MEGOHMMETER 1210N1250N
E N G L I S H User Manual
V 500V
1kV
x 10
300
0 100200
400500
600
2015
304050
100200500
50 20 10 5 4 32
1.5
101 (1kV)
(250V)(500V)
MΩ
MEGOHMMETERModel 1250N
INSTRUMENTS®
600V CAT II / 1000V CAT I!
Statement of Compliance
Chauvin Arnoux®, Inc. d.b.a. AEMC® Instruments certifies that this instrument has been calibrated using standards and instruments traceable to international standards.
We guarantee that at the time of shipping your instrument has met its published specifications.
An NIST traceable certificate may be requested at the time of purchase, or obtained by returning the instrument to our repair and calibration facility, for a nominal charge.
The recommended calibration interval for this instrument is 12 months and begins on the date of receipt by the customer. For recalibration, please use our calibration services. Refer to our repair and calibration section at www.aemc.com.
Serial #: ________________________________
Catalog #: 1326.01 / 1326.02
Model #: 1210 / 1250
Please fill in the appropriate date as indicated:
Date Received: _________________________________
Date Calibration Due: _______________________
Chauvin Arnoux®, Inc.d.b.a AEMC® Instrumentswww.aemc.com
Table of Contents
1. INTRODUCTION ...................................................................31.1 International Electrical Symbols .....................................................31.2 DefinitionofMeasurementCategories ...........................................41.3 ReceivingYourShipment ...............................................................41.4 OrderingInformation ......................................................................4
1.4.1 AccessoriesandReplacementParts ................................4
2. PRODUCT FEATURES ..........................................................52.1 Description .....................................................................................52.2 Model1210NFeatures ..................................................................62.3 Model1250NFeatures ..................................................................62.4 Model1210NControlFeatures ......................................................72.5 Model1250NControlFeatures ......................................................82.6 1210Nand1250NControlFeatures ..............................................9
3. SPECIFICATIONS ...............................................................103.1 Model1210NSpecifications ........................................................10
3.1.1 ElectricalSpecifications ...................................................103.1.2 MechanicalSpecifications ............................................... 113.1.3 SafetySpecifications ....................................................... 11
3.2 Model1250NSpecifications ........................................................123.2.1 ElectricalSpecifications ...................................................123.2.2 MechanicalSpecifications ...............................................123.2.3 SafetySpecifications .......................................................13
4. OPERATION .......................................................................144.1 UsingtheModel1210N ...............................................................14
4.1.1 InstrumentGroundTerminal ............................................144.1.2 Auto-ranging ....................................................................144.1.3 SafetyCheck-VoltageTest ...........................................144.1.4 InsulationResistanceTesting(MΩRange) .....................144.1.5 SuccessfulInsulationResistanceTesting ........................164.1.6 InsulationMeasurement—Connections ........................164.1.7 InsulationResistanceMeasurementsonMotors ............19
2 MegohmmeterModels1210N/1250N
4.2 UsingtheModel1250N ...............................................................214.2.1 InstrumentGroundTerminal ............................................214.2.2 Auto-ranging ....................................................................214.2.3 SafetyCheck-VoltageTest ...........................................214.2.4 UtilizationoftheGuardTerminal .....................................214.2.5 InsulationResistanceTesting(MΩRange) .....................234.2.6 SuccessfulInsulationResistanceTesting ........................254.2.7 InsulationMeasurement-Connections ...........................254.2.8 InsulationResistanceMeasurementsonMotors ............28
5. MAINTENANCE ..................................................................305.1 Warning .......................................................................................305.2 Cleaning .......................................................................................30
RepairandCalibration .................................................................................31TechnicalandSalesAssistance ..................................................................31Limited Warranty .........................................................................................32WarrantyRepairs .........................................................................................32
MegohmmeterModels1210N/1250N 3
CHAPTER 1
INTRODUCTION
Warning Thesesafetywarningsareprovidedtoensurethesafetyofpersonnelandproperoperationoftheinstrument.• Readtheinstructionmanualcompletelyandfollowallsafety
informationbeforeoperatingthisinstrument.• Safetyistheresponsibilityoftheoperator!• Testsaretobecarriedoutonlyondeadcircuits!Checkforlive
circuitsbeforemakingresistancemeasurements(safetycheck).• TheMegohmmeterModels1210N/1250Naresourcesofhigh
voltage,asisthesampleconnectedtothem.Allpersonsperform-ingorassistinginthetestsmustemployallsafetyprecautionstopreventelectricalshocktothemselvesandtoothers.
• AEMC®Instrumentsconsiderstheuseofrubberglovestobeanexcellentsafetypracticeeveniftheequipmentisproperlyoperatedandcorrectlygrounded.
