LMVSeriesTechnicalInstructions
DocumentNo.LV5‐1000
SCCInc. Page21 Section6
O2MaxManVariableandO2MinManVariable–TheseparameterssethowmuchtheO
2
systemcantrim
inanattempttoachievetheO
2
setpoint‐essentiallythetrimlimitsfortheO
2
system.
O2MaxManVariablesetshowmuchthesystemcanincreasetheairrate.Likewise,O2MinManVariable
setshowmuchthesystemcandecreasetheairrate.
Menupath:Params&Display>O2Contr/Alarm>GasSettings>ControlParam
ThesetrimlimitsmustbesetsothattheO
2
systemcanachievetheO
2
setpoint.However,thelimits
shouldnotbesetinawaythatallowstheburnertorunatanunsafefuel‐airratio.
Ideally,theO
2
trimsystemmustcompensatefortwomainenvironmentalconditions.Theseconditions
areambientairtemperatureandbarometricpressure.Figure6‐8illustrateshowmuchthemanipulated
variableneedstochangetocompensatefortheseenvironmentalconditions.ThechartinFigure6‐8
andtheexampleinFigure6‐9serveasaguidelineforsettingtheO2MaxManVariableand
O2MinManVariableparameters.
Figure6‐8:Theoretic
alChangeoftheManipulatedVariablewithChangesinAmbientTemperature
andPressure
WhentheO
2
ControlCurveiscommissioned,allburnerswillbeat(0,0)onthechart,wheretheX‐axis
andY‐axiscross.Asairtemperatureandbarometricpressurechangefromtheairtemperatureand