Siemens LMV51.140C1 - Page 177

LMVSeriesTechnicalInstructions 
DocumentNo.LV5‐1000
SCCInc. Page5 Section6
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4. O
2
Control‐ThisisthesetpointoftheO
2
trimsystemforeachpointonthecurveexceptPoint1.
Thisisalsocommonlyreferredtoasthe“trimcurve”.
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5. O
2
Alarm‐ThisistherichO
2
limitforeachpoint.EveryFuel‐AirRatioCurvepointincludingPoint1
musthaveacorrespondingO
2
alarmpoint.Thisisalsocommonlyreferredtoasthe“richcurve”or
“richalarm”.
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6. O
2
MaxValue‐ThisistheleanO
2
limit,andisasinglevalueforallpoints.Thisisalsoreferredtoas
the“leanalarm”.
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7. LambdaFactor‐AvaluethatislearnedbytheLMV52foreachpointonthecurveexceptPoint1.
ThisvalueislearnedwhentheO
2
controlcurveisbeingset, andisbasedonhowthemeasured%O
2
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respondswhentheburnerisbeingtransitionedfromanO
2
RatioControlpointtotheO
2
Control
pointduringO
2
Controlcommissioning.Thisvaluerepresentshowmuchtheairflowneedstobe
changedtogetachangeinthemeasured%O
2
,andisessentiallythe"signature"oftheburnerfrom
anO
2
trimperspective.
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8. FuelRate–Thisisthepercentageofhighfirefuelflowandisalsoreferredtoasthefiringrate.This
isalsothesameasthe"Load"numberseenduringRatioControlCurvecommissioning.Fora10‐to‐
1turndownburner,highfirewouldbe100%andlowfirewouldbe10%.Fora4‐to‐1 turndown
burner,highfirewouldbe100%andlowfirewouldbe25%.For
O
2
trimsystems,itisvery
importantthatthefuelrate(loadnumber)matches theactualfuelflowtotheburnerwithin+/‐3%.
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9. AirRate‐WhennoO
2
trimistakingplace(runningonRatioControlCurve),theairrateisthesame
asthefuelrate.Thisisalsoknownastheairflow.Forexample,a10‐to‐1turndownburnerrunning
atPoint5ontheRatioControlCurvewillhaveafuelrateof50%andanairrateof50%.IftheO
2
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trimisengagedandtheO
2
sensorreadsvalueshigherthansetpoint,theairratewillbereduced
relativetothefuelrateuntilthesetpointisachieved.
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10. StandardizedValue‐ThisisapercentagereductionoftheairrateandisusedwhentheO
2
Control
Curveisbeingset.Forexample,iftheairrateis50%,andaStandardizedValueof10%isentered,
theairratewillbereducedto45%.Themathwouldbe:(50%*10%=5%),then(50%‐5%)=45%.
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11. Pre‐Control‐Whenlargeloadchangesoccurduringmodulation,thiswille ngageandtemporarily
disabletheclosed‐loopO
2
trim.Thistemporary"open‐loop"trimisbasedonusingacorrect
LambdaFactortopredicthowtheburnerwillreactwhenmodulating.Pre‐controlisnecessaryfor
burnerswheretheO
2
setpointisnotconstantfromlowfiretohighfire.
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