Multiplesingle-chipmicrocomputerapproachtofiredetectionandmonitoringsystem.docx

Multiplesingle-chipmicrocomputerapproachtofiredetectionandmonitoringsystem.docx

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Multiplesingle-chipmicrocomputerapproachtofiredetectionandmonitoringsystem

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.

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,implementationandmaintenanceandprovideseasilyexpandableandportable

design.Thisimplementationwasnotpossiblewitholdtechnology.Mostoffiredetection/monitoringsystemsavailablearetailoredtowardsaspecificapplicationandlacktheuseofrecentadvancesinCMOSVLSItechnology.Inthisstudy,wedevelopafiredetection/monitoringsystemwhichisgeneralinconcept,readilyimplementableinamultitudeofapplicationsforearlydetectionofafirebeforeitbecomescritical,forequipmentandevacuationofpersonnel.Here,weproposeacentralcontrolanddistributedcontrol/detection/monitoringwithadequatecommunication,whereuseismadeofsingle-chipmicrocontrollersinthelocalstations,thusimprovingcontrollabilityandobservabilityofthemonitoringprocess.

2Detectionandalarmdevices

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