• Whentestingcapacitancesamples,makesurethattheyhavebeenproperlydischargedandthattheyaresafetotouch.Dielectricinsulationsamplesshouldbeshort-circuitedforatleastfivetimestheamountoftimetheywereenergized.
• Usetheleadssuppliedwiththemegohmmeter.Ifdefectiveorused,replacebeforetesting.
1.1 International Electrical SymbolsThissymbolsignifiesthattheinstrumentisprotectedbydoubleorrein-forcedinsulation.Useonlyspecifiedreplacementpartswhenservicingtheinstrument.
This symbol on the instrument indicates a WARNING and that theoperatormustrefertotheusermanualforinstructionsbeforeoperatingthe instrument. In this manual, the symbol preceding instructionsindicatesthatiftheinstructionsarenotfollowed,bodilyinjury,installation/sampleandproductdamagemayresult.
Riskofelectricshock.Thevoltageatthepartsmarkedwiththissymbolmaybedangerous.
4 MegohmmeterModels1210N/1250N
1.2 DefinitionofMeasurementCategoriesCat. I: Formeasurementsoncircuitsnotdirectlyconnected to theAC
supplywall outlet such as protected secondaries, signal level,andlimitedenergycircuits.
Cat. II: Formeasurements performed on circuits directly connected totheelectricaldistributionsystem.Examplesaremeasurementsonhouseholdappliancesorportabletools.
Cat. III: For measurements performed in the building installation atthe distribution level such as on hardwired equipment in fixedinstallationandcircuitbreakers.
Cat. IV: For measurements performed at the primary electrical supply(<1000V) such as on primary overcurrent protection devices,ripplecontrolunits,ormeters.
1.3 ReceivingYourShipmentUponreceivingyourshipment,makesurethatthecontentsareconsistentwith thepacking list.Notify yourdistributor of anymissing items. If theequipmentappearstobedamaged,fileaclaimimmediatelywiththecar-rierandnotifyyourdistributoratonce,givingadetaileddescriptionofanydamage.Savethedamagedpackingcontainertosubstantiateyourclaim.Donotuseaninstrumentthatappearstobedamaged.
1.4 Ordering Information
Megohmmeter Model 1210N .............................................Cat. #1326.01
Megohmmeter Model 1250N .............................................Cat. #1326.02Both models include a carrying strap with lead pouch, three color-coded leads, ground lead, two insulated alligator clips, test probe and user manual.
1.4.1 Accessories and Replacement PartsSetof10fuses,0.2A,250Vfast-blow5x20mm...................Cat. #2973.02Leadpouchwiththreecolor-codedsafetyleads,groundlead,twosafetyalligatorclipsandtestprobe..........Cat. #1019.01Leadpouchwiththreecolor-codedleads,groundlead,twoalligatorclips,andtestprobe ...................Cat. #1017.56
MegohmmeterModels1210N/1250N 5
CHAPTER 2
PRODUCT FEATURES
2.1 DescriptionTheAEMC®Models1210Nand1250Narecompact,self-containedhand-crankedmegohmmeters.Theyarepracticalanddependableinstrumentsdesignedforabroadrangeofplantandfieldserviceapplications,suchas acceptance testing and preventive maintenance of wiring, cables,switchgear, and motors. The easy hand-cranked operation provides asteadyrectifiedDCvoltageoutputacrosstheentirerangeforconsistentlyreliablereadings.These megohmmeters incorporate a built-in, sealed alternator and aconstant DC voltage circuit to provide a stable output and give directinsulationresistancereading.Theyare ruggedlybuilt anduseanO-ring-sealed, castaluminumcasewithapolycarbonatefrontpaneldesignedforharsh,heavy-dutyuseandprotectionagainstdustandwater.The Models 1210N/1250N have a unique auto-ranging feature whichexpandsthescalebyx10andalmostdoublesthescalelength.Whenthepointerreachesneartheendofscale,theauto-rangingfeatureactivates,returningthepointertothebeginningofthescalewiththex10redLEDindicator on.Insulation resistance is indicatedwith a rugged taut-bandmetermove-mentonalogarithmicscale.Theindicatorscaleiseasytoread.
