PLS

LIGHTNING PROTECTION By Engineer Ahmed Mahdy

LIGHTNING PROTECTION SYSTEM 1. Lightning rod or air terminal to capture or pick up lightning strike. 2. Down-conductor or copper strip which is used to carry the lightning strike to the earthing system. 3. Lightning strike recorder: to record number of lightning events. 4. Earthing system: to dissipate lightning strike.

LIGHTNING PROTECTION SYSTEM How to design lightning protection system? 1. Risk assessment calculation: To identify LPS class. 2. Air termination system. 3. Down conductor. 4. Earth termination system.

LIGHTNING PROTECTION SYSTEM Risk assessment calculation Factor Definition Nd Expected yearly lightning strike frequency to the structure Nc Ng Tolerable lightning strike frequency to the structure Ae Average flash density in the region per year ( strike/km^2/year) C1 C2 Equivalent collective area of the structure in km^2 C3 Environmental coefficient C4 Structure coefficient C5 Structure contents coefficient Structure occupancy coefficient Lightning consequence coefficient

LIGHTNING PROTECTION SYSTEM Nd or expected lightning frequency calculation Nd = Ng * Ae * C1 *10^-6

LIGHTNING PROTECTION SYSTEM Ng or Average flash density in the region per year ( strike/km^2/year)

LIGHTNING PROTECTION SYSTEM Nc or Tolerable lightning strike frequency to the structure calculation Nc = 1.5∗10^−3 ������2∗������3∗������4∗������5

LIGHTNING PROTECTION SYSTEM Nc or Tolerable lightning strike frequency to the structure calculation Nc = 1.5∗10^−3 ������2∗������3∗������4∗������5

LIGHTNING PROTECTION SYSTEM Risk assessment calculation If Nd > Nc ; we need to install LPS If Nd < or = Nc ; LPS is optional. Lightining protection efficiency = ������ − ������������ ������������

LIGHTNING PROTECTION SYSTEM Applications according to protection level

LIGHTNING PROTECTION SYSTEM Conventional Franklin rod • This type of lightning protectors were made up of a typically 6 meters copper rod. • Protection radius is up to 30 meters meter in radii. • It is used for protecting small structure areas or zones such as households, water tanks, watch towers and gardens.

LIGHTNING PROTECTION SYSTEM Vertical Air termination rod design

LIGHTNING PROTECTION SYSTEM Vertical Air termination rod design Distance between two rods = ������ ������������������ − ������^������ H is height of the rod R is the rolling sphere radius

LIGHTNING PROTECTION SYSTEM

LIGHTNING PROTECTION SYSTEM Mesh Method Mesh Method used for protection of plane (flat) roof structures and should not be used on curved surfaces.

LIGHTNING PROTECTION SYSTEM Mesh Method

LIGHTNING PROTECTION SYSTEM Natural components method

LIGHTNING PROTECTION SYSTEM Down conductor design

LIGHTNING PROTECTION SYSTEM Earth termination system