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
REV5DIRECTION46-014505
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
REV5DIRECTION46-014505
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: