商业建筑外文文献翻译)Word下载.doc
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services,vaults,andelectricalequipmentrooms;
wiringsystems;
systemsprotectionandcoordination;
lighting;
electricspaceconditioning;
transportation;
communicationsystemsplanning;
facilityautomation;
expansion,modernization,andrehabilitation;
specialrequirementsbyoccupancy;
andelectricalenergymanagement.Althoughdirectedtothepowerorientedengineerwithlimitedcommercialbuildingexperience,itcanbeanaidtoallengineersresponsiblefortheelectricaldesignofcommercialbuildings.Thisrecommendedpracticeisnotintendedtobeacompletehandbook;
however,itcandirecttheengineertotexts,periodicals,andreferencesforcommercialbuildingsandactasaguidethroughthemyriadofcodes,standards,andpracticespublishedbytheIEEE,otherprofessionalassociations,andgovernmentalbodies.
Keywords:
Commercialbuildings,electricpowersystems,loadcharacteristics
1.Introduction
1.1Scope
Thisrecommendedpracticewillprobablybeofgreatestvaluetothepowerorientedengineerwithlimitedcommercialbuildingexperience.Itcanalsobeanaidtoallengineersresponsiblefortheelectricaldesignofcommercialbuildings.
However,itisnotintendedasareplacementforthemanyexcellentengineeringtextsandhandbookscommonlyinuse,norisitdetailedenoughtobeadesignmanual.Itshouldbeconsideredaguideandgeneralreferenceonelectricaldesignforcommercialbuildings.
1.2CommercialBuildings
Theterm“commercial,residential,andinstitutionalbuildings”asusedinthischapter,encompassesallbuildingsotherthanindustrialbuildingsandprivatedwellings.Itincludesofficeandapartmentbuildings,hotels,schools,andchurches,marine,air,railway,andbusterminals,departmentstores,retailshops,governmentalbuildings,hospitals,nursinghomes,mentalandcorrectionalinstitutions,theaters,sportsarenas,andotherbuildingsservingthepublicdirectly.Buildings,orpartsofbuildings,withinindustrialcomplexes,whichareusedasofficesormedicalfacilitiesorforsimilarnonindustrialpurposes,fallwithinthescopeofthisrecommendedpractice.
Today’scommercialbuildings,becauseoftheirincreasingsizeandcomplexity,havebecomemoreandmoredependentuponadequateandreliableelectricsystems.Onecanbetterunderstandthecomplexnatureofmoderncommercialbuildingsbyexaminingthesystems,equipment,andfacilitieslistedin1.2.1.
1.2.2ElectricalDesignElements
Inspiteofthewidevarietyofcommercial,residential,andinstitutionalbuildings,someelectricaldesignelementsarecommontoall.Theseelements,listedbelow,willbediscussedgenerallyinthissectionandindetailintheremainingsectionsofthisrecommendedpractice.Theprincipaldesignelementsconsideredinthedesignofthepower,lighting,andauxiliarysystemsinclude:
1)Magnitudes,quality,characteristics,demand,andcoincidenceordiversityofloadsandloadfactors
2)Service,distribution,andutilizationvoltagesandvoltageregulation
3)Flexibilityandprovisionsforexpansion
4)Reliabilityandcontinuity
5)Safetyofpersonnelandproperty
6)Initialandmaintainedcost
7)Operationandmaintenance
8)Faultcurrentandsystemcoordination
9)Powersources
10)Distributionsystems
11)Legallyrequiredandoptionalstandby/emergencypowersystems
12)Energyconservation,demand,andcontrol
13)Conformancewithregulatoryrequirements
14)Specialrequirementsofthesiterelatedto:
seismicrequirements,altitude,soundlevels,security,exposuretophysicalelements,firehazards,hazardouslocations,andpowerconditioninganduninterruptiblepowersupply(UPS)systems
1.10Safety
Safetyoflifeandpreservationofpropertyaretwoofthemostimportantfactorsinthedesignoftheelectricsystem.
Thisisespeciallytrueincommercialbuildingsbecauseofpublicoccupancy,thoroughfare,andhighoccupancydensity.Inmanycommercialbuildings,thesystemsoperatingstaffhaveverylimitedtechnicalcapabilitiesandmaynothaveanyspecificelectricaltraining.
Variouscodesproviderulesandregulationsasminimumsafeguardsoflifeandproperty.Theelectricaldesignengineermayoftenprovidegreatersafeguardsthanoutlinedinthecodesaccordingtohisorherbestjudgment,whilealsogivingconsiderationtoutilizationandeconomics.
Personnelsafetymaybedividedintotwocategories:
1)Safetyformaintenanceandoperatingpersonnel
2)Safetyforthegeneralpublic
Safetyformaintenanceandoperatingpersonnelisachievedthroughtheproperdesignandselectionofequipmentwithregardtoenclosures,key-interlocking,circuitbreakerandfuse-interruptingcapacity,theuseofhigh-speedfaultdetectionandcircuit-openingdevices,clearances,groundingmethods,andidentificationofequipment.
