Kyoritsu Electrical Instruments Works, Ltd. KEW3125A User manual

Instruction manual
High voltage insulation resistance tester
KEW3125A/3025A
www. .com [e-mail]1.800.561.8187

Contents
1.Safetywarnings･････････････････････････････････････････ 1
2.Features･･･････････････････････････････････････････････ 5
3.Specification･･･････････････････････････････････････････ 6
4.Instrumentlayout･･････････････････････････････････････10
4-1Instrumentlayout･･････････････････････････････････10
4-2LCDdisplay･･･････････････････････････････････････11
4-3HowtoremovetheHardcase･･････････････････････12
5.Gettingstarted････････････････････････････････････････13
5-1Checkingthebatteryvoltage････････････････････････13
5-2Connectingtestleads･･････････････････････････････13
6.Measurement･･････････････････････････････････････････14
6-1Mainsdisconnectioncheck(Voltagemeasurement)･･･14
6-2Insulationresistancemeasurement･･････････････････15
6-3Continuousmeasurement･･････････････････････････18
6-4DAR/PImeasurement･･････････････････････････････18
6-5Voltagecharacteristicsatmeasuringterminal････････ 23
6-6UseofGuardterminal･････････････････････････････ 23
6-7Backlightfunction･･････････････････････････････････24
6-8Auto-power-offfunction････････････････････････････24
7.Batteryreplacement･･･････････････････････････････････ 25
8.Accessories･･････････････････････････････････････････ 26
8-1MetalpartsforLineProbe,andreplacement･････････ 26
8-2Howtousetheadaptorforrecorder････････････････ 27
8-3Lineprobewithalligatorclip(optionalaccessory)･････ 28
9.Disposingtheproduct･････････････････････････････････ 29
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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must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usingtheinstrument.
#WARNING
●Readthroughandunderstand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.
Failure to follow the 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 this
cautionarynote.
○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 under the circumstances
exceeding the designed measurement category and the
ratedvoltageoftheinstrumentandthetestleads.
●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 leads when measuring a voltage. It may
causepersonalinjury.
●Do not exceed the maximum allowable input of any
measuringranges.
●DonotpresstheTestbuttonwithtestleadsconnectedto
theinstrument.
●Never open the Battery compartment cover during a
measurement.
●To prevent possible electrical shock, do not touch the
circuit under test during an insulation resistance
measurementorrightafter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.
●Keep your fingers and hands behind the protective
fingerguardduringmeasurement.
#WARNING
●Neverattempttomakeanymeasurementsifanyabnormal
conditions such as broken case and exposed metal parts
arenoted.
●Do not rotate the Range switch with the test leads
connectedtotheequipmentundertest.
●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.
●Do not try to replace the batteries if the surface of the
instrumentiswet.
●
Inserttheplugintotheterminalfirmlywhenusingtestleads.
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●Ensure that the instrument is switched off before opening
theBatterycompartmentcoverforbatteryreplacement.
●Stopusingthetestleadiftheouterjacketisdamagedand
theinnermetalorcolorjacketisexposed.
#CAUTION
●Before starting a measurement, confirm that the Range
switchisatanappropriateposition.
●SettheRangeswitchtoOFFpositionafteruse.Remove
the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
temperaturesandhumidityordew.
●Useadampclothwithalcoholforcleaningtheinstrument
andtheareasaroundthemeasuringterminals.
●Whenthisinstrumentiswet,pleasestoreitafteritdries.
●The Voltage warning mark is being displayed during a
measurementanditstartsblinkingwhenvoltages30V(DC/
AC)ormoreexistonthecircuitundertest.
Symbols
Dangerofpossibleelectricshock
Instrumentwithdoubleorreinforcedinsulation
#Usermustrefertothemanual
DC
AC
Earthterminal
Crossed-out wheel bin symbol (according to WEEE
Directive: 2002/96/EC) indicating that this electrical
productmaynotbetreatedashouseholdwaste,butthat
itmustbecollectedandtreatedseparately.
