Kyoritsu Electrical Instruments Works, Ltd. KEW4105DL User manual

Instruction Manual
Digital Earth Resistance Tester
KEW4105DL

Contents
1.Safetywarnings ････････････････････････････････････････････1
2.Features･･･････････････････････････････････････････････････5
3.Specifications･･････････････････････････････････････････････6
4.Nameofparts･･････････････････････････････････････････････9
5.Accessories･･････････････････････････････････････････････ 12
6.Gettingstarted･･･････････････････････････････････････････ 14
7.Earthresistancemeasurement･････････････････････････････ 15
7-1.Measurementprinciple･･･････････････････････････････ 15
7-2.Precisionmeasurement(withtestleadsforprecision
measurement)･･････････････････････････････････････ 15
7-3.Simplifiedmeasurement(withtestleadsforsimplified
measurement)･･････････････････････････････････････ 19
8.Comparatorfunction･･････････････････････････････････････ 22
8-1.Comparatorfunction ････････････････････････････････ 22
8-2.Howtoenable/disablecomparatorfunction･･････････ 23
9.Switchingindicationsofaux.earthresistancewarning･･･････ 24
10.Backlight･･･････････････････････････････････････････････ 24
11.Batteryreplacement･･････････････････････････････････････ 25
12.Cleaning････････････････････････････････････････････････ 26
13.Notesonhousingcase･･･････････････････････････････････ 27
14.Howtofitstrapbelt･･････････････････････････････････････ 28
15.Cablereels･････････････････････････････････････････････ 28
15-1.Operatinginstruction･･･････････････････････････････ 28
15-2.Cablereplacement ････････････････････････････････ 29

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1
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1．Safety warnings
This instrument has been designed, manufactured and tested
according to IEC 61010: Safety requirements for Electronic
measuring apparatus, and delivered in the best condition after
passing quality control tests. This instruction manual contains
warnings and safety rules which have to be observed by the user
toensuresafeoperationoftheinstrumentandtomaintainitinsafe
condition.Therefore,readthroughtheseoperatinginstructionsbefore
startingtousetheinstrument.
#DANGER
●Readthroughandunderstandtheinstructionscontainedinthis
manualbeforestartingtousetheinstrument.
●Keepthemanualathandtoenablequickreferencewhenever
necessary.
●Theinstrumentistobeusedonlyinitsintendedapplications.
●Understandand followallthesafetyinstructions contained in
themanual.
Itisessentialthat the aboveinstructionsareadheredto.Failure
to follow the above instructions may cause injury, instrument
damage and/or damage to equipment under test. Kyoritsu is by
nomeansliableforanydamage resultingfromthe instrument in
contradictiontothesecautionarynotes.
The symbol #indicatedontheinstrument,meansthattheuser
mustrefertotherelatedpartsinthemanualforsafeoperationofthe
instrument. It is essential to read the instructions wherever the
symbolappearsinthemanual.
#DANGER:is reserved for conditions and actions that are
likelytocauseseriousorfatalinjury.
#WARNING:is reserved for conditions and actions that can
causeseriousorfatalinjury.
#CAUTION:is reserved for conditions and actions that can
causeinjuryorinstrumentdamage.

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#DANGER
●Never make measurements on circuits in which earth
potentialshigherthanthefollowingvaluesexist.
*300 V or higher in CAT II, 150 V or higher in CAT III and
100VorhigherinCATIVenvironment.
●Keepyourhandandfingersbehindtheprotectivefingerguard
duringameasurement.
●Do not attempt to make measurements in the presence of
flammable gasses. Otherwise the use of the instrument may
causesparking,whichcanleadtoanexplosion.
●Neverattempttousetheinstrumentifitssurfaceoryourhand
iswet.
●Be careful not to short-circuit the power line with the metal
part of the test lead during a measurement. It may cause
personalinjury.
●Donotexceedthemaximumallowableinputofanymeasuring
range.
●Ensure that the test leads are firmly connected to the
instrument,andthenpresstheTESTbutton.
●Never open the battery compartment cover during a
measurement.
●The instrument should be used only in its intended
applications or conditions. Otherwise, safety functions
equipped with the instrument do not work, and instrument
damageorseriouspersonalinjurymaybecaused.
#WARNING
●Never attempt to make any measurements if any abnormal
conditions,suchasabrokencoverorexposedmetalpartsare
presentontheinstrumentandclampsensor.
●Do not install substitute parts or make any modifications to
theinstrument.ReturntheinstrumenttoyourlocalKYORITSU
distributor for repair or re-calibration in case of suspected
faultyoperation.
●Donottrytoreplacebatteriesifthesurfaceoftheinstrument
iswet.
●Connectthetestleadsfirmlyintoeachterminal.
●Set the range selector switch to OFF position when opening
thebatterycompartmentcoverforbatteryreplacement.

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#CAUTION
●Always make sure to set the range selector switch to the
appropriatepositionbeforemakingameasurement.
●Power off the instrument after use. Remove batteries if the
instrument is to be stored and will not be in use for a long
period.
●Do not expose the instrument to direct sunlight, high
temperature,humidityordew.
●Useadampclothwithneutraldetergentorwaterforcleaning
theinstrument.Donotuseabrasivesorsolvents.
●Iftheinstrumentiswet,makesuretoletitdrybeforeputtingit
intostorage.
Symbols
CATII Electricalcircuitsofequipmentconnectedtoan
ACelectricaloutletbyapowercord.
CATIII
Primary electrical circuits of the equipment
connected directlytothedistributionpanel, and
feedersfromthedistributionpaneltooutlets.
CATIV
The circuit from the service drop to the service
entrance, and to the power meter and primary
over-currentprotectiondevice(distributionpanel).
Doubleorreinforcedinsulation
#User must refer to the explanations in the
instructionmanual.
Earth

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MeasurementCategory
To ensure safe operation of measuring instruments, IEC 61010
establishes safety standards for various electrical environments,
categorizedasOtoCATIV,andcalledmeasurementcategories.
Higher-numberedcategoriescorrespondtoelectricalenvironments
with greater momentary energy, so a measuring instrument
designedforCATIIIenvironmentscanenduregreatermomentary
energythanonedesignedforCATII.
O :Circuits which are not directly connected to the mains
powersupply.
CATII :Electrical circuits of equipment connected to an AC
electricaloutletbyapowercord.
CATIII:Primary electrical circuits of the equipment connected
directly to the distribution panel, and feeders from the
distributionpaneltooutlets.
CATIV:Thecircuitfromtheservicedroptotheserviceentrance,
and to the power meter and primary over-current
protectiondevice(distributionpanel).
O: Device which is
not directly
connected to the
mains power supply

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2．Features
KEW4105DL is an earth resistance tester for testing power
distributionlines,in-housewiringsystem,electricalappliancesetc.It
alsohasanearthvoltagerangetomeasureearthvoltage.
●Designedtomeetthefollowingsafetystandards.
IEC61010-1,IEC61010-2-030CATII300V,CATIII150V,
CATIV100V,Pollutiondegree3
IEC61010-031,
IEC61557-1,-5
●
Dust and water-proof construction in conformity with IEC 60529
(IP67)
Thisinstrumentiswater-proof,soitiswashable.
●Backlight to facilitate working at dimly illuminated location or at
nighttimework.Thebacklightautomaticallyturnsoffiftherange
selector switch is not moved or a button is not pressed for two
minutes.
●The instrument automatically powers off if the range selector
switch is not moved or a button is not pressed for ten minutes.
This auto-power-off function doesnt work during a continuous
measurement.
●Shoulderstrapforboth-handsoperation
●Earthvoltagemeasurement
-AC/DCautodetection
-WarningLEDforhazardoushighearthvoltage
●Earthresistancemeasurement
-If the auxiliary earth resistance of auxiliary earth spikes is too
high to make a precision measurement, the display shows
warning andindicateswhichterminal, H(C)orS(P),hashigher
valueswithawarningLED.
-Simplified measurement probe has a structure that both the
alligatorclipandthetestbarareavailable.
-Comparator function to give warning when a measured value
exceeds the pre-set reference value. For further detail, see
8-1. Comparator functioninthismanual.Thisfunctioncanbe
disabled.

