 2018
Lightning strike kills 3 in Bagerhat, Sunamganj, 12 September, 2018
Lightning strike kills 4 farmers in Magura, 12 September, 2018
3 killed in lightning strike in Narsingdi, 1 killed in Bogra, 12 June, 2018
3 killed in lightning strikes in Kurigram and Rangpur, 7 June, 2018
Lightning strike kills 6 nationwide, 27 May, 2018