6 MegohmmeterModels1210N/1250N
2.2 Model1210NFeatures• Measuresinsulationat500V,resistance,continuity
• Testvoltageconstantacrosstheentiremeasurementrange
• AutorangingMΩ,kΩandΩranges
• Designedforharshenvironments:offshore,mining,heavy-dutyfield,industrial,andmilitaryuse
• Extraruggedcastaluminumcase;O-ringsealedagainstrain,water,anddust;aluminumlid
• Compact,self-containedpackage;foldingcrank
• Largedirect-readingscale
• 600Vtestvoltagerange(safetycheck)
2.3 Model1250NFeatures• Threetestvoltages:250,500,1000V
• Testvoltageconstantacrosstheentiremeasurementrange
• AutorangingMΩranges
• Designedforharshenvironments:offshore,mining,heavy-dutyfield,industrial,andmilitaryuse
• Extraruggedcastaluminumcase;O-ringsealedagainstrain,water,anddust;aluminumlid
• Compact,self-containedpackage,foldingcrank
• Fourterminalsincludingguardandground
• Largedirect-readingscale
• 600Vtestvoltagerange(safetycheck)
MegohmmeterModels1210N/1250N 7
2.4 Model1210NControlFeatures
kΩΩ
MV
x 10
5
01
26 7
10
V
FUS
123
451020
1020 30
0.5
50
(500V)(1mA)
(5mA)
ΜΩ
2 ! C42
300
0
100200 400 500
600Ω
κΩ 43 89
40
0
Ω
MEGOHMMETER
Model 1210NINSTRUMENTS
®
600V CAT II / 1000V CAT I !
1 2 3
4
5
6
7
8
9
10
Figure 1
1. Line(-)terminalBlack
2. Fuse0.2A
3. Earth(+)terminalRed
4. Instrumentgroundterminalforusersafety
5. AmberLEDilluminateswhenpropercrankspeedisattained,indicatingpresenceofselectedoutput
6. Foldawayhandle
7. Mechanicalzeroadjustmentscrew
8. Rangeswitch-safetytestfirstonMΩ/Vrangeto500VAC
9. Autoranging:RedLEDilluminateswhenreadingneedstobemultipliedx10toobtainthetruevalue(MΩ,kΩ,Ωranges)
10.Securityfingerrestisolatesusershandfromterminalswhilegivingafirmgripduringanoperation
8 MegohmmeterModels1210N/1250N
2.5 Model1250NControlFeatures
V500V
1kV25
0V
x 10
300
0
100200 400 500
600
V
G
20 153040
50100200500
5020 10
5 4 3 2 1.510
1
(1kV)(250V)
(500V)
ΜΩ
2 ! C42
MEGOHMMETER
Model 1250NINSTRUMENTS
®
600V CAT II / 1000V CAT I !
1 2 3
4
5
6
7
8
9
10
Figure 1-A
1. Line(-)terminal-Black
2. Guardterminal-Blue
3. Earth(+)terminal-Red
4. Instrumentgroundterminalforusersafety
5. GreenLEDilluminateswhenpropercrankspeedisattained,indicatingpresenceofselectedtestvoltage
6. Foldawayhandle
7. Mechanicalzeroadjustmentscrew
8. Rangeswitch-Safetytestfirston500V/V~rangeto500VAC
9. Autoranging:RedLEDilluminateswhenreadingneedstobemultipliedx10toobtainthetruevalue(MΩrange)
10.Securityfingerrestisolatesusershandfromterminalswhilegivingafirmgripduringanoperation
MegohmmeterModels1210N/1250N 9
2.6 1210Nand1250NControlFeatures
11.Long,sturdyassemblyboltsfortightcaseclosing.
12. Instrumentgroundterminalforenhancedusersafety.
13. Ruggedtaut-bandmeter movement.
14.Switchslideassembly.
15.Alternatorcrankshaft,gearsandbearingspermanentlylubricatedand sealed.
16.Foldawaycrank.
17.Diecastaluminumcase(covernotshown).
18.O-ringconstructionsealsoutdirtandwater.
19.Simpleprintedcircuitboardassemblyforeasy calibration and maintenance.
