Extech Instruments LT40 User manual

USERMANUAL
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WhiteLEDLightMeter
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ModelLT40
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LT40-en-GB_V3.0 10/17
2
Introduction
CongratulationsonyourpurchaseoftheExtechLT40LEDLightMeterthatmeasureslightintensity
fromwhiteLEDlightsources.TheLT40canalsomeasurelightfromfluorescent,metalhalide,high‐
pressuresodium,andincandescentsources,forreferenceonly(unspecifiedaccuracy).TheLT40
canmeasurelightupto40,000Fc(400,000Lux).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:TheLCDwillshowOL.
LowbatteryIndication.
DisplayUpdateRate:2.5timespersecond.
CosineAnglecorrected.
MeasureswhiteLEDlight.
MeasurestheintensityofilluminationinLuxorfoot‐candles.
Dataholdfreezesdisplayedreading.
Maximum/Average/MinimumreadingHold.
ZeroCalibrationadjustment.
Autopoweroffwithdisablefunction.
Autorange.
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lowbatterysymbolappearsontheLCD.
Donottouchthemeter’scircuitboardforanyreason;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’).
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LT40-en-GB_V3.0 10/17
3
MeterDescription
1. Photodetector(removeprotectivecovertoexposesensor)
2. Display(LCD)
3. Controlpush‐buttons
4. PowerButton:ON/OFF
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Batterycompartmentandtripodmountarelocatedon
rearofinstrument
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Push‐ButtonDescription
1. Lux/Fcunitsselector
2. ZeroCalibrationbutton
3. Maximum/Average/Minimummemorybutton
4. Dataholdbutton
Operation
PowerON/OFF 
LongpressthePowerbuttontopowerthemeter.TopowerthemeterOFF,shortpressthe
Powerbutton.
TakingMeasurements
1. SwitchthemeterONandremovethesensor’sprotectivecovertoexposethelightsensor
dome.ThedisplayshouldswitchON;ifnot,checkthatbatteriesareinstalledandfresh.
2. 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thismeasuredvalueonitsLCD.
3. Positionthemeterandlightsourcesothatthelightstrikesthesensordomestraighton
(perpendicular)withaslittleanangleaspossible.
4. Themeter’sdisplaycanshowavalueupto9999.However,forreadingsthatrepresent
measurementshigherthanthis,themeterusesx10orx100feature.Forexample,to
representameasurementof11,000fcthemeterwilldisplay1100withthex10indicator.
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LT40-en-GB_V3.0 10/17
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AutoPowerOFF
Tosavebatterylife,themeterpowersdownautomaticallyafterapproximately12minutesof
inactivity.
Enable/DisableAutoPowerOff
WhilethemeterisON,longpressthePowerbuttontodisabletheAutoPowerOFFutility(the
ClocksymbolwillswitchOFF).ToenabletheAutoPowerOFFutility,repeatthisprocess.
LUX/FCButton
PresstheLUX/FCbuttontotogglebetweenLuxandFC(foot‐candles)measurementunits.
MAX/MINButton
Themetercanrecordthemaximum,minimum,andaveragereadingsasdescribedbelow:
1. Shortpressthe“MAX/MIN”buttonandthemeterwillbegintotrackthe
maximum/average/minimummeasurements;the“MAX”iconwilldisplayatthetopofthe
LCDwindowindicatingthatthemeterisnowshowingthemaximumreading.Thereading
willnotchangeuntilahigherreadingisregistered.
2. Pressthe“MAX/MIN”buttonagaintoswitchfrom“MAX”to“AVG”,wherethemeterwill
showtheaveragemeasurementvalue.The“AVG”iconwillbedisplayedabovethedisplayed
value.
3. Pressthe“MAX/MIN”buttonagaintochangethemodefrom“AVG”to“MIN”,wherethe
meterwillshowtheminimumvaluemeasured.The“MIN”iconwillbedisplayed.
4. Pressthe“MAX/MIN”buttonagaintoswitchfrom“MIN”backto“MAX”.
5. Toexitthismode,holdthe“MAX/MIN”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.
HOLDButton
PresstheHOLDbuttontofreezethecurrentreadingontheLCD.PresstheHOLDbuttonagainto
releasethereading.IntheDataHoldmode,HOLDisdisplayedontheLCD.
ZeroCalibrationProcedure
1. Ensurethattheprotectivecapisattachedtothelightsensor.
2. PowerthemeterandtheLCDshoulddisplay‘0’.
3. Shortpressthe“CALZERO”buttontoperformthezeroadjustment(CALwillappearonthe
display).
4. TheCALdisplaywillswitchoffwhenthecalibrationhasbeencompleted.
5. 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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LT40-en-GB_V3.0 10/17
5
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.
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Whenthemeterisnotinuse,pleasekeeptheprotectivecapinplaceoverthelightsensor.This
willprolongthelifeofthesensor.
Whenthemeteristobestoredforlongperiods,pleaseremovethebatteriesandstorethem
separately.Batteriescanleakandcausedamagetothemeter’scomponents.
Avoidareasofhightemperatureandhumiditywhenusingthisinstrument.
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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lowbattery
symbol“”willappearontheLCD.Replacethe2x1.5VAAA
batterieslocatedintherearbatterycompartment.
1. Pressandholdthebatterycompartmentlockbutton(seediagram).
2. Slidethebatterycompartmentcoveroffinthedirectionofthe
arrow.
Installtwo(2)1.5V‘AAA’batteriesobservingcorrectpolarityandclose
thebatterycompartment.Ensurethatthecompartmentcoverissecurely
fastenedbeforeusingthemeter.
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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.
1
2
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LT40-en-GB_V3.0 10/17
6
Specifications
UnitsRangeResolutionAccuracy
Lux
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999.90.1WhiteLED:
±(3%reading+3Lux)upto500Lux
±(3%reading)>500Lux
Otherlightsources:Unspecified
9,9991
99,990*10
400,000*100
Foot
candles
99.990.01WhiteLED:
±(3%reading+0.3Fc)upto46Fc
±(3%reading)>46Fc
Otherlightsources:Unspecified
999.90.1
9,9991
40,000*10
*Readingsabove9999useax10orx100multiplier(1Fc=10.76Lux)
Angledeviationfromcosine
characteristics
30°±2%
60°±6%
80°±25%
GeneralSpecifications
Samplingrate2.5timespersecond(digitaldisplay)
PhotodetectorSiliconphoto‐diodewithcosinecorrection
Display4‐digitLCD(maximumdisplay:9999)withlowbatteryicon,
measurementoverload,andotherfunctionindicators
AutoRangeMeterautomaticallyrangesthedisplay
OperatingconditionsTemperature:5to40oC(41to104oF);Humidity:<80%RH
StorageconditionsTemperature:‐10to60oC(14to140oF);Humidity:<70%RH
LowbatteryindicationappearsontheLCDwhenbatteryvoltagefallscriticallylow
LEDType WhiteLEDlight
Powersupply2x1.5V‘AAA’batteries
BatterylifeApproximately200hours
AutoPowerOFFMeterswitchesOFFafter12minutesofinactivity
Dimensions133x48x23mm(5.2x1.9x0.9”)
Weight250g.(8.8oz.)includingbatteries
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Appendices
TypicalLightLevels(1Fc=10.76Lux)
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
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