Disclosure to Promote the Right To Information

Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public.

इंटरनेट मानक

“!ान $ एक न' भारत का +नम-ण”Satyanarayan Gangaram Pitroda

“Invent a New India Using Knowledge”

“प0रा1 को छोड न' 5 तरफ”Jawaharlal Nehru

“Step Out From the Old to the New”

“जान1 का अ+धकार, जी1 का अ+धकार”Mazdoor Kisan Shakti Sangathan

“The Right to Information, The Right to Live”

“!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता है”Bhartṛhari—Nītiśatakam

“Knowledge is such a treasure which cannot be stolen”

“Invent a New India Using Knowledge”

है”ह”ह

IS/IEC 60079-5 (2007): Explosive atmospheres, Part 5:Equipment protection by powder filling 'q' [ETD 22:Electrical Apparatus for Explosive Atmosphere]

June 2009

IS/lEG 60079-5 : 2007(Superseding IS 7724 : 2004)

Indian Standard

EXPLOS~VE ATMOSPHERESPART 5 EQUIPMENT PROTECTION BY POWDER FilLING "q"

ICS 29.260.20

© SIS 2009

BUREAU OF iNDiAN STANDARDSMANAK SHAVAN. 9 SAHADUR SHAH ZAFAR MARG

NEW DELHI11 0002

Price Group 8

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Electrical Apparatus tor Explosi ve Atmospheres Sectional Co mmitte e, ETD 22

NAl lONAL FOREWORD

This Indian Standard (Part 5) wh ich rs identica l with IEC 60079-5 : ?-007 'Expl os ive atmospheres - Part 5:Equipment prot ection by powd er filling "q'' , issu ed by the International Electrotech rucal Commission (IEC)was adopted by tile Bureau of Indian Sta ndards on the recommenda tion 01 the Etectncal Apparatus forExplosive Atmospheres Sectional Committee and approval 01the Elect rotechrucal Division Council.

Th is standard supersedes IS 7724 : 2004 'Electrical apparatus for explosive gas atmo spheres _ . Powd erfilling "q" (first revision)',

The text of IEC Standard has been approved as SUitable lor publication as an Indian Standard Withoutdeviations, Certain conventions are. however, not identical to those used in Indian Standards Attention isparticularly drawn to the following:

a) Wl ierever the WO t ds 'lulet nauoual Standar d' appear referrrng to this stancard. they should b e read as'Indian Standard' .

b) Comma (,) has been used as a decimal marker In the International Standard whi le In Indian Standards,the current pract ice IS to usc

ffndien Standard

EXPlOS[VE ATMOSPHERESPARl 5 (EQIUDfMIENT PlR01rrECli~OWJ leV. fOWID)[ERl IF~ I!..UWJG "q]". .

i Scope

This part of IEC 60079 contains specific requirements for the construction, testing andmarking of electrical equipment, parts of electrical equipment and Ex components in the typeof protection powder filling "q", intended for use in explosive gas atmospheres.

NOTE 1 Electrical equipment and Ex components protected by powder filling "q" may contain electronic circuits,transformers. protection fuses, relays, intrinsically safe electrical apparatus, associated electrical apparatus.switches , etc.

NOTE 2 Type of protection powder filling "q" provides equipment protection level (EPL) Gb. For furtherinformation. see Annex A. .

This standard supplements and modifies the general requirements of IEC 60079-0. Where arequirement of this standard conflicts with a requiremen t 'of IEC 60079-0, the requirement ofthis standard will take precedence. .

This standard applies to electrical equipment, parts ·of electrical equipment and Excomponents with:

a rated supply current less than or equal to 16 A;

- a rated supply voltage less than or equal to 1 000 V;

- a rated power consumption less than or equal to 1 000 W.

The following referenced documents are indispensable for the application of this document,For dated references, only the edition cited applies . .For undated references, the latest editionof the referenced document (including any amendments) applies .

IEC 60079-0 :2004, Electrical apparatus for explosive gas atmospheres - Part 0: Generalrequirements

IEC 60079-1, Electrical apparatus for explosive gas atmospheres - Part· 1: Flameproofenclosure ra:

IEC 60079-7, Explosive atmospheres - Part 7: Equipmf!nt protection by increased safety "e"

IEC 60079-11, Explosive atmospheres - Part 11: Equipment protection by intrinsic safety "i"

IEC 60529, Degrees of protection provided by enclosures (/P Code)

ISO 3310-1 , Test sieves - Technical requirements and testing - Part 1: Test sieves of metalwire cloth .

ISO 3310-2, Test sieves - Technical requirements and testing - Part 2: Test sieves ofperforated plates

1

ISO 2591-1, Test sieving - Methods using test sieves of woven wire cloth and perforatedmetal plate

For the purposes of this document, the following terms and definitions apply; they supplementthe terms and definitions given in !EC 60079-0.

NOTE Additional definitions applicable.to explosive atmospheres can be found in lEe 60050-426 .

