Iec 60695 1 20 2016

In the case of l q id , the combu tible va our is prod ced by va orization of the l q id, an the va orization proces is de en ent on the temp rature an c emical comp sition of the l q id

Fire haz rd testing –

Part 1- 20: Guidance for assessing t he fire haz rd of elect rotechnical products –

Ignit abi ity – General guidance

Essais relat ifs aux risques du feu –

Partie 1- 20: Lignes directrices pour lév aluation des risques du feu des produit s

élect rot echniques – Allumabi it é – Lignes directrices générales

BASIC SAFETY PUBLICATION

®

THIS PUBLICATION IS COPYRIGHT PROT CTED

Copyr ight © 2 16 IEC, Ge e a, Switzer la d

Al r i hts r es r ve Unle s oth r wis s e ifi d, n p r t of this p blc tio ma b r epr od c d or uti z d in a y for m

or b a y me n ,ele tr onic or me h nic l in lu in p oto o yin a d microfim, with ut p r mis io in wr itin fr om

eith r IEC or IEC's memb r Natio al Commite in th c u tr y of th r eq e ter If y u h v a y q e tio s a o t IEC

c p r i ht or h v a e q iry a o t o tainin a ditio al r i hts to this p blc tio , ple s c nta t th a dr es b low or

y ur lo al IEC memb r Natio al Commite for fur th r infor matio

Droits d r epro u tio r és r vé Sa f in ic tio c ntrair e, a c n p r tie d c te p blc tio n p ut êtr e r epro uite

ni uti s e s u q elq e forme q e c s it et p r a c n pr oc d , éle tr oniq e o mé a iq e, y c mp s la p oto o ie

et le micr ofims, s n la c r d é r it d l EC o d Comité n tio al d l EC d p y d d ma d ur Si v u a e d s

q e tio s s r le c p r i ht d l EC o si v u d sire o te ir d s dr oits s p léme tair es s r c te p blc tio , uti s z

le c or do n e ci-a r ès o c nta te le Comité n tio al d l EC d v tr e p y d ré id n e

Th Inter natio al Ele tr ote h ic l Commis io (IEC) is th le din glo al or ga iz tio th t pr ep r es a d p bls e

Intern tio al Sta d r ds for al ele tr i al ele tr onic a d relate te h olo ie

A bout IEC publc tion

Th te h ic l c nte t of IEC p blc tio s is k pt u d r c n ta t r eview b th IEC Ple s ma e s r e th t y u h v th

late t e itio , a c r r ig n a or a ame dme t mig t h v b e p bls e

IEC Catalo u - webstore.e c /cat alo u

Th st an -alo e a plc at io for c on ult in t he e t ire

biblo ra hic al informat io o IEC Int ern t io al St an ard ,

Te h ic al Sp cific at io s, Tec hnic al R ep rt s a d ot her

d c ume t s A v aia le for PC, Ma OS, A ndroid Ta let s a d

iPa

IEC publc t ion s arc - w w w.e c /s archpub

Th a v anc ed s arc h e a le t o fin IEC p blc t io s b a

v riety of c riteria (efere c e n mb r, text, t ec hnic l

c mmit t ee,…) It als giv es informat io o projec t s, re lac ed

Ele tro edia - www.ele tro edia.org

Th world's le din o ln dict io ary of elec t ro ic a d

elec t ric l t erms c ont ainin 2 0 0 t erms a d d finit io s in

En ls a d Fre c , wit h e uiv le t t erms in 15 a dit io al

la g a e A ls k nown a t he Int ern t io al Ele t rot ec hnic al

V oc ab lary (IEV ) o ln

IEC Glos ar y - st d.e c /glos ary

6 0 0 elec t rote h ic l t ermin lo y e t rie in En ls a d

Fre c ex t rac t ed fom t he Terms a d Definit io s cla s of

IEC p blc t io s is u d sin e 2 0 Some e trie h v b e

c lec t ed fom e rler p blc t io s of IEC TC 3 , 7 , 8 a d

CIS R

IEC Cu t omer Servic Ce tre - webst ore.e c /cs

If y ou wis t o giv u your fe d ac k o t his p blc t io or

n e furt her a sist an e,ple s c ont ac t t he Cu t omer Servic

Ce t re: c sc@ie c h

A pro os de l'IEC

L Commis io Ele trote h iq e Inter natio ale (IEC) e t la pr emièr e org nis tio mo diale q i éla ore et p ble d s

Nor me intern tio ale p ur to t c q i a tr ait à léle tr i ité, à léle tr oniq e et a x te h olo ie a p r enté s

A pro os de publc t ion IEC

L c nte u te h iq e d s p blc tio s IEC e t c n tamme t r ev Ve i e v u a s r er q e v u p s é e lé itio la

plu ré e te, u c r r ig n um o ame d me t p ut a oir été p blé

Cat alo u IEC - webstore.e c /cat alo u

A pplc t io a t on me p ur c n ult er t ou le re s ig eme t s

biblo ra hiq e s r le Norme int ern t io ale ,

Sp cific t io s t ec niq e , R ap ort s t ec hniq e et a t re

d c ume t s d l EC Dis o ible p ur PC, Ma OS, t ablet t es

A ndroid et iPa

R ec erc e de publc t ion IEC - w w w.e c /se rc pub

L rec herc e a a c ée p rmet d t ro v r d s p blc at io s IEC

e ut ils nt difére t s crit ère (n méro d référe c , t ex t e,

c mit é d’ét ud s,…) Ele d n e a s i d s informat io s s r le

projet s et le p blc t io s remplac ée o ret iré s

IEC J st Publs ed - webstore.e c /j st publs ed

R est ez informé s r le n uv ele p blc at io s IEC Ju t

Pu ls e d t ai e le n u ele p blc tio s p ru s

Dis o ible e lg e et a s i u e fois p r mois p r emai

Ele tro edia - www.ele tro edia.org

L premier dic t io n ire e lg e d t erme élec tro iq e et

élec t riq e I c nt ie t 2 0 0 t erme et d finit io s e a glais

et e fa ç is, ain i q e le t erme é uiv ale t s d n 15

la g e a dit io n le Eg leme t a p lé V oc ab laire

Ele t rot ec hniq e Int ern t io al (IEV ) e lg e

Glos aire IEC - st d.e c /glos ary

6 0 0 e t ré s t ermin lo iq e éle t rot ec hniq e ,e a glais

et e fa ç is, ext rait es d s art icle Terme et Définit io s d s

p blc t io s IEC p ru s d p is 2 0 Plu c rt ain s e t ré s

Fire haz rd t esting –

Part 1- 20: Guidance for assessing t he fire haz rd of elect rotechnical products –

Ignit abi ity – General guidance

Essais relat ifs aux risques du feu –

Partie 1- 20: Lignes directrices pour l év aluation des risques du feu des produit s

