Lightning-Calculations.doc

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LIGHTNING CALCULATION

CLIENT

: ACC WADI LIMITEDREV/DATE :0/18.07.05

PROJECT

: LIGHTNING ARRESTOR REQUIREMENT CALCULATIONPRE/CHKD : LB/ MK

TITLE :LIGHTNING CALCULATIONSHEET :Page 1 of 48

CONTENTS

SL.NO.

DESCRIPTION

SHEET NO.

1.0

PURPOSE

2

2.0

REFERENCES DOCUMENTS

2

3.0

ASSUMPTIONS

2

4.0

RISK FACTOR CALCULATION

7

5.0

STRIP SIZE CALCULATION

32

6.0

RESULT

46

1.0 PURPOSE

The calculations are done for the following purposes :

a) Lightning protection requirement for Old wadi Cement plant,Power plant and Colony Area.

b) To estimate the number of Lightning electrodes required at the above area.

c) To prove that the maximum value of resistance of the earthing system shall not be more than 3 ohms as per 12.3.1 of IS 2309:1989 .

2.0 REFERENCE DOCUMENTS, CODES AND STANDARDS

a) IS: 2309-1989-Indian Standard Code of Practice for Protection against Lightning.& NFPA78.

3.0 ASSUMPTIONS & RECOMMENDED DESIGN PROCEDURE.

a) Soil resistively is equal to 312 ohm-m , which is assumed to be uniform throughout the plant.

b) Pipe electrode in contact with earth is 300 cm and the diameter of the pipe electrode is 3.8 cm .

c) The effect of interconnection and links between other earthing grids is ignored for the purpose of this calculation.

3.1Protected Structure

Common structures are structures used for ordinary whether commercial, Industrial, institutional or research.

3.2Need for Protection

3.2.1 Desirability of providing lightning protection shall be assessed either by calculating the risk index or by judgement. Structures with inherent explosive risks like factories, fuel tanks etc. need the highest possible class of lightning protection system. Other structures where large number of people congregate, essential public services are concerned, tall/isolated structures, structures of historic and cultural importance should be provided with lightning protection system irrespective of risk index.

3.2.2Risk Index Weighting Factors

Indian standard recommends the following factors which form the basis of calculating the risk index.

a) Weighting factor A Use of structure (Table 1 A).

b) Weighting factor B Type of Construction (Table 1 B)

c) Weighting factor C Contents or consequential effects (Table 1C)

d) Weighting factor D Degree of Isolation (Table 1D)

e) Weighting factor E Type of Country (Table 1E)

Depending upon the characteristic features of above factors, various weighting factors are given in Table 1A to 1E of IS:2309. The probability of the structure being struck by lightning in one year is the product of lightning flash density and the effective collection area of the structure to be protected.

The probable number of strikes/year (Risk) is:

P = Ac * Ng * 10 6

Ng = Number of lightning flashes to ground per Km 2 per year.

Ac = Effective area of collection of the structure.

Risk, P, multiplied by weighting factors A to E gives the risk index.

3.2.3 If the value of risk index is less than 10 -5, then in the absence of other Overriding consideration, protection shall not be necessary.

3.2.4If the risk index is more than 10 -5 then sound reasons shall be necessary to

Support the decision of not providing the lightning protection.

3.3Size and Material of Conductors

3.3.1 The materials of air termination network, down conductors and earth terminals shall be GI as per Table 3 of IS 2309:1989.

3.3.2 Lightning currents have very short duration. Therefore, thermal factors are of little consequence in deciding the cross-section of the conductor. The minimum size of the various components of the system are given below:

Sl.No

Item

Material

Size

1.Vertical Air TerminationsCopper

20 mm dia,1000 mm Long

G.S

20 mm dia,1000 mm Long

2.Horizantal air Terminationscopper 20 X 3 mm Flat

G.S

25X 6mm Flat.

3.Down Conductors

Same as Horizontal Air Terminations.

4.Earth Terminations

a) Horizontal conductorsCu. Strip32 X 6 mm

G.S Strip50 X 6 mm

b) Rod Electrodes

Cu

20mmDia, 3000 mm Long.

Steel


c)Pipe Electrode

Steel


3.4 Air termination Systems

Air Terminations: The vertical and horizontal conductors or combination of both, installed over or near the structure to attract the lightning stroke to themselves are called air terminations.

3.4.2 Protective Zone : The space around the air terminations in which there is almost no

probability

Direct lightning discharge is called the protective zone of air termination. Protective zones of various arrangements shall be as given in IS: 2309 - 1989 etc. for correctness.

3.4.3 The angle between vertical line passing through the conductor and side of protective zone is called protective angle.

3.4.4 Horizontal air terminations: Arranged along the contours such as parapets, ridges and edges of the roof and wherever necessary, over the flat surfaces, horizontal air termination network form basic protection arrangement, if roof of the building has large horizontal dimensions.

3.4.5Protective angle of horizontal air termination is 45 for normal protection and upto 30 if higher protection is needed.

3.4.6 Protective angle for two horizontal air terminations, spaced at a distance not greater than twice the height, shall be used within the space between conductors and 45 and 30 respectively if higher protection is needed.

3.4.7 The spacing, between adjacent horizontal air terminations shall not be more than 10 metres and no part of the roof shall be more than 5 metres away from the nearest horizontal conductor.

3.4.8 Layout of Horizontal Air Terminations

a) A horizontal air termination shall run along the periphery of the roof.

b) Additional parallel horizontal conductors shall be provided if spacing between the

conductors is more than 10 metres or any part of the roof is more than 5 metres

away from the nearest horizontal conductor.

C) Conductors shall be interconnected to form a closed loop.

3.4.9 Vertical Air Terminations

a) Vertical air terminations shall be used for very high structures with small base area.

b) Protective angles of vertical air terminations shall be same as given for horizontal air

terminations under clause 3.4.5/.6.

c) Vertical air terminations shall project at least 300 mm above the protected structure.

d) All the vertical air terminations provided on the same structure shall be interconnected.

e) All the air termination network shall be effectively secured to the roof against

overturning. The fasteners shall be of the same material as the conductor to avoid

bimetallic corrosion.

3.4.10 Where a structure has two elevations, out of which lower is projecting outside the higher elevation such that the network in higher elevation does not protect the lower elevation, both networks shall be interconnected by connecting the higher elevation down conductors to the lower network.

3.4.11 If a particular small portion in the structure is projecting above the level of horizontal conductors by more than 1000 mm, a separate network shall be formed for the same.

3.4.12 All the metal piping, railing, etc. on the roof shall be bonded to the protective network with a bolted connection.

3.5 Down Conductors

The conductors which connect air terminations to earth terminations are called down

Conductors.

3.5.1 Size and material of the down conductors shall be given under clause 3.3.

3.5.2 Number

a) As per IS.2039, a structure having a base area less than 100 sq. mtr shall be provided with only one down conductor. Chimneys, whose over all width at the top or diameter is less than 1.5 metres shall be provided with only one down conductor.

b) For buildings having base area more than 100 m 2 , the number of down conductors shall be

smaller

the number obtained by the following two criteria

i) one down conductor for first 100 m 2 area plus one for every additional 300 m 2 area or part

thereof

ii) one down conductor for every 30 metres of periphery

Non-conducting chimneys whose overall width at the top or diameter is more than 1.5 metres shall be provided two down conductors. Structures on rocky terrain where testing and inspection is difficult shall be provided with minimum two down conductors.

As per BS: 6651 1999 at least one down conductor should be provided for each 20 mtr or part thereof of the perimeter at roof level. Structures greater than 20-mtr height, shall have a down conductor per 10 mtr or part thereof.

3.5.3 Route of Down Conductors

a) Unless aesthetic and architectural considerations prohibit, down conductors shall be uniformly

distributed around the outside walls of the structure.

b) The path between the air terminations and earth terminations shall be as direct as possible and shall avoid sharp bends upturns and kinks.

c) No deep re-entrant loop, in which length of the conductor forming the loop is more than 8 times the width of open side of the loop, shall be recommended. This is shown in Figure-1 and is avoided to prevent large inductive voltage drop across the open side of the loop.

d) In a building cantilevered from first storey onwards, the down conductors shall not follow the

contour of the building as shown in Figure-2.

e) Down conductors shall not be attached to lift shafts.

f) When suitable external route for down conductors is not possible or advisable, the conductors may run in air space provided by non-metallic, non-combustible ducts not smaller than 75 x 15 mm or in any vertical, service duct running through the height of the building, provided it does not contain any unarmoured, non-metal sheath cable.

g) Down conductors may be embedded in the wall of the structure. In such case, reinforcing bars shall be bonded to the down conductor.

h) In case metallic object such as pipes, structures etc. exists in the vicinity of down conductors,

there is a risk of side flash over between the down conductor and these objects. In such cases, the object shall be bonded to or installed on the basis of the recommendations given under

Clause3.7.1.

Each down conductor shall be provided with testing point as discussed in Clause 3.7.2 (f)

j)Holes in cornice and parapet walls shall be used for the passage of down conductors, wherever possible.

3.6Earth Terminations

3.6.1 Earthing conductors embedded in the soil and designed for the safe discharge of lightning currents into the soil are called earth terminals.

3.6.2 Down conductor shall be provided an earth electrode and all earth electrodes shall be interconnected.

3.6.3 Earthing resistance of earth terminations shall be such that the combined resistance is not more than 3 ohms. In case, the earthing resistance is not within limits, the earth electrodes shall be located in treated earth pit.

3.6.4 Disconnecting facility shall be provided in some of the earth electrodes so that it is possible to measure the earthing resistance.

3.6.5 Lightning protective earthing system may be interconnected with operational and safety earthing system.

3.6.6 Earthing conductors shall not be more than 1.5 to 2.0 metres away from the structure except when high temperatures are likely to be encountered in subsoil or when sufficient space near the structure is not available.

3.6.7 Metal pipes and other structures buried in earth shall be bonded to or isolated from the

earthing conductors on the basis of the recommendation given under clause 3.7.1.