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3．Specifications
●Measuringrangeandaccuracy(23ºC±5ºC,RH75%orless)
Earthvoltagemeasurement
Measuringrange Displayrange Accuracy
0to300VAC
(45-65Hz) 0.0to314.9V ±1%rdg±4dgt
±0to±300VDC 0.0to±314.9V
Measuringmethod:Averagesensing,TrueRMSvaluedisplay
*AC/ DC auto-detection for an input of 2 V or higher. The LCD
showsACorDCmarkaccordingtotheinputpolarity.
Earthresistancemeasurement
Range Measuring
range Displayrange Accuracy*1
20Ω
Range
0.00to2000Ω
0.00to20.99Ω ±1.5%rdg±0.08Ω*2
200Ω
Range 0.0to209.9Ω
±1.5%rdg±4dgt
2000Ω
Range 0to2099Ω
Measuringmethod:Constantcurrentinverter/825Hz
  Approx.3mA(20ΩRange)
  Approx.1.7mA(200ΩRange)*3
  Approx.0.7mA(2000ΩRange)*3
*1For precision measurement, auxiliary earth resistance should be
100Ω±5%orless.
*2At precision measurement or when using optional test leads
M-7241A,add±0.10Ωtothespecifiedaccuracy.
*3Currentisreducedasfollowsifauxiliaryearthresistanceishigh.
Approx.0.7mA:200ΩRange,ifaux.earthresistanceis25kΩor
higher.
Approx.0.3mA:2000ΩRange,ifaux.earthresistanceis50kΩ
orhigher.

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7

●Applicable
standards
●IEC61010-1
CATII300VCATIII150VCATIV100V
Pollutiondegree3
●IEC61010-2-030
●IEC61010-031
●IEC61557-1,-5
●IEC60529IP67
●IEC61326-1,-2-2
MODEL7127B…CATIII300VCATIV150V
*Whentestleadsareconnectedtoandused
with the instrument, the lower category
eitherofthembelongstoisapplied.
●Locationforuse Altitude2000morless,in-door/out-dooruse
●Display Liquidcrystaldisplaywithbacklight
●Operatingtemp.
&humidity
-10ºCto50ºC,80%orless(nocondensation)
●Storagetemp.
&humidity
-20ºCto60ºC,75%orless(nocondensation)
●Withstandvoltage 2210VAC(50/60Hz)/5sec
Betweenelectricalcircuitandenclosure
●Insulation
resistance
50MΩormore/1000VDC
Betweenelectricalcircuitandenclosure
●Autopoweroff
function
Turns off the instrument automatically if
thereisnofunctionchange,rangechangeor
buttonpressforabout10min.
●Backlight Automatically turns off if there is no activity
forabout2min.
*Auto-offisdisabledduringameasurement.
●Dimensions
121(L)×188(W)×59(H)mm*includingcaselid
●Weight Approx.690g*includingbatteriesandcaselid
●Powersource SixsizeAAalkalinebatteries(LR6)
●Operatinguncertainty
Operating uncertainty (B) is an uncertainty obtained under the
rated operating conditions, and calculated with the intrinsic
uncertainty(A),whichisanerroroftheinstrumentused,andthe
error(En)duetovariations.
According to IEC61557, the maximum operating uncertainty
shouldbewithin±30%.

