GUIDE Motors And Drives In Potentially Explosive .

—GUIDEMotors and drives inpotentially explosive atmospheresWhat you need to know

2M O T O R S A N D D R I V E S I N P O T E N T I A L LY E X P L O S I V E AT M O S P H E R E S W H AT YO U N E E D TO K N O W—OverviewA potentially explosive atmosphere is defined as a location in whichgases, vapors, mist or dust mixed with air can form a flammable mixture.Electrical equipment installed in such locations must be designed andtested in such way that it does not cause arcing or high temperaturesthat could provide a source of ignition for such a mix.The purpose of this brochure is to provide the reader with basicinformation on the regulations, standards, definitions and equipmentrequirements for motors and drives in potentially explosive areas.

3—Table of contents04 – 05 What is a potentially explosive atmosphere?06 – 07Understanding the standards forexplosive atmospheres08 – 09 Main standards for explosive atmospheres10 – 11 Groups12 – 13 Zones, categories and equipment14 – 15 Motor protection types16 Certification markings17 – 19 The effects of variable speed drives on motors20 – 21 ATEX-certified safety functions22 – 23 Selecting motors and drives forexplosive atmospheres

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M O T O R S A N D D R I V E S I N P O T E N T I A L LY E X P L O S I V E AT M O S P H E R E S W H AT YO U N E E D TO K N O W5—What is a potentially explosiveatmosphere?Explosive atmospheres occur when flammable gases, mist, vapors or dust mixwith air. This creates the risk of an explosion. The amount of a substance neededto create an explosive atmosphere depends on the substance in question.—01 Oil and gas—02 Chemical industry—03 Mining—04 Water treatment—05 Food and beverage—06 Sawmills—07 Pharmaceutical—08 Textile industry—09 Marine—10 Power generationThe area where this possibility exists is definedas a potentially explosive atmosphere. Theseatmospheres can be found in many industries,from chemical, pharmaceutical and food, topower generation and wood processing.The areas may also be known as “hazardousareas” or “hazardous locations.”The number of substances that are flammablewhen mixed with air is very large. This meansthere are many industrial sectors that can havea potentially explosive atmosphere somewhere intheir process. Some of these are not so obvious.For example, sawmills by default are not apotentially explosive atmosphere, but if sawdustis allowed to collect in large amounts in onearea, that area can become one.

6M O T O R S A N D D R I V E S I N P O T E N T I A L LY E X P L O S I V E AT M O S P H E R E S W H AT YO U N E E D TO K N O W—Understanding the standardsfor explosive atmospheresGlobally, there are many regulations and certification systems with differentrequirements. The technical requirements in these regulations are becomingincreasingly harmonized with the global IEC standards.IECExThe IECEx system (www.iecex.com) – fromthe International Electrotechnical Commission,is a voluntary certification system that verifiescompliance with IEC standards related to safetyin explosive atmospheres. IECEx covers fourmain areas: Certification of service facilities IECEx equipment certification Ex marking conformity Certification of Personnel CompetenciesIECEx Conformity Mark SystemIn order for equipment to receive a conformity“Ex” marking under IECEx, it must obtain acertificate of conformity.This requires: An accepted IECEx Quality AssessmentReport (QAR) An accepted IECEx Test Report for typetesting (ExTR)Products with the IECEx conformity mark havereceived an IECEx Certificate of Conformity,which confirms that the product has theappropriate protection for use in explosiveatmospheres and that it has been manufacturedunder a system subject to ongoing surveillance bycertification bodies. The marking also indicatesthat the product can be supplied to the marketwithout the need for additional testing. Theexception is increased safety (Ex e) motorprotection type, which must always be testedwith the drive it will be used with.European DirectivesCommonly referred to as ATEX, from theFrench “ATmosphères EXplosibles”, the Europeanregulations combine two EU directives: theWorker Protection Directive (1999/92/EC) andthe Product Directive (2014/34/ EU). The EUDirectives have some difference from IECEx, andthey do not include certification of servicefacilities or certification of personnelcompetencies. Compliance with the “EssentialHealth and Safety Requirements” described inthe directives is mandatory within EU countries.The easiest way to show compliance is tofollow harmonized standards.Protective devicesProtective devices are often required byIEC 60079 series of standards for safe operationof Ex equipment. Protective devices can belocated inside or outside explosive atmospheres.A typical example of a protective device is surfacetemperature protection for motors controlledby a variable-speed drive (VSD). This type ofprotective device is an alternative to a certifiedand tested combination of motor and VSD.Protective devices for Ex equipment andproducts fall within the scope of the ATEXregulations: harmonized standard EN 50495:2010.IECEx does not have an applicable standard forelectrical safety devices for Ex equipment, andtherefore certification can only be done accordingto ATEX. However, a new IEC publication (IEC TS60079-42) will give guidance on protectivedevices under IECEx. Also remember to alwayscheck the local regulations as well.

