火灾报警器中英文文献翻译Word文档下载推荐.docx

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Multiplesingle-chipmicrocomputerapproachto

firedetectionandmonitoringsystem

A.J.AI-Khalili,MSc,PhD

D.AI-Khalili,MSc,PhD

M.S.Khassem,MSc

Indexingterm:

Hazards,Design,Plantconditionmonitoring

Abstract:

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

1Detectionandalarmdevices

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

thebyproductofacombustion.Smokedetectors,ofbothionizationandopticaltypes,arethemostcommonlyused

detectordevices.Whenatypicaldetectorofthistypeentersthealarmstateitscurrentconsumptionincreases

fromthepAtothemArange（say,fromamere15pAinthedormantmodeto60mA）intheactivemode.Inmanydetectorsthedetectoroutputvoltageiswelldefinedundervariousoperatingconditions,suchasthose

giveninTable1.Themoresensitivethedetector,themoresusceptibleitistofalsealarms.Inordertocontrolthedetectorprecisely,eitherofthefollowingmethodsisused:

acoincidencetechniquecanbebuiltintothedetector,orafilteringtechniquesuchthatalogiccircuitbecomesactiveonlyifxalarmsaredetectedwithinatimeperiodT.Thedetectiontechniquedependsgreatlyonthelocationandplantbeingprotected;

smokedetectorsareusedforsleepingareas,infraredorultravioletradiationareusedwhenflammableliquidsarebeinghandled,heatdetectorsareusedforfiresuppressionorextinguishingsystems.Ingeneral,lifeandpropertyprotectionhavedifferentapproaches.

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

reviewofalltypesofdetectorsandextinguishersystems.

1.1Controlphilosophyanddivisionoflabour

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）

2Generalhardware

I:

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