Extech Instruments LT45 User manual

USERGUIDE
LEDLightMeter
ModelLT45

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Introduction
CongratulationsonyourpurchaseoftheExtechLT45LEDLightMeterthatmeasureslightfromLED
lampsinadditiontofluorescent,metalhalide,high‐pressuresodiumandincandescentsources.
TheLT45iscapableofmeasuringtheilluminationofwhite,red,yellow,green,blue,andpurple
LEDsupto400,000Lux(40,000Fc).
TheLT45canalsocalculateluminousintensity(CD)usingadistance‐to‐the‐lightvalueprogrammed
bytheuserinmetersorfeetunits.
TheLT45canstoreupto99readingsforlaterrecallandincludesOverloadindication,Battery
statusicon,Datahold,Maximum/Average/Minimum(MAX/MIN)tracking,push‐buttonZero
calibrationadjustment,AutoPoweroff(withdisablefunction),andautorangingfeatures.
Thisinstrumentisshippedfullytestedandcalibratedand,withproperuse,willprovideyearsof
reliableservice.Pleasevisitourwebsite(www.extech.com)tocheckforthelatestversionofthis
UserGuide,ProductUpdates,andCustomerSupport.
Features
OverloadIndication:LCDscreenwillshow“OL”attheupperleft‐handcorner
Batterystrengthstatusindication
DisplayUpdateRate:2.5timespersecond
SpectralresponsenearCIEluminousspectralefficiencyratings
CosineAnglecorrected
ConformstoJISC1609:1993andCNS5119generalclassASpecifications
Measurestheintensityofilluminationofwhite,red,yellow,green,blue,andpurpleLED
lightandallvisiblelightinLuxorfoot‐candles
CalculatesLuminousIntensity(CD)
Dataholdfreezesdisplayedreading
Maximum/Average/MinimumMemoryHold
Zeroadjustment
Autopoweroffwithdisablefunction
Automaticrangeadjustoptimizesaccuracyandresolution
Manuallystore/recallupto99readings
Completewithlightsensor,protectivesensorcover,andcoiledcableexpandableto59”
(1.5m),9Vbattery,andhardshellcase

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Safety
Donotoperatethemeterinenvironmentswherethefollowingarepresent:explosivegases
(ormaterials),combustiblegases(ormaterials),steam,ordust.
Pleasereplacethebatteryimmediatelywhenthebatterysymbol appearsontheLCD.
Donottouchthemeter’scircuitboardforanyreasonasstaticelectricityorcontamination
coulddamagethesensitivecomponents.
ForIndooruseonly.Thisinstrumentwasdesignedforpollutiondegree2.
OperationAltitude:Upto2000m(7000’).
MeterDescription
1. Display(LCD)
2. Lux/Fc/CDunitselectbutton
3. MEM/READbutton(for99readingmemory)
4. UparrowbuttonandMAX/MIN/AVGbutton
5. PowerandAutoPowerOFFcontrolbutton
6. ZeroCalibrationbutton
7. DataHoldandLightsourceselectbutton
8. Downarrowbutton
9. Coiledsensorconnectioncable
10. Photodetector
Note:Thebatteryandtripodmountarelocated
onthebackofthemeter

