low frequency electro-magnetic

WHENDOWNTIMEISNOTANOPTIONANDSAFETYISP

LOWFREQUENCYELECTRO-MAGNETICSHIELDINGSOLUTIONS

• ShieldedCableTrays.• Shieldedbackplanesfor

TransformerandPowerrooms.

Ref.0320

Copyright:FlexVPCS.L.2020

WHYSHIELDING 3

GENERALDESCRIPTION 3

SHIELDMAX 4

EFFECTOFELECTROMAGNETICFIELDSONPEOPLE 5EMFEFFECTSONELECTRONICEQUIPMENT 6EMFEFFECTSONHUMANBEINGS 7

ORIGINOFEMFANDSOURCES 8

BENEFITS 8

SHIELDINGTECHNOLOGY 9

MAGNETICFIELDLOWFREQ.:HYBRIDTECHNOLOGY 9

LIMITSANDSTANDARDS 10

MAGNETICANDELECTRICFIELDLOWFREQUENCY 10

NORMS:EN61000-4-8 10

RECOMMENDATIONS 10

NCRPDRAFTRECOMMENDATIONSONEMFEXPOSUREGUIDELINES 10

GENERALAPPLICATIONS 11

HOWTOPROTECTPEOPLEANDELECTRONICSFROMELECTROMAGNETICFIELDS 11BENEFITSOFEMCBUILDING 11

SELECTIONGUIDE 18

ATTENUATIONTEST 19

MECHANICALWEIGHTPERFORMANCE 19

OVERLAPPING 20

VENTILATION 20


MODELS&DIMENSIONS 21

INSTALLATIONGUIDE 25

APPLICATIONSANDINSTALLATIONSEXAMPLES 26

MAGNETICANDELECTRICFIELDLOWFREQUENCY 26

SELECTIONGUIDE 27

SELECTIONGUIDE 28

MODELSANDDIMENSIONS 28

REF.NUMBER(EXAMPLE) 28

FLATANDCORNERPLANES 28


APPLICATIONSANDINSTALLATIONEXAMPLES 30

MODELSANDDIMENSIONS 31


APPLICATIONSANDINSTALLATIONEXAMPLES 35

DISTRIBUTIONLINESANDSHIELDINGCHANNELS 13

DESCRIPTIONOFSHIELDINGMATERIALS 15

CERTIFICATES 36


TUTORIALWHYSHIELDINGGeneralDescriptionElectroMagneticFields(EMF)generatedbyhighpowercablesandbus-barsareagrowingconcernandatechnicalchallengetoConsultants,FacilityManagersandpeopleingeneral,world-wide,inmanyfacilitiesandbuildings,duetonewrestrictingEMFemissionstandardsthatlimitcontinousexposuretopeopleandmachinesduetohealthandperformanceissues.ShieldMaxtechnologyistheresultofyearsofexperienceandover500successfulinstallationsthathaveprovidedtheknow-howtostandarizehigh-performanceEMFShieldMaxproductspresentedinthiscatalog.ContinuousexposuretoLowFrequencyElectroMagneticFields(EMF),causedbyhighpowerelectricloads,ashighpowercables,alterthenormalfunctioningofelectronicequipmentandaffectshumanbeingshealth.15%ofelectronicequipmentfailures(suchasservers,electro-medical,PLCs...malfunction)orcommunicationnetworksÅLunderperformancearereportedtobecausedbyEMF.


EMFrelatedproblemsaregrowingrapidlyasperincreasingpowerconsumptioninanybuiding,creatingmoreEMFsourcesandatthesametime,affectingmorepeople,asperspacescarcetyandproximitytosuchloads.EMFexposureislimitedbyvariouscompulsorynorms:-ElectronicequipmentandMachinery:LimitofMagneticFieldexposurebynormIEC/EN61000-4-8is3,75uT(microTeslas)andiscomplusorytoprovideanenvironmentwithlessthansuchleveltoensurethesecureandgoodperformanceofevery-day-more-sensitiveelectronicsandmachinery.NormIEC/EN61000-4-3establishesforsensitiveelectronics<1v/mlimitexposuretohighfrequencyEMF.-HumanBeings:limitofEMFcontinousexposurebyNCRPto1μT,mustbeobservedtoensurepeopleÅLssafetyandavoidanyhealthrisk.

ShieldMaxInalldomesticandbusinessenvironmentsthereareelectromagneticfieldswhichmayoccurnaturally,asaconsequenceoflightitself,orwhichmaybeartificiallygeneratedbytheextensivepresenceofelectricalplantsanddevices.Inthetwentiethcentury,environmentalexposuretoartificialelectromagneticfieldshassteadilyincreasedasaresultofahugeincreaseinenergydemand,thecontinuingdevelopmentofwirelesstechnologiesandbecauseofchangesincommunicationandworkpractices.Whenpeopleareexposedtoelectromagneticfieldstheirbodyabsorbsenergy.Thiscausesanimbalancetothebody’snaturalequilibriumand,whilethescientificand


medicalcommunityisstilllookingforconclusiveevidence,itisimportanttoprotectpeoplefromthepossiblelong-termeffectsofelectromagneticfields.Interestinelectromagneticpollutionhasincreasedinrecentyearsasaresultofextensiveresearchandstudies.Standardsandtechnicaldocumentshavebeendraftedandspecificlawsapprovedtoprotecttheenvironmentsmostatrisk,suchastheworkplace.Itisimportantthereforethattherisktohumanhealthbeevaluatedandmeasurestakentolimitelectromagneticexposureinordertoguaranteehealthandsafetyatwork.Aswellaspossibleeffectsonhumanhealth,electromagneticfieldscancreatedisturbanceandcauseinterferencewithelectronicequipment.Europeanlegislationhasthereforesetlimitstoguaranteetheadequateandsafeperformanceofinstruments.Asaresult,theuseofappropriatescreeningsystemsisessentialinallindustrialprocessesthatinvolvehighcurrentintensityortheuseofintenseelectricormagneticfields.ThisistoprotectbothworkersandelectricequipmentneartothefieldsourcesEffectofElectromagneticFieldsonPeopleElectricandmagneticfieldsthatvaryovertimeinteractwiththeelectricallychargedparticleswhichmatterismadeof.Ofparticularinterestistheinteractionwithbiologicalsystemsrangingfrombasiccellularstructurestocomplexorganismssuchasplantsandanimals.Toproperlyquantifytheenergyabsorbedbyamaterial,especiallybyhumantissue,dosimetricquantitiesareused.Dosimetryexpressesthecurrentandpowerdensityandtheenergyabsorbedperunitareaorvolumeasdefinedbelow:•Currentdensity‘J’:isthecurrentflowingthroughacrosssectionofaconductorsuchasthehumanbodyorapartofit.ItismeasuredintermsofA/m2.•Densityofpower‘S’:isusedforveryhighfrequencytypesofcurrentwheredepthofpenetrationissmall.ItiscalculatedastheradiantpowerperpendiculartoasurfacedividedbythesamesurfaceareaandisexpressedinW/m2.•Specificenergyabsorption‘SA’:isdefinedastheenergyabsorbedperunitofmassofbiologicaltissueandisexpressedinJoule/kg.•SpecificAbsorptionRateofenergy‘SAR’:Thisistherateofabsorptionofenergyperunitmassofbodytissueaveragedovertheentirebodyorspecificpartsofit.Itisusedtoassessandeventuallylimitexcessiveenergydepositioninsmallpartsofthebodyresultingfromparticularexposureconditions.BothSAR,averagedoverthewholebody,aswellaslocalbodypartvaluesareused.ItismeasuredinW/kg.


Thequantitiesmentionedaboveareusedasreferencestomeasuretheeffectsonthehumanbodyandtodefineexposurelimits.These,however,cannotbemeasureddirectlyontheindividualexposedtoassesstheintensityofradiation.Instead,measurablephysicalquantities

EMFEffectsonElectronicEquipment

1. Electromigration:causebrokenstripsandcommunicationproblems.


2. HotElectronEffect:inducedtransients,provokelogicerrorsanddestroytransistors.

3. AntennaeEffect:EMFInterferenceandsomeoftheelectronsareradiated,transformingthenarrowstripinanantenna.

4. ImageDistortion

5. Hardwaredegradationanddestruction.EMFEffectsonHumanBeings-U.V.Radiations:skinproblems(reductionofLangerhanscells)andeyes.-InfraredRadiations:thermaleffects-Radiofrequency(R.F.):thermaleffectsandbioelectricinterferences,genetictransmissionproblems,nervousandheartsystem.Somerelevantstudiesconductedtodate:-NationalInstituteofOccupationalHealth(MagneticFieldsandCancer:cellularstudy.BoHolmberg):researchoncancertumorsandEMFexposure.-DivisionofBiomedicalandBehavioralSciences,NationalInstituteforOccupationalSafetyandHealth(OSHA)(Cincinnati)MagneticFieldexpositioninskincells,J.Snawder,R.Edwards):researchontumorandmagneticfieldsof100μTovera14dayperiod.-ElectricPowerResearchInstitute(PaloAlto)(MagneticFieldsandAnimalCells,J.Mc.Cann,R.Kavet,C.Rafferrty):researchontumorandmagneticfield.


