电气设计的几点建议和继电保护英文.docx
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电气设计的几点建议和继电保护英文.docx
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电气设计的几点建议和继电保护英文
Thecurrentbuildingseveralproblemsinelectricaldesign
1Introduction
Engineeringdesignisthemostimportantinfrastructure,designdocumentsarethemainbasisfortheconstruction,designqualityistodeterminethequalityoftheprojectthefirstpart.Myprojectqualityaccidentstatisticsshowthatfromthedesignoftheprojectqualityaccidentcausesaccountedfor40.1%;constructioncausesaccountedfor29.3%;otherreasons(suchasequipmentandmaterialsquality,etc.)causedbyaccountingfor30.6%.Thisshowstheimplementationoftheprojectqualitycontrolisthekeytothedesignqualitycontrol.Electricalengineeringisnoexception.
2affectthequalityoftheprojectelectricaldesignofseveralbuildings
Qualifiedarchitecturaldesignshouldmeettherequirementsofsevenqualitycharacteristics,namelyfunctionality,security,economy,credibility,canbeimplemented,adaptabilityandtimeliness.Designunitsthroughthedesignofthisassessmentshouldbequalifiedtodelivertheconstructiondesigndocuments.Infactmanyofthedeliveryofconstructiondesigndocumentsexist,orthelackofqualitycharacteristicsdeviatefromtherequirementsdefects.Theimpactonthequalityofelectricalengineeringdesignproblemsareprimarilymanifestedinthesecurity,reliability(includingtheavailability,reliability,maintainability,etc.)andcanbeimplementedofmissingordeviatefrom.Thefollowingcommentonafewofthemostcommonaspectswerediscussed.
2.1Designinbreachofordeviationfromtheprovisionsofdesignspecifications,safety,credibilitywithrespecttonon-implementationofthedesignspecificationsarequitecommon
Forexample,beforeaCityHallSquareGarden(includingthesquaregreengardenlighting,lawnlightingandsoundandlightFountainSquareCenter)projectdiscretionaryelectricalconstructiondrawingssubmittedtothefollowingproblems:
theabsenceofelectricalprotectiveearthingandequipotentialbondingdesign;wronguseofTN-Clow-voltagedistributionsystem;fountainfailuretouseproperprotectiongraderequirementsofelectricalequipmentandcables.Thisdesigniscompletelycontrarytothenormsprescribedsafetyrequirements,accordingtothedrawingswillremainaserioussecurityrisk.PriortoAugust1999,QingdaoCity,afountain,severalpeopletookplace,leisuredeathwasshockcasualties,itisbecauseofdesignerrors,underwaterlighting,andsubmersiblepumpsduetopowerleakagewhichcannotbetimely.Supervisioninthepre-constructiontrialmaps,andfoundtheaboveproblem,bytheownerstodesignunitsinstrictaccordancewithdesignspecificationsseektoamendthedesign.Thecorrectapproachis:
outdoorcourtyardsandfountainsshouldbeusedlocallyTTpowerdistributionsystem,orTN-Ssystem,andsettheearthleakageprotection(operatingcurrentshouldbenomorethan30mA),whichdoesnotallowuseofTN-Csystem;shouldbesetwell-groundeddevices,fountainsequipotentialbondingshouldbedonethedesign,butnotsolelyfromthebuildingleadstoaPEtrunkgrounding;submersiblepumpsandunderwaterlightingshouldbeuseddivingcabledistribution;0areaelectricalequipmentshouldbeused1Px8protectionlevel,aDistrictshouldbe1Px5so.
Anotherexampleislow-voltagedistributionlines,civilsectionofchoice.Becausethevastmajorityofcivilelectricityloadforthesingle-phaseloads,three-phaseloadimbalancewillinevitablyleadtothecenterlinethroughunbalancedcurrent;asComputerequipmentandvarioushomeappliancestheDevelopmentandpopularizationoflow-voltagepowergridhigh-orderharmonicpollution,increasing,3timesandtheoddmultiplesofharmonicsconstituteaneutralcurrent.Midlineover-currentandthusleadtothephenomenonofelectricalfiresarealsoincreasing.Tothisend,theprovisionsoftherelevantdesignspecificationhasbeen'three-phasefour-wireortwo-phasethree-wirepowerdistributionlines,whentheelectricityloadthemajorityofsingle-phaseload,theNlineorPEN-linecross-sectionshouldnotbelessthanthephase-linecross-section;togasdischargelampasthemainloadcircuit,N-linecross-sectionshouldnotbelessthanthephasecross-section......',wecanseethatcivilpowerdistributionsystemofthetrunk,branchlinesandextensionsofthewirecross-sectionprinciple,shouldbeselectedforNorPEN-linecross-sectionandphasesectionofthesameline.However,pre-trialsupervisionplansfoundthattherearestillalargenumberofcivilpowerdistributiondesignisstillinuse80yearsago,thepracticehasbeenintroduced,choiceofNorPEN-linecross-sectionisstillphase1/2oreven1/4to1/3.Thisisthemostcommonelectricaldesignsafetyproblems.