3.ipowdsr 1lmllUg "«l]"type of protection in which the parts capable of igniting an explosive gas atmosphere are fixedin position and completely surrounded by filling material to prevent the ignition of an externalexplosive gas atmosphere

NOTE The type of protection may not prevent the surround ing exp!osive gas atmosphere from penetrating into theequipment and components and being ignited by the circuits. However. due to the small free volumes in the fillingmaterial and due to the quenching of a flame which may propagate through the paths in the filling material, anextemet explosion is prevented. .

3.2fam~g materlalsolid quartz or solid glass particles

3.3(l] ls~alllce through l1mong materialshortest distance through a filling material between two.conductive parts

4.1 Enclosure

In addition to the enclosure requirements of lEe 60079-0, the following requirements apply.

4.'1 .1 Closing a:nd seal ing

Enclosures of electrical equipment, parts of electrical equipment or Ex components protectedby powder fimng "q" shail be filled and sealed at the time of manufacture. The closing andsealing shali be the methods of 4.1.1.1 or 4.1.1 .2.

4.1.1.1 CI1lCIOSLlres permanently sealed at 'the 'time of manufacture

The enclosure shall be permanently sealed at the time of manufacture and shall not becapable of being opened wlthout leaving visible evidence that the enclosure has beenopened. The enclosure shall be marked in accordance with 6 a).

4.1. "l.2 Enclosures intende'c] to be opened for rep2li!'

Electrical equipment, parts of electrical equipment, or Ex components that are designed to berepaired shall incorporate sealing methods that are capable of being renewed without damageto the enclosure when the equipment is repaired, re-filled, and re-sealed. The enclosure shallbe marked in accordance with 6 b). .

NOTE Suitable techniques that may provide visible evidence of being opened are, for example , welding,soldering, cemented joints , rivets, cementing of screws , or lead-seal safety-wiring of screws.

2

~sm=c 60079-5: 2007

4\.11.2 Pressure tes~ o~ enclosure

The electrical equipment, parts of electrical equipment or Ex components protected by powderfilling -q" shall meet the pressure test requirements specified in 5.1 .1.

4\.1.3 Degree of protectio n of tt'le enclosure

The enclosure of the electrical equipment, parts of electrical equipment, or Ex componentsprotected by powder filling "q", in its normal service condition, l.e. with all openings closed asin normal use, shall comply at least with the degree of protection IP54 as defined inIEC 60529. If the degree of protection is IP55 or higher, the enclosure shall be provided witha breathing device. The enclosure with the breathing device in place shall comply at least withthe degree of protection IP54 according to IEC 60529. The test shall be conducted on anempty enclosure without the powder fming installed. At the end of any water ingress tests, nowater shall be visible inside the enclosure.

NOTE 1 It is acknowledged that the enclosure may need to be destroyed in order to determine the entrance ofdust or water. Two separate test samples may be required, '

The ingress protection of enclosures or parts of electrical equipment protected by powder, filling "q", intended for use only In clean, dry rooms, may be reduced to degree of protection

IP43. These enclosures shall be marked with the symbol "X" in accordance with 29 .2 i) ofIEC 60079-0 and the specific condltlons for use shall detail the restrictions of use.

When Ex components protected by powder filling "q" are intended to be mounted insideanother enclosure complying with IEC 60079·0, this outer enclosure shall have a degree ofprotection of at least 1?54 . The IP of the inner enclosure does not need to be specified .provided that the Ex component is mounted in a position where it is unlike!y to becontaminated by an~ small amounts of water that may enter the outer enclosure.

The maxim um gap of an enclosure protected by powder filling "q" shall be at least 0,1 mmsmaller than the specified smallest dimension of the filling material.

NOTE 2 The restriction on the size of the gap is intended to reduce the escape of filling malerial.

4\. i.4 Fomn91 proceeure

Filling shal l be' carried out so as not to reave any void within the filling material (for exampleby shaking down). The free space within electr ical equipment, parts of electrica l equipment orEx components protected by powder filling "q" shall be effectively filled .with filling material(see also 4.3.2).

4.2 Filling niaterca[

4.2.1 Requirements

The material shall be tested dry in accordance with ISO 2591-1, using a 1 mm nominalaperture sieve in accordance with ISO 3310-1 or ISO 3310-2 and a 500 um nominal aperturesieve in accordance with ISO 3310-1 .

3

ISIIEC 60079~5 : 2007

4.2.2 Documentation

The documents prepared by the manufactur.er in accordance with lEe 60079-0 shall incl udethe specifi cation of the parti cle mat eria l, the size range of the particles, as well as the fillingprocess and the measures taken to ensure proper fi lli ng.

NOTE It is not a requi rement of this standard that conformity to the specification of the part icle material and sizerango of the particles needs to be verified ,

4.2.3 Testi ng

The fillin g materi al shall be subjected to the dielect ric strength test specified in 5.1.4.