élect rotechniques – A llumabi it é – Lignes direct rices générales

BASIC SAFETY PUBLICATION

®

W arnin ! Mak e s re t hat you o t ain d t his publc t ion from a a t horize dist ribut or

At t en on! Veui ez vou a s rer qu vou avez o t en c t t e publc t ion v ia u dist ribut eur a ré

5.4 Typ s of test sp cimen 19

5.5 Test proced re an a p ratu 2

6 Use an interpretation of es lts 2

An ex A (informative) Examples of ac idents d e to arc f ires in u dergrou d

h dro lectric p wer plants or urb n s bstation 21

A.1 General 21

A.2 Examples whic are general y avaia le (non-ex au tive l st 21

A.2.1 Un ergrou d h dro lectric p wer plants 21

A.2.2 Urb n s bstation (non-ex au tive l st 21

Bibl ogra h 2

INTERNATIONAL ELECTROTECHNICAL COMMISSION

Part 1-20: Guidance f or assessing the

fire hazard of electrotechnical products –

Ignitabi ity – General guidance

1 Th Intern tio al Ele trote h ic l Commis io (IEC) is a worldwid org niz tio for sta d rdiz tio c mprisin

al n tio al ele trote h ic l c mmite s (IEC Natio al Commite s) Th o je t of IEC is to promote

intern tio al c -o eratio o al q e tio s c n ernin sta d rdiz tio in th ele tric l a d ele tro ic f i ld To

this e d a d in a ditio to oth r a tivitie , IEC p bls e Intern tio al Sta d rd , Te h ic l Sp cif i atio s,

Te h ic l Re orts, Pu lcly Av ia le Sp cific tio s (PAS) a d Guid s (h re fter refere to a “IEC

Pu lc tio (s)”) Th ir pre aratio is e tru te to te h ic l c mmite s; a y IEC Natio al Commite intere te

in th s bje t d alt with ma p rticip te in this pre aratory work Intern tio al g v rnme tal a d n

n-g v rnme tal org niz tio s laisin with th IEC als p rticip te in this pre aratio IEC c la orate clo ely

with th Intern tio al Org niz tio for Sta d rdiz tio (ISO) in a c rd n e with c n itio s d termin d b

a re me t b twe n th two org niz tio s

2) Th formal d cisio s or a re me ts of IEC o te h ic l maters e pre s, a n arly a p s ible, a intern tio al

c n e s s of o inio o th rele a t s bje ts sin e e c te h ic l c mmite h s re re e tatio f rom al

intere te IEC Natio al Commite s

3) IEC Pu lc tio s h v th form of re omme d tio s for intern tio al u e a d are a c pte b IEC Natio al

Commite s in th t s n e Whie al re s n ble eforts are ma e to e s re th t th te h ic l c nte t of IEC

Pu lc tio s is a c rate, IEC c n ot b h ld re p n ible for th wa in whic th y are u e or f or a y

misinterpretatio b a y e d u er

4) In ord r to promote intern tio al u iformity, IEC Natio al Commite s u d rta e to a ply IEC Pu lc tio s

tra s are tly to th ma imum e te t p s ible in th ir n tio al a d re io al p blc tio s An div rg n e

b twe n a y IEC Pu lc tio a d th c r e p n in n tio al or re io al p blc tio s al b cle rly in ic te in

th later

5) IEC its lf d e n t pro id a y ate tatio of c nformity In e e d nt c rtif i atio b die pro id c nformity

a s s me t s rvic s a d, in s me are s, a c s to IEC mark of c nf ormity IEC is n t re p n ible for a y

s rvic s c rie o t b in e e d nt c rtif i atio b die

6) Al u ers s o ld e s re th t th y h v th late t e itio of this p blc tio

7) No la i ty s al ata h to IEC or its dire tors, emplo e s, s rv nts or a e ts in lu in in ivid al e p rts a d

memb rs of its te h ic l c mmite s a d IEC Natio al Commite s for a y p rs n l injury, pro erty d ma e or

oth r d ma e of a y n ture wh ts e er, wh th r dire t or in ire t, or f or c sts (in lu in le al fe s) a d

e p n e arisin o t of th p blc tio , u e of, or rela c u o , this IEC Pu lc tio or a y oth r IEC

Pu lc tio s

8) Ate tio is drawn to th Normativ ref ere c s cite in this p blc tio Us of th refere c d p blc tio s is

in is e s ble for th c re t a plc tio of this p blc tio

9) Ate tio is drawn to th p s ibi ty th t s me of th eleme ts of this IEC Pu lc tio ma b th s bje t of

p te t rig ts IEC s al n t b h ld re p n ible f or id ntifyin a y or al s c p te t rig ts

International Stan ard IEC 6 6 5-1-2 has b en pre ared by IEC tec nical commite 8 :

Fire hazard testin

This f irst edition of IEC 6 6 5-1-2 can els an re laces the f irst edition of IEC TS 6 6 5-1

-2 publ s ed in 2 0 This edition con titutes a tec nical revision

This edition in lu es the f ol owin sig if i ant tec nical c an es with resp ct to the previou

edition:

a) ISO 5 6 -1 has b en ad ed to the normative ref eren es;

b) defi ition of “pyroly is” an “s ort-circ it have b en ad ed to Clau e 3;

c) some text from the introd ction has b en moved to Clau e 5 an is now p rt of the

normative text;

d) Clau e 5 now contain several man atory statements

The text of this stan ard is b sed on the fol owin doc ments:

Ful information on the votin for the a proval of this stan ard can b f ou d in the re ort on

votin in icated in the a ove ta le

This publcation has b en draf ted in ac ordan e with the ISO/IEC Directives, Part 2

It has the statu of a b sic safety publ cation in ac ordan e with IEC Guide 10 an

ISO/IEC Guide 51

In this stan ard, the terms def i ed in Clau e 3 are printed in b ld typ

A lst of al p rts in the IEC 6 6 5 series, publ s ed u der the general title Fire h z rd te tin ,

Part 1-21: Guidan e f or as es in the f ire hazard of electrotec nical prod cts – Ig ita i ty

– Summary an relevan e of test method

Part 1-3 : Guidan e for as es in the f ire hazard of electrotec nical prod cts –

Preselection testin proced res – General g idel nes

Part 1-4 : Guidan e f or as es in the f ire hazard of electrotec nical prod cts – In ulatin

l q id

The commit e has decided that the contents of this publcation wi remain u c an ed u ti

the sta i ty date in icated on the IEC we site u der "htp:/ we store.iec.c " in the data

related to the sp cifi publ cation At this date, the publ cation wi b

• recon rmed,

• with rawn,

• re laced by a revised edition, or

INTRODUCTION

Fires are resp n ible for cre tin hazard to l f e an pro erty as a res lt of the generation of

he t ( hermal hazard), an also as a res lt of the prod ction of toxic ef f luent, cor osive

ef f luent an smoke (non-thermal hazard) Fires start with ig ition an then can grow, le din

in some cases to flas -over an a f ul y develo ed f ire Ig ition resistan e is theref ore one of

the most imp rtant p rameters of a material to b con idered in the as es ment of f ire

hazard If there is no ig ition, there is no fire

For most materials (other than metals an some other elements), ig ition oc urs in the gas

phase Ig ition oc urs when combu tible va our, mixed with air, re c es a hig enou h

temp rature f or exothermic oxidation re ction to ra idly pro agate The e se of ig ition is a

f un tion of the c emical nature of the va our, the f uel/air ratio an the temp rature

