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Light Loss Factor Determination AUG 14 2012
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LRL_SAT_LLF_2012_08_14 LRL Satellite TM Series Light Loss Factor Determination LLD = 0.89 Lamp Lumen Depreciation (LLD). The lumen depreciation (LLD) for the LED is determined from LM‐80 [1] reported data provided by the LED manufacturer. The LM‐80 report gives lumen depreciation data for LEDs operating at solder pad temperatures (T s ) of 55°C, 85°C, and 105°C. In the Satellite Series fixtures the LEDs are operated well under the maximum drive current, as low as 280mA. In‐situ temperature measurement tests (ISTMTs), performed as per UL 1598 [2] and Energy Star [3], confirm that the difference between ambient (T amb ) and solder pad temperature (T s ) is 17.9°C at 280mA. For an ambient temperature of 20°C and an operating current of 280mA T s will be 37.9°C The low T s is achieved through our unique thermal management system with cooling fins integrated into the fixture housing. The fixture’s curved design is self ‐cleaning, preventing the buildup of dirt and debris which could adversely affect heat dissipation. Using the methodology of TM‐21 [4], an exponential curve fit to the LM‐80 depreciation data and the Arrhenius Equation are used to interpolate lumen maintenance at the operating temperatures seen in the Satellite Series. This yields the lumen depreciation factors for the LEDs . For an average ambient of 20°C and an operating current of 280mA, LLD = 0.89 over 20 years (12 operating hours per day). LOD = 0.94 Luminaire Optical Depreciation (LOD). Satellite Series luminaires are IP‐66 rated. This means they are impervious to dust and powerful water spray. The optical lenses are mounted at 30° angles on the underside of the fixture meaning they are protected from the elements. In extreme conditions, winds may deposit some slight dust onto the fixture’s lenses, but the mounting angles make these lenses self ‐ cleaning. The lenses are made of UV resistant acrylic which does not discolor. Under the most extreme laboratory testing conditions, this material will optically depreciate by no more than 6% over 20 years based on manufacturer information.
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Transcript of Light Loss Factor Determination AUG 14 2012
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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.
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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.
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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.
