Lightning Protection For Building.

CONTENTS

Definition. Different Standards. Procedure. Case Study-JOKA Station building.

DEFINITION

Protection from physical damage of structure, equipments, human life from step and touch voltage due to external lightning ; is termed as lightning protection.

LIGHTNING CURRENT AS A SOURCE OF DAMAGE

Flash to the structure. Flash near to the structure. Flash to service connection to the structure. Flash near a service connection to the structure

R1=Risk of loss of a Human life .

R2=Risk of loss of service to public.

R3= Risk of loss of cultural heritage.

R4=Risk of loss of economic value.

INJURIES TO LIVING BEINGS DUE TO STEP AND TOUCH VOLTAGE.

DIFFERENT STANDARDS

IS 2309:1989. BS 6651. (withdrawn August 2008) BS EN/IEC 62305. NFPA 780:2014.

DIFFERENCE BETWEEN BS 6651 AND BS EN/IEC 62305

BS 6651 Std (withdrawn Aug:2008) BS EN/IEC 62305Focus on protection of the structure against lightning. Broader focus on protection against lightning including the

structure and service connected to the structure.

Specific tables relating to choice and dimension of LPS components and conductors.

Specific tables relating to sizes to types of conductor and earth electrodes. LPS components-specifically related to BS EN 50164. IEC 62561 testing regimes.

General advice(recommendation) for protection of electronic equipment with separate risk assessment.

BS EN/IEC 62305-4 is devoted entirely to protection of electric and electronic system within the structure and implemented through a single separate risk assessment.

Risk level set at 1 in 100,000 based on comparable exposures. 3 primary risk levels defined.R1:Loss of Human Life.R2:Loss of service to the public. R3: Loss of Cultural Heritage.

Mesh arrangement is promoted as the company used means of air termination network.

Mesh arrangement, protective angle method, catenary system, extensive use of air finials, all form part of or all of air termination network.

2 levels of lightning Protection mesh design:(20MX 10 M , 10M X 5 M)

4 sizes of mesh defined according to structural class of lightning protection system.Class I 5 M X 5 M , Class II 10 M X 10 M , Class III 15 M X 15 M Class IV 20 M X 20 M .

2 levels of down conductor spacing. 20M and 10 M 4 levels of down conductor spacing.Class I 10 M, Class II 10 M , Class III 15 M Class IV 20 M

DIFFERENCE BETWEEN IS 2309:1989 AND BS EN/IEC 62305

IS 2309 BS EN/IEC 62305

Is 2309 was first issued in 1963. Revised in 1969. Not a specification, gives recommendation and guidance. IS 2309:1989(Second Revision) prepared based on assistance derived from BS 6651:1985 and reformed in 2010.

BS 6651: 1989 then 1999 supersedes BS 6651:1985. For a finite period BS/EN/IEC 62305 and BS 6651 ran in parallel. As of August 2008 BS 6651 was withdrawn. Now BS EN/IEC 62305 is the recognized standard for lightning.

Protection of structure have been considered. No risk on living being has been considered.

Injuries of living being caused by electric shock inside the structure are considered since 2010.

There is no classification of protection level The current level calculated based on the probability.

Four lightning protection level has been used. For each LPL as set of maximum and minimum lightning current parameter is fixed.

Collection Area Collection Area

22

22 (3 ) ( ) (3 )cA L W H L H H 22 ( ) 2 ( )cA L W L W W H H

IS 2309 BS EN/IEC 62305

Risk is estimated on the following factors

(a) Use of structure (purpose)(b) Type construction (c) Contents(d) Degree of isolation(e) Type of (hill/ etc)

The risk to be evaluated in a structure may be as follow R1=Risk of loss of a Human life

R2=Risk of loss of service to public

R3= Risk of loss of cultural heritage

R4=Risk of loss of economic value.

Each risk has fail component.(a) due to flash on to the structure(b) flash on near the structure(c) Flash on to a line connected to a structure(d) Flash near a line connected to the structure

Protection needed if risk factor is more than 10-5

Tolerable risk RT(a) loses of human life or permanent injuries 10-5(b) loss of service to the 10-3(c) loss of cultured heritage 10-4

IS 2309 BS EN/IEC 62305

poisoning of air termination system is based on(a) Protective angle method(b) Mesh method(c) Wire air termination method

In IEC Rolling sphere method is added to three method in IS

In protective angle method no relation of angle vs height considered.

In this method there is relation between height and protective angle with class of protection shown in fig. below.

IS 2309

BS EN/IEC 62305

In mesh method, mesh size is not mentioned above 20 m height.

Mesh size is mentioned for each class of protection.

Down conductor requirement for less than 20 m height is mentioned but above 20 m height is not mentioned.

Down conductor requirement is clearly mentioned for each class of protection.

Mesh method is not applicable for sloped structure.

PROCEDURE

Risk CalculationSelection of Lightning Protection

Scheme.Rolling Sphere Method.

Protective Angle Method.

Mesh Method.

RISK CALCULATION

SELECTION OF LIGHTNING PROTECTION SCHEME

LPL I II III IV

Maximum Current.(KA)

200 150 100 100

Minimum Current.(KA) 3 5 10 16

ROLLING SPHERE METHOD

ROLLING SPHERE METHOD

Class of LPS Rolling Sphere

Radius (m)

I 20

II 30

III 45

IV 60

PROTECTIVE ANGLE METHOD

MESH METHOD

Class of LPS

Mesh Size

I 5X5

II 10X10

III 15X15

IV 20X20

IRON STRUCTURE AS ELECTRODE

CASE STUDY : RISK ANALYSIS-JOKA

CASE STUDY : RISK ANALYSIS-JOKA

CASE STUDY : RISK ANALYSIS-JOKA

CASE STUDY : JOKA

Instant 1

DDC Design

Instant 2

Instant 3

CHANGING POSITION OF AIR TERMINATION

Proposed Design

CHANGING POSITION OF AIR TERMINATION

For All rolling sphere position building is safe

Height of Air termination rod used is 1.5 M.

THANK YOU