In the case of l q id , the combu tible va our is prod ced by va orization of the l q id, an

the va orization proces is de en ent on the temp rature an c emical comp sition of the

l q id

In the case of sol d , the combu tible va our is prod ced by pyroly is when the temp rature

of the sol d is s f ficiently hig The va orization proces is de en ent on the temp rature an

c emical comp sition of the sol d, an also on the thic nes , den ity, sp cifi he t, an

thermal con u tivity of the sol d

The e se of ig ition of a test sp cimen de en s on man varia les F ctors to b con idered

f or the as es ment of ig ita i ty are:

a) the ge metry of the test sp cimen, in lu in thic nes an the presen e of ed es,

corners or joints;

b) the s rface orientation;

c) the rate an direction of air f low;

d) the nature an p sition of the ig ition source;

e) the mag itu e an p sition of an external he t f l x; an

f) whether the combu tible material is a sol d or a lq id

The primary aims are to prevent ig ition cau ed by an electrical y energized comp nent p rt,

an in the event of ig ition, to con ne an res ltin f ire within the b u d of the en los re of

the electrotec nical prod ct

Secon ary aims in lu e the minimization of an f lame spre d b yon the prod ct’s en los re

an the minimization of harmf ul ef fects of fire ef f luents in lu in he t, smoke, an toxic or

cor osive combu tion prod cts

Fires in olvin electrotec nical prod cts can also b initiated from external non-electrical

sources Con ideration of this nature are de lt with in an overal f ire hazard as es ment

This international stan ard gives an overview of ig ita i ty an its relevan e to the f ire hazard

of electrotec nical prod cts

FIRE HAZARD TESTING –

Part 1-20: Guidance f or assessing the

f ire hazard of electrotechnical products –

Ignitabi ity – General guidance

This p rt of IEC 6 6 5 provides g idan e on the ig ita i ty of electrotec nical prod cts an

the materials from whic they are f ormed It gives guidan e on:

a) the prin iples of ig ita i ty;

b) the selection of a pro riate test method , an

c) the u e an interpretation of es lts

This p rt of IEC 6 6 5 is inten ed f or u e by tec nical commite s in pre aration of stan ard

in ac ordan e with the prin iples laid down in IEC Guide 10 an ISO/IEC Guide 51

One of the resp n ibi ties of a tec nical commit e is, wherever a pl ca le, to make u e of

b sic safety publ cation in the pre aration of its publcation The req irements, test method

or test con ition of this b sic safety publ cation wi not a ply u les sp cif i aly ref er ed to

or in lu ed in the relevant publ cation

The f olowin doc ments, in whole or in p rt, are normatively referen ed in this doc ment an

are in isp n a le f or its a pl cation For dated ref eren es, only the edition cited a pl es For

u dated ref eren es, the latest edition of the referen ed doc ment (in lu in an

amen ments) a pl es

IEC 6 6 5-1-10, Fire h z rd te tin – P art 1-10: Guid an e for a s s in th fire h z rd of

ele trote h ic l products – Ge eral g ideli e

IEC 6 6 5-1-1 , Fire h z rd te tin – P art 1-1 : Guid an e for a s s in th fire h z rd of

ele trote h ical produ ts – F e h z rd a s s me t

IEC 6 6 5-1-12, Fire h z rd te tin – P art 1-12: Guid an e for a s s in th fire h z rd of

ele trote h ic l products – Fire s fety e gin erin

IEC TR 6 6 5-1-21, Fire h z rd te tin – P art 1-21: Guida c for a s s in th fire h z rd of

ele trote h ical products – I gnita ility – Summary a d rele a c of te t methods

IEC 6 6 5-2-1 , Fire h z rd te tin – P art 2-1 : Glowin /h twire b s d te t meth ds –

Glow-wire flamma ility te t meth d for e d -produ ts (GWEP T)

IEC 6 6 5-2-12, Fire h z rd te tin – P art 2-12: Glowin /h twire b s d te t meth ds –

Glow-wire flamma ility index (GWFI ) te t meth d for materials

IEC 6 6 5-2-13, Fire h z rd te tin – P art 2-13: Glowin /h twire b s d te t meth ds –

Glow-wire ig itio temp rature (GWI T) te t meth d for materials

IEC 6 6 5-4:2 12, Fire h z rd te tin – P art 4: Termin lo y c n ernin fire te ts for

ele trote h ic l products

IEC 6 6 5-1 -5, Fire h z rd te tin – P art 1 -5: Te t flame – N eed le-flame te t meth d –

Ap aratu , c nfirmatory te t ara g me t a d g idan e

IEC 6 6 5-1 -10, Fire h z rd te tin – P art 1 -10: Te t flame – 5 Wh riz ntal a d v rtic l

flame te t methods

IEC TS 6 6 5-1 -1 , Fire h z rd te tin – P art 1 -1 : Te t flame – Determin tio of th

c ara teristic h at flu for ig ition fom a no -c nta tin flame s urc

IEC 6 6 5-1 -2 , Fire h z rd testing – P art 1 -20: Te t flame – 5 0 W flame te t meth ds

IEC Guide 10 , Th pre aratio of s fety p b c tio s a d th u e of b sic s fety p blc tio s

a d gro p s fety p blc tio s

ISO/IEC Guide 51, Safety a p cts – Guideline for th ir in lu io in sta dards

ISO 13 4 , Fire s fety – Vo a ulary

ISO 8 1:2 0 , P la tic – Determin tio of ig itio temp rature u in a h t air furn c

ISO 2 9 , Determin tion offla h a d fire p ints – Cle ela d o e c p meth d

ISO 2 19, Determin tion offla h p int – P en k -Marte s clos d c p meth d

ISO 5 5 , Re ctio to fire te ts – I gnita i ty of b id in products u in a rad ia t h at s urc

ISO 5 6 -1, Re ctio to fire tests – H eat rele s smo e prod uctio a d ma s lo s rate –

P art 1: H eat relea e rate (c n c lorimeter meth d )

ISO 10 4 , P lastic – Guid an e for th u e ofsta dard fire te ts

3 Terms and definitions

For the purp ses of this doc ment, the terms an def i ition given in ISO 13 4 :2 0 an

IEC 6 6 5-4:2 12 (some of whic are re rod ced b low), as wel as the fol owin , a ply

