Siemens LMV51.140C1 - Page 193

LMVSeriesTechnicalInstructions 
DocumentNo.LV5‐1000
SCCInc. Page21 Section6

O2MaxManVariableandO2MinManVariable–TheseparameterssethowmuchtheO
2
systemcantrim
inanattempttoachievetheO
2
setpoint‐essentiallythetrimlimitsfortheO
2
system.
O2MaxManVariablesetshowmuchthesystemcanincreasetheairrate.Likewise,O2MinManVariable
setshowmuchthesystemcandecreasetheairrate.
Menupath:Params&Display>O2Contr/Alarm>GasSettings>ControlParam

ThesetrimlimitsmustbesetsothattheO
2
systemcanachievetheO
2
setpoint.However,thelimits
shouldnotbesetinawaythatallowstheburnertorunatanunsafefuel‐airratio.

Ideally,theO
2
trimsystemmustcompensatefortwomainenvironmentalconditions.Theseconditions
areambientairtemperatureandbarometricpressure.Figure6‐8illustrateshowmuchthemanipulated
variableneedstochangetocompensatefortheseenvironmentalconditions.ThechartinFigure6‐8
andtheexampleinFigure6‐9serveasaguidelineforsettingtheO2MaxManVariableand
O2MinManVariableparameters.



Figure6‐8:Theoretic
alChangeoftheManipulatedVariablewithChangesinAmbientTemperature
andPressure

WhentheO
2
ControlCurveiscommissioned,allburnerswillbeat(0,0)onthechart,wheretheX‐axis
andY‐axiscross.Asairtemperatureandbarometricpressurechangefromtheairtemperatureand

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