various+ese&das+terminals

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Harger Lightning & Grounding © 2005

Harger Lightning & GroundingHarger Lightning & Grounding20052005

Lightning Protection SystemsLightning Protection Systems





Lightning Protection Systems

I. What is Lightning/Lightning Protection?II. Basic Principles of Lightning Protection

III. Risk AssessmentIV. Applicable Codes/Standards

V. Basic Components VI. “ Typical ” Roof Top Detail


http://slidepdf.com/reader/full/variousesedasterminals 4/55Harger Lightning & Grounding © 2005

What is Lightning Protection?

NFPA 780 -

A Complete System of Air Terminals,

Conductors, Ground Terminals,Interconnecting Conductors, SurgeSuppression Devices, and other Connectors orFittings required to complete the System.



Lightning Damage Can Be

Traced To :¾ Inadequate (or no) direct strike protection



Risks Posed from a Direct StrikeRisks Posed from a Direct Strike



Risks Posed from an Indirect StrikeRisks Posed from an Indirect Strike




What is not not Lightning Protection?

¾Early Streamer Emission – ESE Radioactive

Pulsed Voltage

Sparking – Controlled Leader Trigger (CLT)

¾Lightning Elimination Dissipation Array Systems (DAS)

Charge Transfer Systems (CTS)




ESE – Early Streamer Emissionz Manufacturers claim that the ESE launch an upward

streamer faster than conventional Franklin Rods or thefeatures on the structures to be protected.

z Claim streamer speeds of 106 m/s to provide this

advantage

z Actual field measures from multiple investigators havedocumented streamer speeds ranging from

z McEachron - 5.2 x 104 to 6.4 x 105 m/s

z Yokoyama - 0.8 to 2.7 x 105 m/s

z Laboratory propagation speeds 104 m/s

z Striking distance directly proportional to Leader charge.

Reference: M.A. Uman & V.A Rakov (University of Florida)

American Meteorological Society Paper 2002




ESE – Early Streamer Emissionz Heary Bros – Preventor

z Indelec - Prevectronz Erico – Dynasphere

z Franklin France – Saint Elmo

z Ingesco

z Duval Messien – Satelit

z Helita

1999 Byran Report commissioned by

NFPA – found no technical basis for the

claims of enhanced performance



Prevectron

Dynasphere

19mm Blunt

Franklin Rod

Seven year period - air terminals on 6 m masts

Neither ESE or Sharp Franklin Rods struck

12 Blunt Franklin Rods were struck (12.7 to 25.4 mm)

Charles Moore - Principal Investigator - New Mexico Tech



French Made - Duval Messien Satelit

ESE 30m from damaged wall

Photos courtesy Hartono & Robiah

Malaysia Apartment Building

One of numerous such cases in

Malaysia where ESE have failed to

protect structures where the ESEwas located at a distance well

within the claimed radius of

protection.





High Voltage Lab Test

Mississippi State University




Dynasphere Damaged




ESE Lawsuit

¾ In connection with the NFPA’s rejection of ESE draft standard 781, three ESEcompanies (Heary Bros. Lightning Protection Co., Inc., Lightning Preventor of America,Inc., and the National Lightning Protection Corp., of which the two first mentioned havemerged) filed a law suit against the Lightning Protection Institute, Thompson LightningProtection Inc., and East Coast Lightning Equipment, Inc.

¾ The lawsuit, which was initiated in 1996, contained allegations of conspiracy, falseadvertising and product defamation regarding the advertised improved efficiency of ESE terminals compared to conventional Franklin rods.

¾ In October, 2003, the Federal District Court of Arizona dismissed the lawsuit.

¾ The dismissal was largely based on the fact that the ESE vendors presented no admissibleevidence at all to support their claims. Additionally, the Court granted a favorable ruling to acounterclaim against the ESE vendors. The ESE vendors were convicted of falsely advertisingthe claimed increase in efficiency of ESE rods in comparison to conventional Franklin rods.

¾ Significantly, the verdict rejected the ESE vendor’s claims that their ESE terminals’

compliance with various ESE standards justified the advertised expanded zones of protection for ESE devices. The Court found that the conformance with foreign ESEstandards failed to prove claimed increased zones of protection for ESE rods. TheCourt found that the ESE vendor’s claims are not supported by tests sufficiently reliableto support those claims and are therefore in violation of American “truth-in-advertising”laws.





Lightning Elimination

¾ According to proponents the charge released via corona

discharge at the sharp points will either:

1. Discharge the overhead thundercloud thereby eliminating any

possibility of lightning (Dissipation Array)

2. Discourage a downward-moving leader from attaching to thearray or structure by reducing the electric field near the array

and, hence, suppress the initiation of an upward streamer.





Dissipation / Charge Transfer System)

z Splineball

z Lightning Master

z LEC – Dissipation Array System DAS

z LEC – Charge Transfer System CTS

z Lightning Prevention Systems – ALS StaticDissipater





Lightning EliminationDevices have failed to perform as claimed by manufacturers.

¾ US Federal Aviation Administration (FAA)

• Banned after towers and DAS struck

¾ National Aeronautical Space Administration

• Banned after towers struck at Kennedy Space Center

¾ US Military• Banned towers at military bases struck

¾ Japan - field test showed statistical distribution of peak

current unchanged. (Kuwabara et al.)

¾ Trees & grass often generate more corona discharge

than dissipation arrays without apparently inhibiting

lightning.




Non Conventional Lightning

Protection Systems

These systems are not allowed by:z US National Fire Protection Association (NFPA)

z IEEE

z IEC

z US Military

z

Underwriters Laboratory (UL)




II. Basic Principles of Lightning Protection

• Intercept the Lightning Discharge• Safely Conduct the Lightning Currents

• Minimize the Effects of Lightning Currents

• Dissipate the Lightning Currents in the Earth

Zone of Protection - space adjacent to LPS substantiallyimmune to direct lightning discharges. Determined using

Rolling Sphere Method.