DEPRECATED: sp ntane u combu tion

ignition (3.2 ) res ltin f rom a rise in temp rature without a se arate ignition sourc (3.2 )

Note 1 to e try: Th ig itio c n b c u e eith r b s lfh atin or b h atin foma e tern l s urc

Note 2 to e try: In North Americ , “s o ta e u ig itio ” is th prefer e term u e to d sig ate ig itio c u e

b s lfh atin

[SOURCE: ISO 13 4 :2 0 , 4.18]

3.2

a to-ignition temperature

sponta eous ignition temperature

minimum temp rature at whic a to-ignition (3.1) is o tained in a fire test

Note 1 to e try: Th ty ic l u its are d gre s Celsiu ( C)

[SOURCE: ISO 13 4 :2 0 , 4.19]

3.3

combu tion

exothermic re ction of a s bstan e with an oxidizin agent

Note 1 to e try: Comb stio g n raly emits fire eff l e t a c mp nie b flame (3.1 ) a d/or glowin

[SOURCE: ISO 13 4 :2 0 , 4.4 ]

3.4

f ire 〈general〉

proces of combu tion (3.3) c aracterized by the emis ion of he t an fire ef f luent an

u ual y ac omp nied by smoke, f lame (3.1 ), glowin or a combination there f

Note 1 to e try: In th En ls la g a e th term “ire” is u e to d sig ate thre c n e ts, two of whic , fire

(3.5) a d fire (3.6), relate to s e ific ty e of s lfs p ortin c mb stio with difere t me nin s a d two of th m

are d sig ate u in two difere t terms in b th Fre c a d Germa

f ire 〈u controled〉

self-s p ortin combustion (3.3) that has not b en del b rately ar an ed to provide u ef ul

minimum temp rature at whic a material ig ites an contin es to burn f or a sp cif ied time

af ter a stan ardized smal flame (3.1 ) has b en a pled to its s rf ace u der sp cif ied

con ition

Note 1 to e try: In s me c u trie th term "ire p int" h s a a ditio al me nin : a lo atio wh re fire-ig tin

e uipme t is site , whic ma als c mpris a fire-alarm c l p int a d f ire in tru tio n tic s

Note 2 to e try: Th ty ic l u its are d gre s Celsiu ( C)

Note 3 to e try: Se fla h p int (3.16)

[SOURCE: ISO 13 4 :2 0 , 4.1 9]

3.9

f ire retarda t, nou

s bstan e ad ed, or a tre tment a pl ed, to a material in order to delay ignition (3.2 ) or to

red ce the rate of combu tion (3.3)

Note 1 to e try: Th u e of (a) fire retard nt(s) d e n t n c s ariy s p re s fire (3.4) or termin te combu tion

q al tative des ription of the course of a fire (3.6) with resp ct to time, identif yin key events

that c aracterise the stu ied fire an dif ferentiate it f rom other p s ible f ires

Note 1 to e try: It ty ic ly d fin s th ignition (3.2 ) a d fire growth pro e s s, th fuly develo ed fire (3.17)

sta e, th f ire d c y sta e, a d th e viro me t a d s stems th t imp ct o th c urs of th f ire

[SOURCE: ISO 13 4 :2 0 , 4.12 ]

3.1

f lame, nou

zone in whic there is ra id, self -s stainin , s b-sonic pro agation of combustion (3.3) in a

gase u medium, u ual y with emis ion of l g t

[SOURCE: ISO 13 4 :2 0 , 4.13 – modif ied – The word "zone in whic there is" have b en

ad ed at the b gin in of the def i ition

3.12

f lame retard nt, nou

s bstan e ad ed, or a tre tment a pled, to a material in order to s p res or delay the

a p aran e of a flame (3.1 ) an /or red ce the flame-spre d rate

Note 1 to e try: Th u e of (a) flame retard nt(s) d e n t n c s ariy s p re s fire (3.6) or termin te

minimum temp rature at whic , u der sp cif ied test con ition , s f f icient f lamma le gases

are emit ed to ig ite momentari y on a pl cation of a pi ot flame (3.1 )

Note 1 to e try: This n te a ple to th Fre c la g a e o ly

[SOURCE: ISO 8 1:2 0 , 3.1]

3.15

f la hov r, 〈stage of f ire〉

tran ition to a state of total s rface in olvement in a f ire (3.4) of combu tible materials within

an en los re

[SOURCE: ISO 13 4 :2 0 , 4.15 ]

3.16

f la h point

minimum temp rature to whic it is neces ary to he t a material or a prod ct f or the va ours

emit ed to ig ite momentari y in the presen e of f lame (3.1 ) u der sp cified test con ition

Note 1 to e try: Th ty ic l u its are d gre s Celsiu (˚C)

glowin combustion

combu tion (3.3) of a material in the sol d phase without f lame (3.1 ) but with emis ion of

l g t from the combu tion zone

[SOURCE: ISO 13 4 :2 0 , 4.18 ]

3.2

lower flammabi ity l mit

LFL

minimum con entration of f uel va our in air b low whic pro agation of a f lame (3.1 ) do s

not oc ur in the presen e of an ignition sourc (3.2 )

Note 1 to e try: Th c n e tratio is u u ly e pre s d a a v lume fa tio at a d fin d temp rature a d

c emical decomp sition of a s bstan e by the action of he t

Note 1 to e try: Pyroly is is ofte u e to refer to a sta e of fire (3.4) b fore flaming combu tion (3.13) h s

u inten ed con ection of two nodes of an electrical circ it

Note 1 to e try: Cure t f l w mig t o c r, whic c uld c u e circ it d ma e, o erh atin , fire or e plo io

3.2

sponta eou -ig ition temperature

SIT

minimum temp rature at whic , u der sp cif ied test con ition , ig ition (3.2 ), is o tained by

he tin , in the a sen e of an ad itional ignition sourc (3.2 )

⋅m-4

⋅K-2

Th th rmal in rtia of p ly tyre e fo m is

1,4 × 10

3

J ⋅s-

⋅m-4

⋅K-2

Note 1 to e try: Wh n a material is e p s d to a h at f l x, th rate of in re s of s ra e temp rature d p n s

stro gly o th v lu of th th rmal in rtia of th material Th s ra e temp rature of a material with alow th rmal

in rtia ris s relativ ly q ic ly wh n it is h ate ,a d vic v rs

Note 2 to e try: Th ty ic l u its are jo le s u re p r s c n p r metre to th fo rth p wer p r Kelvin s u re

(J ⋅s

-⋅m-4

⋅K-2

Ig ition of a gas de en s on how the gas is mixed with air If the gas is mixed with air b fore

ig ition, the s bseq ent re ction is k own as premixed combu tion In a burner, the

combu tion is control ed, but if a large volume of a gas/air mixture is ig ited, a gas explosion

res lts

In most f ires, ig ition res lts in the develo ment of dif fusion flames where combu tible gas

comes in contact with air without b in previou ly mixed

Gas mixtures can b ig ited in two b sic way :

a) auto-ig ition – where the temp rature of al the gas mixture is raised, an

b) pi oted ig ition – where a local source of he t is introd ced, e.g a f lame or an electrical

sp rk

Some fires are the res lt of the ig ition of a material whic is alre d in the gase u state,

but combu tible gases can also b prod ced by the va orization of l q id (se 4.2) or by the

pyroly is of sol d (se 4.3)