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○ Measurement categories (Over-voltage categories)
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
overcurrentprotectiondevice(distributionpanel).
O: Device which is
not directly
connected to the
mains power supply
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2. Features
KEW3125A/3025A are high voltage insulation resistance
testers with 5-range(3125A)/ 4-range(3025A) for measuring
insulationresistance.
●Designedtomeetthefollowingsafetystandards:
IEC 61010-1,-2-030 (CAT III 600V/CAT IV 300V Pollution
degree2)
IEC61010-031(Requirementsforhand-heldprobes)
●Withauto-dischargefunction
When an insulation resistance like a capacitive load is
measured, electric charges stored in capacitive circuits are
automatically discharged after the measurement. Discharge
canbecheckedonthevoltagemonitor.
●Backlight function to facilitate working at dimly illuminated
locationoratnighttimework.
●Bargraphdisplay
●AudibleandvisibleLIVEcircuitwarning
●WithAuto-powerofffunction
The instrument automatically will turn itself off if there is
no function change or button press for 10 min to conserve
batterypower.
●Auto-measurementanddisplayofPI(PolarizationIndex),DAR
(DielectricAbsorptionRatio)
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3. Specification
●Applicablestandards
 IEC61010-1,-2-030
  MeasurementCATIII600VPollutiondegree2
  MeasurementCATIV300VPollutiondegree2
 IEC61010-031Standardforhand-heldprobes
  MODEL7165A(CATIV600V)
  MODEL7264(CATIV600V)
  MODEL7265(CATIV600V)
  *WhenKEW3125A/3025Aandthetestlead
are combined and used together, whichever
islowercategoryeitherofthembelongstois
applied.
 IEC61326-1,-2-2 EMCstandard
 IEC60529IP40
 EN50581  RoHSDirective
●Measuringrangeandaccuracy
(Temperature,humidity:23±5Cº,45-75％RH)
【Insulationresistancetester】：KEW3125A/3025A
Ratedvoltage 250V 500V 1000V 2500V
Measuring
Range
0.0-100.0MΩ 0.0-99.9MΩ
80-1000MΩ
0.0-99.9MΩ
80-999MΩ
0.80-2.00GΩ
0.0-99.9MΩ
80-999MΩ
0.80-9.99GΩ
8.0-100.0GΩ
Display
range 0.0‒105.0MΩ 0.0-1050MΩ 0.0M-2.10GΩ 0.0M-105.0GΩ
Opencircuit
Voltage
DC250V
+10%,-10%
DC500V
+20%,-10%
DC1000V
+20%,-0%
DC2500V
+20%,-0%
Rated
Current
1mAormore,
1.2mAorless
(at1MΩload)
1mAormore,
1.2mAorless
(at2.5MΩload)
Short-circuit
Current 1.5mA±0.5mA
Accuracy ±5%rdg±3dgt
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*KEW3125Ahasanadditionalrange.
Rated
voltage 5000V
Measuring
Range(*1)
0.0-99.9MΩ
80-999MΩ
0.80-9.99GΩ
8.0-99.9GΩ
80-1000GΩ
Display
range 0.0M-1200GΩ
Opencircuit
Voltage DC5000V
Rated
Current
1mAormore,
1.2mAorless
(at5MΩload)
Short-circuit
Current 1.5mA±0.5mA
Accuracy ±5%rdg±3dgt ±20%
Voltagemonitorforinsulationresistancerange
KEW3125A:30-6000V(resolution10V):±10%rdg±20V
KEW3025A:30-3000V(resolution10V):±10%rdg±20V
Thismonitorisusedtocheckwhetherelectricchargesstored
ontheequipmentundertestaredischargedornot.Thevoltage
value measured and displayed on the LCD is a reference
value.Pleasenotethatthe indicatedvalue,whenanexternal
ACvoltageisappliedtotheinstrument,isnotacorrectvalue.
