GE 血管机技术文档 46-014505

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GE Medical SystemsTechnicalPublications

OperatingDocumentationDirection46-014505Revision5

ElectricalSafety-EquipmentGrounding

Copyrighte1986,1991ByGeneralElectricCo.ELECTRICALSAFETY-GEMEDICALSYSTEMSEQUIPMENTGROUNDING

REV5DIRECTION46-014505

i/ii (Blank)TABLEOFCONTENTS

SECTIONTITLEPAGEREVISIONHISTORYiii...............................................1GENERAL1.........................................................2ALLEQUIPMENT-GENERALREQUIREMENTS2...................3PERMANENTLYCONNECTEDEQUIPMENT3........................4CORDCONNECTEDEQUIPMENT4..................................5PROCEDUREFORMEASURINGPROTECTIVEEARTHCONDUCTORRESISTANCE5................................

6SPECIALGROUNDINGREQUIREMENTSFORPERMANENTLYINSTALLEDX-RAYEQUIPMENT6..................DefinitionsforTermsUsedinGroundingofX-rayEquipment6..................................GroundingRequirements-XĆraySystemsUsedinGeneralCareAreas7.....................................GroundingRequirements-XĆraySystemsUsedinCriticalCareAreas7......................................ELECTRICALSAFETY-GEMEDICALSYSTEMSEQUIPMENTGROUNDING

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iiiREVISIONHISTORYREVDATEREASON FOR CHANGECOct.7,1983Thiswasthelastofthreerevisions(AthroughC)usingtheoldrevisioncontrolsystem.

4Mar.31,1986Updatedlistingofstandards;generalrevisions.5Sept.20,1991ConvertdirectiontoallelectronicforCD-ROM.

LISTOFEFFECTIVEPAGESPAGEREVISIONPAGEREVISIONPAGEREVISIONNUMBERNUMBERNUMBERNUMBERNUMBERNUMBER

TitlePage5Dir.46-0138615i5iiBlankiii5

1thru95ELECTRICALSAFETY-GEMEDICALSYSTEMSEQUIPMENTGROUNDING

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1SECTION1GENERAL

Thisdirectioncoverselectricalpowergroundingrequirementsforprotectionfromelectricalshockandfirehazards,andisareprintofDesignStandard806-1,󰀷ElectriĆcalSafety-EquipmentGrounding".Itdoesnotaddresssignalshieldingandgroundsfornoisesuppression.

TheprimaryprotectionagainstelectricalhazardsisprovidedbythecontrolofmateriĆalusedforconductorsandinsulators,theselectionofcomponentstomeetpowerreĆquirements,andthespacingofliveelectricalelements.EquipmentgroundingisinĆtendedtosupplementthisprimaryprotection.

Themainfunctionsofequipmentgroundingare:DTominimizetheelectricalpotentialbetweensurfacessubjecttopersonalcontactduringliveconductortononcurrentcarryingmetalparts(deadmetal)faultconĆditions.

DToprovidealowimpedancepathtothepowersourceforactivatingovercurrentdevicesduringliveconductortodeadmetalfaultconditions.

DToprovideapathtoconductawayleakagecurrentstominimizeriskcurrentsdurĆingnormaloperation.

Thebasisforthegroundingrequirementsestablishedbydesignstandard806-1istheNationalElectricalCode(NEC)NFPA70-1984,ULStandardsforSafety,NFPA99-1984,andestablishedacceptablehospitalpractices,andIEC601-1.

Lowohmsmeasurementsaretobemadeusingaresistancemeasuringdevicecapableofreadingdownto0.1ohm.SeeTableforwiresizeversusohmage.

TABLE 1DCRESISTANCEINOHMS/1000FT.AT25_C,77_F

SizeAWGCopperBareCond.18166.514.10

14121082.571.621.0180.6404

643210.4100.2590.2050.1620.129

00000000000.1020.08110.06420.0509ELECTRICALSAFETY-GEMEDICALSYSTEMSEQUIPMENTGROUNDING

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2SECTION2ALLEQUIPMENT-GENERALREQUIREMENTS

1.Allnoncurrentcarrying(deadmetal)partswithinanenclosurewhichcontainsliveelectricalelements,andallexposedconductivemetalsurfaces,shallbeconĆnectedtotheequipmentgroundingmeans.

Exceptions:Metalhandles,trim,labels,etc.,whicharenotlikelytobecomeenergized.

2.Onlycopperconductorsorfixedmetallicstructuralpartsshallbeusedforgroundingequipmentelementslikelytobecomeenergizedfromwithin.

Bearings,hinges,andotherdeviceswhichdonotprovidepermanentnon-moĆtionalcontactshallnotbeusedasthegroundingmeansforequipmentelementslikelytobecomeenergizedfromwithinorforanyexposedconductingsurfaceonequipmentintendedforuseincriticalcareareas.

3.Fastenersorterminalsusedtobondthegroundingconductortotheequipmentshallbeusedsolelyforgroundingandshallnotdependuponsolder.

Groundingconductorsshallbeattachedtotheequipmentsuchthattheyarenotlikelytoberemovedduringnormalservicingoftheequipment.

Starwashersorothersuchdevicesmaybeusedasagroundingmeansthroughpaintedcoversaslongastheconnectionismadesecurelyandreliably.

4.Acurrentcarryingconductor,suchastheneutral,shallnotbeusedasagroundĆingconductor,eventhoughtheneutralofthesupplysystemmaybegrounded.

5.Theinsulationofallgroundingconductorsshallbecoloredgreenwithayellowstripethroughoutitslength.ThiscolorcombinationshallonlybeusedforidentiĆficationofgroundingconductorsorpotentialequalizationconductors.

AnexceptionwouldbeforequipmentthatwouldbeusedonlyintheUSThenthegroundingconductormaybeeither: