火灾报警器中英文资料外文翻译文献.docx

火灾报警器中英文资料外文翻译文献.docx

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火灾报警器中英文资料外文翻译文献

中英文资料外文翻译文献

Multiplesingle-chipmicrocomputerapproachto

firedetectionandmonitoringsystem

Indexingterm:

Hazards,Design,Plantconditionmonitoring

Abstract:

Acompletesystemforfiredetectionandalarmmonitoringhasbeenproposedforcomplexplants.Thesystemusesmultiplesinglechiparchitectureattachedtoapartyline.Thecontrolalgorithmisbasedonatwo-levelhierarchyofdecisionmaking,thusthecomplexityisdistributed.Acompletecircuitdiagramisgivenforthelocalandthecentralstationwithrequirementsforthesoftwarestructure.Thedesigniskeptingeneralformsuchthatitcanbeadaptedtoamultitudeofplantconfigurations.Itisparticularlyshownhownewdevelopmentsintechnology,especiallyCMOSsinglechipdevices,areincorporatedinthesystemdesigntoreducethecomplexityoftheoverallhardware,e.g.bydecomposingthesystemsuchthatlowerlevelsofhierarchyareabletohavesomeautonomyindecisionmaking,andthusamorecomplexdecisionissolvedinasimpledistributedmethod.

1Introduction

Regulatoryrequirementsformosthighriskplantsandbuildingsmandatetheinstallationoffiredetectionandwarningsystemsforallsensitiveareasoftheplantorthebuilding.Mostfirecodesstatetherequirementformonitoringandcontrolspecificallyrelatedtoatypeofaplantorbuildingsuchaschemicalplants,petroleum,nuclearplants,residentialhigh-risesetc.Ageneralconclusionofthesecodescanbespecifiedasthefollowingrequirements:

（a）Thesourceofalldetectorsignalsshouldbeexactlyidentifiablebythecentralstation

（b）Anextrapathofcommunicationbetweenthecentralstationandalllocalcontrollers

（c）Directmeansofcontrolofalarmandcentralequipmentbythecentralstation

（d）Meansofcommunicationbetweenthecentralstationandthefiredepartment

（e）Availabilityofemergencypowersupply.Thecodesusuallyalsospecifythetypesandfrequencyoftestsforallequipment.

Afiredetectionandalarmsystemisacombinationofdevicesdesignedtosignalanalarmincaseofafire.Thesystemmayalsoaccomplishfancontrol,firedoorholdorrelease,elevatorrecall,emergencylightingcontrolandotheremergencyfunctions.Theseadditionalfunctionssupplementthebasicsystemwhichconsistsofdetectionandalarmdevicesandcentralcontrolunit.

Technologyhasaninfluenceonsystemarchitecture.Whentechnologychanges,thearchitecturehastoberevisedtotakeadvantageofthesechanges.Inrecentyears,VLSItechnologyhasbeenadvancingatanexponentialrate.FirstNMOSand,inthelastyearortwo,CMOSchipshavebeenproducedwiththesamepackingdensitywithmoregatesperchipyetatalowerpowerconsumptionthanNMOS.Surelythischangeintechnologymustaffectourdesignofhardwareatboththechipandthesystemlevel.Atthechiplevel,singlechipsarenowbeingproducedwhichareequivalenttoboardlevelsofonlythepreviousyearortwo.Thesechipshavemicroprocessor,memoryinRAMandROM,IOPortsbothserialandparallel,A/Dtimer,flagsandotherfunctionsonchip.Atthesystemlevel,thenewchipsmakenewarchitecturespossible.Theobjectiveofthispaperistoshowhowtechnologycaninfluencesystemarchitectureinthefieldoffirecontrol.Thenewhighdensitysinglechipmicrocontrollersareincorporatedinthedesignofalargescalesystemandyetweobtainasmallersystemwithabetterperformance.Intermsoffiredetectionandalarmmonitoring,thisisreflecteddirectlyinthelocalstationhardware,becauseoftheirremotenessandpowersupplyrequirements.AcompletelocalstationcanbedesignedaroundasingleCMOSchipwithpowerconsumptionofafewmWdependingonsystemoperation.Thisapproachreducesthecostandcomplexityofdesign,implementationandmaintenanceandprovideseasilyexpandableandportabledesign.Thisimplementationwasnotpossiblewitholdtechnology.Mostoffiredetection/monitoringsystemsavailablearetailoredtowardsaspecificapplicationandlacktheuseofrecentadvancesinCMOSVLSItechnology.Inthisstudy,wedevelopafiredetection/monitoringsystemwhichisgeneralinconcept,readilyimplementableinamultitudeofapplicationsforearlydetectionofafirebeforeitbecomescritical,forequipmentandevacuationofpersonnel.Here,weproposeacentralcontrolanddistributedcontrol/detection/monitoringwithadequatecommunication,whereuseismadeofsingle-chipmicrocontrollersinthelocalstations,thusimprovingcontrollabilityandobservabilityofthemonitoringprocess.

2Detectionandalarmdevices

Abasicfiredetectionsystemconsistsoftwoparts,detectionandannunciation.Anautomaticdetectiondevice,suchasaheat,smokeorflamedetector,ultravioletorinfrareddetectorsorflameflicker,isbasedondetecting

thebyproductofacombustion.Smokedetectors,ofbothionizationandopticaltypes,arethemostcommonlyused

detectordevices.Whenatypicaldetectorofthistypeentersthealarmstateitscurrentconsumptionincreases

fromthepAtothemArange（say,fromamere15pAinthedormantmodeto60mA）intheactivemode.Inmanydetectorsthedetectoroutputvoltageiswelldefinedundervariousoperatingconditions,suchasthose

giveninTable1.Themoresensitivethedetector,the

moresusceptibleitistofalsealarms.Inordertocontrolthedetectorprecisely,eitherofthefollowingmethodsisused:

acoincidencetechniquecanbebuiltintothedetector,orafilteringtechniquesuchthatalogiccircuitbecomesactiveonlyifxalarmsaredetectedwithinatimeperiodT.Thedetectiontechniquedependsgreatlyonthelocationandplantbeingprotected;smokedetectorsareusedforsleepingareas,infraredorultravioletradiationareusedwhenflammableliquidsarebeinghandled,heatdetectorsareusedforfiresuppressionorextinguishingsystems.Ingeneral,lifeandpropertyprotectionhavedifferentapproaches.

Alarmdevices,apartfromtheusualaudibleorvisiblealarms,mayincorporatesolidstatesoundreproductionandemergencyvoicecommunicationorprintersthatrecordtime,date,locationandotherinformationrequiredbythestandardcodeofpracticeforfireprotectionforcomplexplants.Heaviside[4]hasanexcellent

reviewofalltypesofdetectorsandextinguishersystems.

2.1Controlphilosophyanddivisionoflabour

Ourcontrolphilosophyisimplementedhierarchically.Threelevelsofsystemhierarchyareimplemented,withtwolevelsofdecisionmaking.Thereisnocommunicationbetweenequipmentonthesamelevel.Interactionbetweenlevelsoccursbyupwardstransferofinformationregardingthestatusofthesubsystemsanddownwardstransferofcommands.ThisisshowninFig.1whereatlevel1isthecentralstationmicrocomputerandistheultimatedecisionmaker（whennotinmanualmode）.Atlevel2arethelocalcontrollers,whichresideinthelocalstations.Atlevel3aretheactualdetectorsandactuators.Amanualmodeofoperationisprovidedatalllevels.

Informationregardingthestatusofalldetectorsistransmittedonaperareabasistothelocalcontrollers.Theirinformationiscondensedandtransmittedupwardtothecentralmicrocomputer.Transferofstatusisalwaysunidirectionalandupwards.Transferofcommandsisalwaysunidirectionalanddownwards,withexpansionatthelocalcontrollevel.Thisapproachpreservesthestrictrulesofthehierarchyforexactmonitoringdetectionandalarmsystemsassociatedwithhighriskplants.

Theclassificationofthetwolayersofcontrolsisbaseduponlayersofdecisionmaking,withrespecttothefactsthat

（a）Whenthedecisiontimecomes,themakingandimplementationofadecisioncannotbepostponed

（b）Thedecisionshaveuncertainty

（c）Itwillisolatelocaldecisions（e.g.locallywemighthaveanalarmalthoughtheremaybeafaultwiththesystem）

3Generalhardware

I:

Fig.2depictsourdesigninthesimplestofforms.Thesystemusesanopenpartylineapproachwithfourconductorcablesgoinginaloopsharedbyalltheremotedevicesandthecontrolpanel.Thisapproachissimpleinconceptandiseconomicallyfeasible.However,onemajordisadvantageisthedependencyonasinglecableforpowerandsignaling.Incaseswherereliabilityisofextremeimportance,twooreventhreecablestakingdifferent

routesthroughoutthesystemmaybeconnectedinparallel.Fig.3givesthedrivercircuitryrequiredtoderiveanexpandablebus.Thisdesigntakesadvantageofrecentadvancesinthesinglechipmicrocomputertechnologytoreducetheinterface

betweenthecentralstationandthelocalstations.

3.1Centralcontroltask

Acentralunitprovidesacentralizedpointtomonitorandcontrolthesystemactivities.Inthesystemtobedescribedthecentralcontrolunitservesafivefoldpurpose.

（i）Itreceivesinformationfromthelocalstationsandoperatesthealarmsandotheroutputdevices.

（ii）Itnotifiestheoperatorincaseofsystemmalfunction.

（iii）Itprovidesanoverallsystemcontrolmanualandautomatic.

（iu）Itprovidesasystemtestpointoflocalstationsanditself.

（u）Itprovidesacentralpointforobservation,learningandadaptation.

3.2Localstations

Thelocalstationscantakelocaldecisionsregardingrecognitionofarisksituation,andactindependentlyonlocalaffairs.Inthistechniquewedependon‘load-typecoordination’,e.g.thelowerlevelunitsrecognizetheexistenceofotherdecisionunitsonthesamelevel;thecentralorthetoplevelprovidesthelowerunitswithamodeloftherelationshipbetweenitsactionandtheresponseofthesystem.

Itisevidentthatapowerfulmachineisrequiredatthisstagesothatalltherequiredfunctionscanbeimplemented.Theavailabil