4.1.2 Flammabi ity l mits

Flame pro agation can ot oc ur in a f uel/air gas mixture if the f uel con entration is to low or

to hig The l mitin con entration values are k own as the lower f lamma i ty l mit (L L) an

the up er f lamma i ty l mit (UF ) These l mits arise b cau e f lames ne d a minimum

temp rature to exist To mu h air or f uel prevents the temp rature b in maintained at a

s f f iciently hig level Flamma i ty l mits are normaly expres ed as the p rcentage of f uel, by

volume, in the fuel/air mixture

4.1.3 Arc fire

Faults in some electrical eq ipment s c as ju ction b xes an p wer tran f ormers can res lt

in disruptive electrical dis harges (electric arc ) whic can pyroly e in ulation materials to

prod ce hig temp rature combu tible gases Su h gases exp n ra idly an in contact with

air can res lt in an explosion (se 5.3.4.4)

4.2 Liq ids

4.2.1 Ov rview

With the ex e tion of some u sta le or re ctive s bstan es, bulk l q id do not general y

ig ite Normal y it is combu tible va our whic ig ites The combu tible va our is prod ced

by va orization of the l q id, an the va orization proces is de endent on the temp rature

an c emical comp sition of the l q id

4.2.2 Ignition parameters

Temp rature is normal y u ed to def i e the ig ita i ty of a l q id Thre dif f erent temp ratures

are u ed These are the auto ig ition temp rature (se 3.2), the f ire p int (se 3.8) an the

f las p int (se 3.16) Auto-ig ition ref ers to ig ition in the a sen e of a local zed he t

source Flas p int con ern momentary ig ition Fire p int con ern s stained combu tion

af ter ig ition

Several dif ferent test method are u ed to me s re these c aracteristic temp ratures The

me s red temp rature de en s on the p rtic lar detais of the test a p ratu u ed It is

theref ore imp rtant to def i e the test method when q otin these p rameters

4.2.3 Ins lating l quids

4.2.3.1 Fla h point me s reme t

ISO 2 19 (Pen k -Marten closed c p method) is cited in IEC stan ard f or the me s rement

of the f las p int of in ulatin lq id It me s res the f las p int in a con ned sp ce an is

inten ed to detect minor amou ts of volatie material An alternative method is ISO 2 9

(Clevelan o en c p method) whic is u ed to me s re the f las p int over an o en l q id

s rf ace The f las p int me s red by ISO 2 9 is sig if i antly lower than that me s red by

ISO 2 19

4.2.3.2 Cone c lorimeter me s reme ts

IEC 6 6 5-8-3 was develo ed to me s re the q antity of he t rele sed from burnin

in ulatin l q id The test specimen is exp sed to a u if orm he t f l x in the presen e of a

sp rk ig ition source Ig ition related prop rties can b def i ed as the time to ig ition at a

sp cif ied he t f l x, or the minimum in ident he t f l x that wi s p ort ig ition

NOT IEC 6 6 5-8-3 is to b with rawn Th ISO inte d to d v lo a relate te t meth d with a wid r s o e

4.3 Sol ds

With some ex e tion (se b low) sol d do not general y ig ite Normal y, the material that

ig ites is in the gas phase an can b a mixture of gases, a rosols an s sp n ed p rticles

The combu tible va our is prod ced by pyroly is of the sol d, an the va orization proces is

de en ent on the temp rature an c emical comp sition of the sol d

The ex e tion to this general statement are:

– metals (se 4.3.3);

– some non-metal c elements, f or example carb n (se 4.3.4), s lph r an phosphorou ;

– certain re ctive s bstan es (se 4.3.5); an

– d st clou s (se 4.3.6)

4.3.2 Parameters af f ecting ignition

In the case of a sold, the generation of f lamma le volati es from the material is f un tion of the

temp rature of that material This is af f ected by the nature of the he t input whic may b , f or

example, a radiant he t fl x, a con ective he t f l x, a con u tive he t f l x, an imp sed f lame,

a hot wire or a combination of these sources

The e se of ig ition wi also de en on the c emical nature of the flamma le volati es, whic

e) a sorptivity (in the case of radiative he tin )

In a thic test sp cimen, material b low the s rf ace is a le to con u t he t away th s

red cin the rate of s rf ace he tin an in re sin the resistan e to ig ition In a thin

sp cimen, con u tion of he t f rom the s rface is negl gible, an so resistan e to ig ition is

lower

Thermo lastic materials have a ten en y to melt away from the he t source (e.g f lame or

hot-wire) of ten res ltin in non-ig ition Becau e of this b haviour sp cial con ideration

s ould b given to the testin of the ig ita i ty of thermo lastic The pro lems that can arise

when thermo lastic are tested in stan ard f ire tests are dis u sed in ISO 10 4

The prod ct, k ⋅ ρ ⋅ c, is k own as 'thermal inertia' If the thermal inertia is hig , for example as

in the case of a sol d metal, the rate of s rface he tin wi b relatively low an it wi

theref ore take a relatively lon time f or the ig ition temp rature to b re c ed If the thermal

inertia is low, e.g as in the case of some foamed plastic or low den ity combu tible

materials, the rate of s rf ace he tin wi b relatively hig an it wi therefore take a

relatively s ort time for the ig ition temp rature to b re c ed

Af ter ig ition of the test sp cimen, flame pro agation wi oc ur if the f lame tran f ers s f f icient

he t f l x, mostly as thermal radiation, ahe d of the pyroly is f ront so as to continue pyroly is

an ig ition at a s ff icient rate

The mag itu e of the he t f l x tran f er ed ahe d of the pyroly is f ront de en s on the he t

rele se rate of the test sp cimen an on whether there is a contin in imp sed he t fl x,

where s the resistan e to ig ition is a f un tion of the minimum ig ition temp rature of the test

sp cimen an the rate of he tin of the s rf ace

4.3.3 Metals

When a metal burn in air the prod ct of combu tion is the metal oxide Man metals have a

f ilm of metal oxide on the s rface whic is f ormed from low temp rature oxidation The oxide

f ilm can ot burn b cau e it is alre d the prod ct of the metals oxidation an so b f ore the

bulk metal can burn, the s rf ace layer of oxide mu t b removed in some way

Metals can b clas if ied into thre groups with resp ct to their ig ition c aracteristic

a) Metals that ig ite at or b low their meltin p int (f or example iron an mag esium) These

metals al have meltin p ints a ove 6 0 °C These metals general y do not f orm a

protective oxide layer

b) Metals that ig ite af ter they melt (f or example aluminium, le d, tin an zin ) These metals

al have meltin p ints b low 6 0 °C These metals generaly f orm a protective oxide

layer

c) Metals of low re ctivity whic do not ig ite (f or example merc ry, si ver, gold an

platin m)

