LRL_SAT_LLF_2012_08_14

LRLSatelliteTMSeriesLightLossFactorDetermination

LLD=0.89LampLumenDepreciation(LLD).Thelumendepreciation(LLD)fortheLEDisdeterminedfromLM80[1]reporteddataprovidedbytheLEDmanufacturer.TheLM80reportgiveslumendepreciationdataforLEDsoperatingatsolderpadtemperatures(Ts)of55C,85C,and105C.IntheSatelliteSeriesfixturestheLEDsareoperatedwellunderthemaximumdrivecurrent,aslowas280mA.Insitutemperaturemeasurementtests(ISTMTs),performedasperUL1598[2]andEnergyStar[3],confirmthatthedifferencebetweenambient(Tamb)andsolderpadtemperature(Ts)is17.9Cat280mA.Foranambienttemperatureof20Candanoperatingcurrentof280mATswillbe37.9CThelowTsisachievedthroughouruniquethermalmanagementsystemwithcoolingfinsintegratedintothefixturehousing.Thefixturescurveddesignisselfcleaning,preventingthebuildupofdirtanddebriswhichcouldadverselyaffectheatdissipation.UsingthemethodologyofTM21[4],anexponentialcurvefittotheLM80depreciationdataandtheArrheniusEquationareusedtointerpolatelumenmaintenanceattheoperatingtemperaturesseenintheSatelliteSeries.ThisyieldsthelumendepreciationfactorsfortheLEDs.Foranaverageambientof20Candanoperatingcurrentof280mA,LLD=0.89over20years(12operatinghoursperday).LOD=0.94LuminaireOpticalDepreciation(LOD).SatelliteSeriesluminairesareIP66rated.Thismeanstheyareimpervioustodustandpowerfulwaterspray.Theopticallensesaremountedat30anglesontheundersideofthefixturemeaningtheyareprotectedfromtheelements.Inextremeconditions,windsmaydepositsomeslightdustontothefixtureslenses,butthemountinganglesmaketheselensesselfcleaning.ThelensesaremadeofUVresistantacrylicwhichdoesnotdiscolor.Underthemostextremelaboratorytestingconditions,thismaterialwillopticallydepreciatebynomorethan6%over20yearsbasedonmanufacturerinformation.

LRL_SAT_LLF_2012_08_14

EF=1.00EquipmentFactor.Ourinhousedesignedpowersupplyhasbeenmanufacturedusinghightemperaturerated,vibrationresistant,highreliabilitycomponents.ThepowersupplyhasbeendesignedtoprovideconstantcurrenttotheLEDsoverthe20yearlifeundernormalconditions.LLF=0.89x0.94x1.00=0.83UsingthismethodologytotalfixtureLightLossFactor(LLF)canbecalculatedforallSatelliteSeriesLEDDriveCurrentsasshowninthegraphbelow.

Figure1SatelliteSeriesLEDFixtureLLFforvaryingdrivecurrentatanambienttemperatureof20C.Representativecurvesfor10,15and20yearsofoperationareshown.

LRL_SAT_LLF_2012_08_14

REFERENCES

1. IlluminatingEngineeringSociety,LightingMeasurement(LM)80,ApprovedMethod:MeasuringLumenMaintenanceofLEDLightSources.2008.

2. UnderwritersLaboratories(UL)1598Luminaires.3rdEdition,17September20083. ENERGYSTARManufacturersGuideforQualifyingSolidStateLightingLuminairesVersion

2.1,http://www.energystar.gov/ia/partners/manuf_res/downloads/ENERGYSTAR_Manufacturers_Guide_v2.1.pdf

4. IlluminatingEngineeringSociety,TechnicalMemorandum(TM)21,ProjectingLongTermLumenMaintenanceofLEDLightSources.2011.