3.6.7 Earth Electrodes

a) The use of rod/pipe/plate electrodes is permissible. their choice will depend upon the site conditions, soil resistivity and economic considerations. In general, the use of pipe electrodes is recommended.

b) The material of earth electrodes shall be either galvanised steel or copper. The choice will depend upon the material of the air termination, down conductors and soil resistivity. It is preferable to use the same material throughout the system.

Horizontally buried interconnecting conductors shall be laid at minimum 600 mm depth.

Earthing system shall be in accordance with IS: 3043.Minimum spacing between rod/pipe electrodes and plate electrodes shall be 6 and 8 metres respectively.

4.0 Lightning protection for structure- Evaluation of lightning flash

density,collection area of structure and overall risk factor.

4.1 Evaluation of lightning ground flash density:

The lightning ground flash density can be estimated using the following formula indicated in IEC 61024-1-1.

Lightning groung flash density Ng=0.04x(Td) 1.25 per Km2 per year

Where Td is the number of thunderstorm days per year

In Gulbarga the Annual thunderstorm days is 34 days( As per IS 2309:1989 Page number 5).Therefore the lightning ground flash density per Km2 per year is calculated using the above formula as follows

Ng=0.04x(34) 1.25

=3.284 per Km2 per year

which is commen throughout the plant area

4.2 Evaluation of probable No of strikes for the structure per year P:

Probable No of strikes for the structure per year P can be calculated using the formula

P= Ng x Ac x 10 6 per year

Where Ac is the equivalent collection area of structures on a plain surface.

Ac=(L XB)+2(L X H)+2(B X H)+ H2 For complex structure it can be calculated based on the guidelines given in item 4.2 of

IEC 61024-1-1 standard.

The risk factor P is multiplied by the product of the weighting factors( Table 1A-1E of IS

2309:1989).

If the overall risk factor is greater than 10-5 protection is required for the structure.

Calculation for the overall risk factor is done below for each building in the Old Wadi Cement

plant, Colony and Power plant.

OLD WADI CEMENT PLANT

BULK LOADING SILO:

Diameter(D)

: 11 M

Height (H)

: 49.5 M

Lightning Flashes/Sq.Km / year(Ng): 3.284 (AS CALCULATED ABOVE)

-Rating factor for Wadi

Weighing Factors

A

: 1.0

B

: 0.8

C

: 0.8

D

: 1.0

E

: 0.3

Overall weighing Factors

: A x B x C x D x E

: 1.0 x 0.8 x 0.8 x 1.0 x 0.3

: 0.192

Collection Area AC

: H2

: (49.5) 2

: 7693.785 m2Probable no.of strikes for the

: Ac x Ng x 10-6

structure per year P

: 7693.785 x 3.284 x 10-6

: 2.526 x 10-2Therefore, the overall risk Factor

: P x Overall Weighing Factor

: 2.526 x 10-2 x 0.192

: 4.84 x 10-3 which is greater than 10-5Therefore for Bulk loading Silo Lightning Protection is essential.

CEMENT STORAGE SILO:

Diameter(D)

: 10 M

Height (H)

: 29.8 M

Lightning Flashes/Sq.Km / year(Ng): 3.284

- Rating factor for Wadi

Weighing Factors

A

: 1.0

B

: 0.8

C

: 0.8

D

: 1.0

E

: 0.3


: A x B x C x D x E

: 1.0 x 0.8 x 0.8 x 1.0 x 0.3

: 0.192

Collection Area AC

: H2

: (29.8) 2


: Ac x Ng x 10-6


: 2788.45 x 3.284 x 10-6



: 9.157 x 10-3 x 0.192

: 1.75 x 10-3 which is greater than 10-5Therefore for Cement storage Silo Lightning Protection is essential.

KILN NO.3 PREHEATER:

Length (L)

: 19.2 M

Width ( W)

: 16 M

Height (H)

: 106 M



Weighing Factors

A

: 1.0

B

: 0.8

C

: 0.8

D

: 1.0

E

: 0.3


: A x B x C x D x E

: 1.0 x 0.8 x 0.8 x 1.0 x 0.3

: 0.192

Collection Area AC

: (L x W) + 2(L x H) + 2(W x H) +

: (19.2x16)+2(19.2x106)+2(16x106)+


: AC x Ng x 10-6structure per year P

: 1290105.505 x 3.284 x 10-6

: 4.236

Therefore, the overall risk Factor


: 4.236 x 0.192

: 0.8133 which is greater than 10-5Therefore Lightning Protection is essential for Kiln No.3 Preheater.

CEMENT MILL BUILDING :

Length (L)

: 34 M

Width ( W)

: 36 M

Height (H)

: 11.5 M

Length (L)

: 22 M

Width ( W)

: 36 M

Height (H)

: 16.5 M



Weighing Factors

A

: 1.0

B

: 1.0

C

: 0.8

D

: 1.0

E

: 0.3


: A x B x C x D x E

: 1.0 x 1.0 x 0.8 x 1.0 x 0.3

: 0.24

Collection Area AC

: (L x W) + 2(L x H) + 2(W x H) +

: (12x36)+2(12x11.5)+(36x11.5)+

(22x36)+2x(22x16.5)+(36x16.5)+



: 4088.86 x 3.284 x 10-6



: 1.34 x 10-2 x 0.24

: 3.22 x 10-3 which is greater than 10-5Therefore Lightning Protection is essential for Cement Mill Building.