【Voltagemeasurementrange】
DCvoltage ACvoltage
Measuringrange ±30-±600V 30-600V(50/60Hz)
Resolution 1V
Accuracy ±2%rdg±3dgt
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●Display: Liquidcrystaldisplay

Insulationresistancerange:(Max.1200counts)
VAC/DCrange:(Max.630counts)
 Bargraph:Max.36points
 DAR/PIvalue:Max.9.99
 Time:Max.99:59
●Lowbatterywarning: Batterysymbol(in4levels)
●Overrangeindication: OLmark appea rs on insulation
resistancerange.
 Himarkappearsonvoltagerange.
●Auto-ranging:
Rangeshiftstoupperrange:1000counts
 Rangeshiftstolowerrange:80counts
 (Onlyontheinsulationresistancerange)
●Auto-power-off: 
Theinstrumentwillbepoweredoffifthere
isnoswitchorbuttonoperationfor10min.
 (This function does not work during a
measurement.)
●Altitude: 2000morless
●Temperature&humidityrange(guaranteedaccuracy):
23ºC±5ºC/Relativehumidity85%orless(nocondensation)
●Operatingtemperature&humidityrange:

0ºCto40ºC/Relativehumidity85%orless(nocondensation)
●Storagetemperature&humidityrange:
 -20ºCto+60ºC/Relativehumidity75%orless(nocondensation)
●Overloadprotection:  Insulationresistancerange:AC1200V/10sec.
 Voltagerange:AC720V/10sec.
●Withstandvoltage: AC5160V(50/60Hz)/5sec.

(Betweenelectricalcircuitandenclosure)
●Insulationresistance:1000MΩormore/DC1000V
 (Betweenelectricalcircuitandenclosure)
●Dimension: 177(L)×226(W)×100(D)mm
●Weight:
KEW3125A:approx.1.9kg（batteryincluded),
 KEW3025A:approx.1.7kg（batteryincluded)
●Powersource: DC12V: LR14(Alkaline battery size C)x
8pcs
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● Currentconsumption(representativevaluesat12Vofsupplyvoltage)
Range 250V 500V 1000V 2500V 5000V VAC/DC
Outputat
short-circuit
200mA
110mA
Whenrated
currentis
outputted
3125A 350mA
/0.25MΩ
400mA
/0.5MΩ
500mA
/1MΩ
750mA
/2.5MΩ
900mA
/5MΩ
3025A 250mA
/0.25MΩ
300mA
/0.5MΩ
350mA
/1MΩ
500mA
/2.5MΩ −
Outputat
opencircuit
40mA 40mA 50mA 80mA 150mA
Stand-by 25mA
Backlighton Increasedby40mA
●Measurementtime: 3125A：approx.for25hours
 *under a load of 100MΩ on the
Insulationresistance5000Vrange.
 3025A：approx.for80hours
 *under a load of 100MΩ on the
Insulationresistance2500Vrange.
●Accessories: Lineprobe:MODEL7165A
 (Including MODEL8255 Straight type
prodwithmoldedparts)
 Earthcord:MODEL7264
 Guardcord:MODEL7265
 LR14(Alkaline battery size C)x 8pcs
Instructionmanual
 HardCase:MODEL9179
 PickelTypeProd:MODEL8019
 StraightTypeProd:MODEL8254
●Optionalaccessories:Adaptorforrecorder:MODEL8302
 Line probe with alligator clip:
MODEL7168A
 LongLineprobewithalligatorclip(15m):
MODEL7253
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4. Instrument layout
4-1 Instrument layout
１LCDdisplay
２RangeSwitch
３Testbutton
４BackLightbutton
５DISPbutton
６LineTerminal
７EarthTerminal
８GuardTerminal
９LineProbe(red)
10EarthCord(black)
11GuardCord(green)
12 Protectivefigerguard
Itisapartprovidingprotectionagainstelectricalshockand
ensuringtheminimumrequiredairandcreepagedistances.
