Extech Instruments LT45 User manual

USERGUIDE

LEDLightMeter

ModelLT45

LT45-en-EU_V1.5 9/14

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

LT45-en-EU_V1.5 9/14

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

LT45-en-EU_V1.5 9/14

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.

LT45-en-EU_V1.5 9/14

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).



LT45-en-EU_V1.5 9/14

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)

LT45-en-EU_V1.5 9/14

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

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

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

Allrightsreservedincludingtherightofreproductioninwholeorinpartinanyform

www.extech.com

RELATIVE SENSITIVITY (%)

WAVELENGTH (nm)

LT45

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