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Operation
PowerON‐OFF 
MomentarilypressthePowerbuttontopowerthemeter.TopowerthemeterOFF,
momentarilypressthePowerbuttonagain.
TakingMeasurements
1. SwitchthemeterON
2. Removethesensor’sprotectivecovertoexposethelightsensordome.Thedisplayshould
switchON,ifnotcheckthatfreshbatteriesareinstalled.
3. Themetermeasurestheintensityofthelight(illuminance)thatstrikesthesensordomein
footcandlesandluxunits(1fc=10.76lux)displayingthemeasuredvalueontheLCD.
4. UsetheLUX/FC/CDbuttontoselectLuxorFootcandleunits(CD,luminousintensity,is
explainedinthededicatedsection‘LuminousIntensity’).When‘OL’isdisplayed,the
measurementexceedsthemeter’srangecapability.
5. Positionthemeterandlightsourcesothatthelightstrikesthesensordomeperpendicularly.
Althoughthemetercompensatesforanincidenceangle,optimumperformanceisachieved
withasmallerincidenceangle.
6. Themeter’sLCDcanshowavalueupto3999onthelargedigitsandwhenmoredigitsare
neededtorepresentthereadingtwoadditional(smaller)digitsappeartotherightofthe
largerdigits,e.g.399900.
LUX/FC/CDUnits
MomentarypressesoftheLUX/FC/CDbuttontogglesLuxandFC(foot‐candles)units.Pressand
holdthebuttontoentertheCD(luminousintensity)mode.Referto‘LuminousIntensity’section
forfurtherinformation.
AutoPowerOFF
Tosavebatterylifethemeterpowersdownautomaticallyafterapproximately5minutesof
inactivity(nobuttonpresses).
Enable/DisableAutoPowerOff
WiththemeterON,pressandholdthePowerbuttonuntiltheAPOclocksymbolswitches
OFF(theAutoPowerOFFutilityisnowdisabledandtheusermustmanuallyswitchthemeter
off).Tore‐enabletheAutoPowerOFFutility,repeatthisprocess.TheClocksymbolwillswitch
ONwhentheAutoPowerOFFutilityisre‐enabled.
ZeroCalibration
1. Ensurethattheprotectivecoverisattachedtothelightsensor.
2. PowerthemeterandtheLCDshoulddisplay‘0’.
3. Momenarilypressthe“ZERO”buttonandtheADJ(adjusting)iconwillswitchONindicating
thatthezeroadjustment(calibration)isworking.Whenthecalibrationisfinished,theADJ
iconwillswitchOFFandthemeterwillreturntothenormaloperatingmode.
4. IftheprotectivecapisnotcoveringthesensorwhentheZEROcalibrationisstartedtheLCD
displaywillread“CAP”.Inthiscase,pleasecoverthesensorwiththecapandrestartthis
procedure.

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MAX/AVG/MINMemoryMode
Themetercanrecordthemaximum,minimum,andaveragereadingsasdescribedbelow:
1. MomentarilypresstheMAX/AVG/MINbuttonandthemeterwillbegintotrackthe
maximum/average/minimummeasurements;the“MIN”iconwilldisplayontheLCD
indicatingthatthemeterisnowdisplayingtheminimumreading.Thereadingwillnot
changeuntilalowerreadingisregistered.
2. Pressthebuttonagaintoswitchfrom“MIN”to“MAX”wherethemeterwillshowthe
maximummeasurementvalue.The“MAX”iconwillbedisplayedontheLCD.
3. Pressthebuttonagaintochangethemodefrom“MAX”to“AVG”,wherethemeterwill
showtheaverageofthereadingstakensincethebuttonwasfirstpressed.The“AVG”
iconwillbedisplayed.
4. Pressthe buttonagaintoswitchfrom“AVG”backto“MIN”.
Toexitthismode,pressandholdthebuttonforatleast2seconds.TheMAX/AVG/MINicons
shouldallbeswitchedOFFwhentheunitreturnstothenormaloperatingmode.
MemoryRecord/ReadMode
1. MomentarilypresstheMem/Readbuttontostoreareading.TheLCDwilldisplayasmall‘M’
icononthelowerleft‐handareaoftheLCDalongwiththememorylocationnumber(1to
99)representingthestoragelocationfortherecordedreading.Upto99readingscanbe
stored.
2. Toreview(read)thestoredreadings,pressandholdtheMem/Readbuttonuntilthe‘MEM’
iconappearsatthetopoftheLCD.Nowusethearrowbuttonstoscrollthroughthestored
readings.Thesmall‘M’iconandthememorylocationcounter(1to99)willbeshownonthe
lowerleft‐handcorneroftheLCDwhilethemaindisplaydigitsshowthestoredreadingfor
theselectedmemorylocation.
3. Tostoreanaverage(AVG)reading,firstaccesstheAVGmode(SeeMIN/MAX/AVGsectionof
thisguide)andwhileanaveragereadingisdisplaying(AVGiconswitchedON),momentarily
presstheMem/Readbuttonforonesecond.TheLCDwilldisplay‘AVGM’andthememory
locationnumber(1to99)indicatingthatanaveragereadinghasbeenstoredinthe
numberedmemorylocation.
4. WhenastoredreadingisanAVGvalue,thescreenwilldisplay‘AVG’onthelowerleft‐hand
corner.
5. MomentarilypresstheMem/ReadbuttontoexittheMemorymodeandreturntothe
normaloperatingmode.
6. Toclearall99memorylocations:WiththemeterswitchedOFF,pressandholdthe
Mem/ReadandOn/Offbuttonssimultaneouslyfortwoseconds.ThemeterwillswitchON
andthescreenwilldisplay“CLr”indicatingthatallofthe99memorylocationshavebeen
erased.
DataHold
PresstheHoldbuttontofreezethedisplayedreading(the‘HOLD’iconwillswitchON).Pressthe
buttonagaintoreleasetheheldreading(the‘HOLD’iconwillswitchOFF).