4.3 Distances

4.3.1 Distances through fil l ing mat erial

Except where specified otherwise in this standard, the minimum distance through the fil lingmateria l between electrically conducting parts of the equ ipment and the inner surface of theenclosure sha ll com ply with Table 1. This does not apply to con ductors used for externalconnections wtuch penetrate the wall of the enclosure Such conduc tors shall comply with anyrequirements for the type of protecti on emp loye d for the external connections

Table 1 - Distances th ro ugh th e filling material

Volt age a.c . r rn.s or d. c, Mi nimum dlstancc

V mm-/.I :;;250 5

'-----40-.- =t-----~----.-----_. -- - --- -500 8---- _ ._--- - - ._ - - - - - - -BOO '0---------- -- - - - -- ------ - --

1 COO 14- - -----_.- - - ---1 eoo 16---------------~--- -_ ._- -----2500 25--- --- -- - ------ --- ----~3200 32_ 4 ____ _ - -4 000 40

~-----------------~._----_ ...... --_......_--_..--_---

5000 50f---"--- - -----,. .--. --- ----

6300 63f- - -- --f----- -- - ----

II ODD BO-----

10 000 100--- -

NOTE Voltages shown are derived from iEG 60664· 1 and are based on therationalization of supply voltages given in Table 3b. When determining the requitedvalues for distance, the voltage value in the table may be increase d by a fact or of1 , in order to recognize the rang e or rated volta ges in common use .

'- -

Fault condit ions accordi ng to 4.9 shall be considered when determin ing the working voltage.

t~OTE While tlus standard IS appli cable to equipmen t with a rated supply voltage not exceedi ng 1 000 V, Table 1takes Into acco unt working volt ages greal er than 1 000 V which may be developed or generated Within theequipment or Ex component A typical example is a fl uorescenl luminaire ballas t With a rated voltage of 240 V, butwith an arc imtratron volt age or approximate ly 2 000 V.

4

IS/lEe 50019-5: 2607

4.3.2 Distances surrounding free space

If electrical equipment contains components which have an enclosed free space not filled withthe filling material (e.g. a relay), the following requirements apply:

if the enclosed free space of the component is less than 3 cm3 , the minimum distancethrough filling material between the component wall and the inner surface of the enclosureshall comply with Table 1;

- if the enclosed free space of the compor:ent is between 3 cm3 and 30 cm3 , the minimumdistance through filling material between the component wall and the inner surface of theenclosure shall comply with Table 1 but with a minimum of 15 mm;

the component shall be fixed, so that movement nearer to the wall of the enclosure is natpossible;

free volumes of more -than 30 cm3 are not permitted;

- the enclosure of the component shal! resist the thermal and mechanical stresses to whichit will be subjected even under fault conditions according to 4.9. There shall be no damageor distortion which could reduce the protection provided by the filling material.

4.4 Nlater:als used for SUP90rt of energized parts

Materials used between the electrically energized parts and the wall of the enclosure (exceptfor the insulation of external wiring and the filling material) in the region specified in 4.3 shallcomply with the flammability requirements specified in 5.1.3.

4.5 Eltiernal field-wiring connections

Terminations or cables used for the entry of electrical conductors into a powder filled "q"enclosure shall be an integral part of the enclosure and shall be protected and sealed asspecified in 4.1.1. When a cable provides the entry of conductors into ' a powder filled "q"equipment or Ex component, the clamping means shall comply with the cable glar.drequirements of lEG 60079-0 and shall not be capable of being removed without obviousdamage to the powder filled "q" enclosure.

4.6 Capacitors

The total stored energy of all capacitors in an enclosure of electrical equipment. part ofelectrical equipment 0; Ex component protected by powder filling "q" shall not exceed 20 J innormal operation.

4.7 Cells ann foatleries

Enclosures for powder fiiled "q" electrical equipment, parts of eiectrical equipment or Excomponents that .contain cells or batteries shall incorporate a breathing device to thesurrounding atmosphere (see 4.1.3) unless the batteries or cells:

a) have a capacity of 1,5 Ah or less, or

b} do not release gas under normal operatlnq conditions, and comply with the requirementsfor primary and secondary batteries w:th capacity up to 25 Ah, in lEe 60079-7.

NOTE 1 Sealed gas-tight cells do not release gas under normal operating conditions •.

NOTE 2 Consideration shall be given to the effect that a release from the breather may have-on the surroundingatmosphere.

5

IS/IEC 60079-5: 2007

4.8 Temperature limitat ions

Each electrical equipment , part of electrical equ ipment or Ex compone nt prot ected by powderfilling "q" shan be pro tected aga inst ove rload prescribed in th e rel ev ant product standa rdspec ified by the manufacturer so that the per miss ib le limit temperature of the applicabletemperature class is not exceeded at the wall of the enclosure and inside the fil li ng materialup to a depth of 5 mm from the wall of the enclosure. The effectiveness of the protection shallbe confir med by th e test of 5.1.5 .

NOTE It IS ofte n djfficull to limit the temperatures with only a fuse , and an internal thermal prote ctive device maybe necessary.

4.9 Temperature l imitations unde r fault conditions

The enclo sure sh all no t be damaged an d the limiting temperature shall not be exceeded ovenin the case of faults . The effec tiveness of the temperature protection shall be co nfirmed bythe test uf 5..i .5.