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8
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●Operating uncertainty in earth resistance measurements
(IEC61557-5)
*Formula:B=±(｜A｜+1.15x√E22+E32+E42+E52)
AIntrinsicuncertainty
E2Variation due to changing the Battery voltage (till the
batteryindicatorbecomesempty  )
E3Variationduetochangingthetemperature
(-10ºCto50ºC)
E4Variationduetoseriesinterferencevoltage
16·2/3Hz,50Hz,60Hz:25V
DC:10V
400Hz:5V
E5Variationduetoresistanceoftheauxiliaryearthelectrode
20Ωrange:0‒10kΩ
200Ωrange:0‒50kΩ
2000Ωrange:0‒100kΩ
*Themeasuringrangetokeepoperatinguncertaintyof±30%:
20Ωrange :5.00Ω‒20.00Ω
200Ωrange :20.0Ω‒200.0Ω
2000Ωrange :200Ω‒2000Ω
●Possiblenumberofmeasurementswherebatteryvoltageiswithin
theeffectiverange(measurementof5sec.,pauseof25sec.)
Function Testresistor Possiblenumberof
measurements
Earthmeasurement 10Ω Approx.10000times

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9

4．Name of parts
(1)Frontpanel
Name Description
①LCD LCDwithbacklight
② Testbutton Starts/stopsameasurement.
③Backlightbutton Turnson/offthebacklight.
④ Rangeselectorswitch Selects arangeforearth resistanceor
earthvoltagemeasurement.
⑤LED for aux. earth
resistance
Green LED lights up in earth
measurementswhiletheauxiliary earth
resistanceiswithintheallowablerange.
⑥Earthvoltagewarning
LED
Red LED lights up in earth voltage
measure-ments if the earth voltage is
overtheallowablerange.
②
④
③
①
⑤
⑥
Fig.4-1

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10
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(2)Terminalpart
Terminal Designatedfunction
① E Foranearthelectrode
②S(P) Foranaux.earth(potential)electrode
③H(C) Foranaux.earth(current)electrode
(3)LCD

●Symbolscommontoallfunctions
Batterylevelindicator
Segmentsfornumericaldisplay
IndicatesOver-rangestatus‒themeasured
valueisexceedingthedisplayrange.
Resistance:>20.99(20Ωrange)
>209.9(200Ωrange)
>2099(2000Ωrange)
Voltage:>314.9V(<-314.9Vis displayed
fornegativeDCinput)
① ② ③
Fig.4-2
Fig.4-3

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11

●Symbolsforearthmeasurement
Measurementunit
Warning - Aux. earth resistance is too high.
(SeeP.18.)
Dataholdisactive.
Comparatorfunctionisactive.
While the comparator function is active, these
signs indicate that the present input is more
thanthepre-setthresholdvalues.
>10Ω(20Ωrange)
>100Ω(200Ωrange)
>500Ω(2000Ωrange)
#While the comparator function is active, this
sign indicates that the present input is more
thanthepre-setthresholdvalue.
●Symbolsforvoltage/earthvoltagemeasurement
Alternatingcurrent,directcurrent
Unitforvoltagemeasurement
Indicatesthatthenegativevoltageismeasured.

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12

5．Accessories
(1)TestleadsforprecisionmeasurementMODEL7266
(Red:20m,Yellow:10m,Green:5m)
(2)TestleadsforsimplifiedmeasurementMODEL7127B
*4Protective finger guard is a part providing protection against electrical
shockandensuringtheminimumrequiredairandcreepagedistances.
(3)AuxiliaryearthspikeMODEL8041
(4)Cablereel(supplieddependingonthepurchasedmodel)
2pcs (red & black)
Protective
finger guard*
4
2pcs (black)
Protective
finger guard*
4
Fig.5-1
Fig.5-2
Red cable (20m) Yellow cable (10m)
Fig.5-3
Fig.5-4
Cablereel+Redcable(20m)MODEL7267
Cablereel+Yellowcable(10m)MODEL7268

