Lightning protection 1 by ambuj mishra

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Lightning protection 1 by ambuj mishra

  1. 1. LIGHTNING PROTECTION PRESENTATION BY AMBUJ MISHRA
  2. 2. LIST OF CONTENTS 1/30/2015 LEAP INFRAASYS PVT LTD 1- What is lightning & lightning protection system?  Anatomy of a Lightning Stroke, 2- Why need lightning protection?  Need for lightning protection, Calculation of need for protection as per standard, 3- Main concept of the protection. 4- Component parts:-  a) Air Terminations;  b) Down Conductors;  c) Earth Terminations;  d) Earth Electrodes.
  3. 3. What is lightning & lightning protection system? Lightning- Electrical discharge of atmospheric origin between cloud and earth comprising one or more impulse of many kilo amps. Lightning protection system- The whole system of the conductors used to protect a structure from the effects of lightning. 1/30/2015 Leap Infraasys Pvt Ltd
  4. 4. Anatomy of a Lightning Stroke 1/30/2015 Leap Infraasys Pvt Ltd  As a thunderstorm grows, electrical charges build up within the cloud. Oppositely charged particles gather at the ground below. The attraction between positive and negative charges quickly grows strong enough to overcome the air's resistance to electrical flow. Racing toward each other, they connect and complete the electrical circuit. Charge from the ground then surges upward at nearly one-third the speed of light and we see a bright
  5. 5. Electrons begin zigzagging downward. This is the “stepped leader.” As the stepped leader nears the ground, it draws a streamer of positive charge upward. As the leader and streamer come together, a powerful electrical current begins flowing. Current begins the return stroke, an intense wave of positive charge traveling upward about 60,000 miles per second. 1/30/2015 Leap Infraasys Pvt Ltd
  6. 6. Why need lightning protection? More impulse of Kilo amps, is injurious for the peoples and animals, either directly or indirectly by causing fire and explosions and it can also disturb the Electrical / Mechanical system. 1/30/2015 Leap Infraasys Pvt Ltd
  7. 7. need for lightning protection 1/30/2015Leap Infraasys Pvt Ltd Where large numbers of people congregate. Where essential public services are concerned. Where the area is one in which lightning strokes are prevalent. Where there are very tall or isolated structures.
  8. 8. Calculation of need for protection as per standard 1/30/2015 Leap Infraasys Pvt Ltd • The probability of a structure or building being struck by lightning in any one area is the product of the ‘lightning flash density, Ng’ and ‘effective collection area’ of the structure. • The lightning flash density is the number of (flashes to ground) per km² per year. • The effective collection area of a structure is the area on the plan of the structure extended
  9. 9. Example to check the necessity of lightning protection Checking of protection requirement for hospital building I/P O/P Length (L) m 70 Collection area (Ac) m² width (W) m 12 (LXW)+2X(LXH)+2X(WX H)+∏H² 2794 Height (H) m 10 The probable number of strikes (risk) to the structure per year is: P =Ac X Ng X 10¯6, Where Ac=collection area Ng=Flash density 0.0019558 Thunder storm days / year From IS 2309, location wise 30 Flash density (Ng) Lightning flashes per km² per year 0.7 Weighting factor A (Use of structures) 1.7 Overall multiplying factor 1.4 B (Type of construction) 0.8 C (Contents or consequential effects) 1.7 D (Degree of isolation) 2 E (Type of country) 0.3 Overall risk factor 0.0027130862.7 x 10¯³ As per IS 2309, clause no. 8.16 if result is greater than 10¯5, then protection is necessary
  10. 10. Main concept of the protection 1/30/2015  Air termination installed above the structure intercept lightning discharges and sends the current to the ground electrode through the down conductor (Fig-1). Leap Infraasys Pvt Ltd
  11. 11. (Fig-1) Typical scheme arrangement Leap Infraasys Pvt Ltd 1/30/2015
  12. 12. 1/30/2015 Electrons begin zigzagging downward. streamer of positive charge move to upward.
  13. 13. 1/30/2015 As the leader and streamer come together, a powerful electrical current begins flowing
  14. 14. 1/30/2015
  15. 15. 1/30/2015 Air termination Down conductor Earth Electrode
  16. 16. 1/30/2015 Air termination Down conductor Earth Electrode
  17. 17. 1/30/2015 Air termination Down conductor Earth Electrode
  18. 18. Component parts 1/30/2015  The principal components of a lightning protection system are as follows:  a) Air Terminations;  b) Down Conductors;  c) Earth Terminations;  d) Earth Electrodes. Leap Infraasys Pvt Ltd
  19. 19. Air terminations 1/30/2015 Leap Infraasys Pvt Ltd  Air termination networks may consist of vertical or horizontal conductors or combined of both.  Minimum Dimensions Component Parts Reference- Clause no.12.1.1 (IS-2309) Component(Air termination) Dimensions (mm) Area ( mm2) Aluminium, copper and galvanized steel strip 20 X 3 60.00 Aluminium, aluminium alloy or phosphor bronze and galvanized steel rods 10.0 dia 78.54
  20. 20. Down Conductors 1/30/2015 Leap Infraasys Pvt Ltd  Conductor that connects an air termination with an earth termination. The function of down conductor is to provide a low impedance path from the air termination to the earth electrode so that the lightning current can be safely conducted to earth.  The following table defines the minimum dimensions for down conductors according to IEC 1024-1 Down Conductor Material Down Conductor (mm2) Cu 16 Al 25
  21. 21. Earth Termination 1/30/2015 Leap Infraasys Pvt Ltd The part of the lightning protective system which is intended to discharge lightning current in to the general mass of earth.
  22. 22. Earth Electrode 1/30/2015Leap Infraasys Pvt Ltd • The part of the earth termination making direct electrical contact with earth. • The function of the earth electrode is to dissipate the lightning strike safely in to the ground.
  23. 23. LIGHTNING PROTECTION LAYOUT for bhakti park station 1/30/2015Leap Infraasys Pvt Ltd
  24. 24. Section details 1/30/2015Leap Infraasys Pvt Ltd
  25. 25. THANK YOU FOR YOUR ATTENTION

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