Unless the equ ipmen t supply IS pro tected by an fuse rated at no t more tha n 170 % 01 themaximum norm al cur rent , the equipment sha ll be subjected to any single internal electricalfaull which may cause either an overvoltaqe or overcur rent, for example'

snort-cnc uit of any component:

.- open clrcuit du e lu any compone nt failure;

_. taull 111 the pi in ted circuttrv;

- eic

Over-current dev ice s, if employed , shall have a voltage ratin g not less th an th at of the cucuttand shall nav e a bre aki ng ca pacity nol less than the prospective fault current 01 the ci rcuit.

if a fault can lead to one or more subsequent faults , for example overloading of a component,the primary and subsequent fauns are considered to be a single fault

\"JllMe there IS .)0 product standard, tl"e overloads to ne conside red are th ose specined hy theman ufacturer

The vol taqe UN shall be assumed to be applied to the supply termina ls wh en consideunq faul!condnions and faul! exclusions

Whl2'n the fuse IS not integral to the electrica l equipme nt or pa d s ol electncal equipment , thernal long shall mciude the symbol "X" in accordance wi th 29. 2 I) of lEG 60 079 0 and tilespecific condruons for use sha ll detail th e required fu se

INhell the fus e is not inteqrat to an Ex compon ent, the marking shall include the symbol "U" inaccordance with 29.5 g) of lEe 60079-0 and th e schedule of limitations sha ll detaIl therequired fus e.

4.9.1 Fa u lt ex clusions

The foll owing faults nee d not be con sidered.

6

[S/~EC 6Q01S-5: 2QQ1

a) Resistance values [ower than the rated values for:

- film type resistors;

- wire wound resistors and coils with a sing le layer in helical form;

when they are used at no more than 2/3 of their rated voltage and rated power at themaximum service temperature as specified by the manufacturer of the respectivecomponents.

b) Short-circuit conditions for :

plastic foil capacitors;

- ceramic capacitors;

- paper capacitors;

when they are used at no more than 2/3 of their rated voltage as specified by themanufacturer of the respective components.

c) Insulation failure of:

- optocouplers and relays designed for segregation of different circuits;

when the sum U of the r.m.s. values of the maximum voltages of the two circuits is notmore than 1 000 V and the rated voltage of the component between the two different ucircuits is at least 1,5 times U. .

Transformers, coils and windings, which comply with IEC 60079··7 or transformers whichcomply with the requirements for mains transformers , level of protection .la or ib, inIEC 60079-11 are not subject to fault.

It is not necessary to consider the possibility of a short circuit if the distances or creepagedistances between bare live parts or printed tracks are at least equal to the values of Table 2(for methods of measuring creepage distances see IEC 60079-7 and iEC 80079-11)..

The maximum voltage between the parts shall be used to determine the distances accordingto Table 2. If the parts are electrically isolated, the sum of the maximum peak voltages of thetwo circuits shall be considered as , peak voltage. The maximum peak voltage shall beassessed taking into account normal operating conditions (transients being disrega rded) andfault conditions as specified in this standard.

For distance under a coating accordlng to Table 2, the foHowing conditions apply:

- a conformal coating shall have the effect of sealing the conductors in question againstingress of.moisture;

- it shall adhere to the conductive parts and to the lnsulatlon material;

- if the conformal coating is applied by spraying, then two separate coats are to be applied;

- other methods of application require only one coat: for example, dip coating, brushing,vacuum impregnating; but the intention :s to achieve an effective, lasting, unbroken seal;

- a solder mask is considered as one of the two coatings, 'provided it is not damaged duringsoldering. .

Conductive parts protruding from the insulation (including soldered component pins) shall notbe considered as coated unless special measures have been applied to obtain an effectiveunbroken seal,

Where bare parts of energized circuits emerge from the coating, the comparative trackingindex (CTI) in Table 2 applies to both insulation and conformal coating.

7

ISIIEC 60079-5: 2007

Table 2 - Creepage distances and distances through filling material

0,6

0.6175

175

1.6

1.6

1,6

Creepage Minimum Distance under Distance throughdistance value coating filling material

--mm CTI mm mrn--_..-1,6 - 0.6 1,5 -----

20

16

12,5

See Note

Voltage a.c. or d.c.V,.m,o.

------.-----i-----10

v

1,5-------t----------+--------+-.---.----'--------....-

1,5._----------+---_._----+---------1-._-------_._------ .- - - -175 0,6 1,5-- .-._ - - - - - {- - _ ._- - --- - ---------- -- ---_._-- --- --_.- ... - -_._-

25 1,7 175 0,6 1,5

~l-.---------3~~-·-t _2:' -=t H~-!~=O!_:__ _r==~C;----~=---=--:: --=--=l--~-===~- -:~== ~==~;-=-~~~=~~~-~::::~~==~-*- =~l-=:=f;:~-~-= ~-- ._'~:~_f_~=:1=----.. 1

25------·---:----I----11.:....--..-J~- __.~2...._ t------:-------- -- 1

.. ~:=~-_=6~_=_,_~~_=~+_=~~~~r t-=:-j.._._. __3:20.___ . 10 . 175 __ . 2,~_._._ . 'l j

:~: J-..---1~:--- ....···--+i~------···---~~~---- .-----+. - ----j---s;o----r·----;o ----- ---·17~~-·-·_· ..-. -.-'6 -- -- ,- ---'5 -----. --"j-'-'-&00 --"--~---25--- .------~15 ---..- ---- ---~- -- --t- -- ._-.-;;; ._.--.. -.~-----,oo~=-~ ,~r__=-'2;_==_-;;- ==j=_=..o_-_~:

E'--- 1 ~o_~. . --.-32----·-

l-- ---·---=--- ·-·- · ------?:...--- -------!..? j

---=~~:=--=-l- -~:: ==T=-~-==- ~~ -=-~~=:::: :~~:=-~: .~- . 1.------------.. 1-.-----.- - --- _. "-' .. -_.. --_.. ---·-i

f__.__4 OO!:__ _ -='2....__J !.!.:....__..._.__ .21_... .,__._ :~. __ j

~----+::~ ----. ----·-1~O---- ::: --._ ..--. ~:--_.- ----- ~:..--.-.._.j------- ----- -----------j

1-' 180 °:0°0 . ::: ---::: -- --~:-_. .... -----:~~.-----.--j

rNOTE V ; llages shown are der~v~d from IEC 60664 -1 and is based on the-;;;;;;allzatlon of su~~i;'~Olt~~~~~'~e~-jin Table 3b. When deterrrumnq the required values for creepage and clearance, the voltage value 111 the table may j'be Increased by a factor of 1 1 in order 10 recognize the range of rated voltages In common use1..._. --'

NOTE At 10 V and below, the value of CTI is not relevant

8

ISIIEC 60079-5: 2007

4.9.2 Protective devices for temperature limitation

Temperature limitation may be achieved by an internal or, external, electrical or thermal,protective device. The device shall not be self-resetting .

Wh ere integ ra l fuses are used as protective devices , the fusing element shall be of theenclosed type , for exa mp le, in glass or cer amic.

Ov er-current devices shall have a vo ltage rating not less than that of the circuit and shall havea breaking capacity not less than the prospective fault current of the circuit.

4.9.3 Powe r supply prosp ective short-circuit current

Electrical equipment , parts of electrical equipment and Ex components pro tected by pow derfill ing "q" and designed to be connected to an external source of supply not exceed ing 250 Va c. shall be sui table for a prospective short-circuit current of i 500 1\ un les s the markingmcludes the valu e of the permi tted prospectiv e short -circuit cur rent. Higher pro spectivecurrents than i 500 A could be present in some installat ions, for example at higher voltages.

If a cur rent -ltmiunq device is necessary to limi t the prospective short-circui t current to a val uenot grea ter than the rate d breaking ca paci ty of the fuse. thi s devi ce shall be a res istoraccording to 4.9 1a) an d the rated VAlues shall be:

- current rallng 1,5 x 1,7 x In of the fuse.

- external ly applied maximum voltag e Pm;

power idt ing 1,5 x (1 ,7 y. In of the fuse) ? x resis tance of limiti ng devi ce .

If the ma nufacturer do es not provide a required short cu cult, protect ive dev ice. the electricalequipm ent or part s of elect rical equ ipm ent shall be marked With the symb ol "X" in accorda ncewith 29.2 I) of lEG 6007 9·0 and the specific conditions of use shal ! deta il the short-circu itprotective dev ice s req uired .

5 Verifications and tests

5.1 Type verlflcatlons and t est s

5.1. 1 Press u re type te-st of en closure

irrespective at its volume, the enclosure shall be subjected to a pressure type test Wi th an over-pres sure of 50 kPa without the occurrence of pel manent deformat ion exceed ing 0,5 mm inany of its dimensions . The pre ssure sh all be applied for at least 10 s.

FOI enclosures, Without breath ing or degassing openings. whi ch contain capacitors other tha nplast ic fo il, pape r or ceramic type an d where the volume of th e fill ing materral IS lower thane ight t imes the volume of the capacitors . a pressure type tes t with an cv erpressur e of1,5 MPa applied for at least 10 s

Tests shall be carried out in normal conditions of the equipment, but may be done witnout thefi lli ng material pr ese nt

9

IS/~EC 610079-5: 2007

5.1.2 Verification of the degree of protection of the enclosure

The degree of protection of the enclosure shall be verified in accordance with the methodspecified in IEC 60529. Any breathlnq devices shall be in place. This test shall be carried outafter the pressure type test in 5.1.1.

5.i.3 flammability of materlais

The flammability requirements for enclosures, or parts of enclosures made of plasticsmaterials; of lEG 60079-1, shall be applied.

5.1.4 Dlelectrlc strength test of the filling materlat

The insulating properties of the filling material shall be tested prior to the filling process usinga sample of the fi1!ing material. For this purpose, the electrode arrangement shown in Figure 1shall be used. The electrodes shall be covered by the filling mate'rial in all directions with athickness of at least 10 mm.