The e se of ig ition is also governed by the s rf ace are /volume ratio of the metal Thin f ilms

of metal an f i ely divided p wders are mu h e sier to ig ite than bulk pieces of metal This

is b cau e the he t rele sed by the oxidation proces is pro ortional to the burnin s rface

are , where s the initial removal of he t f rom the s rface by con u tion is pro ortional to the

volume of the metal

4.3.4 Carbon (graphite) a d c rbona eous c ar

4.3.4.1 Graphite

Pure carb n in the f orm of gra hite can ig ite in air a ove a temp rature of a out 8 0 °C In

the ran e 8 0 °C to 1 2 0 °C, non-flamin s rf ace combu tion (glowin combu tion) is fou d

to oc ur Ab ve a out 1 2 0 °C f lamin combu tion oc urs with a CO f lame b in o served

Carb nace u c ars are impure forms of carb n Volati e content an p rosity are two

imp rtant varia les whic contribute to the wide ran e of o served ig ition temp ratures As

with gra hite b th f lamin combu tion an non-f lamin combu tion may b o served Man

carb n-containin materials ten to f orm a carb nace u c ar on their s rf ace when they

burn, an at the e rly stages of f ire this c ar layer can, to some extent, protect the u derlyin

material A cor elation has b en o served b twe n ig ition resistan e, as me s red by

l mitin ox gen in ex, an c ar yield f or a ran e of organic p lymers [1]

1

4.3.5 Re ctiv s bsta c s

In most f ires the oxidisin agent is the ox gen in air However, in some materials the oxidisin

agent, u ual y ox gen, is p rt of the molec lar stru ture of the material or is mixed with the

sol d f uel in the form of a sold oxidisin agent These materials are u ualy del b rately made

to b combu tible or explosive Some examples are:

– “blue tou h p p r” (cel ulose an p tas ium nitrate);

– g np wder (carb n, s lph r an p tas ium nitrate);

– cigaret es ( o ac o an p tas ium nitrate);

– TNT ( rinitrotoluene)

4.3.6 Du t clouds

Du t clou s are mixtures of air (or some gas or gases) an f i e sol d p rticles whic are

micros o ical y disp rsed in it, an their ig ition b haviour is more lke that of a premixed gas

than that of a sol d

5 Consideration f or the selection of test methods

Imp rtant factors to b con idered when selectin the test method to b u ed in lu e; the fire

s enario or s enarios of con ern, the p s ible ig ition sources, the typ of test sp cimen, an

the typ of test proced re an a p ratu

1

Numb rs in s u re bra k ts refer to th biblo ra h

IEC TR 6 6 5-1-21 gives a s mmary an relevan e of test method as ociated with

ig ita i ty

5.2 Fire s e ario

In the desig of an electrotec nical prod ct, the ris of f ire an the p tential hazard

as ociated with f ire ne d to b con idered In this resp ct the o jective of comp nent, circ it

an eq ipment desig as wel as the c oice of materials is to red ce to ac e ta le levels the

p tential ris s of f ire even in the event of f orese a le a normal u e, malfun tion or f aiure

IEC 6 6 5-1-10, IEC 6 6 5-1-1 an IEC 6 6 5-1-12 provide g idan e on how this is to b

ac ompl s ed

The test method(s) selected s al b relevant to the fire s enario of con ern Imp rtant

p rameters to b con idered in lu e:

a) the ge metry of the test sp cimen, in lu in thic nes an the presen e of ed es,

corners or joints;

b) an anisotro y;

c) the s rface orientation;

d) the rate an direction of air f low;

e) the nature an p sition of the ig ition source;

f) the mag itu e an p sition of an external he t f l x; an

g) whether the f lamma le material is a sol d or a l q id

In cases where f ire tests are not yet sp cif ied, an ne d to b develo ed or altered f or the

sp cial purp se of an IEC tec nical commite , this s al b done in l aison with TC 8 in

ac ordan e with IEC Guide 10

5.3 Ignition sourc s

The ignition source u ed in a la oratory test s al b relevant to the f ire s enario of con ern

In the case of the f ire hazard of electrotec nical eq ipment, two typ s of ig ition source are of

con ern:

a) a primary internal source of he t of ohmic nature an a secon ary source of he t in the

f orm of a smal f lame whic may oc ur as res lt of ig ition cau ed by the primary (ohmic)

If the ig ition source u der evaluation is within a prod ct or located in ide a comp nent or an

a p ratu , s ita le test method are those whic are a le to simulate the overhe tin cau ed

by:

a) the internal metal c p rts (e.g electrical contacts, con u tors, etc.);

b) a smal f lame with a low he t tran fer, cau ed by combu tion started within the prod ct or

located in ide the comp nent or the a p ratu u der evaluation;

c) electrical arc (se 5.3.4)

The f ol owin test method can b u ed, as a pro riate, to me s re an des rib the

pro erties of a material, prod ct, comp nent or a p ratu in resp n e to he t an /or f lame

u der control ed la oratory con ition

ISO 8 1 sp cif ies a la oratory method f or determinin the f las -ig ition temp rature an

sp ntane u -ig ition temp rature of plastic u in a hot-air f urnace It is one of a n mb r of

method in u e for evaluatin the resistan e of plastic to the ef f ects of ig ition sources

The glow wire test method (IEC 6 6 5-2-1 , IEC 6 6 5-2-12 an IEC 6 6 5-2-13) simulate

the f irst cau e of ig ition d e to overhe tin by contact with a he ted p rt, without an o en

flame

IEC 6 6 5-2-1 (GWEPT) a ples to en prod cts It provides a q al tative evaluation of the

ig ition b haviour an , a ove the minimum ig ition temp rature, it provides a p s /f ai

criterion by as es in the burnin d ration u der sp cif ied temp rature con ition

IEC 6 6 5-2-12 (GWFI) an IEC 6 6 5-2-13 (GWIT) are s ita le f or the preselection of

in ulatin materials The GWFI test is desig ed to as es the maximum temp rature at whic

a material, when ig ited, has a l mited d ration of burnin without spre din f ire from the test

sp cimen The GWIT test is desig ed to as es the resistan e to ig ition by me s rin the

minimum ig ition temp rature

IEC 6 6 5-1 -5 is s ita le to simulate ig ition by a smal f lame It is a pl ca le to

electrotec nical eq ipment, its s b-as embl es an comp nents an to sol d electrical

in ulatin materials or other combu tible materials This test evaluates the ig ita i ty of a

given test sp cimen an me s res its a i ty to self-extin uis

IEC 6 6 5-1 -10 an IEC 6 6 5-1 -2 e c provide a sl g tly dif ferent test method Both of

