Presentation

on

Lightning Protection practices in Bangladesh:An overview

Abidur Rahaman

Dept. of Applied Physics and Electronics

University of Dhaka, Bangladesh

Outline

� Lightning and lightning protection systems

� Current practices and measures in Bangladesh

Haunting Memoirs in Bangladesh

Haunting Memoirs in Bangladesh

• Lightning strikes kill 9 in Bangladesh (21 Mar 2008, Asia World News)

• Five killed by lightning (28 May 2007, DPA)

• 6 killed in lightning in Bangladesh's southern districts (08 August 2006, UNI)(08 August 2006, UNI)

• Lightning Kills 5 in Bangladesh (12 September 2006, The Indian Express)

• Lightning bolt killed nine and injured 23 in northeastern Bangladesh, 16 February 2006.

• 8 people were killed and 40 people were injured at Chapainawabgonj, on the 12th July 2005.

• Globally 44,000 thunderstorms/day and 100lightning strokes /sec

•Duration of one stroke of lightning, 1/5 th ofsecond.

•Voltages 1,00,000 kV and peak current 30 kA.

•Total energy released 40 GJ.

LIGHTNING FACTS

•Total energy released 40 GJ.

•Temperatures rises 50,000 degrees Celsius

• Lightning strokes ranges from 100 m – 8 kmlength.

•Lightning can travel at speeds of 60,000m/sec

•Lightning heats nearby air to about 10,000 °C.

Real captured image of lightning strike

Some examples of damage by Lightning and surge current

Cumulative

The microscopic runs on a processor chip are extremely susceptible to surge related heat stress. The surges meets resistance, converts to heat and causes a blister on the run.

!!As the repetitive surges continue to “hit the spot” over time, the blister grows until it effectively blocks the power or data flow on that circuit.

Surge Protective Device (SPD)

Cumulative

Catastrophic

Installation in Bangladesh

World’s Thunderstorm days per yearBangladesh has 80 to 120 days/year

Annual flash rate: NASA satellite report, Bangladesh has 40-50 flash per square kilometer

WHAT IS LIGHTNING

LIGHTNING is a SPARK

Lightning a Gigantic Electrical Spark Traveling between Cloud to Cloud or Cloud to Earth Containing an average Cloud to Earth Containing an average charge of 30 to 50 lakhs Volts and a current of 30 Kilo amperes with a speed of 220 km per hour.

A Complete LIGHTNING PROTECTION system

� Air Terminals

� Down Conductors

� Ground Terminals

� Interconnecting Conductors � Interconnecting Conductors

� Surge Protective Devices, and

� Other Connectors or fittings required to complete the system.

Capturing system:

� Franklin rod system

� Meshed Conductor by Faraday cage

Lightning Protection System

� Meshed Conductor by Faraday cage

� Early Streamer Emission

FRANKLIN RODS

� Based on the Benjamin Franklin’s (1752) original

design which uses points effects.

� Charges around a conductor accumulate on the

sharpest ends and easily overcome airsharpest ends and easily overcome air

resistance.

� The protected area is limited and

depends directly on the height at

which the point is placed and on

the required protection level.H

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MESHED CONDUCTORS

� Commonly known as “FaradayCages”

� In use since 1884 when Melsens

proposed this practice for

buildings protection.buildings protection.

� Fundamentals: inside a perfect continuousconductive cage there is no risk and no

electrical field variation appears when an

electrical current is flowing over its surface.

� In practice, this is possible with costly and most

of the times unaesthetic arrangements.

EARLY STREAMER EMISSION AIR TERMINAL : ESE

Bigger protection area (min 32 meter radius)

Right moment trigerring (15-45 micro second)

Easy installation

� Air terminal with a triggering devicewhich ionizes the end point of therod, controlling the generation.

� This control leads an early streamer� This control leads an early streameremission before any Franklin roddoes (∆∆∆∆t) and in the right moment,achieving a bigger protection area.

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LIGHTNING PROTECTION SYSTEM (LPS)

�

�

�

�

DAT CONTROLER PLUS®

ESE METHOD WITH SIMPLE AND COST EFFECTIVE ESE METHOD WITH SIMPLE AND COST EFFECTIVE INSTALLATION WORKSINSTALLATION WORKS

Protecting very costlyAnd sensitive equipmentAt the tower

Installation in Bangladesh

�At the tower and beneath its control room from direct Lightning strike

Lightning Protection: Implementation

Franklin method

Radius of influence : 3m

Height of lightning rod: 1m

Cost per 32 meter radius protected area: 3Million BDT

Faraday case method

Cost per 32 metre radius protected area: 5 million BDT

ESE method

Cost per 32 meter radius protected area: 0.3 Million BDT

With imported ESE lightning rod

Continuous Effort in Bangladesh

�Bangladesh National Building Code (BNBC) first proposed in 1993 and

legally binding in 2006 gives clear regulations for setting up “Lightning

Arrestor” in buildings more than 33m high .

�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. It is obligatory to take the NOC (No

Objection Certificate) for all realtors which comply with BNBC code.Objection Certificate) for all realtors which comply with BNBC code.

�Border Guards Bangladesh (BGB) completed a survey on lightning and

surge protection in September 2008 in the country’s hilly southeast portion

signaling sites and camps.

� Barapukuria coal mining company started for setting up modernized

lightning protection device from 29th September 2008

Continuous Effort in Bangladesh

• More than 35000 Base Station Subsystem (BSS) sites by six cellular

operators all over the country. Two WiMAX operators & Radio-TV

broadcast stations tower only increases this number. These are all

structures built on plain fields or rooftops. The average height ranging

of these tower are 15-50 meters. All of these tower and high rise

structures are more prone to get a lightning strike. As these sites arestructures are more prone to get a lightning strike. As these sites are

backed up by Batteries, IPS and auto start diesel driven generator, the

probable occurrence of lightning and subsequent firing damage is a

looming threat. In 2006, mobile operator Teletalk Bangladesh Ltd.

completed setting up modern lightning protector to their 150 BTS.

Their estimated budget for lightning protection is 110 million BDT.

• A Dhaka based organisation named TARA(Technological Assistance

for Rural Advancement) working on lightning awareness program to

mass people that achieved notable attention.

For safety and protection the following measures are essential:

• Proper installation of ESE Type Lightning Protection System (LPS)

• Proper installation of Surge Protective Devices (SPD)

Preventive Measures

• Installation of Residual Current Circuit Breaker (RCCB) or Residual Current Device

• Installation of Miniature Circuit Breaker (MCB or MCCB)

• Very low resistance Grounding / Earthing as per international standard.

Thank You