CEMENT MILL 4 & 5 BUILDINGS:

Length (L)

: 34 M

Width ( W)

: 36 M

Height (H)

: 16.5 M



Weighing Factors

A

: 1.0

B

: 1.0

C

: 0.8

D

: 1.0

E

: 0.3


: A x B x C x D x E

: 1.0 x 1.0 x 0.8 x 1.0 x 0.3

: 0.24

Collection Area AC

: (L x W) + 2(L x H) + 2(W x H) +

: (34x36)+2(34x16.5)+2(36x16.5)+



: 4388.86 x 3.284 x 10-6



: 1.44 x 10-2 x 0.24

: 3.46 x 10-3 which is greater than 10-5Therefore Lightning Protection is essential for Cement Mill 4 & 5 Buildings .

CEMENT MILL CONTROL ROOM:

Length (L)

: 16 M

Width ( W)

: 7.5 M

Height (H)

: 11.5 M



Weighing Factors

A

: 1.0

B

: 1.0

C

: 0.8

D

: 1.0

E

: 0.3


: A x B x C x D x E

: 1.0 x 1.0 x 0.8 x 1.0 x 0.3

: 0.24

Collection Area AC

: (L x W) + 2(L x H) + 2(W x H) +

: (4x16)+(3.5X6)+(5.25x7.5)+(5.25x13)+ (6X5.25)

+(7X5.25)+2X(11.5X3.5)+(11.5X4)+5/4



: 552.32 x 3.284 x 10-6



: 1.81 x 10-3 x 0.24

: 4.3526 x 10-4 which is greater than 10-5Therefore Lightning Protection is essential for Cement Mill Control room .

PACKING PLANT:

Length (L)

: 36.9 M

Width ( W)

: 27 M

Height (H)

: 24.75 M



Weighing Factors

A

: 1.0

B

: 1.0

C

: 0.8

D

: 1.0

E

: 0.3


: A x B x C x D x E

: 1.0 x 1.0 x 0.8 x 1.0 x 0.3

: 0.24

Collection Area AC

: (L x W) + 2(L x H) + 2(W x H) + : (23.4x27)+(13.5X15.5)+(24.75x27)+(24.75x11.5)+

(8.5X13.5)+(8.5X15.5)+(36.9X8.5)+

(15.5X8.5)+5/4



: 4890.132 x 3.284 x 10-6



: 1.6 x 10-2 x 0.24

: 3.85 x 10-3 which is greater than 10-5Therefore Lightning Protection is essential for Cement Packing plant.

CEMENT SILO EXPANSION AND PACKING PLANT:

CEMENT SILO:

Diameter(D)

: 12 M

Height (H)

: 34.5+2.5=37 M



Weighing Factors

A

: 1.0

B

: 0.8

C

: 0.8

D

: 1.0

E

: 0.3


: A x B x C x D x E

: 1.0 x 0.8 x 0.8 x 1.0 x 0.3

: 0.192

Collection Area AC

: H2

: (37) 2


: Ac x Ng x 10-6


: 4298.66 x 3.284 x 10-6



: 1.41 x 10-2 x 0.192

: 2.71 x 10-3 which is greater than 10-5Therefore for Cement Silo Lightning Protection is essential.

PACKING PLANT:

Length (L)

: 14 M

Width ( W)

: 16 M

Height (H)

: 30 M



Weighing Factors

A

: 1.0

B

: 1.0

C

: 0.8

D

: 1.0

E

: 0.3


: A x B x C x D x E

: 1.0 x 1.0 x 0.8 x 1.0 x 0.3

: 0.24

Collection Area AC

: (L x W) + 2(L x H) + 2(W x H) + : (14x16)+2(14X30)+2(16x30)+

: 2024 m2Probable no.of strikes for the


: 2024 x 3.284 x 10-6



: 6.646x 10-3 x 0.24

: 1.59 x 10-3 which is greater than 10-5Therefore Lightning Protection is essential for Cement Packing plant.

KILN NO. 1 & 2 PREHEATER:

Length (L)

: 11 M

Width ( W)

: 24 M

Height (H)

: 69.36 M



Weighing Factors

A

: 1.0

B

: 0.8

C

: 0.8

D

: 1.0

E

: 0.3


: A x B x C x D x E

: 1.0 x 0.8 x 0.8 x 1.0 x 0.3

: 0.192

Collection Area AC

: (L x W) + 2(L x H) + 2(W x H) +

: (11x24)+2(11x69.36)+2(24x69.36)+



: 20225.142 x 3.284 x 10-6



: 6.64 x 10-2 x 0.192

: 1.27 x 10-2 which is greater than 10-5Therefore Lightning Protection is essential for Kiln No.1 & 2 Preheater.

RAW MILL 4& 5:

Length (L)

: 60.1 M

Width ( W)

: 36 M

Height (H)

: 31.35 M



Weighing Factors

A

: 1.0

B

: 1.0

C

: 0.8

D

: 1.0

E

: 0.3


: A x B x C x D x E

: 1.0 x 1.0 x 0.8 x 1.0 x 0.3

: 0.24

Collection Area AC

: (L x W) + 2(L x H) + 2(W x H) +

: (60.1x36)+2(60.1x31.35)+2(36x31.35)+



: 11275.132 x 3.284 x 10-6



: 3.7 x 10-2 x 0.192

: 7.1 x 10-3 which is greater than 10-5Therefore Lightning Protection is essential for Raw mill 4 & 5.

COAL MILL :

Length (L)

: 46 M

Width ( W)

: 33 M

Height (H)

: 44 M



Weighing Factors

A

: 1.0

B

: 0.8

C

: 0.8

D

: 1.0

E

: 0.3


: A x B x C x D x E

: 1.0 x 0.8 x 0.8 x 1.0 x 0.3

: 0.192

Collection Area AC

: (L x W) + 2(L x H) + 2(W x H) +

: (46x33)+2(46x44)+2(33x44)+



: 14549.04 x 3.284 x 10-6



: 4.77 x 10-2 x 0.192

: 9.17 x 10-3 which is greater than 10-5Therefore Lightning Protection is essential for Coal mill .

POWER PLANT AREA :

DG SET BUILDING:

Length (L)

: 52 M

Width ( W)

: 20 M

Height (H)

: 15 M



Weighing Factors

A

: 1.0

B

: 0.4

C

: 1.0

D

: 1.0

E

: 0.3


: A x B x C x D x E

: 1.0 x 0.4 x 1.0 x 1.0 x 0.3

: 0.12

Collection Area AC

: (L x W) + 2(L x H) + 2(W x H) +

: (52x20)+2(20x15)+



: 2346.5 x 3.284 x 10-6



: 7.705 x 10-3 x 0.12

: 9.247 x 10-4 which is greater than 10-5Therefore Lightning Protection is essential for DG Set Building .

3 NOS. OF 1 X 25 MW TG BUILDING :

Length (L)

: 52.5 M

Width ( W)

: 26.7 M

Height (H)

: 23.56 M



Weighing Factors

A

: 1.0

B

: 0.4

C

: 1.0

D

: 1.0

E

: 0.3


: A x B x C x D x E

: 1.0 x 0.4 x 1.0 x 1.0 x 0.3

: 0.12

Collection Area AC

: (L x W) + 2(L x H) + 2(W x H) +

: (8x52.5)+(18.7x37.5)+(14.5x12.2)+2(8x14.86)

+(52.5x14.86)+2(18.7x23.56)+2(14.5x15.26)

+

: 5382.67 m2There are 3 Nos of 1x25 MW Generator

Areas. Therefore Total collection area is : 3x5382.67 m2

: 16146 m2

Probable no.of strikes for the


: 16146 x 3.284 x 10-6



: 5.3 x 10-2 x 0.12

: 6.36 x 10-3 which is greater than 10-5Therefore Lightning Protection is essential for TG Building .

CHIMNEY -1

Diameter(D)

:4 M

Height (H)

: 113 M



Weighing Factors

A

: 1.0

B

: 0.4

C

: 1.0

D

: 2.0

E

: 0.3


: A x B x C x D x E

: 1.0 x 0.4x 1.0 x 2.0 x 0.3

: 0.24

Collection Area AC

: H2

: (113) 2


: Ac x Ng x 10-6


: 40094.66 x 3.284 x 10-6

: 13.16x 10-2Therefore, the overall risk Factor


: 13.16 x 10-2 x 0.24

: 3.16 x 10-2 which is greater than 10-5Therefore for Chimney Lightning Protection is essential.

CHIMNEY -2

Diameter(D)

:4 M

Height (H)

: 106.8 M



Weighing Factors

A

: 1.0

B

: 0.4

C

: 1.0

D

: 2.0

E

: 0.3


: A x B x C x D x E

: 1.0 x 0.4x 1.0 x 2.0 x 0.3

: 0.24

Collection Area AC

: H2

: (106.8) 2


: Ac x Ng x 10-6


: 35815.59 x 3.284 x 10-6



: 11.76 x 10-2 x 0.24

: 2.82 x 10-2 which is greater than 10-5Therefore for Chimney Lightning Protection is essential.

COLONY AREA

WATER TANK (454000 LITRES):

Diameter(D)

:13.90 M

Height (H)

: 23.40 M



Weighing Factors

A

: 0.7

B

: 0.4

C

: 0.8

D

: 1.0

E

: 0.3


: A x B x C x D x E

: 0.7 x 0.4x 0.3x 1.0 x 0.3

: 0.0252

Collection Area AC

: H2

: (23.4) 2

: 1719.338 m2


: 1719.338 x 3.284 x 10-6Probable no.of strikes for the

: Ac x Ng x 10-6



: 5.67 x 10-3 x 0.0252

: 1.428 x 10-4 which is greater than 10-5Therefore for Water tank Lightning Protection is essential.