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LuminousIntensity(CD)Measurements
1. PresstheOn/OffbuttontoturnpowerON.
2. PressandholdtheLX/FC/CDbuttonuntilthemeter’sunitdesignatorswitchestoCD.
3. Usethearrowbuttonstoselectft(feet)orm(meter)unitstorepresentthedistancethe
sensorwillbefromthelightsource.
4. MomentarilypresstheLX/FC/CDbutton;thesmallerdigits(lower‐righthandcornerofLCD)
willswitchON,thesedigitsrepresentthedistancetothelightsource.
5. Usethearrowbuttonstosetthedistancefromthecenterofthelamptothemeasurement
baselevel.Pressandholdanarrowbuttontoscrollquickly.
6. MomentarilypresstheLX/FC/CDbutton.
7. Removetheprotectivesensorcapandplacethesensorperpendiculartothelightatthe
programmeddistance.
8. ReadtheLuminousIntensitycalculationonthemeter’sLCDdisplay.
9. PressandholdtheLX/FC/CDbuttontoexitthismode.
LuminousIntensity=illumination(Lx)xdistance(ft2orm2)
Theprogrammabledistancerangeis0.01~30.47m(0.01~99.99ft.)
LightSource(L.S.)Selection
Thereare10lightsourceselections(L0–L9)eachhavingauniquecalibrationcorrectionfactor
(multiplier).SeetheLightSourceFactorslistbelow.ThemultipliersforlocationsL0throughL6
arefixedforthelightingtypeslisted.LocationsL7throughL9areextralocationsthattheuser
cancustomize(withamultiplierfrom0.001to1.999).Tochangethelightsource(L.S.)selection:
1. PressandholdtheHold/LSbuttonfor2seconds.Thelightsourcecode,atthebottomcenter
oftheLCD,willflash.UsethearrowbuttonstoselectL0throughL9.Thelocation’smultiplier
(correctionfactor)willbeshowntotherightoftheLxvalue(L8…1000,forexample).
2. Tocustomizealocation,selectL7,L8orL9and,onceselected,momentarilypressthe
Hold/LSbuttontoenterthemultiplierprogrammingmode.Nowusethearrowkeysto
changethemultiplier.Pressandholdanarrowbuttontoscrollfaster.
3. Whenfinished,pressandholdtheHold/LSbuttonforatleast1secondtoconfirmtheedit
andexitthismode.
LightSourceFactors
L0:Standardlightsource:1.00.
L1:LEDwhitedaylight:0.99.
L2:LEDREDlight:0.516.
L3:LEDAMBER(YELLOW)light:0.815.
L4:LEDGREENlight:1.216.
L5:LEDBLUElight:1.475.
L6:LEDPURPLElight:1.148.
L7~L9:ProgrammableUserCustomLocations(presetto1.00)

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MeasurementConsiderationsandUserTips
Formaximumaccuracyallowthelightbeingmeasuredtofalldirectlyonthesensoras
perpendicularaspossiblewithaminimalangleofincidence.


Whenthemeterisnotinuse,pleasekeeptheprotectivecapinplace,coveringthelight
sensor.Thiswillprolongthelifeofthesensor.
Whenthemeteristobestoredforlongperiods,pleaseremovethebatteryandstoreit
separately.Batteriescanleakandcausedamagetothemeter’scomponents.
Avoidareasofhightemperatureandhumiditywhenusingthisinstrument.

BatteryReplacementandMaintenance
Cleaningandstorage
1. Thewhiteplasticsensordomeshouldbecleanedwithadampclothwhennecessary.Use
onlyamildsoapifneeded.Donotusesolvents,abrasives,orharshdetergentstocleanthe
dome.
2. Storethemeterinanareawithmoderatetemperatureandrelativehumidity.
BatteryReplacement
Whenthebatterypowerdecreasestoacriticallevel,thebatterysymbolwillappearasemptyon
theLCD.Replacethe9Vbatterylocatedintherearbatterycompartment.Thebattery
compartmentslideseasilydownwardforremoval(inthedirectionoftheprintedarrowonthe
rearofthemeter).Ensurethatthecompartmentcoverissecurelyfastenedbeforeusingthe
meter.
Neverdisposeofusedbatteriesorrechargeablebatteriesinhouseholdwaste.
Asconsumers,usersarelegallyrequiredtotakeusedbatteriestoappropriate
collectionsites,theretailstorewherethebatterieswerepurchased,orwherever
batteriesaresold.
Disposal:Donotdisposeofthisinstrumentinhouseholdwaste.Theuserisobligatedtotake
end‐of‐lifedevicestoadesignatedcollectionpointforthedisposalofelectricalandelectronic
equipment.