Again,withregardtothechoiceofvariabledistributionofthelocationoftherelevantdesignspecificationshaveclearlysuggestedthatweshouldconsider'liftingandtransportequipment,convenience',whichistoensuretheavailabilityandmaintenanceofbasicrequirements.Weareresponsibleforsupervisioninrecentyears,manyhigh-risebuildingproject,whichissetinthebasementofthechangewith!
Electricdieselgeneratorroomconfigurationofreachofmorethanaviolationofthisrequirement.Exampleofavariabledistributionreachofhigh-risecommercialandresidentialundergroundgeneratorroom,itstransportpathwaywascompletelyblockedchillersandgroundwaterbox.Constructionandinstallationoftheordercanonlybeafirstchange,distributionequipmentandinstallationinplaceaftertheinstallationofgeneratingunitsandwaterchillers,butsimplydidnotconsiderrunningafterthefatsubstationequipmentmaintenance,replacementandtransportissues;Anotherexampleofahigh-riseofficecomplexVariabledistributionofthegroundfloorroomwithhair,setonthefirstfloorconferenceroomofabottombasementneithertoconsiderthenecessaryTransportationmaintenanceaccess,nordoesitprovideadequatewidthofthedevicecanbebroughtintothedoorframe.WhentheCommissionerofthetrialplantodiscoverandraisethisissue,thedesignunitsintheanswerturnedouttobe:
TheoriginaldesignintentfromalayeroftheChamberOfficewillchangedistributionandpowergenerationequipmentinplacebeforepouringliftingthefloorofthehall.Thatintentionwasobviouslywrong,evenwithoutconsideringcivilconstructionmayhaveontheplaceofthedamagecausedbyelectricalequipment,buildingoperationalaftertherepairandreplacementofelectricalequipmentandtransportationisonlyforcedopenthefloorconferenceroomfloortosolveit!
Noticeofreinforcedconcreteframestructurebuildingareasonableservicelifeofupto50years,whilethetransformationanddistributionequipmentlifeofonly20yearsorless,regularorfailureofthemaintenancecycleisevenmoreshort.Therefore,electricaldesignmustbeproperlyconsidereditstransportationandmaintenanceofliftingtheproblemofaccess.
2.2DesignofshallowdepthofthecurrentconstructiondesignthantheMinistryofConstruction'constructionandengineeringdesigndocumentation,thedepthoftheprovisions'requirementsarequitecommon,mainlyintermsofdesigndocumentscanbeimplementeddeficiencieswillleaddirectlytoconstructionandinstallationproblemsorerrors
Mayalsoleadtolackofavailability.Requireddepthbecausetheydonotcarryoutthenecessarycalculationandlabeling,butalsooftenresultinthedesignprinciplesofthedocumentitselfappearsratherdifficulttodiscovertheerrorwillaffecttheprojectcompletionofuse.
Forexample,accordingtothedepthofthatpowerandlightingsystemdiagramandthecorrespondingequipmentandmaterialsshouldbedetailedinthetableindicatechoiceofelectricalequipmentandmaterialsmodel,name,sizeandquantityparameters.Sincethereformandopening,China'scolorfulelectricalproductsmarketathomeandabroaddazzlingarrayofproductsforvariousmodelsspecification,thestatecannotbealltypesofelectricalequipmentandmaterialstoestablishaunifiedmodel.Designedtoidentifyavarietyofequipmentandmaterialsparametersofthemodelspecificationappearstobeparticularlyimportant,itistheownersorconstructionequipmentunitsordersandprocurementbasis.Inrecentyears,electricaldesigndocuments,however,generallyusedonlyinthesystemdiagramofthedevicesymbolnexttotheannotationofthemodelsorthedevicemanufacturerproductnumber,sothatequipmentordersataloss,andoftenleadtoerrors.Suchaselectricallightingdesignofaproject,thedesignerinthesystemdiagramofthecircuitbreakermarkedonlythesymbolnexttothe'A063M20A',devicesinthetableisnoexception,buthavenotspecifiedthenameanddetailsofparameters,theconstructionunitinterpretedasaregular20Acircuitbreaker,becausetofindlessthanthenumberofproductsunderaseparateprocurementofanothercircuitbreaker.Theequipmentandmaterialsaftertheinspectionbythesupervisorscheckwhentheoriginal'A063M'NaishiHaig'sakindofelectromagneticleakagecircuitbreakerproductnumber,ratedcurrent20A,ratedresidualoperatingcurrentof30mA.ShowsthattheoriginaldesignoftheseLoop-basedleakageshouldbeprotected.Unclearbutthedesignmarkcausedbyorderingerrors.Hadtore-purchasethereplacement.Anotherexampleistheconstructionofmanyelectricaldiagramofthecabletrenchmarkedonlythesizeanddirectionofthecablebracketandthecoverdoesnotmakeanyprovision,oronlymarked'refertopageXXAtlasXX',infactplottingthecountryfocusedoneitherthesizecabletrench,itscablebracketandcoverpracticeshaveprovidedanumberofo
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