WATER TANK (227000 LITRES) 2 Nos:

Diameter(D)

:9.4 M

Height (H)

: 24.55 M



Weighing Factors

A

: 0.7

B

: 0.4

C

: 0.8

D

: 1.0

E

: 0.3


: A x B x C x D x E

: 0.7 x 0.4x 0.3x 1.0 x 0.3

: 0.0252

Collection Area AC

: H2

: (24.55) 2


: Ac x Ng x 10-6


: 1892.485 x 3.284 x 10-6



: 6.21 x 10-3 x 0.0252


KAGINA GUEST HOUSE:

Length (L)

: 40 M

Width ( W)

: 15 M

Height (H)

: 10 M



Weighing Factors

A

: 1.2

B

: 0.4

C

: 1.7

D

: 0.4

E

: 0.3


: A x B x C x D x E

: 1.2 x 0.4 x 1.7 x 0.4 x 0.3

: 0.0979

Collection Area AC

: (L x W) + 2(L x H) + 2(W x H) +

: (40x15)+2(40x10)+2(15x10) +



: 2014 x 3.284 x 10-6



: 6.613 x 10-3 x 0.0979

: 6.47 x 10-4 which is greater than 10-5Therefore Lightning Protection is essential for Kagina Guest House .

MANAGEMENT TRAINEE HOSTEL:

Length (L)

: 17 M

Width ( W)

: M

Height (H)

: 10 M



Weighing Factors

A

: 1.2

B

: 0.4

C

: 1.7

D

: 0.4

E

: 0.3


: A x B x C x D x E

: 1.2 x 0.4 x 1.7 x 0.4 x 0.3

: 0.0979

Collection Area AC

: (L x W) + 2(L x H) + 2(W x H) +

: (40x15)+2(40x10)+2(15x10) +



: 2014 x 3.284 x 10-6



: 6.613 x 10-3 x 0.0979

: 6.47 x 10-4 which is greater than 10-5Therefore Lightning Protection is essential for Management Trainee hostel .

V. P BUNGALOW:

Length (L)

: 22.76 M

Width ( W)

: 15.25M

Height (H)

: 6.80 M



Weighing Factors

A

: 1.2

B

: 0.4

C

: 1.7

D

: 0.4

E

: 0.3


: A x B x C x D x E

: 1.2 x 0.4 x 1.7 x 0.4 x 0.3

: 0.0979

Collection Area AC

: (L x W) + 2(L x H) + 2(W x H) + : (10x22.76)+(5.58x14.11)+(10x4.1)+2(8.65X4.1)

+(5.58X6.8)+2(14.11X6.8)+(15.25X6.8)+



: 861.53 x 3.284 x 10-6



: 2.829 x 10-3 x 0.0979

: 2.76 x 10-4 which is greater than 10-5Therefore Lightning Protection is essential for Vice president Bungalow .

SPORTS CLUB:

Length (L)

: 55 M

Width ( W)

: 20M

Height (H)

: 18 M



Weighing Factors

A

: 1.3

B

: 0.4

C

: 1.7

D

: 1.0

E

: 0.3


: A x B x C x D x E

: 1.3 x 0.4 x 1.7 x 1.0 x 0.3

: 0.2652

Collection Area AC

: (L x W) + 2(L x H) + 2(W x H) + : (55x20)+2(55x18)+2(20x18)+

: 4817.36

Probable no.of strikes for the


: 4817.36 x 3.284 x 10-6



: 1.58 x 10-4 x 0.2652

: 4.1955 x 10-3 which is greater than 10-5Therefore Lightning Protection is essential for Sports club building .

QUARY CRUSHER:

Length (L)

: 24 M

Width ( W)

: 12M

Height (H)

: 15 M



Weighing Factors

A

: 1.0

B

: 0.8

C

: 0.8

D

: 1.0

E

: 0.3


: A x B x C x D x E

: 1.0 x 0.8 x 0.8 x 1.0 x 0.3

: 0.192

Collection Area AC

: (L x W) + 2(L x H) + 2(W x H) +

: (24x12)+2(24x15)+2(12x15)+



: 2074.9 x 3.284 x 10-6



: 0.6812 x 10-2 x 0.192

: 1.3 x 10-4 which is greater than 10-5Therefore Lightning Protection is essential for Quary crusher .

WATER TANK IN RIVER PUMP AREA 3 Nos:

Diameter(D)

:4 M

Height (H)

: 12 M



Weighing Factors

A

: 0.7

B

: 0.4

C

: 0.8

D

: 1.0

E

: 0.3


: A x B x C x D x E

: 0.7 x 0.4x 0.3x 1.0 x 0.3

: 0.0252

Collection Area AC

: H2

: (12) 2


: Ac x Ng x 10-6


: 452.16 x 3.284 x 10-6



: 1.48 x 10-3 x 0.0252


5.0 Resistance of Pipe Electrode (Ref. 9.2.2 of IS: 3043-1987)

Re = 100 x ( loge 4 x l 2 x ( x l d

Where l = length of the rod or pipe = 300 cm.

d = diameter of the rod or pipe = 3.8 cm.

( = resistivity of soil = 312 -m assumed uniform.

Re = 100 x 312 loge 4 x 300 2 x ( x 300 3.8

= 16.55 loge 315.789

= 41.36 .

