Instruction manual

-7-
Section2-Systemdesignguidelines
LOOP LENGTHS
LOOP LOADING-Maximumnumberofaddresses
LOOP LOADING-Shortcircuitisolators
LOOP CABLESELECTION
LOOP CABLERESISTANCE
Themaximumpermittedlooplengthcanbedeterminedusing Apollo’sloopcalculator,availablefreefromEDL.
Remembertoincludetheverticaldistanceswhenlookingatplandrawingsandalsoensurecablecapacitanceis
withinthepanelsspecification.
Themaximumnumberofaddressesis126perloop.Systemdesignersshouldavoidfullyloadingloops. The
optimumnumberofaddressesperloopisapproximately90to100,thisensuresthesystemisoperatingwell
withinitscapacityandallowsthecustomerflexibilityinthefuturetoaddadditionaldevices.
Shortcircuitisolatorsshouldbefittedwithnomorethan20detectorsbetweenisolators.Nomorethan10
detectors(orequivalentload)betweenthepanelandthefirstisolatorandnomorethan10detectors(or
equivalentload)betweenthepanelandlastisolator.Ideallythefirstandlastitemsfittedtoaloopshouldbe
isolators.
Isolatorsshouldalwaysbefittedatzoneboundariesanditisgoodpracticetoreducethenumberoftimesloop
wiringentersandleavesthesamezone. A singlefaultonaloopshouldnotremoveprotectionfromanarea
greaterthanasinglezone.
Twosimultaneousfaultsonaloopshouldnotremoveprotectionfromanareagreaterthan10,000sqm. This
requirementlimitsthetotalfloorareacoveredbyoneloopto10,000sqmregardlessofthenumberof
detectors.
Isolatorsareavailableasstandaloneorbuiltintodetectorbasesandintegratedinto Apollointerfacemodules.
Theadditionalcostofthebuiltinisolatorsissmallcomparedtothenonisolatedbasesorinterfaceunits
thereforeasmanyisolatorsshouldbefittedaspossible.
Shortcircuitisolatorsdonotuseupaddressesandthereisnolimittothenumberofisolatorsfitted.
Eachloopcardisfittedwithtwoonboardshortcircuitisolators,oneforloopoutandoneforloopreturn,
protectingthewiringbetweenthepanelandfirstandlastisolator.
Thecablemustbeasuitabletypee.g.FireTuf,FP200orequivalentandmusthavethefollowingcharacteristics:
1. Thecablemustbe2corewithscreen+draincore.
2. Loopoutandloopinshouldneverberunwithinthesamecable.
3. Multicorecableshouldneverbeused.
Themaximumpermissibleresistancepercoreis12.8Ohmsatmaximumload(300mA).Loopswithlower
loadscanaccepthighercableresistance,howeveritisgoodpracticetoconsiderthemaximumloadatthe
designstagethusallowingforfutureexpansion.
Corediameter Typicalresistance(FP200/FireTuf)
1.0mm 18.1Ohms/Km/Core
1.5mm 12.1Ohms/Km/Core
2.5mm 7.4Ohms/Km/Core
4.0mm 4.6Ohms/Km/Core
ED816A AddressableFireandgasdetectionInstallationmanual8-9-08Rev-a