Safetyforthegeneralpublicrequiresthatallcircuit-makingandcircuit-breakingequipment,aswellasotherelectricalapparatus,beisolatedfromcasualcontact.Thisisachievedbyusingdead-frontequipment,lockedroomsandenclosures,propergrounding,limitingoffaultlevels,installationofbarriersandotherisolation(includingspecialventilatinggrills),properclearances,adequateinsulation,andsimilarprovisionsoutlinedinthisrecommendedpractice.
Circuitprotectionisafundamentalsafetyrequirementofallelectricsystems.Adequateinterruptingcapacitiesarerequiredinservices,feeders,andbranchcircuits.Selective,automaticisolationoffaultedcircuitsrepresentsgoodengineeringpractice.Faultprotection,whichiscoveredinChapter9,shouldbedesignedandcoordinatedthroughoutthesystem.Physicalprotectionofequipmentfromdamageortampering,andexposureofunprotectedequipmenttoelectrical,chemical,andmechanicaldamageisnecessary.
1.12DesignConsiderations
Electricalequipmentusuallyoccupiesarelativelysmallpercentageoftotalbuildingspace,and,indesign,itmaybeeasiertorelocateelectricalserviceareasthanmechanicalareasorstructuralelements.Allocationofspaceforelectricalareasisoftengivensecondaryconsiderationbyarchitecturalandrelatedspecialties.Inthecompetingsearchforspace,theelectricalengineerisresponsibleforfulfillingtherequirementsforaproperelectricalinstallationwhileatthesametimerecognizingtheflexibilityofelectricsystemsintermsoflayoutandplacement.
Architecturalconsiderationsandappearancesareofparamountimportanceindeterminingthemarketabilityofabuilding.Aestheticconsiderationsmayplayanimportantroleintheselectionofequipment,especiallylightingequipment.Providedthatthedictatesofgoodpractice,coderequirements,andenvironmentalconsiderationsarenotviolated,theelectricalengineermayhavetonegotiatedesigncriteriatoaccommodatethedesiresofothermembersofthedesignteam.
1.12.1CoordinationofDesign
Theelectricalengineerisconcernedwithprofessionalassociatessuchasthearchitect,themechanicalengineer,thestructuralengineer,and,whereundergroundservicesareinvolved,thecivilengineer.Theymustalsobeconcernedwiththebuilderandthebuildingowneroroperatorwho,asclients,maytakeanactiveinterestinthedesign.Moreoften,theelectricalengineerwillworkdirectlywiththecoordinatorofoveralldesignactivities,usuallythearchitect,ortheprojectmanager;
andmustcooperatewiththesafetyengineer,fireprotectionengineer,perhapstheenvironmentalenginner,andahostofotherconcernedpeople,suchasspaceplannersandinteriordecorators,allofwhomhaveasayintheultimatedesign.Theelectricaldesignermustbecomefamiliarwithlocalrulesandknowtheauthoritieshavingjurisdictionoverthedesignandconstruction.Itcanbeinconvenientandembarrassingtohaveanelectricalprojectheldupatthelastmomentbecauseproperpermitshavenotbeenobtained,forexample,apermitforastreetclosingtoallowinstallationofutilitiestothesiteoranenvironmentalpermitforanon-sitegenerator.
Localcontractorsareusuallyfamiliarwithlocalordinancesandunionworkrulesandcanbeofgreathelpinavoidingpitfalls.Inperformingelectricaldesign,itisessential,attheoutset,toprepareachecklistofallthedesignstagesthathavetobeconsidered.Majoritemsincludetemporarypower,accesstothesite,andreviewbyothers.Certainelectricalworkmayappearinnonelectricalsectionsofthespecifications.Forexample,thefurnishingandconnectingofelectricmotorsandmotorcontrollersmaybecoveredinthemechanicalsectionofthespecifications.Foradministrativecontrolpurposes,theelectricalworkmaybedividedintoanumberofcontracts,someofwhichmaybeunderthecontrolofageneralcontractorandsomeofwhichmaybeawardedtoelectricalcontractors.Amongitemswithwhichthedesignerwillbeconcernedare:
preliminarycostestimates,finalcostestimates,plansordrawings,technicalspecifications(whicharethewrittenpresentationofthework),materials,manuals,factoryinspections,laboratorytests,andtemporarypower.Thedesignermayalsobeinvolvedinprovidinginformationonelectricalconsiderationsthataffectfinancialjustificationoftheprojectintermsofowningandoperatingcosts,amortization,returnoninvestment,andrelateditems.
Manyelectricaldesignsfollowtheconceptofcompetitivenessinthecommercialsense.Here,costisaprimaryconsideration,andsuchdesignstendtowardminimumcoderequirements.Thereisgreatpressureonthedesignertoconsidercostabovemaintainabi