Principles
Alarmdetectorsselectdifferentsignalsensorsaccordingtodifferentpreventionplaces,andusedifferenttechnologiesofdifferentsensorstoautomaticallydetectoccurrencesinthedeploymentmonitoringareaInternalintrusionbehavior,thecorrespondingsignalistransmittedtothealarmhostofthealarmmonitoringcenter,andthehostdrivesthecorrespondingoutputdevicetoperformrelatedactionsaccordingtothepresetalarmstrategy.
Differentsignalsensorsareusedfordetection,andthedetectionandpredictionofdangeroussituationsarealsodifferent.Forexample,theinfraredsensorintheinfrareddetectorcandetecttherateofthermalchangeonthesurfaceoftheobjecttobemeasured,soastodeterminethemovementoftheobjecttobemeasuredandcauseanalarm;thevibrationsensorcandetectthevibrationoftheobjectandfixitonthegroundorasafe.Itcandetectthemovementoftheintruderwalkingorpryingthesafe.
Eachalarmdetectorhasacertainmeanstodetectthepresenceofintrudersinthefortifiedarea.Theidealalarmdetectoronlyrespondswhentheintruderappears,anddoesnotneedtopayattentiontoothers.,Theactivitiesofanimalssuchascats,dogsandmicewillnotrespond.Itisnoteasytoachievethis.Unpredictablechangesintheclimateandfieldconditionsinnature,suchastemperature,humidity,visibility,etc.,suchasthunder,rainandfog,mayaffectthedetectionresultsofsomedetectors.Therefore,theseunfavorablefactorsshouldbefullyconsideredintheselectionandinstallationlocationofthealarm.
Variousdetectorshavetheirowndifferentworkingprinciples,eachhasitsownadvantagesanddisadvantages,andthedetectionrangeisalsodifferent.Tomakethedetectorfunctioneffectivelyinanyoccasion,itshouldbecarefullyselectedandcarefullyinstalled.Wheninstalling,itshouldtakeintoaccountthedifferentsituationsofdifferentindustriesanddifferentunitsasmuchaspossible,sothespecificationsandparametersofthedetectorusedNotthesame.Inordertoachievethebestidealresults,itisnecessarytodoadetailedunderstandingandmeticulousinvestigationoftheactualsituationoftheuser,tominimizefalsealarms,andtomakethedetectorfunctionmoreeffectively.
Choose
Alarmdetectorsareusedassensordetectiondevicestodetectintruders’intrusionsandvariousabnormalsituations(suchasfireoccurrencesandequipmentabnormalities).Therefore,thealarmdetectoritselfisrequiredtohaveanti-dismantlingandanti-vandalfunctions.Whenthealarmdetectorisdamaged,itstransmissionlineisartificiallyshort-circuitedordisconnected,ortheprotectivecoverisillegallyattemptedtobeopened,itshouldbeabletogenerateanalarmsignaloutput.
Thealarmdetectorshouldhavecertainanti-interferencemeasures.Foralarmdetectorstopreventintrusionbehavior,theabilitytopreventexternalinterferenceisrequiredtopreventvariousfalsealarmsfromoccurring.Forexample,harassmentbypetsandsmallanimals;falsealarminterferenceduetochangesinenvironmentalconditions,etc.
Thesensitivityandreliabilityofalarmdetectorsinfluenceeachother.Reasonablyselectingthedetectionsensitivityofthealarmdetectorandadoptingdifferentanti-interferencemeasurescanimprovetheperformanceofthealarmdetector.Understandingtheperformanceandcharacteristicsofvariousalarmdetectors,accordingtodifferentapplications,areasonableconfigurationofalarmdetectorsisakeytodesignagoodintrusionalarmsystem.Inallkindsofintelligentbuildingsandordinarybuildings,therearemanyplacesthatneedsafetyprotection,andtheseplaceshavevarioussafetyprotectionpurposesandrequirementsaccordingtotheactualsituation.Therefore,reasonableselectionandinstallationofvariousalarmdetectorsaccordingtotheactualsiteenvironmentandsafetyprecautionrequirementscanbetterachievethepurposeofsafetyprecautions.Whentheselectionandinstallationofthealarmdetectorisnotappropriate,theremaybeloopholesinsecurityprecautions,whichcannotachievetherigorofsecurityprecautions,givingintrudersanopportunitytotakeadvantageof,andthusbringingunduelossestosecurityprecautions.