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13

(5)ShoulderstrapMODEL9121
(6)SixAAalkalinebatteries(LR6)
(7)Instructionmanual
(8)
HardcaseMODEL9191(supplieddependingonthepurchasedmodel)
(9) SoftcaseMODEL9190(supplieddependingonthepurchasedmodel)
●Optionalaccessories
(1)AdapterformeasurementterminalMODEL8259
#DANGER
Do not connect the adapter of precision test leads to mains
power or a circuit in which electrical potentials exceeding 33 V
rms, 46 V (peak value) or 70 V DC exist; otherwise, electrical
shockmaybecausedbytheexposedelectrode.
Red, yellow, green
Offering easy connection of a
cable with spade connector
Fig.5-7
Fig.5-8
Each item can be stored as shown below.
Main unit
Auxiliary earth spikes
Test leads for
simplified measurement Test leads for
precision measurement
Each item can be stored as shown below.
Main unit
Auxiliary earth spikes
Test leads for
simplified measurement
and for
precision measurement (green)
Cable reels
Fig.5-5
Fig.5-6

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14

#CAUTION
Resistance of test leads to be connected to E terminal affects
measuredresults.Thespecifiedaccuracymaynotbeguaranteed
iftestleadsotherthantheonessuppliedwiththisinstrumentare
used.
(2)TestleadsforprecisionmeasurementMODEL7241A
(Red,Yellow,Green:1.5m)
6．Getting started
Batteryvoltagecheck
(1)Pleasereferto11. Battery replacementinthismanualandinsert
batteriesinKEW4105DL.
(2)Turnandsettherangeselectorswitchtoanypositionotherthan
OFFtopowerontheinstrument.
(3)Battery level indicator appears at the upper left on the LCD.
Battery voltage is extremely low if  mark is displayed.
Replace batteries with reference to 11. Battery replacement to
carryoutfurthermeasurements.
If empty  mark is displayed, battery voltage is below the
lowerlimitoftheoperatingvoltage.Insuchacondition,accuracy
ofthemeasuredresultisntguaranteed.Replacethebatteriesas
soonasthismarkappears.
Use of AA alkaline battery is recommended. Use of other
batteriesmaycauseimproperindicationofbatterylevel.
Fig.5-9

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15

7．Earth resistance measurement
With the earth resistance measurement function of this instrument,
earth resistance of power distribution lines, in-house wiring system
andelectricalappliancescanbemeasured.
#DANGER
●Be extremely careful when measuring earth resistance; high
voltage,50VmaxisgeneratedacrossH(C)‒Eterminals.
●When measuring earthvoltage,donotapply300V orhigher
voltagebetweenS(P)‒EandbetweenH(C)‒Eterminals.
●When measuring earth resistance,donotapplyvoltage,more
than25V,betweenmeasuringterminals.
7-1.Measurementprinciple
This instrument makes earth resistance measurement with fall-of-
potential method, which is a method to obtain earth resistance value
Rx by applying AC constant current I between the measurement
objectE(earthelectrode)andH(C)(currentelectrode),andfindingout
thepotentialdifferenceVbetweenEandS(P)(potentialelectrode).
7-2.Precisionmeasurement(withtestleadsforprecisionmeasurement)
(1)Connection
Stick the auxiliary earth spikes S(P) and H(C) into the ground
deeply. They should be aligned at an interval of 5 - 10 m from
theearthedequipmentundertest.Connectthegreenwiretothe
earthed equipment under test, the yellow wire to the auxiliary
earth spike S(P) and the red wire to auxiliary earth spike H(C)
fromterminalsE,S(P) and H(C)oftheinstrumentinorder.See
Fig.7-2and7-3.
E(Earth)
S(P)(Potential) H(C)(Current)
Rx = V / I
V = Rx × I
Constant current generator
I
Voltmeter
V
～
Fig.7-1