Resistance of the Earth Strip 50 x 6 G.I Flat

5.1 Old Wadi plant

5.1.1 Bulk loading silo

Rs= 100 ( Log e 2L2

2( L wt

L=Estimated Length Strip

: 12500 cm

Width of the Strip (t)

: 50 x 6 mm

Depth of the Buried Strip (W)

: 60 cm

Rs= 100 x 312 Log e 2 x 125002 = 2.38 (

2x3.14x12500 60x5

There are 3 Nos of earth pits are used, therefore

Re= Re /3 = 41.36 / 3 = 13.78 (Rt= Re x Rs= 13.78 X 2.38 = 2.03 ( Re + Rs 13.78+2.38

Thus the Total resistance is less than 3 ohms .

50x6 G.I Flat strip is selected for vertical down conductor and horizondal earth conductor.

5.1.2 Cement storage silo

Rs= 100 ( Log e 2L2

2( L wt


: 14640 cm

Width of the Buried Strip (t)

: 50 x 6 mm


: 60 cm

Rs= 100 x 312 Log e 2 x 146402 = 2.0 (

2x3.14x14640 60x5


Re= Re /2 = 41.36 / 2= 20.68 ( Rt= Re x Rs= 20.68 X 2 = 1.8 ( Re + Rs 20.68+2.



5.1.3 Kiln No:3 Preheater

Rs= 100 ( Log e 2L2

2( L wt


: 30160 cm


: 50 x 6 mm


: 60 cm

Rs= 100 x 312 Log e 2 x 301602 = 1.1172 (

2x3.14x30160 60x5


Re= Re /2 = 41.36 / 2= 20.68 (Rt= Re x Rs= 20.68 X 1.1172 = 1.054 ( Re + Rs 20.68+1.1172.



5.1.4 Cement Mill Building

Rs= 100 ( Log e 2L2

2( L wt


: 20405.6 cm


: 50 x 6 mm


: 60 cm

Rs= 100 x 312 Log e 2 x 20405.62 = 1.568 (

2x3.14x20405.6 60x5


Re= Re /2 = 41.36 / 2= 20.68 (Rt= Re x Rs= 20.68 X 1.568 = 1.4469 ( Re + Rs 20.68+1.568.



5.1.5 Cement Mill Building 4 & 5

Rs= 100 ( Log e 2L2

2( L wt


: 20405.6 cm


: 50 x 6 mm


: 60 cm

Rs= 100 x 312 Log e 2 x 20405.62 = 1.568 (

2x3.14x20405.6 60x5


Re= Re /2 = 41.36 / 2= 20.68 (Rt= Re x Rs= 20.68X 1.568 = 1.4469 ( Re + Rs 20.68+1.568.



5.1.6 Cement Mill Control Room

Rs= 100 ( Log e 2L2

2( L wt


: 10394.8 cm


: 50 x 6 mm


: 60 cm

Rs= 100 x 312 Log e 2 x 10394.82 = 2.799 (

2x3.14x10394.8 60x5

Only one earth pit is used, therefore

Re= Re /1= 41.36 / 1= 41.36 (Rt= Re x Rs= 41.36 X 2.799 = 2.6 ( Re + Rs 41.36+2.799.



5.1.7 Packing Plant

Rs= 100 ( Log e 2L2

2( L wt


: 17730 cm


: 50 x 6 mm


: 60 cm

Rs= 100 x 312 Log e 2 x 177302 = 1.77 (

2x3.14x17730 60x5





5.1.8 Cement silo Expansion

Rs= 100 ( Log e 2L2

2( L wt


: 32033 cm


: 50 x 6 mm


: 60 cm

Rs= 100 x 312 Log e 2 x 320332 = 1.07 (

2x3.14x32033 60x5





5.1.9 Kiln No:1& 2 Preheater

Rs= 100 ( Log e 2L2

2( L wt


: 25672 cm


: 50 x 6 mm


: 60 cm

Rs= 100 x 312 Log e 2 x 256722 = 1.285 (

2x3.14x25672 60x5

Only one earth pit is used, therefore

Re= Re /1= 41.36 / 1= 41.36 (Rt= Re x Rs= 41.36X1.285 = 1.240 ( Re + Rs 41.36+1.285.



5.1.10 Raw Mill 4 & 5

Rs= 100 ( Log e 2L2

2( L wt


: 56730cm


: 50 x 6 mm


: 60 cm

Rs= 100 x 312 Log e 2 x 567302 = 0.64 (

2x3.14x56730 60x5





5.1.11 Coal Mill

Rs= 100 ( Log e 2L2

2( L wt


: 52000cm


: 50 x 6 mm


: 60 cm

Rs= 100 x 312 Log e 2 x 520002 = 0.64 (

2x3.14x52000 60x5





5.2 Power plant

5.2.1 DG Set

Rs= 100 ( Log e 2L2

2( L wt


: 63800cm


: 50 x 6 mm


: 60 cm

Rs= 100 x 312 Log e 2 x 638002 = 0.578 (

2x3.14x63800 60x5


Re= Re /3= 41.36 / 3= 13.78 (Rt= Re x Rs= 13.78X0.578 = 0.55 ( Re + Rs 13.78+0.578



