rison presentation on ese

8/3/2019 Rison Presentation on ESE

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Recent Researcwith Implications

illia

Professor of ElecNew Mexico Institute o

Socorro,

on Lightning,or Air Terminals

Risonr

ical EngineeringMining and Technologyew Mexico


2/29

Recent LightninImplications fo

Computer Modeling of

Process

High Speed Videos of t

g Research withAir Terminals

the Lightning Attachment

e Lightning Attachment


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Video by Tom Warner, June 17, 20

High SpeeNegative Cloud to

7,100 Frame

7, near Devils Tower, Wyoming

d Video ofGround Discharge

s per Second


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Video by Tom Warner, June 17, 20 7, near Devils Tower, Wyoming


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Video by Tom Warner, August 4, 2

High Spee

AttachmentNegative Cloud to

7,100 Frame

500 foot tall tower

07, near Rapid City, South Dakota

d Video of

rocess for aGround Discharge

s per Second


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History of Attemptfor ESE Ai

1980s --- Laboratory e

100 s time advantage

Early 1990s --- Push b

1990s --- Prolonged prover proposed NFPA st

Early 2000s --- NFPAstandard and retain NF

2005 through 2008 ---ESE manufacturers

to Pass a StandardTerminals

periments indicate

or ESE air terminals

ESE manufacturers for

cedural and legal fightndard

ecides to reject ESEA 780

ederal court rules against


7/29

History of Attemfor ESE Ai

ESE based on three ass

1) Laboratory time advanpresent in real lightnin

upward leader

3) Upward leader speed i

If these three assumptioESE terminals a 100 m

No input from scientifi

development of standar

t to Pass StandardTerminals

mptions

tage of about 100 s will alsog

about 1 x 106 m/s

ns are true, they will giveter capture radius

community on


8/29

History of Attemfor ESE Ai

No scientific consensus

when the standard was

t to Pass StandardTerminals

on ESE assumptions at

roposed


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Validity of ES

1) Laboratory time advantage of 1

No scientific research indic

Golde (1941), The ValiditModels

there is a question regatest designed to simulatleader and the attachmelengths, tens of meters,

experiment (Rakov & Becerra and Cooray (2008),

be Utilized to Justify the A

Terminals

Assumptions

00 s also present in real lightning

ting that this is the case

of Lightning Tests with Scale

rding the validity of any laboratorythe physics of the lightning steppedt process, since typical leader stepxceed the size of the laboratory

man, 2003)Laboratory Experiments Cannottion of Early Streamer Emission


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Validity of ES

2) Initial early streamer

successful upward lea

No research at time st

oore e aRod Responses to Neastreamers ineffective

Assumptions

ill develop into

er

ndard proposed

easuremen s o g n ngrby Strikes shows early


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Validity of ES Assumptions

Early

streamers donot develop

into leaders


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Validity of ES

3) Upward leader speed i

Not many measuremetime standard propose

,speed of about 1 x 105

Tom Warner tower str1.2 x 105 m/s

Speed of 1 x 105 m/s gradius

Assumptions

s about 1 x 106 m/s

ts of upward leader speeds at

m/s

ke video: average speed of

ives only 10 meter capture


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Validity of ES

Research since the ES

shows all three ESE a

There have been no in

There is now scientifiterminals are ineffecti

It was premature to adterminals in early 199

Assumptions

standard was proposed

sumptions are incorrect

dependent field studies

consensus that ESEe

opt a standard for ESEs


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CVM

Idea initially proposed by

Theory was further devel

Gumley(2000) and DAle

Tested by DAlessandro iKon Petro & DAless

and Petrov, 2006)

istory

Eriksson (1979)

ped by DAlessandro and

ssandro (2002)

Kuala Lumpur and Hongndro 2 1 DAlessandro


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CVM As(DAlessandro a

1) Electric field intensificati

formation of upward lead

2) Critical radius of 38 cm f

the critical value must be

b) [T]he criterion for the inia stable upward leader is tcritical radius

3) Ratio of velocity of dowis about 1.2

umptionsd Gumley, 2000)

on by structures affects

er

om laboratory measurements

rounded off to this value

tiation of corona and consequentlye attainment of 3.1 MV/m at the

ward leader to upward leader


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1) Electric field intensificati

formation of upward lead This is correct, from basic


on by structures affects

erfreshman physics


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a) Any sharp geometrical fcritical value must be ro

Moore et al (2000) show

much less than a few cendifferently from those wi



atures with a radius of less that thended off to this value

d air terminals with radius of

imeters behave quiteh radius of a few centimeters


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b) [T]he criterion for the inia stable upward leader is tcritical radius

It is necessary for the field bedownward leader to be strong

No field measurements to confi

Becerra & Cooray (2007) mo

leader and found this not to b

It is shown that the collectionlightning protection areas of ai



tiation of corona and consequentlye attainment of 3.1 MV/m at the

ween the critical radius and theenough to sustain propagation

rm this

eled development of upward

the case:

olume concept overestimates theterminals placed on complex structures


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3) Ratio of velocity of dow

about 1.2:1



During initial upward

leader, velocity ratio is

about 10 to 1

Overall, velocity ratiois about 3 to 1

DAlessandro: [A]higher velocity ratio

yields a smaller

attractive radius


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3) Ratio of velocity of dow

is about 1.2 During critical initial lea

of upward leader) velocit

This is when other objectswith the air terminal

DAlessandro & Gumley

In fact, if one attempts todoes not have a real soluti



er development (first 100 feetratio is about 10:1

on the structure are competing

(2001)

use a ratio of 4 [or higher], Eq. (9)n.


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Field Valida(Petrov & DAl

(DAlessandro a

Studies in Hong Kong an

Buildin s rotected b E

according to CVM calcul

Claim to show protection

2 to 15% of low intensity

lightning protection syste

ion of CVMessandro, 2000)d Petrov, 2006)

d Kuala Lumpur, Malaysia

ICO D nas heres laced

ations

levels in the 85-98% range

flashed under 10 kA could bypass


22/29


(DAlessandro a

Study in Kuala Lumpur

Data in stud has been dis

Lightning Research Pte. LtThis review shows that the fis invalid and should not be uof air terminal placement.

No independent verification o


uted b Hartono & Robiah of

d. of Kuala Lumpureld data given in the above studyed to validate the CVM method

f CVM method


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(DAlessandro a

Two problems with methodo

1 Two different techni ues

with no way to differenti

2) There was no control


ogy of field study:

were tested with one stud

te between the two


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(DAlessandro a

1) Two different techniquesway to differentiate betw

Study used ERICO DynaCVM technique

If there was an effect, wa

to the CVM?


tested with one study, with noen the two

spheres placed according to

s it due to the Dynasphere or


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(DAlessandro a



26/29


(DAlessandro a

2) There was no control

Onl CVM lacement w

Would the results have bplacement method?


s tested.

en different with another


27/29


28/29

Critique Lightning research does

assumptions of CVM

No field study confirmingcritical radius reaches 3.1

Contrary to laboratory stumatter when smaller than

Recent high-speed video ithat leader velocity ratios

Problems with field verif

Having only two field tesby proponents of CVM, iscientific consensus

of CVMot support most of the

leader will develop when field atMV/m

dies, field studies show radius doescritical radius

s in conflict with the assumptionare about 1:1

cation need to be resolved

ts, with same methodology,s not sufficient to meet


29/29

Critique There is no consensus in

CVM is valid

IEEE standards should bby the scientific commun

of CVMthe scientific community that

based on principles acceptedity

rison presentation on ese

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