BatterySafetyReminders
oPleasedisposeofbatteriesresponsibly;observelocal,state,nationalregulations.
oNeverdisposeofbatteriesinafire;batteriesmayexplodeorleak.


LT45-en-EU_V1.5 9/14
8
Specifications
Samplingrate2.5timespersecond(digitaldisplay)
Display6‐digitLCDwithbatteryicon,measurementoverload,and
otherfunctionindicators
Sensor(detector)Siliconphotodiodewithspectralresponsefilterandcosine
correction
RangesandResolutionLux:399.9,3999,*39999,*399999
Foot‐candles:39.99,399.9,3999,*39999
*Above3999,theLCDusessmallerdigitsontherightside
(1Fc=10.76Lux)
Auto‐rangeThemeterautomaticallyrangesthedisplay
Accuracy±(3%ofreading+3digits)upto500Lux
±(3%)above500Lux
Calibratedtostandardincandescentlamp2856oKatan
ambienttemperatureof23oC
±6%+3digitsforothervisiblelightsources
Angledeviationfromcosine
characteristics
30○ ±2%
60○±6%
80○±25%
LEDTypes Metermeasureswhite,red,yellow,green,blue,purpleLEDlight
OperatingconditionsTemperature:5to40oC(41to104oF);Humidity:<80%RH
StorageTemperature/RH‐10to60oC(14to140oF);Humidity:<70%RH
BatterystatusindicationBatterysymbolappearsemptywhenbatteryvoltagereachescriticallevel
Powersupply 9Vbattery
AutoPowerOFF Meterpowersdownafter5minutesofinactivity(canbedefeated)
Dimensions Meter:38x55x130mm(1.5x2.2x5.1”)
Sensor:25x44x80mm(9.8x2.2x3.1”)
Cablelength:1.5m(4.9ft.)
WeightApprox.250g(8.8oz.)withbatteryinstalled

LT45-en-EU_V1.5 9/14
9
Appendix
TypicalLightLevels
LuxFoot
Candles
LuxFoot
Candles
FactoriesHome
20‐752‐7EmergencyStairs,Warehouse 100‐15010‐15Washing
75‐1507‐15Exit/EntrancePassages150‐20015‐20Recreational
Activities
150‐30015‐30PackingWork200‐30020‐30DrawingRoom,
Table
300‐75030‐75VisualWork:ProductionLine300‐50030‐50Makeup
750‐1,50075‐150Typesetting:InspectionWork500‐1,50050‐150Reading,Study
1,500‐3,000150‐300ElectronicAssembly,Drafting1,000‐2,000100‐200Sewing
OfficeRestaurant
75‐1007‐10IndoorEmergencyStairs75‐1507‐15CorridorStairs
100‐20010‐20CorridorStairs150‐30015‐30Entrance,
WashRoom
200‐75020‐75Conference,
ReceptionRoom
300‐75030‐75CookingRoom,
DiningTable
750‐1,50075‐150ClericalWork750‐1,50075‐150ShowWindow
1,500‐2,000150‐2000Typing,Drafting
StoreHospital
75‐1507‐15Indoors30‐753‐7EmergencyStairs
150‐20015‐20Corridor/Stairs75‐1007‐10Stairs
200‐30020‐30Reception100‐15010‐15SickRoom,
Warehouse
300‐50030‐50DisplayStand150‐20015‐20WaitingRoom
500‐75050‐75Elevator200‐75020‐75MedicalExamRoom
750‐1,50075‐150ShowWindow,
PackingTable
750‐1,50075‐150OperatingRoom
1,500‐3,000150‐300Storefront,ShowWindow5,000‐10,000 500‐1000EyeInspection
SpectralSensitivity
Peaksensitivitywavelength:550nm
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Allrightsreservedincludingtherightofreproductioninwholeorinpartinanyform
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RELATIVE SENSITIVITY (%)
WAVELENGTH (nm)
LT45