The sample shall be conditioned for 24 h at a temperature of (23 ± 2) ·C and relative humidityof between 45 % and 55 %. A test voltaqe of 1 000 V d.c. +g % shall then be applied to theelectrodes.

The filling material complies with the requirements, if the leakage current does not exceed;, 10-6 A. If the material fails to comply, further conditioning and retesting are not permitted.

5.:1:.5 Maximum temperatures

Where fuses are used as protective devices for temperature limitation, the maximumtemperature under overload conditions shall be measured with a continuous current at least-1,7 times the fuse rating.

Where items other than fuses are used as protective devices for temperature limitation, theequipment shall be tested to verify that the- limiting temperature is not exceeded when thoseprotective devices operate.

NOTE To simulate overload conditions which may cause higher temperatures than in normal operation, it mightbe suitable to use power components mounted in the equipment and subject to the maximum available power.Such components should be chosen and located in the equipment so that they are representative of the thermalcharacteristlcs of the components they represent. '

5.2 Routine verifications and tests

5.2.1 Routine pressure test of enclosure

Each enclosure having a volume greater than 100 cm3 shall be subjected to a routinepressure test with an overpressure of 50 kPa without the occurrence of permanent deformationexceeding 0,5 rnrn'in any of its dimensions. The pressure shall be applied for at least 10 s.

.Tests shall be carried out under normal equipment conditions, but may be effected without thefilling material present.

The routine pressure test may be waived where the enclosure has passed a ,type test withfour times the reference pressure (50 kPA or 1,5 MPa) in 5.1.1.

10

15flEC 60079-5 : 2007

5.2.2 Die lect ric strength test of the fli ling materia l

Th e insulat ing properties of each lot of the fill ing materia l shall be tested prior to the fillingprocess using a sa mple of the filling materi al. For this purpose, the electrode arrangementshown in Figure 1 sh alt be used. The electrodes sha ll be covered by the filling material in all

directi ons with a thickness of at least 10 mm. The test vo ltage sha ll be 1 000 V d.c. +g %und er the followin g climatic conditions:

- temperature

- relative humidity

(23 :t 2) °C;

45 % to 55 % .

Th e fil li ng material co mp lies with the requ ire ments. if th e leakage current does not exceed10-6 A.

If the filling matenat does not initially comply with these requ irements , the lo t ma y be driedand retested .

s Marking

Electrrcal equipm ent . parts ') f ele ctr .cal euuipment , and Ex components of powder filling "q"shall be marked in accordance with IEC 60079-0 . with th e follOWing additional marking:

a) "1 his enclosure has been permane ntly sealed and cannot be repaired";

b) "Trus en closure is factory sealed - Consult man ufacturer 's instructi ons for rep ai r";

c) each connection facil ity for externa l connection shall be mal ked wi th an ident ificat ion ofrated voltage and rated cur rent ( "24 V d.c.. 200 mA", "230 V, i Da rnA"):

0) ext ernal fuse data If the type (If protec tion depen ds upon such a lus e, "Pequired externalfuse . '315 mA".

e) permittee prospect ive short-circui t current of the external electr ical supply if the equi pm entis designed fo r a short-circuit cutr ent le ss than 1 50 0 A, according to 4 9 3, for ex ample"Permi tted supp ly short-CIrcuit current 35 A" ;

f} opuonallv, permitted prospective short-c ircuit current of the ext ern al ele ctrical supply If theequ ipm ent IS nesigned fur a short- Circu it current of 1 500 A or more accoroinq to 4.13.3 , forexample "Permitted SUPPIV sno rt-circult cur rent 3500 A".

Any of these marY-ings may be replaced by technically equiva lem informanon

1 ln structlons

All powder fill ed "0, ' equipment shall be accompanied by mstrucuons as required byIEC 60079-0 , including the followi ng additional part iculars as a mtmm urn

- Where permitted by the ma nufacturer , details on the re-filling, re -sealing , and re- te sti nqrequirements for powder filled "q" equipment that has been opened for rep air.

_ Where the enclosure is permanently sealed and repa ir is not permitted by themanufacturer, tlus shall be staled clearly in the instructions.

11

u

Dimensions in mil1imetres with a tolerance of :t1,O mm

Figllrre 1 - Tes~ aHi"rangemell'l~ forr the dlelectrlc strength test olf the fiHil1lg: material

12

isnec 60079-5: 2007

Annex: A(informative)

introduction of an alternative risk assessment methodencompassing "equipment protection levels" fo r Ex equipment

A.O Introduction

This anne x provi des an expl ana tion of the concept of a risk ass ess ment methodencompassing equipment protection levels (EPLs). These EPLs are int roduced to enable analternative approach to current methods of selecting Ex equipmen t.

A.1 His toric al backg round

Historically, it has been acknowledged thai not all types of pro tection provide the same levelof assurance against the poss ibility of an ince ndive condition occurring. The rnstall ationstandard, lEG 60079 ·14, allocates spec ific types of protection to specific zones . on thesta tistical basis that the more lik eiy or frequent the occurrence of an explo sive atmosphere.the greater the level of secu rity required aqarnst the possibility of an ign ition source bemgactive.