１
２３
４
５
６
７８
９1011
12 12
12
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4-2 LCD display
１Insulationresistance
２Bargraph
３Voltagemonitor
４Batterymark
５Voltagewarningmark
６Timerdisplay
７DARmark
８PImark
９DAR/PIvalue
10DC
11AC
12Minusdisplay
13Unit
１
２
３
４
11
13
10
６
７
８
９
５
12
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4-3 How to remove the Hard case
Holdthesidesurfaceoftheterminalpart,andgentlypullthe
unittowardthefront.
① Hold the side surface of the terminal part.
② Pull the unit toward the front.
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5. Getting started
5-1 Checking the battery voltage
(1)SettheRangeswitchtoanypositionotherthanOFF.
(2)WhentheBatterymarkshownattheupperleftontheLCD
islastonelevel ,thebatteriesarealmostexhausted.
Replace the batteries with new ones to perform further
measurements.
Theinstrumentoperatesproperlyevenifundersuchalow
batterylevel,anditmaynotaffectontheaccuracy.
When the empty Battery mark appears, the battery
voltageisbelowthelowerlimitoftheoperatingvoltage.So
theaccuracycannotbeguaranteed.
Please refer to clause 7. Battery Replacement, for the
batteryreplacementprocedures.
5-2 Connecting test leads
Insert the test lead firmly to the connector terminal on the
instrument. Connect the Line Probe(red) to the Line terminal,
the Earth Cord(black) to the Earth terminal and the Guard
Cord(green) to the Guard terminal. A Guard cord connection
maynotberequired,ifthereisnoneedtoestablishaguard.
#DANGER
●Ifthe Test button ispressedwhentheRangeswitchisat
theinsulationmeasurementpositions,highvoltagemaybe
appliedtothetestleadsandyoumaygetanelectricshock.
●Stopusingthetestleadiftheouterjacketisdamagedand
theinnermetalorcolorjacketisexposed.
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6. Measurement
6 -1 Mains disconnection check (Voltage measurement)
#DANGER
●Never make measurements under the circumstances
exceeding the designed measurement category and the
ratedvoltageoftheinstrumentandthetestleads.
●When testing installations which have large current
capacities, such as a power line, be sure to make
measurement on the secondary side of the circuit breaker
inordertoavoidgettinganelectricalshock.
●Extracautionshouldbetakentominimizethepossibilities
ofshortingthepowerlinewiththemetaltipoftestleadat
voltagemeasurement.Itmaycausepersonalinjury.
●The Battery cover must be closed and screwed before
startingameasurement.
●ConnecttheEarthcord(black)totheEarthterminalofthe
circuitundertest.
●Keep your fingers and hands behind the protective
fingerguardduringmeasurement.
Voltage can be measured by setting the Range switch on this
instrument toVAC/DCposition. No need to press the Test
button. This instrument is equipped with an AC/DC auto-
detection circuit and can measure DC voltage. During a DC
voltage measurement, when applying a positive voltage to the
LineProbe(red),positivevaluesaredisplayedontheLCD.
Besuretoturnoffthecircuitbreakerofthecircuitundertest.
(1)Connect the Earth Cord (black) to the earth side of
the circuit under test and the
LineProbe(red)tothelineside
respectively.
(2)The voltage displayed on the
LCD shall beLo. If it is not
Lo, a voltage is applied on
the circuit under test. Check
thecircuitundertestagainand
turnoffthecircuitbreaker.
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6-2 Insulation resistance measurement
#DANGER
●Useameasuringapparatus,suchashighvoltagedetector,
andconfirmthatthereisnoelectricalchargeinthecircuit
undertest.
●Wearapairofinsulatedglovesforhighvoltage.
●
IftheRangeswitchisattheinsulationresistancerangeand
the Test button is being pressed down, high voltages are
generatedandappliedtothetestleadsandthecircuitunder
testcontinuously.Donottouchthecircuitorthetestleads.
●The Battery cover must be closed and screwed before
startingameasurement.
●Nevermakemeasurementwhenthunderrumbling.
●ConnecttheEarthCord(black)totheearthterminalofthe
circuitundertest.
●When any modes other thanVOLTis selected, live
circuitwarningsymbolappearsontheLCDandtheaudible
warningactivatesifavoltageof30Vorhigherismeasured.