Classification
(1)Classificationbysensortype(detectedphysicalquantity)
Switchalarm,vibrationalarm,Ultrasonicalarms,infrasoundalarms,infraredalarms,microwavealarmsandvideoalarms,electricfieldalarmsandlaseralarms,etc.
Switchingdetectorsandmicrowave/passiveinfrareddualtechnologydetectorshavebeenincludedinthemandatoryproductcatalog.
(2)Classificationaccordingtotheworkingmodeofthedetector
Therearetwotypesofactivedetectionalarmsandpassivedetectionalarms.
1.Activedetector
Whenworking,thetransmitterinthedetectoremitssomeformofenergytotheguardsite,formingastableandchangingsignaldistributiononthereceivingsensor.Onceadangeroussituationoccurs,thestableandchangingsignalisdestroyed,formingadetectionsignalwithalarminformation,andanalarmsignalisgeneratedafterprocessing.Thesensorsinthistypeofdetectorincludetransmittingandreceiving,suchasultrasonicdetectors;therearealsotransmittersandreceiversintwodifferenthousings,suchasactiveinfrareddetectors,laserdetectors,andsoon.
2.Passivedetector
Whenworking,thedetectoritselfdoesnotemitenergytotheguardsite(excludingtheradiationenergyofthecircuit),butreliesonreceivingnaturalenergytoformastableandchangingsignalonthedetector’sreceivingsensor.Whenadangeroussituationoccurs,thestableandchangingsignalisdestroyed,formingadetectionsignalwithalarminformation,whichisprocessedtoproduceanalarmsignal,suchaspassiveinfrareddetectors,vibrationdetectors,etc.
(3)Classificationaccordingtothedetectionelectricsignaltransmissionchannel
Wiredalarmandwirelessalarm.Thewireddetectorisconnectedbetweenthedetectorandthealarmcontroller;thewirelessdetectoristhewirelessdetectorthatusesradiowavestotransmitthealarmsignal.
(4)Classifiedaccordingtoalarmrange
Pointcontroldetector,linecontroldetector,surfacecontroldetectorandspacecontroldetector.
1.Point-controlleddetectors
Thealertrangecanberegardedasapoint.Whenthealertstateofthispointisdestroyed,itwillsendoutanalarmsignal,suchasamagneticswitchdetector.
2.Line-controlleddetector
Thealertrangeisaline.Whenthealertstateofthislineisdestroyed,itwillsendoutanalarmsignal,suchasactiveinfrareddetectors,laserdetectors.
3.Surface-controlleddetectors
Thewarningrangeisonesurface.Whenthewarningstateofanypointonthewarningsurfaceisdestroyed,itwillsendoutanalarmsignal,suchasvibrationdetectors,soundcontrol/vibrationglassbreakdetectors.
4.SpaceControlledDetector
Itswarningrangeisaspace.Whenthewarningstateofanyplaceinthisspaceisdestroyed,itwillsendoutanalarmsignal,suchaspassiveinfrareddetectors,microwavedetectors,ultrasonicDetector,videodetector,microwave/passiveinfrareddualtechnologydetector.
(5)Classificationbyapplication
Accordingtotheapplication,itcanbedividedintooutdooralarm(peripheralandperimeter)andindooralarm.Applicationoccasionscanalsobeperimeter,showcase,fireprevention,anti-theft,vault,etc.Asfarasthesametypeofdetectorisconcerned,thetechnicalindicatorsusedoutdoorsaremuchhigherthanindoorones,becausetheoutdoorenvironmentalconditionsaremuchharsher.Forexample:theapplicabletemperaturerangeofanoutdooractiveinfrareddetectorproducedbyacertainfactoryis-25℃-+70℃;theapplicabletemperaturerangeofanindooractiveinfraredalarmis-10℃～+55℃.
(6)Differentclassificationaccordingtotheswitchsignaloutputbythedetector
1.Normallyopen(NO)detector
Undernormalcircumstances,theswitchisopen;whenthedetectoristriggered,theswitchisclosedandtheloopresistanceiszero,andthezonealarms.
2.Normallyclosed(NC)detector
Undernormalcircumstances,theswitchisclosed;whenthedetectoristriggered,theswitchisopenedandtheloopresistanceisinfinite,andthezonealarms.
3.Normallyopen/normallycloseddetector
Thistypeofdetectorhastwoinputmodes:normallyopenandnormallyclosed.Itisnecessarytohavebothanormallyopenoutputpointandanormallyclosedoutputpointontheterminalboard.