Hazardous areas {wit h the norm al excep tion of coal mining} are div ided into zon es accordingto the degree of hazard. The degree of haza rd is defined according to the probabil ity of theoccurrence of expl osive atmospheres Generall y, no account is taken of the potentialconsequen ces of an explosion , nor of other facto rs such as th e toxicity of materials. A truerisk assessment would consider all fact ors.

Acceptance of equipment rnto each zone is historicall y based on the type pro tect ion . In somecases th e type of protection may be div ided into different levels of protect ion which againhrstoncatly correlate to zones For exam ple . intri nsic safety is civided into levels of protectlonla 8 11d lb. Th e encapsulation "m" standard includes two levels or protec tion " rna" and " mb" .

In the past. the equipment selection standard has provided a solid link betwee n the type otprotec tion for the equipment and the zone in which the equipme nt can be used. As notedearlier, nowhere in the IEG system of explosion protection is there any account taken of thepotential consequences of an explos ion, should It occur

However, plant operators often make intuitive decisions on extending (or restrictmg) theuzones in order to compensate for thrs omission A typical example is the installation of "zone 1type" navrqat ion equipment in zone 2 areas of offshore oil production platforms. so that thenavigation equipment can remain functio nal even in the presence of a totally unexpecte dprolonged gas release. In the other duecnon, it IS reasonable for the owner of a remote, wellsecured, small pum ping sta tion to drive the pump with a "zone 2 type" motor, even in zone 1,if the total amount of gas available to explode is small and the risk to life and property fromsuch an explosion can be discou nte d.

1 he situation became more complex with the publ ication of the first editron of lEG 60079-26which introduced additional requirements to be appl ied for equipment intended to be used inzone O. Prior to this , Ex ia was considered to be the only technique acceptable in zone O.

13

fiS/~IEC 50079-5-: 2007

It has been recognized that it is beneficial to identify and mark all products according to theirinherent ignition risk . .This would make equipment selection easier and provide the ability tobetter apply a risk assessment approach, where appropriate. .

A risk assessment approach for the acceptance of Ex equipment has been introduced as analternative method to the current prescriptive and relatively inflexible approach linkingequipment to zones. To facilitate this , a system of equipment protection levels has beenintroduced to clearly indicate the inherent ignition risk of equipment, no matter what type ofprotection is used.

The system of designating these equipment protection levels is as follows.

A.2.1 Coal mining (g roup I)

A.2.1.1 IEPl Ma

Equipment for installation in a coalmine, having a "very high" level of protection, which hassufficient secur ity that it is unlikely to become an ignition source, even when left energized inthe presence of an outbreak of gas.

NOTE Typicalty, communications circuits and gas detection equipment will be constructed to meet the Ma .requirements - for example an Ex ia telephone circuit.

A.2.1.2 EPL lWb

Equipment for installation in a coal mine, having a "high" level of protection, which hassufficient security that it is unlikely to become a source of ignition in the time span betweenthere being an outbreak of gas and the equipment being de-energized.

NOTE Typically. all the coal winn ing equipment will be constructed to meet the Mb requirements - for example Exd motors and switchgear.

A.2.2 Gases tgroup U)

A.2.2.1 IEPL Ga

Equipment for explosive gas atmospheres, having a "very high" level of protection, which isnot a source of ignition in normal operation, expected faults or when subject to rare faults.

A.2.2.2 IEPl Gib

Equipment for explosive gas atmospheres, having a "high" level of protection , which is not a-source of ignition in normal operat ion or when subject to faults that may be expected, thoughnot necessarily on a regular basis.

NOTE T.he majority of the standard protection concepts bring equipment within this equipment protection level.

14

A.2,2.3 EPL Gc

~snrEC 60079-5: 2001

Equipment for explosive gas atmospheres, having an "enhanced'; level of protection, which isnot a source of ignition in normal operation, and which may have some additional protectionto ensure that it remains inactive as an ignition source in the case of regular expectedoccurrences (for example failure of a lamp).

NOTE Typically, this will be Ex n equipment.

A.2.3 Dus ts (group lJI)

A.2.3.1 EI?L Da

Equipment for combustible dust atmospheres, having a "very high" level of protection, whichis not a source of ignition in normal operation or when subject to rare faults.

A.2.3.2 E?L Db

Equipment for combustible dust atmospheres, having a !'high" level of protection, which is nota source of ignition in normal operation or when subject to faults that may be expected,though not necessarily on a regular basis.

A.2.3.3 !EPL Dc

Equipment for combustible dust atmospher.es, having an "enhanced" level of protection, whichis not a source of ignition in normal operation and which may have some additional protectionto ensure that it remains inactive as an ignition source in" the case of regular expectedoccurrences.

For the majority of situations, with typical potential consequences froma resultant explosion,it is intended that the following would apply for use of the equipment in zones (this is notdirectly applicable for coal mining, as the zone concept does not generally apply). See TableA.1.