Note:AlthoughnoneofthestudiesconductedtodatecanabsolutelycorrelateEMFandhumanhealtheffects.ShieldMaxstronglyrecommendstoapplytheALARA(AsLowAsReasonableAchievable)principleinaccordancewithNCRPrecomendation.

OriginofEMFandSourcesMagneticandElectricFieldLowFrequency(0Hz–100kHz)MagneticFields:-Transformers-LowVoltageCabinets-LowVoltageLines(includingBus-barandSubwaycables)-HighVoltageLines(aerial,underground)-Railwayslines,SubwayLines-UPS-Others:lightning,engines,electricalheaters,...ElectricField:-HighVoltageLinesElectricFieldHighFrequency(100kHz-10GHz)-Radars,Radioemitters,MobilePhoneSubstations,ACDrives

BenefitsEnsuretheaccomplishmentofcompulsoryEMFlimitstandardsandprovidesecurityandsafetyofanyequipmentorpeoplenearby:-Cabletrays(providingshieldingandpowerdistributionatthesametime)-Switchcabinets-TransformersBy-Fullystandardizedproducts.-Specialsolutionsuponrequest.-Providessecureenvironmentforelectronicequipmentandmachineryandforpeople.-CertifiedEMFshieldingperformanceaccordingtoIECstandards.-Suitedtoanysortofbuildingandapplications:Officevbuildings,Hospitals,vSemiconductorplants,...-Completeturn-keysolutionfromonesinglecatalogvandsource(trays,fasteners,supports,...)-Easytoinstall.-Suitedtoinstallinhorizontalorverticalcablerisers.-Shield-Trayprovidesconvenientair-coolingtocables.-Variousmodels,sizesandShieldingperformancesuitedtodifferentneedsandapplications.-Maximumsafety


-Easytoselect.-Shield-TraysegmentsoverlappedtominimizeEMFleakbyBelttechnique.-Documentedcertification.-CEmarked.-Earthingconnectionpoints.-Heavydutyconstruction.-Warranty10years.-Anti-rusttreatment

ShieldingTechnologyMagneticFieldLowFreq.:HybridTechnology

ShieldMaxSolutionconsistsofacost-effectivehybridshieldingtechnologythatbythecombinationofhigh-permeabilityandhighconductivitymaterialsproduceadoubleeffectofEMFabsortionminimizingtheresidualmagneticfieldbyan“eddycurrent”effectthatpushesbacktheresidualfieldback-in.Asmartdesign,thatoverlapsallcabletraysegmentsminimizesanyEMFleakage.


LimitsandStandardsMagneticandElectricFieldLowFrequency

Norms:EN61000-4-8

RecommendationsNCRPDraftRecommendationsonEMFExposureGuidelinesHerebelowisrepoducedSection8oftheJune13,1995,draftofthereportofNCRP(NationalCouncilRadiationofProtection)ScientificCommittee89-3onExtremelyLowFrequencyElectricandMagneticFields,whichcontainsitsconclusionsandrecommendations.


GeneralApplicationsHowtoprotectpeopleandelectronicsfromElectroMagneticFields

BenefitsofEMCBuildingCompleteprotectionto:

• Hardware:electronicsdestruction,degradation,screenflickering,harddiskcdamage,..

• Software:dataloss,datacorruption,networkspeeddecrease,..• HumanBeings:shortandlongtermdiseases,headache,migraine,child

leukemia..


OutputofMV/LVTransformersOneofthemaincausesofmagneticfieldexposureinMV/LVelectricalsubstationsisrepresentedbytheoutputoftheLVtransformer.AsshowninFig2,theoutputisequivalenttothethreesectionsoftheconductorwhicharespacedoutthesamedistanceastheterminalsofthetransformer(D)onthetransformerside.Theyareclosertogether(d)ontheotherside,wheretheyformthebundleofcablesdirectedtowardtheLVdistributionsubstation.Theheightofthecablesisaparameterthatcanvarydependingontheinstallationmode.Thedistancesonthedifferentaxis(withreferencetoFig2)whenmagneticinductionisequalto3μT(qualitytarget)havebeencalculatedonthebasisofthenominalpowerandthereforeonthebasisofthesecondaryLVcurrents.

TheresultsareshowninTables1,2and3respectivelyforx,yandz.ItisclearfromthetablesthattheoutputLVisasubstantialpollutantcomponentandthatinthecaseofmajorpowersuppliesthedistancesaffectedcanbesignificantlymorethan10metres.Whensubstationsarelocatedinthevicinityofcivilian,commercialorindustrialsettingswherethequalitytargetmustbesatisfied,itisnecessarytoimplementshieldingsystemsforalmostallpowersupplylevels.