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8M O T O R S A N D D R I V E S I N P O T E N T I A L LY E X P L O S I V E AT M O S P H E R E S W H AT YO U N E E D TO K N O W—Main standards for explosive atmospheresIEC and EN standards IEC 60050-426 Equipment for explosive atmospheres IEC/EN 60079-0: Equipment – General requirements IEC/EN 60079-1: Equipment protection by flameproofenclosures “d” IEC/EN 60079-7: Equipment protection by increasedsafety “e” IEC/EN 60079-10: Classification of hazardousareas (gas areas) IEC 60079-10-1: Classification of areas – Explosivegas atmospheres IEC 60079-10-2: Classification of areas – Combustibledust atmospheresRegulations around the globeCEC, CSANEC, CSA/US/ULInmetroSABS IEC/EN 60079-14: Electrical installations design,selection and erection IEC/EN 60079-15: Equipment protection by type ofprotection “n” (no longer applicable to rotating machines) IEC/EN 60079-17: Electrical installations inspectionsand maintenance IEC/EN 60079-19: Equipment repair, overhaul andreclamation IEC/EN 60079-31: Equipment dust ignition protectionby enclosure “t”

M A I N S TA N D A R D S F O R E X P LO S I V E AT M O S P H E R E SATEX directivesThe Worker Protection Directive (1999/92/EC) specifiesthe minimum health and safety requirements for workersperforming duties in potentially explosive atmospheres.The Product Directive (2014/34/EU) specifiesrequirements for equipment that is used in potentiallyexplosive atmospheres. It also specifies the requirementsfor protective systems that are needed for equipmentprotection.In addition to IECEx and ATEX there are several localstandards that may be in effect in certain countries.9Other standardsMany countries have regulations concerning both thedesign and use of electrical devices in potentially explosiveatmospheres, and these may differ. These regulationshave become increasingly harmonized within the frameworkof IEC recommendations and European standards. Nationalrequirements may still need to be met for final approvalof installation (e.g. in Russia, Brazil, Australia or Japan), butthey generally relate to one of the main standards below. IEC: International Electrotechnical Commission EN: European standard NEC/CEC: National Electrical Code / Canadian ElectricCode (500 or 505) in North AmericaATEXTR-CU / EACUkrSeproTIISKorean StandardCNEXITRIPESOANZExIECEx (worldwide)

10M O T O R S A N D D R I V E S I N P O T E N T I A L LY E X P L O S I V E AT M O S P H E R E S W H AT YO U N E E D TO K N O W—GroupsGroupsInternationally, IEC 60079-0 and EN 60079-0in Europe define three groups for potentiallyexplosive atmospheres: Group I coversunderground mines or mines susceptible tofiredamp. Group II relates to surface environmentswith gas, and Group III to surface environmentswith dust. The Product Directive defines only twogroups: Group I for underground mines or minesendangered by firedamp and/or combustibledust, and Group II for all surface installations.The group designation is essentially based onwhere equipment can be used (equipmentclassification).Subgroups and temperature classesExplosive gases, vapors and dusts have differentchemical properties that affect the likelihood andseverity of an explosion. Such properties includeflame temperature, minimum ignition energy,upper and lower explosive limits, and molecularweight. Based on the nature of the explosivegas/dust, gases are grouped into IIA, IIB and IICand dusts into IIIA, IIIB and IIIC.Temperature classes are defined for equipmentbased on its maximum surface temperature.When selecting a piece of equipment for apotentially explosive atmosphere, the maximumsurface temperature of the equipment must belower than the ignition temperature of thepotential gas or dust mixture.—Gas classificationTemp. classIgnition temp. of gas/vapor( C)Max. permitted temp. of equipment( C)Gas examplesHydrogenT1 450450T2 300 but 450300EthanolT3 200 but 300200Hydrogen sulfideDiethyl etherT4 135 but 200135T5 100 but 135100–T6 85 but 10085Carbon disulfide—Gas subdivisionIIAApprox. 120 gases and vapors, e.g.butane/petroleum/propaneIIBApprox. 30 gases and vapors, e.g.ethylene/dimethyl ether/coke oven gasIICThree gases: hydrogen (H₂)/acetylene (C₂H₂) /carbon disulfide (CS₂)

GROUPS11—Dust subdivision—Dust micalsTCL(cloud)( C)T5mm(layer)( C)Surface temp.provided that dustlayer below 5 mmWheat350270195Barley, 0230195Hard coal460240165PVC450330255Synth. rubber470220145Sulfur240250160IIIACombustible flyingsIIIBNon-conductive dustIIICConductive dustRelationships between ATEX directivesWorker Protection Directive1999/92/ECClassifies the zones and statesthe corresponding categoryProduct Directive 2014/34/EU(formerly 94/9/EC)Defines the equipmentrequirements (EHSRs)for each categoryZonesRisk analysisEHSRsProduct requirementsProbability, frequency,duration of occurrenceof potentially explosiveatmosphereZone 0/20Category 1Zone 1/21Category 2Zone 2/22Category 3Capability of theequipment in respect ofEHSR and theinstallation zone(EHSR essential health & safety requirements)The manufacturer is responsible for product safety and for delivering installation and maintenance instructions.The Product Directive guides the manufacturer to prepare the product classification and to certify the product and production.The end user is responsible for ensuring that the product is installed, maintained and operated in a way that doesnot pose any risk of explosion. The Worker Protection Directive guides end users to use certified products and toprepare risk analysis, safety instructions, training and procedures for operation and maintenance.