Table A.1 - Tradition al relat lonsh lp of !EPLs 10 zonas(no add itional ri sk assessment)

Equipment protection level Zone

Ga,

o IGb 1 "

Gc 2

Os 20

Db 21

Dc 22

A.3 Risk of ig nition protectlon a1foll'ded

The various levels of protection of equipment must be capable of functioning in conformltywith the operational parameters established by the manufacturer to that level of protection.See Table A,2.

15

ISIIEC 60079-5: 2007

Table A.2 - Description of risk of ignition protection provided

Protectionafforded Group

Performance ofprotection

Ma

Very high

Group I

I-------j-------------Ga

Very high

Group II

Two independent means ofprotection or safe even

- -. _. when two faults occurIndependently of eachothe r

Two independe nt means ofprotection or safe even

. - . when two faults occurindependentl y of eachothe r

r------j------------r---- --------t------ - - ---- -

Very high

Da

Group III

Two Independent means ofprotection or safe even

- - when two taults occurIndependently of eachother

Equipment re m ainsfunctioning In zones :20. ;>1and 22

l---------f----------------I-------.-------!------- - ------ -

HighMb

Group I

SUitable for normaloperation and severeoperating condition s

Equipm ent de -energiz edwhe n explosweatmosphere present

I---------!--------------+------------I-----------

High

Enhanced

E'nhanced

Gb

Group II

Db

Group 11/

Gc

Group 1/

Dc

I Group 1/1

SUitable for normaloperation and frequ entl yoccurring disturbances orequ ipment where fau lts arenormally taken Into account

Suitable for norm aloperation and frequentlyoccurring disturbances orequipment where faults arenormally taken IOta account

Suitable for normaloperation

SUitable for normaloperation

Equipment rernarnsfunct ioning In zones 1 and2

Equipment remainsfunctioning in zones 2 1 and22

Equrprnent remainsfunctrorunq In zone 2

'--------"--------------'---------_.-- ---

A.4 Implementation

The fourth edition of lEG 60079·14 (encompassing the former requirements of lEG 61241-14)will introduce the EPLs to allow a system of "risk assessment" as an alternative method forthe selection of equipment. Reference will also be included in the classification standardslEG 60079-10 and lEG 61241-10.

The additional marking and the correlation of the existing types of protection are beingintroduced into the revisions to the following lEG standards :

o IEC 60079-0 (encompassing the former requirements of IEC 61241-0)

.. lEG 60079-1

o lEG 60079-2 (encompassing the former requirements of lEG 61241-4)

.. lEe 60079-5

16

ISIIEC 60079-5: 2007

o IEC 60079-6

IEC 60079·7

.. IEC 60079-11 (encompassing the former requirements of IEC 61241-11)

~ IEC60079-15

~ lEe 60079-18 (encompassing the former requirements of IEC 61241-18)

.. lEG 60079-26

" lEG 60079-28

For types of protection for explosive gas atmospheres the EPLs require additional marking .For explosive dust atmospheres . the present system of marking the zones on equipment isbeing replaced by marking the EPLs .

17

GMGIPN-120 BIS/ND/09-300 CopIes

(Continued from second cover)

lmemeuonet Standard Title

ISO 3310 -1

ISO 3310-2

ISO 2591 -1

Test skves -- Techn ical requirements and testing -- Part 1: Test sieves ofmetal wi re cloth

Test sieve s - Tech nical requirements and testllig - Part 2: Test sieves ofperforated plates

Test sieving - Meth ods usmq test sieves of woven wire cloth and perforatedmetal plate

On ly the English language text of the International Standard has been retained whi le adopting it in this IndianStandard. and as suc h the page num bers given here are not the same as in lEG Standard .

For til e purpose of deciding whether a particular requirement of this standard is com plied With, the fina lvalue, observed or ca lculated exp ressing the resu lt of a test. shall be rounded off Irl acco rdance withIS 2: '1960 'Rules for rounding off numerical values (revls ed)' . The numb er of significant places retained Inthe round ed off value shou ld be tho same as thai of the specined value in this standard.

Bureau of Indian Standards

BIS is a statutory institution established under the Bureau of Indian Standards Act, 1986 to promoteharmonious development of the activities of standardization , marking and quality certi fication ofgoods and attending to connected matters in the country.

Copyright

SIS has the copyright of all its publications. No part of the these publications may be reproduced inany form without the prior permission in writing of BIS. This does not preclude the free use, in thecourse of implementing the standard, of necessary details, such as symbols and sizes, type or gradedesignations. Enquiries relating to copyright be addressed to the Director (Publications), BIS.

Review of Indian Standards

Amendments are issued to standards as the need arises on the basis of comments. Standards arealso reviewed periodically; a standard alongwith amendments is reaffirmed when such review indicatesthat no changes are needed; if the review indicates that changes are needed, it is taken up for revision.Users of Indian Standards should ascertain that they are in possession of the latest amendments oredition by referring to the latest issue of 'BIS Catalogue' and 'Standards: Monthly Additions'.

This Indian Standard has been developed from Doc No.: ETD 22 (5886).

Amendments Issued Since Publication

Amend No. Date of Issue

BUREAU OF INDIAN STANDARDS

Text Affected

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