these test method in olve direct contact of an o en f lame onto the s rface of the test

sp cimen The materials are rated de en in on the len th of time they burn (or glow) af ter

removal of the test f lame an whether or not f lamin dro lets are prod ced

In IEC 6 6 5-1 -10, a 5 W test f lame is u ed In IEC 6 6 5-1 -2 , a 5 0 W test f lame is

u ed an the f lame a pl cation time is lon er In b th cases the test method provide

clas ifi ation s stems whic may b u ed f or q al ty as uran e, or the pre-selection of

comp nent materials of prod cts

NOT Th s o e of IEC 6 6 5- 1 10 a d IEC 6 6 5- 1 2 d n t refer to th simulatio of eith r intern l or

e tern l ig itio

IEC 6 6 5-1 -1 is s ita le to simulate ig ition by the he t f l x f rom a smal non-contactin

f lame

5.3.3 Extern l ig ition sourc s

If the ig ition source u der evaluation is located outside the electrotec nical eq ipment,

s ita le test method are those that are a le to simulate the thermal stres cau ed by:

a) direct impin ement of an o en flame up n the s rf ace of the eq ipment;

b) direct contact of hig thermal stres (overhe ted metal c p rt on the s rf ace of the

eq ipment;

c) in irect thermal he t f l x

i) radiant,

i ) con ective,

d) electrical arc (se 5.3.4)

The method des rib d in 5.3.2 can also b u ed to simulate external ig ition as wel as

internal ig ition The dif f eren e is the location of the a pl cation of the thermal stres

IEC 6 6 5-1 -5, whic simulates ig ition by a smal f lame (se 5.3.2) has gained ac e tan e

in evaluatin external ig ition sources s c as o en can le flames (se IEC TS 6 4 1 [2])

Ad itional test method could b :

IEC 6 6 5-1 -10 an IEC 6 6 5-1 -2 : Both these test method in olve direct contact of an

o en f lame onto the s rface of the test sp cimen Materials are rated de en in on the len th

of time they burn (or glow) af ter removal of the test f lame an whether or not f lamin dro lets

are prod ced In IEC 6 6 5-1 -10 a 5 W test flame is u ed In IEC 6 6 5-1 -2 a 5 0 W

test f lame is u ed an the f lame a pl cation time is lon er In b th cases the test method

provide clas ifi ation s stems whic may b u ed f or q al ty as uran e, or the pre-selection

of comp nent materials of prod cts

NOT Th s o e of IEC 6 6 5- 1 10 a d IEC 6 6 5- 1 2 d n t refer to th simulatio of eith r intern l or

e tern l ig itio

In irect thermal fl x, as f rom an item burnin ne rby, can b evaluated by the f ol owin

method

IEC 6 6 5-1 -1 (se 5.3.2) simulates ig ition cau ed by the he t fl x f rom a smal non

-contactin f lame

ISO 5 5 : This is a smal -s ale test method that is typical y u ed to as es materials rather

than prod cts However, if the prod ct size is les than 10 mm, it can b tested directly The

test sp cimen is he ted by a conical electrical resistan e he ter, an af ter ig ition the he t

rele se rate is me s red

ISO 5 6 -1 sp cif ies a method, u in the Cone Calorimeter a p ratu , to as es the he t

rele se rate of a sp cimen exp sed in the horizontal orientation to control ed levels of

ir adian e Time to ig ition as a fun tion of the imp sed he t f l x can b me s red an can

b u ed to calc late u eful ig ition related p rameters s c as the thermal inertia of

materials

5.3.4 Arc ignition of materials

5.3.4.1 Arc ignition of ga e

Arc ig ition of a f lamma le gas ne d a minimum energ This pro erty is exploited f or

in tan e in “intrin ical y safe” ca les The voltage an in u tan e of these ca les l mits the

energ of an sp rk , whic mig t b cau ed by s ort-circ its or relay , to a value b low that

whic could cau e ig ition Simi ar prin iples are u ed in sp cif yin voltages an c r ents in

ca les u ed in fuel tan s

Where it is desired to ig ite a f lamma le gas or a rosol mixture, a hig voltage source is

normal y u ed to p wer a sp rk plu or an ig ition device as u ed in gas or oi f urnaces

5.3.4.2 Arc ignition of l quids

In general, a l q id ne d to b volati sed in order f or arc ig ition to oc ur An example is a

hig voltage p wer arc burnin acros the air/lq id s rface of tran former oi Radiant he t

tran f er may e si y generate a hig enou h temp rature in the lq id to volati se an ig ite it

It is hig ly desira le to ex lu e this p s ibi ty by desig

5.3.4.3 Arc ignition of sol d

Arc ig ition of a sol d, in either wet or dry con ition , may b cau ed by an combination of

hig or low c r ent or voltage There are several tests avai a le to evaluate b th materials

an f i is ed prod cts u der the a pro riate con ition

Test method IEC 6 1 2 [3] is u ed to evaluate trac in up to 6 0 V on materials

NOT IEC 6 1 2 is n t a te t of ig ita i ty, b t If ig itio o c rs folowe b p rsiste t flamin within th te t

p rio , this c n titute faiure of th te t

Test method EN 3 7 -6 3 [4] an EN 3 7 -6 4 [5] are for wires u ed in the a rosp ce

in u try an they simulate wet an dry arc pro agation, resp ctively, in electrical wirin

Momentary s ort-circ it arc b twe n a def ective in ulated wire an another con u tor may,

throu h ohmic he tin , thermal y pyroly e an c ar the in ulatin material The c ar ed

in ulation, b in con u tive, is ca a le of s stainin the s ort-circ it arc The s stained arc

may pro agate alon the wire throu h contin ou pyroly is of the in ulation (arc trac in ) If

the arcin wire is p rt of a multiple wire bu dle, the in ulation of other wires within the bu dle

may b come thermal y c ar ed an also start to arc trac Theref ore, arc trac in may le d to

complete f ai ure of an entire wire bu dle or harnes

For low c r enthig voltages, the IEC 6 5 7 [6] in l ned plane wet trac in test is a s ita le

protocol an it is worth notin that PTFE (p lytetrafl oro th lene) is re orted as ig itin on

this test whic would b in on eiva le in a flame ig ition test

In al these tests, initial le kage c r ents are of the order of mi iamps

An ad itional con ition whic oc urs on hig voltage / hig c r ent eq ipment is ig ition by

p wer arc of h n red or thou an s of amp res Su h arc can generate con idera le

radiant he t an also molten/f lamin dro lets This mode of ig ition is u ual y covered by

mode of fai ure testin on the complete eq ipment where a fault is del b rately introd ced an

rated f ault c r ents put throu h the f ault circ it An example would b IEC 6 0 9-4 [7] on

s rge ar estors where a p wer arc c ts throu h the p lymeric hou in an may ig ite it The

sp cif i ation al ows a maximum af terburn of 2 min

5.3.4.4 Arc f ire in power tra sf ormers

Faults in some electrical eq ipment s c as ju ction b xes an p wer tran f ormers can res lt

in disruptive electrical dis harges (electric arc ) whic can pyroly e in ulation materials to

prod ce hig temp rature combu tible gases Su h gases exp n ra idly an in contact with

air can res lt in an explosion

Power tran formers whic contain oi f or in ulation are prone to s c pro lems Tests car ied

out at several hig -p wer la oratories se m to in icate that p wer tran formers larger than