Lightning Strike Probability

The probability that a structure will bestruck by lightning is the product of theequivalent collection area of the

structure times the flash density for thearea that the structure is located.




Risk Assessment Formula

If N d > N c Lightning Protection Should be Installed

N d = The Yearly Lightning Strike Frequency

N c = Tolerable Lightning Frequency





Nd

= (Ng)( A

g)(C

1)

Where:

Ng = The yearly average flash density in the

region where the structure is located.

Ag = The equivalent collective area of the

structure in km2.

C1 = The environmental coefficient.

10 Fl h D it)




10-year Flash Density

Map - U.S.

0.1

0.5

1.0

2.0

3.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

N g = The Yearly Average Flash Density

Units: flashes/km2/yr

Lightning Density Map provided by Global Atmospherics, Inc. Tucson Arizona.




A g = The Equivalent Collective Area

Refers to the ground area having thesame yearly direct lighting flash

probability as the structure. It is an

increase area for the structure thatincludes the effect of the height and

location of the structure.There are 3 models:




Model 2




Model 3





C 1

= The Environmental Coefficient

Relative Structure Location C1

Structure located within a space containingstructures or trees of the same height or taller

with a distance of 3H

0.25

Structure surrounded by smaller structureswithin a distance of 3H

0.5

Isolated structure, no other structures located

with a distance of 3H

1

Isolated structure on a hilltop 2




Tolerable Lightning Frequency (Nc)

The Tolerable Lightning Frequency is ameasure of the damage risk to thestructure including factors affecting

risks to the structure, environment andmonetary loss.

It is calculated as follows:




Tolerable Lightning Frequency (N c )

N c = 1.5 x 10-3

C

Where:C = (C2)(C3)(C4)(C5)




C 2 – Structural CoefficientRoof

Structure Metal Nonmetallic Flammable

Metal 0.5 1.0 2.0

Nonmetallic 1.0 1.0 2.5

Flammable 2.0 2.5 3.0




C 3 – Structural Contents CoefficientStructure Contents C

3

Low value and nonflammable 0.5

Standard value and nonflammable 1.0

High value, moderate flammability 2.0

Exceptional value, flammable, computer or electronics

3.0

Exceptional value, irreplaceable cultural items 4.0




C 4 – Structural Occupancy Coefficient

Structure Occupancy C4

Unoccupied 0.5

Normally occupied 1.0

Difficult to evacuate or risk of panic 3.0




C 5 – Lightning Consequence

Coefficient

Lightning Consequence C 5

Continuity of facility service not required, no

environmental impact

1.0

Continuity of facility service required, noenvironmental impact

5.0

Consequences to the environment 10.0




Risk Assessment Formula

If N d > N c Lightning Protection Should be Installed


N c = Tolerable Lightning Frequency

Lightning Risk Assessment for Rectangular Structure

Lightning Flash Density (Fig H 2) Ng = 4



Lightning Flash Density (Fig. H.2) ………………… Ng 4

Relative Structure Location (Table H.4.3) ………… C1 = 2

Rectangular Structure Length (ft) : L = 80 ft

Width (ft) : W = 50 ft

Height (ft) : H = 30 ft

Equivalent Collective Area: Ae = 4.91E-03 km^2

Lightning Strike Frequency: Nd = 3.93E-02

Structural Coefficients (Table H.5.a) ……………… C2 = 3

Structural Contents Coefficients (Table H.5.b) …… C3 = 3

Structural Occupancy Coefficient (Table H.5.c) …… C4 = 1

Lightning Consequence Coefficient (Table H.5.d) … C5 = 5

Tolerable Lightning Frequency: Nc = 3.33E-05

Lightning Protection System Should Be Installed

Based on NFPA780-2000

Rectangular

Model

Example




IV. Applicable Codes/Standards

NFPA 780

UL 96A

UL 96




NFPA 780

• Standard for the Installation of Lightning Protection Systems (2004)

• Most Active Standard Available• Not a Code, (not enforced)




UL 96 & 96A

• 96A - Installation Standard• “Master Label”

• Independent Third Party Testing• 96 - Manufacturing Standard for Listed

LP Components




UL Master Label Program

Must be UL Listed to be Eligible

Materials must be UL Listed

System will be subjected to Inspectionby UL



Types of




Types of

Air Terminals

• Plain Air Terminals

• Safety Air Terminals

• Flexible Air Terminals




New Mexico Tests

19mm (3/4”) blunt rod was most effective

T f Li ht i C d t




Types of Lightning Conductors

• UL Listed Lightning Conductors

• Copper • Aluminum

• Class I• Class II

• Structural SteelFramework

Types of Ground Terminals




Types of Ground Terminals

• Ground Rods

• Plain/Sectional Copper-Clad Steel,Copper, Galvanized Steel,Stainless Steel

• Enhanced Ground Rods



Connectors/Fittings




Connectors/Fittings

Functions

• Bonds Conductors to StrikeTerminals and GroundTerminals

• Bond Metal Bodies to Providea Path to Ground

• Alleviates Potential

Differences between Systemand Metal Bodies

• Helps Prevent Flashover

Potentials

Surge Suppression Devices




Surge Suppression Devices

Helps Prevent Surge Currents fromEntering the Structure via

Electrical, Data, Phone, CableLines, etc.

Integral Part of Total ProtectionPackage

UL96A & NFPA Surge SuppressionRequirements vague

VIII.



Roof TopDetail


Details



Thank You


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