5.2.2 T.G CPP Building

Rs= 100 ( Log e 2L2

2( L wt


: 81802.2cm


: 50 x 6 mm


: 60 cm

Rs= 100 x 312 Log e 2 x 81802.22 = 0.588 (

2x3.14x81802.2 60x5


Re= Re /4= 41.36 / 4= 10.34 (Rt= Re x Rs= 10.34X0.588 = 0.5532 ( Re + Rs 10.34+0.588



5.2.3 Chimney-1

Rs= 100 ( Log e 2L2

2( L wt


: 23659cm


: 50 x 6 mm


: 60 cm

Rs= 100 x 312 Log e 2 x 236592 = 1.379 (

2x3.14x23659 60x5





5.2.4 Chimney-2

Rs= 100 ( Log e 2L2

2( L wt


: 24899cm


: 50 x 6 mm


: 60 cm

Rs= 100 x 312 Log e 2 x 248992 = 1.379 (

2x3.14x24899 60x5





5.3 Colony5.3.1 Water Tank (454000 Litres)

Rs= 100 ( Log e 2L2

2( L wt


: 15875.2cm


: 50 x 6 mm


: 60 cm

Rs= 100 x 312 Log e 2 x 15875.22 = 1.94 (

2x3.14x15875.2 60x5





5.3.2 Water Tank (227000 Litres)

Rs= 100 ( Log e 2L2

2( L wt


: 13329.2cm


: 50 x 6 mm


: 60 cm

Rs= 100 x 312 Log e 2 x 13329.22 = 2.26 (

2x3.14x13329.2 60x5





5.3.3 Kagina Guest house

Rs= 100 ( Log e 2L2

2( L wt


: 22100cm


: 50 x 6 mm


: 60 cm

Rs= 100 x 312 Log e 2 x 221002 = 1.46 (

2x3.14x22100 60x5





5.3.4 V.P Bungalow

Rs= 100 ( Log e 2L2

2( L wt


: 14194m


: 50 x 6 mm


: 60 cm

Rs= 100 x 312 Log e 2 x 141942 = 2.14 (

2x3.14x14194 60x5





5.3.5 Sports Club

Rs= 100 ( Log e 2L2

2( L wt


: 33200m


: 50 x 6 mm


: 60 cm

Rs= 100 x 312 Log e 2 x 332002 = 1.027 (

2x3.14x33200 60x5


Re= Re /2= 41.36 / 2= 20.68 (

Rt= Re x Rs= 20.36X1.027 = 0.97 ( Re + Rs 20.36+1.027.



6.0 RESULTS

a) 38 mm ID,3 M long pipe suggested for earth pit refer drg. No. E-ECB-A565-LTNG-001(Sheet 2 of 4).b) 50 x 6 G.I flat strip suggested for down conductors and burried conductor.

c) The No.of Lightning conductors and earth pits required are as shown in the drawing.

d) The Lightning conductor shall be placed at the topmost height of every Building.

e) The Location of Earthpits shall be fixed as per the site conditions.

f) The Earthing Resistance shall be maintained below 3 ohms.

g) The down conductors shall be insulated from the metal structures inorder to reduce the leakage current.

h) All the down conductors shall have a test Link arrangement between the arrestor and Earthpit.

Old Wadi plant Area:

Location of the Lightning ConductorNo.of Lightning Conductor.No.of Earth PitsRemarks

KilnNo-1&2 Preheater22

Bulk loading cement silo 23One Arrestor at each silo.

Packing plant

12Shall be placed at the topmost structure.

Cement storage silo

22Arrestor Shall be placed at the topmost structure.

Cement mill building 4&5

22Arrestor Shall be placed at topmost structure.

Raw mill 4&5


Coal mill


Kiln No.3 preheater


Cement silo expansion

444 silo in a line.In each silo one arrestor shall be placed.

Cement mill building


Colony Area

Note: The Horizotal Air terminations to be Placed as marked in the drawing for Water Tanks and Gust houses.

DescriptionNo.of ArrestorNo.of Earth PitRemarks

Water Tank (2 Nos)

22One Arrestor is placed in each Tank. So no need to provide additional arrestor.

Kagina guest house

12One Arrestor is already existing No need to provide additional arrestor.

Management trainee hostel

12One Arrestor is already existing No need to provide.

V.P Bungalow 12One Arrester is already existing No need to provide.

Sports club

22One Arrestor is placed, one more should be placed.

Power plant Area

Note: The Horizotal Air terminations to be Placed as marked in the drawing for D.G set building & T.G building.

As the Chimneys are provided with the 2 nos of 25x3 GI Flat as down conductor, the same shall be retained as it is and the required earth value of less than 3 ohms should be confirmed.

DescriptionNo.of ArrestorNo.of Earth PitRemarks

D.G Set

23Two Arrestor is existing. No need to provide.

T.G CPP building

1047 Arrestor is already existing remaining 3 should be placed as per drawing.

Chimney 2Nos

24One Arrestor is existing in each chimney. No need to provde.

River pump Area

a) There are three Tank in this area ,in each Tank one Arrester shall be

placed.

c) In quary crusher area one Arrestor and Two nos. of earth pits shall be placed as marked in the drawing.

Documents

Lightning-Calculations.doc