इंटरनेट मानक 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. “जान1 का अ+धकार, जी1 का अ+धकार” “प0रा1 को छोड न’ 5 तरफ” Mazdoor Kisan Shakti Sangathan Jawaharlal Nehru “The Right to Information, The Right to Live” “Step Out From the Old to the New” IS/IEC 61241-4 (2001): Electrical Apparatus for Use in the Presence of Combustible Dust, Part 4: Type of Protection 'pD' [ETD 22: Electrical Apparatus for Explosive Atmosphere] “!ान $ एक न’ भारत का +नम-ण” Satyanarayan Gangaram Pitroda ““IInnvveenntt aa NNeeww IInnddiiaa UUssiinngg KKnnoowwlleeddggee”” “!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता हहहहै””ै” Bhartṛhari—Nītiśatakam “Knowledge is such a treasure which cannot be stolen” IS/IEC 61241-4 : 2001 m- ~fUiT ~ rtf ~ if >rirT "Clffi" ~ -t ~ wm 'qJ1T 4 "pD" ~ Indian Standard ELECTRICAL APPARATUS FOR USE IN THE PRESENCE OF COMBUSTIBLE DUST PART 4 TYPE OFPROTECTION "pD" ICS 29.260.20 © BIS 2009 BUREAU OF INDIAN STANDARDS . MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG NEW DELHI110002 December2009 Price Group8 ElectricalApparatus for Explosive Atmospheres Sectional Committee, ETD 22 NATIONALFOREWORD This Indian Standard (Part 4) which is identical with IEC 61241-4 : 2001 'Electrical apparatus for use in the presence of combustible dust - Part 4: Type of protection "pO" , issued by the International ElectrotechnicalCommission (IEC)wasadoptedbytheBureauofIndianStandardsonthe recommendation of the Electrical Apparatus for Explosive Atmospheres Sectional Committee and approval of the ElectrotechnicalDivisionCouncil. The text of IEC Standard has been approved as suitabie for publication as an Indian Standard without deviations. Certain conventions are, however,notidenticalto those used inIndian Standards. Attention is particularly drawntothefollowing: a) Whereverthewords'InternationalStandard'appearreferringtothisstandard,theyshouldbereadas 'IndianStandard'. b) Comma(,)hasbeenusedasadecimalmarkerintheInternationalStandardwhileinIndianStandards, thecurrentpractice istouseapoint(.)asthedecimal marker. Inthisadoptedstandard, references appear tocertain International Standards forwhich Indian Standards also exist.The corresponding Indian Standards, which areto be substituted intheir respective places are listedbelowalongwiththeir degree ofequivalence fortheeditionsindicated: InternationalStandard CorrespondingIndianStandard DegreeofEquivalence IEC60034·1:1996 Rotatingelectrical IS 325 :1996 Three-phase induction Technically Equivalent machines - Part 1: Rating and motors (first revision) performance IEC 61241 (all parts) Electrical IS/IEC 61241 (all parts) Electrical do lipparatusfor use inthe presence of apparatus for use in the presence of combustibledust combustible dust IS/IEC 61241-0 : 2004_ Electrical apparatus for use in the presence of IEC 61241·1·1 : 1999'1 Electrical combustible dust: Part 0 General apparatusprotectedbyenclosuresand requirements Identical surface temperature limitation IS/IEC 61241·1 : 2004 Electrical Specificationforapparatus apparatus for use in the presence of combustibledust:Part1 Protection by enclosures"to" IEC 61241·1·2 : 199921Electrical IS/IEC 61241·14: 2004 Electrical do apparatusprotectedbyenclosuresand apparatus for use in the presence of surface temperature limitation combustible dust: Part 14 Selection Selection, installatlon and andinstallation maintenance IEC61241·3:199z>1 Classificationof IS/IEC 61241·10 : 2004 Electrical do areaswherecombustibledustsareor apparatus for use in the presence of maybepresent combustibledust:Part10Classification ofareas wherecombustibie dusts are ormaybepresent "SupersededbylEG61241-0: 2004 and lEG61241-1 :2004. Bothadopted asidentical Indian Standards. •SupersededbylEG61241-14: 2004 andadopted asidentical indian Standard. "SIJpersededbylEG61241-10 andadopted asidentical Indian Standard. (Continuedon third cover) IsnEC 61241-4: 2001 Indian Standard ,etfCTRICAL APPARATUS FOR USE IN THE .PRESENCE OF COMBUSTIBLE DUST PART 4 TYPE OF PROTECTION "pO" ~'~.Oope iJlls part of IEC61241 gives requirements on the design, construction, testing and marking of electrical apparatus for use in combustible dust atmospheres in which a protective gas (air or inert gas), maintained at a pressure above that of the external atmosphere, is used to prevent the entry of dust which might otherwise lead to the formation of a combustible mixture within enclosures whichdo'not contain ascurce of combustible dust. This standard contains the specific requirements for construction and testing, including prqteclive requirementll that applyto electrical apparatus with type of protection pressurization "pO"intended for use in potentially combustible dustatmospheres. This stendard includes the requirements for the construction of the enclosure and its associated components, including, if any,the inlet and outlet ducts for the protective gas, and for the safety provisions and devices necessary to ensure that pressurization Is established andmaintiJinedfor typeof protection pressurization "pO". Rllqulrements for pressurized enclosures with an Intllrnal source of dust rlliease are not includlld in this standard. This standard does not cover the requirements for pressurized roQIIIswith or without Inlllrnal sourcesof dust release. This standard does not apply to dust$ of explosiVes which do not require atmospheric oxygen forcombustion ortopyrophoric subsrnlllls. This s"ta',"nda'r,d'.doe.s not cover combi.i'llld,.' gas and dust hazard. Those requirements are under consideration. ' Therequirements contalnlld Inthis standardare supplementary to those in IEC61241-1-1. 2 Normative reference. The following normative documents contain provisions which, through reference In this text, constitute provisions of this part of IEC61241. Fordated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this part of IEC 61241 are encouraged to investigate the possibility of applying the most recent editions of the normative documents listed below. For undated reference's, the latest edition of the normative document referred to applies. Members of IEC and ISO maintain regillters of currently valid International Standards. ~;~1:1996, Rotating electricalmachines - Part 1:Rating and performance1) 1)"thereexists aconsolidated edition 10.2(1999)thatincludes edition 10.0andits amendments. 1 ISIIEC 61241-4: 2001 IEC61241(all parts), Electricalapparatus for usein thepresence ofcombustible dust IEC 61241-1-1:1999, Electrical apparatus for use in the presence of combustible dust Part 1-1: Electrical apparatus protected by enclosures and surface temperature limitation Specification forapparatus IEC 61241-1-2:1999, Electrical apparatus for use In the presence of combustible dust Part 1-2: Electrical apparatus protected by enclosures and surface tempereture limitation Selection, installation and maintenance IEC61241-3:1997, Electrical apparatus for use In the presence ofcombustible dust - Part 3: Classification ofareas where combustible dusts are ormay beprasent . 3 Definitions Forthepurpose of this part of IEC 61241,the definitions from IEC 61241-1-1 and the following apply. 3.1 type ofprotection "pO" technique of applying a protective gas to an enclosure in order to prevant the forma~of an explosive dust atmosphere inside the enclosure by maintaining an overprassure agelnsllba surrounding atmosphere 3.2 overpressure pressure above ambient pressure within apressurized enclosure 3.3 pressurization technique of guarding against the ingress of the external dust atmosphere, which may be explosive, into an enclosure bymaintaining a protective gas therein at a pressure above that of theexternal atmosphere .' 3.4 protective gas airor inertgas usedfor maintaining anoverpressure NOTE For the purpose of this standard Inert gas means nitrogen. carbon dloxlde, "",,\~"""~I(;h:. when mixedwithoxygen Intheratio of4:1 asfound inair, does notmake the ignitionandcombuattbf...,.apertles, such 8S combl,lBtlblelimits, more onerous. 3.5 enclosure all thewellswhich surround the live parts of electrical apparatus Including dool'8,covers, cable entries, rods, spindles and·shafls andwhichensurethe proteCtionOfthe electrical apparatus 3.6 pressurized enclosure • . .. enclosure Inwhich protective gas Is maintained at a pressure !lreater than that of the external atmosphere NOTE Thepressurized enclosure mayor maynot also bethe enclosure surrounding the live partsand ensuring theprotection in other respects ofthe electricalapparatus. 2 ISIIEC 61241-4 : 2001 ·,a.71~ .,till "..aurlZlltlon ~ of an overpressure within a pressurized enclosure without the addition of ~..g. as'in ahazardous area '~Ilrlzatlon, with leakage compenaatlon ' 'Uilt"lJnance of an overpressure within a pressurized enclosure so that, when the outlet .rtures - if any- are closed, the supplyof protective gas is suffi~ient to compensate for any leakage from the pressurized enclosure anditsducts 3.9 pressurization with continuous flow ofthe protective gas maintenance of an overpressure within a pressurized enclosure with continuous flow of the protective gasthrough the enclosure 3.10 , , electrical apparatus itel'llsapplied asa whole or in part for the utilization of electrical energy. These include, among others, items for the generation, transrnlsslon, distribution, storage, measurement, regulation, conversion, andconsumption of electrical energyanditemsfor telecommunications 3.11 Ignltlon-eapable apparatus apparatus which, in normal operation, constitutes a source of ignition for a specified combustible dust atmosphere. This includes electrical apparatus not protected by a type of protection listed in lEe61241-1-2 3.12 se"-revealing fault fault which would cause a malfunctionof'the'lipparatus necessitating- correction before proceadingwithfurtheroperation of til.apparatus andwhich maybe indicated, for example, by anaudibleor visible signal • 3.13 opening , ' aperture, door, windOWor non-aIrtightfixed panel 3.14 protective device , a deviceprovidedtc protect systemagainst conditions which could result in afire orexplosion 3.15 alarm pieceof apparatus that generates avisual oraudible signalthat is intended to attractattention 3.16 Indicator piece of apparatus that shows flow or pressure and is monitored periodically, consistent with therequirement ofthe applic.ation ....1 iIIIIlIIJactedapparatus -.,apparatusinternal to the pressurizedenclosure 3 ISIIEC 61241-4: 2001 3.18 pressurization system groupingofcomponentsusedto pressurizeendmonitora pressurized enclosure 3.19 alternate (or auxiliary) source of supply ofprotective gas secondsourceofprotective gasthat maytakeoverIntheevent offailure of the primery source 3.20 zones classified areas are divided Into zones based upon the frequency and duration of the occurrence of explosive dusl/alr mixtures. Dustlayere should also be taken Into consideration [IEC61241-3,definition 2.10] 3.21 zone 20 sreaInwIllch combustible dust, asa cloud, Ispresentcontinuouslyorfrequently, during normal operation, in sufficient quantity to be capable of producing an exploBiV8 concentration of combustible dust mixed with air, and/or where layers of dust of uncontrollable and excessive thicknesscanbeformed. This can be the case inside dust containment areas where dust can form explosive mixtures frequentlyorfor longperiodsof time. This occurstypicallyInsideequipment [IEC61241-3,definition 2.11] 3.22 zone 21 areanot classified as zone 20 in which combustible dust, as a cloud, Is likely to occur during normaloperation, in sufficientquantities to becapableof producing anexplosive concentration ofcombustibledustmixed withair. ThIS zone can Include, among others, areas in the immediate vicinity of powder filling or emptyingpoints and ereaswhere dust layersoccur andare likely. in normel operelion, to give risetoenexplosive concentration of combustibledustmixedwith air [lEe 61241-3,definition 2.12] 3.23 zone 22 areasnot classified as zone 21 in which combustible dust clouds may occur Infrequently, end persistfor only a short period, or inwhich accumulationsor layers of combustible dustmay be presentunderabnormal conditions and give riseto combustible mixtures of d~}!l illr Where, e, following an abnormal. condition, the removal of dust accumulalions or ~ ClI/Inot be assured,then theareaisto beclassified zone21. This zonecan include, among others, areas intheviCinityof equipmentcontelnlng dust. where dustcenescapefrom leaks andform deposits(suchesmilling roomsInwhich dUltcanescape fromthemills endthen settle) IEC61241-3,definition 2.13] 4 ISIIfe 61241-4: 2001 :4 i.i~..•.o.•"..n principle ~. pressurization is atype of protection that relies upon the interiorof the enclosure . ... . .' d to a continuous overpressure from a supply of protective gas while electrical _ : .yrithinthe enclosure isenergized. . "'~ apressurization system, thefollowing basic principles apply. 4J;·,,Iitrot.ctlvegas fiIent Is a suitable supply of protective gas capable of maintaining the pressure above a JWedetermlned level except for static pressurization asgiven in clause 7. 4.2 .AIitomatlcdisconnection Pressurization failure automatically disconnects the system from the electricity supply andlor initiates alarms.' . . . 4.3 CI.anlng TIl.enclosure is cleaned before the electrical supplycan be connected, in order.to remove any accu",ulsled combustible dust left in the enclosure, either accidentally following failure of the pressurization system, or following normal shutdown. 4.4 Dischargeofprotective gas Preferably, the protactive gas may be discharged Into a non·ha~OI,Isllfee, In.the .case of pressurization with ccntinuous. flow, arid where thepro~.geJ! ie.d1scher.ged ,10.10 the hazardous area, means are to be provided to prevent hot pmtCIes or other Ignilion sources from equlpmenlunder normal or fault condilions entering the hezardousarea.. ,_ , ' - -". Co-,'," . . . '.• ",."": • 5 Oeneral constructional requirements 5.1 1!IecIt!:'C~1 perfonnsnce~~p~us The electrical performance of apparatus contained within the enclosure shall be such thet the apparalus Iscapableof functtoning up to its full rating and recognized o,!erloads, if any,without detrlmenllothe enclosureor rII&.In'.urfacetemper~turein excess of the specified limits. "OTE Safeguarding sgslnll pq'snllsl.•rclng faults that mightI.ad 10 th. fallu.. of an .nclosure should ba conaldered.takinginto account raultlevelstogetherwithprotection andsafety devices fltted. 5.2 Mechanicalstrength The pressurized enclosure dlll;lB, if any, and their connecting parts, shal.1 withstand a pressure equal to 1,5 times the maximum overpressure specified bythe manufacturer for normal service withall outlets closed, with-a minimum of 200Pa(2mbar). If a pressure can occur In service that can cause a deformation of the enclosure ducts, if any, 01' connecting parts, a safety device shall be fitted by the manufacturer to limit the maximum ltItemaloverpressureto a level.belowthat which could adversely affectthe type of protection. .j:_.p:.m.nt with larg. IUrflce areas, which ara subj.ct.d to pra.sur.1 In excess of 1 kPa (for .x.mpl., n." anclosur.s). may requtr••pprovet from the r.l.vlnl luthorily raspon.ibl. for pr•••ure v••••1 5