10 MVA are not safe if an internal f ault cau es a s ort-circ it The f ault cau es the pyroly is

of some of the oi an the prod ction of a gase u mixture containin saturated h drocarb n

The pyroly is re ction generates a ra idly growin q antity of gas at hig pres ure an

temp rature in ide the tran f ormer, of ten res ltin in the stru tural fai ure of the tran f ormer

together with a s bseq ent explosion

An ex A contain some examples of re l ac idents cau ed by arc f ires in u dergrou d

h dro lectric p wer plants or urb n s bstation

5.4 Type of te t spe ime

The test sp cimen may b a man f actured prod ct, a component of a prod ct, a simulated

prod ct (re resentative of a p rtion of a man f actured prod ct , materials as sp cif ied in the

relevant sp cifi ation (sol d or l q id), or a comp site of materials

Variation in the s a e, size an ar an ement of the test sp cimen s ould b l mited.

5.5 Te t proc dure a d apparatus

The test proced re s ould prefera ly b desig ed so that the res lts can b u ed f or hazard

analy is However, this may not b neces ary in the case of simple tests inten ed only f or

q al ty control or reg latory purp ses

The test a p ratu s al b a le to test the actual electrotec nical prod ct, a simulated

prod ct, a material or a comp site, as des rib d in 5.4

The test a p ratu s al b a le to imp se a he t f l x from an external he t source or from a

f lame, in an a proximately u iform fas ion to the test sp cimen in the region where ig ition is

inten ed to oc ur

The test a p ratu with imp sed he t f l x s ould b a le to ig ite the va our air mixture

emanatin from the test sp cimen An electrical sp rk ig iter or a premixed gas-air f lame

have b en fou d to b s ita le

An air f low rate whic is relevant to the fire s enario of con ern s al b u ed

6 Use and interpretation of results

The oc ur en e of ig ition an whether or not there is s bseq ent s stained burnin b th

de en on a large n mb r of f actors as dis u sed a ove It is most imp rtant that the

selection of varia les in a test for ig ita i ty s ould ref lect the nature of the f ire s enario that

The determination of the dif f ic lty or e se of ig ition u der a def i ed set of con ition an

imp rtant f actor in the as es ment of the relative hazard exp cted in fires of electrotec nical

prod cts The as es ment is b sed on the prin iple that the gre ter the resistan e to ig ition,

the lower the exp cted hazard A hig resistan e to ig ition is alway desira le

Gas explosion ac idents in u dergrou d h dro lectric p wer plants or urb n s bstation may

oc ur as a con eq en e of electric faults in oi -in ulated comp nents s c as tran f ormers

An electric arc in ide the comp nent cau es the pyroly is of p rt of the oi , an the gase u

pyroly is prod cts can then es a e from the comp nent to mix with air

Due to the c emical comp sition of the mixture, an explosion can oc ur givin rise to a

pres ure s oc wave whic , if not s ita ly con ned by blast- esistant b r iers, can pro agate

throu h the p wer plant or s bstation

A.2 Examples whic are general y avai able (non-e haustive l st

A.2.1 Und rgrou d hy roele tric power pla ts

Ton tad, Norway, 19 3 – Outside sp rk-over on the ca le p rcelain terminal with a f las

Explosion of e ctive gases an oi mist: 3 p o le ki ed, 1 he v burn injury

Bard fos , Norway, 19 5 – Short-circ it in the control ca le con ection to one of the u it

Explosion: he v damages in the p werhou e

Ron ovalgran e, Italy, 19 8 – Grou d dis harge in the in ulator Explosion of re ctive gases

an oi mist: damage to eq ipment an stru tures

Skjomen, Norway, 19 8 – Material an s stem defects in the control s stems Explosion an

oi fire al : tran former total y damaged

Aroy, Norway, 2 01 – Op rational mistake an material we k es in the win in s or win in

in ulation No explosion or f ire

A.2.2 Urba s bstations (non-e ha stiv l st)

Toronto, Canada, 19 9 – Toronto Hy ro, Win sor Station

Sy ney, Au tral a 19 9 – Chatswo d s bstation

Sy ney, Au tral a 2 0 – Pad in ton s bstation

Chicago, USA 2 0 – Chicago downtown

Pitsburg , USA 2 0 – Pit sburg downtown

Brisb ne, Au tral a 2 01 – Ten y on s bstation

Bibl ography

[1] Van Krevelen, D W P ro ertie of P olymers, third edition, Elsevier, 19 0, p 7 2

[2] IEC TS 6 4 1, Safe u rds a ainst a cid entaly c u ed c ndle flame ig itio for

a d io/video, c mmu ic tion a d information te h olo y e uipme t

[3] IEC 6 1 2, M eth d for the d etermin tio of th pro f a d the c mp rativ tra kin

ind ic s of s lid ins latin materials

Re ista c to wet arc tra kin

Re ista c to dry arc pro a atio

[6] IEC 6 5 7, Electric l ins lating materials u ed u der s v re ambient c nd itio s – Te t

meth ds for e aluatin re ista c to tra kin a d ero io

[7] IEC 6 0 9-4, Surg are ters – P art 4: Metal-oxide s rg are ters with ut g p for

National Fire Protection As ociation Pres , Quin y, MA (USA), 19 5

[10] Dry dale, D An Introductio to Fire Dy amic , Joh Wi ey an Son , New York, N.Y

(USA), Cha ters 6 an 7, p 18 -2 2, 19 5

[1 ] Hi ado, C.J Flamma ility Te t M eth ds H andb ok, Tec nomic Publ s in Co In

Westp rt, Co (USA), 19 3

[12] Kan ry, A.M I gnitio of Liq id Fu ls, Section 2, Cha ter 10, p 2-16 to 2-17 in

SFPE Han b ok of Fire Protection En ine rin , National Fire Protection As ociation

Pres , Quin y, MA (USA), 19 5

[13] Kan ry, A.M Flamin I gnitio ofSo d Fu ls, Section 2, Cha ter 13, p 2-19 to

2-2 4 in SFPE Han b ok of Fire Protection En ine rin , National Fire Protection

As ociation Pres , Quin y, MA (USA), 19 5

[14] Fire-an -Explosion Hazard of Substan es an Materials an Fire Sup res ion Me n

Han b ok Volumes 1, 2 Mos ow (Ru sia), Khimiya, 19 0

_ _ _ _ _ _ _