KEW3125A/3025Adontstartatest,even the Test button
ispresseddown,ifthemeasuringvoltageis160Vorhigher.
Beforestartingatest,ensurethattheequipmentundertest
is disconnected from the mains supply and not energized
in order to avoid possible electrical hazards. These
instrumentsmaystartatestforenergizedelectricalcircuits
ifthemeasuringvoltageislessthan160V.
●Keep your fingers and hands behind the protective
fingerguardduringmeasurement.
This instrument measures insulation resistances and check
whether the insulations of electrical equipments or circuits are
in good condition or not. So, please check the voltage that
can be applied to the equipment under test before making a
measurement.
Note)
●Theinsulationresistancevaluesoftheequipmentsundertest
maynotbestable,andthereadingsmaybeunstable.
●Bleep sound may be heard during an insulation resistance
measurement,butitisnotmalfunction.
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●Ittakestimetomeasureacapacitiveload.
●At insulation resistance measurement, positive (+) voltage is
outputted from the Earth terminal and negative (-) voltage is
outputtedfromtheLineterminal.
ConnecttheEarthcordtotheEarth(ground)terminal.
Itisrecommendedtoconnectthepositive(+)poletotheearth
sidewhenmeasuringinsulationresistanceagainsttheground
orwhenapartoftheequipmentundertestisearthed.
Withthisconnection,smallermeasuredvaluecanbeobtained
comparingwithotherwayround.
(1)Check the voltage which can be applied to the circuit
undertest,andsettherangeswitchtoadesiredinsulation
resistancerange.
(2)ConnecttheEarthcord(black)totheEarthterminalofthe
circuitundertest.
(3)Place the tip of the Line probe (red) to the circuit under
test. Then press thePRESS TO TESTbutton. The
buzzersoundsintermittentlyduringameasurementwhena
rangeotherthan250/500Visselected.
(4)ThemeasuredvaluewillbedisplayedontheLCD,anditis
keptdisplayedafterthemeasurement.
#Caution
Alwaysturnoffthe
Breakerforthe
circuitundertest.

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(5)Thisinstrumenthasanauto-dischargefunction.
With the test leads connected to the circuit under test,
release the Test button to discharge capacitances in the
circuitaftertest.Confirmthattheindicationonthevoltage
monitorbecomes0V.
#DANGER
●
Donottouchthecircuitundertestimmediatelyaftertesting.
 Capacitancesstoredinthecircuitmaycauseelectricshock.
●Leave the test leads connected to the circuit and never
touchthecircuituntiladischargeiscomplete.
Auto-discharge function
This is a function to release the capacitances stored in the
circuit under testautomaticallyafter test. The voltagemonitor
shows the discharge condition. This function will be disabled
bydisconnectingthetestleads2sec.ormorebeforedischarge
iscomplete.
(6)Set the Range switch toOFFposition, and disconnect
thetestleadsfromtheinstrument.
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18
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Principle of Insulation Resistance Measurement
Aresistancevaluecanbeobtainedbyapplyingacertainhigh
voltagetotheresistor(insulationresistance)andmeasuringthe
flowingcurrent.
Resistancevalue=Voltage/Current
(RX=V/I)
6-3 Continuous Measurement
PressandturntheTestbuttonclockwiseandlockthebutton
to measure insulation resistances continuously. Turn the
buttoncounterclockwiseandsetittotheinitialpositionaftera
measurement.
#DANGER
●Be extremely careful not to get electric shock as a high
voltageispresentonthetipofthetestleadscontinuously.
●Keep your fingers and hands behind the protective
fingerguardduringmeasurement.
6-4 DAR/PI measurement
1. PI - Polarization index
This is to check a temporal increase of leakage currents
flowingoninsulationsandtoconfirmleakagecurrentsarent
increasedastimepasses.
PI is usually determined by the insulation resistances
measured1minand10minafterameasurementisstarted.
PI is dependent on the shape of insulations and influenced
bymoistureabsorption,therefore,acheckofPIisimportant
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