16

Inserttheplugoftestleadsfirmlyintoeachterminal.Iftheyarenot
insertedfirmly,thelooseconnectionmaycauseinaccuratereadings.
Note:
Makesuretosticktheauxiliaryearthspikesinthemoistpartofthe
soil.Giveenoughwaterwherethespikeshavetobestuckintothe
dry,stonyorsandypartoftheearthsothatitmaybecomemoist.
Incaseofconcrete,laytheauxiliaryearthspikedownandwaterit,
orputawetclothetc.onthespikewhenmakingmeasurement.
Confirm that the LED for aux. earth resistance lights up before
pressing the TEST button. For further detail, please refer to
Clause7.2, (4) Auxiliary earth resistance.Aux.earthelectrodes
cannotbeusedonthegroundsuchasasphaltwherewaterwillnot
permeate.
(2)Earthvoltagecheck
●SelecttheEarth voltagefunction andcheckthevoltage value
displayed on the LCD. The displayed earth voltage is the
voltagebetweenS(P)andEterminals.
Displayexample
Red
Red
Green
Green
Earthed electrode
under test
Auxiliary
earth spikes
Yellow
Yellow
Fig.7-2
Fig.7-3
Fig.7-4

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17

Confirmthatthedisplayedvoltagevalueis25Vorless.Whenthedisplay
readsmorethan25V,thewarningLEDasshownbelowlightsup.
(ThewarningLEDlightsupat;morethan10VforDCearthvoltage
andmorethan5Vforearthvoltageof400Hz.)
Excessive errors in earth resistance measurement may be caused
in the condition that warning LED for high earth voltage is lighting
up.To avoidthis, make measurement after reducing the voltage by
turning off the power supply of the equipment which is connected
totheearthed electrodeundertestetc.Earth voltagewarningLED
worksonearthresistancefunction.
#DANGER
●Donotconnecttheprecisionmeasurementtestleadstoacircuit
inwhichelectricalpotentials exceeding 33 Vrms, 46 Vpeakor
70VDCexist,inaddition,notusethemforvoltagemeasurement.
(3)Measurement
Select a desired range and press the TEST button to start
measurement.
TESTbuttonLEDblinkstoindicatetheinstrumentisperforming
measure-ment. The displayed value is the earth resistance of
the earthed electrode under test. Press the TEST button again
tostopmeasurement.Ifthemeasuredresultexceedsthedisplay
range,settherotaryselectorswitchtoahigherrange.
Displayexample
Whenthemeasuredresultexceedsthedisplayrange(over-range),
theLCDshows:
>20.99Ω(20Ωrange)
>209.9Ω(200Ωrange)
>2099Ω(2000Ωrange).
Red LED lights up.
Fig.7-5
Fig.7-6


18
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(4)Auxiliaryearthresistance
If the auxiliary earth resistance is within the allowable range
and doesnt affect measurement, the green LED shown below
lightsup.Thetablebelowshowstheupperlimitofauxiliaryearth
resistance.
Upperlimitofauxiliaryearthresistance
Measurementrange Aux.earthresistance
20Ω 10kΩ
200Ω 50kΩ
2000Ω 100kΩ
If the auxiliary resistance of auxiliary spike H(C) or S(P) is too high to
makemeasurement,thedisplayreadsRHHorRSH.Recheckthe
connectionoftestleadsandtheearthresistanceofauxiliaryearthspike.
WhenearthresistanceatH(C)
(aux.earth(current)electrode)
istoohigh:
WhenearthresistanceatS(P)
(aux.earth(potential)electrode)
istoohigh:
Indications of aux. earth resistance warning are switchable: RHH
-> RCH, RSH -> PRH. For further detail, please refer to 9.
Switching indications of aux. earth resistance warning.
Green LED lights up.
Fig.7-7
Fig.7-8 Fig.7-9