DistributionLinesandShieldingChannelsUnipolarpowercablesarecommonlyusedforhighcurrentdistributionlinesinindustrialandcivilianenvironments.Aclassicexampleisthepowersupplyofairconditioningsystemengineswhereitiscommontofindmorecablesusedinparallel,addingtothousandsofamperes.Theexposurelevelcausedbyinductionisclearlytobekeptwithinthequalitytarget(3μT),butsometimesmorestringentlimitsarerequired(0.1μTnearelectronicmicroscopesforexample).


Figure3showsthecolouredmapofthemagneticinductionofathree-phaselinewith400mm2cableswithanampacityof605A.Itcanbeseenthatinordertostaybelow3μTthedistancefromthecentreofthelineisabout1.4m.Table4showsthebufferzonevaluesassociatedwiththeinductionof3μTforlinesupto2000Aconsistingofsinglecorecablesinparallel.

Shieldingchannelshaveahighshieldingperformancewithanaveragescreenfactorofapprox30.Figure4showsacolouredmapofthemagneticinductionofathree-phaselinewith400mm2cableswithanampacityof605A.Thecomparisonwithinductionlevelsintheabsenceofshieldingisobvious.Thereductioninlevelsofinductioninvolvesasignificantreductioninbufferzones.Table5showsthebandswithrespecttothedifferentlinesinsertedintotheshieldingchannelwhileFigure4showsthecomparisonbetweenthebufferstripswithandwithoutchannelshielding.


DescriptionofShieldingMaterialsMitigationofthemagneticfluxdensityisachievedforbothshieldingplatesandshieldingchannelsbyaffixing


magneticshieldsmadeoftwodifferentmaterials:•Materialwithhighmagneticpermeability.•Materialwithhighelectricalconductivity.Theeffectofincorporatingbothmaterialsisclearlyvisiblefromsimulationscarriedoutusingspecificsoftwarethatallowsviewingtheevolutionofthefieldlinesfortheshieldingmaterialswhentheyareaffectedbyamagneticfieldgeneratedbyacoil.Figure5whichalsoshowstheprogressofthefieldlinesintheabsenceofashieldingsystemclearlydemonstratestheeffectivenessoftheshieldingmaterials:

Thelayerofmaterialwithhighmagneticpermeabilityeliminatesmagneticinductionthroughabsorptionofthemagneticfield.Itsbehaviourissimilartoashielding“umbrella”asprotectionfromtheintensityofthemagneticfieldcanbeveryhighclose

totheshield,buttendstodecreaseawayfromit.

Thelayerofmaterialwithhighelectricalconductivityinthepresenceofavariablemagneticfield(inductionfield)becomesthesiteofcurrentmovement,whichinturngeneratesamagneticfieldofreaction(inducedfield).Thecombinedeffectsofthefields,inductionandinduced,resultsinareductionintheoveralltotalmagneticfield.


Thelayerofmaterialwithhighelectricalconductivityinthepresenceofavariablemagneticfield(inductionfield)becomesthesiteofcurrentmovement,whichinturngeneratesamagneticfieldofreaction(inducedfield).Thecombinedeffectsofthefields,inductionandinduced,resultsinareductionintheoveralltotalmagneticfield.


ShieldedTrays(Power&Data)Selectionguide


AttenuationTest

MechanicalWeightPerformance


DesignHighlights

Overlapping

Ventilation


Models&Dimensions


Installationguide


ApplicationsandInstallationsExamplesMagneticandElectricFieldLowFrequency


ShieldedBackplanesSelectionguide


SelectionguideModelsandDimensions(alldimensionsinmm)

Ref.Number(example)Flatandcornerplanes

InstallationGuideInstallationmethoddependsonwallmaterial.Ifwallismadeofbrickorconcrete,shieldingpanelswillbefixeddirectlytowallwithscrews.Incaseofwallismadeofgypsumwall,panelsmustbefixedwithscrewsandspecialnuts.NOTE:Panelsmustbeconnectedtogroundwith25mm2copperwire.


ApplicationsandInstallationExamplesMagneticandElectricFieldLowFrequency


ShieldedTransformersCagesSelectionGuide

ModelsandDimensions

Ref.Number(example)


InstallationGuideThereare3differentkindofinstallationsforshieldingtransformers:-Wallprotection(side)-Ceilingprotection-Completeprotection(wallsandceiling)


*Selfstandingstructurequotedunderrequest


ApplicationsandInstallationExamples


Certificates

SHIELDINGPERFORMANCECERTIFICATE


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low frequency electro-magnetic

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