20.Highimpactpolycar-bonatefaceplate. Figure 2
12
13
14
15
16
17
18
19
20
11
10 MegohmmeterModels1210N/1250N
CHAPTER 3
SPECIFICATIONS
3.1 Model1210NSpecifications
3.1.1 ElectricalSpecifications
INSULATION TESTSDC Test Voltage: 500V(testvoltagegeneratedinfullacrosstheentiremeasurementrange)Megohm Range (Auto-ranging): 0.5 to 5.5MΩ;5.5to200MΩShort Circuit Current: 5mA(max)Accuracy:2.5%offullscalelengthCharging Time: 0.5s/µFDischarging Time (Auto): 5s/µF
RESISTANCE TESTSDC Test Current:1mAconstant,600VmaxKilohm Range (Auto-ranging): 0to45kΩ;45to500kΩAccuracy: 2.5%fullscalelengthCharging Time: 0.5s/µFDischarging Time (Auto): 5s/µF
CONTINUITY TESTSDC Test Current: 5mAconstant,10VmaxOhm Range (Auto-ranging): 0 to 9Ω;9to100Ω Accuracy: 2%offullscalelengthFuse Protection: 0.2A,250V,fast-blow,5x20mm
VOLTAGE TESTS (Safety Check):Voltage Range: 0to600VACFrequency: 45 to 450HzAccuracy: 3%offullscaleInput Impedance: 100kΩ(approx)
MegohmmeterModels1210N/1250N 11
3.1.2 MechanicalSpecificationsTest Voltage Indicator:AmberLEDindicatespropertestvoltageandcrankspeed
Scale: Directreadingsonallranges;3"(76mm),blackonwhite
Autorange Indicator:RedLEDindicatesAuto-range;multiplyresistancereadingsx10
Power Supply:Hand-cranked,heavydutybrushlessalternatorandsolidstaterectifica-tionandamplificationforstablevoltage;testvoltagereachedat140rpm(approx)
Dielectric Test: 2000V50/60Hz,between(-),(+),andgroundterminals
Meter Movement: Ruggedtautbandsuspension
Dimensions: 4.7x4.7x5.1"(120x120x130mm)
Weight: 3.3lbs(1.5kg)
Temperature Range:Reference range:64to75°F(18to24°C),30-50%RHOperating range:14to122°F(-10to50°C),0-80%RHStorage range:-4to176°F(-20to80°C),0-90%RH
Case:Castaluminumalloycaseandlidpaintedsafetyyellow,withheavydutygraypolycarbonatefrontpanel;O-ringsealbetweenfrontpanelandcase;sealedagainstwateranddust;foldingcrank
Terminals:“+”Line(red);“-”earth(black);acceptsstandard4mmsafetybananaplugs;groundaccepts4mmbananaplugorspadelugs
3.1.3 SafetySpecificationsSealed: IP54withlid,IP52withoutlid
Insulation Tester:VDE413part1/4exceptf
Safety:IEC1010-1;600VCATII;1000VCATI
Envelope Protection: IEC529
Vibration: MIL-T-38800D
Shock: IEC51
12 MegohmmeterModels1210N/1250N
3.2 Model1250NSpecifications
3.2.1 ElectricalSpecifications
INSULATION TESTS
DC Test Voltages: 250,500,1000V(Testvoltagesgeneratedinfullacrosstheentiremeasurementrange)
Megohm Ranges (Auto-ranging):250V: 1to11MΩ 11 to 500MΩ
500V: 1to11MΩ 11 to 500MΩ
1000V: 10to110MΩ 110 to 5000MΩ
Short Circuit Current:5mA(approx)
Accuracy:2%offullscalelength
Charging Time: 250V:0.2s/µF 500V:0.5s/µF 1000V:0.5s/µF
Discharging Time (Auto): 8s/µF
VOLTAGE TESTS (Safety Check)
Voltage Range:0to600VAC
Accuracy:3%offullscale
3.2.2 MechanicalSpecificationsTest Voltage Indicator:GreenLEDindicatespropertestvoltageandcrankspeed
Warning: IfthecrankspeedLEDisnotONduringtest-ing,thereadingisnotvalid.
Scale:Directreadingsonallranges;3"(76mm),blackonwhite
MegohmmeterModels1210N/1250N 13
Autorange Indicator:RedLEDindicatesautorange;multiplyresistancereadingsx10
Dielectric Test: 2000V50/60Hz,between(-),(+),guardandgroundterminals
Power Supply:Hand-cranked,heavydutybrushlessalternatorandsolidstate rectifica-tionandamplificationforstablevoltage;testvoltagereachedat140rpm(approx)
Meter Movement:Ruggedtautbandsuspension
Dimensions: 4.7x4.7x5.1"(120x120x130mm)
Weight: 3.3lbs(1.5kg)
Temperature Range:Reference range: 64to75°F(18to24°C),30-50%RHOperating range: 14to122°F(-10to50°C),0-80%RHStorage range: -4to176°F(-20to80°C),0-90%RH
Case:Castaluminumalloycaseandlidpaintedsafetyyellow,withheavydutygraypolycarbonatefrontpanel;O-ringsealbetweenfrontpanelandcase;sealedagainstwateranddust;foldingcrank
Terminals:“+”Line(red);“-”earth(black);“G”guard(blue);acceptssafety4mmbananaplugs;groundaccepts4mmbananaplugsorspadelug
3.2.3 SafetySpecificationsSealed:IP54withlid,IP52withoutlid
Insulation Tester: VDE413part1/4exceptf
Safety: IEC1010-1;600VCATII;1000VCATI
Envelope Protection:IEC529
Vibration: MIL-T-38800D
Shock: IEC51
*All specifications are subject to change without notice
14 MegohmmeterModels1210N/1250N
CHAPTER 4
OPERATION
4.1 UsingtheModel1210N
4.1.1 Instrument Ground TerminalTheMegohmmeterModel1210Nisequippedwithaninstrumentgroundterminalforenhancedusersafety.Groundyourinstrumentwheninuse.
4.1.2 Auto-rangingHow it works:Whenthepointerreachesapproximately90%of thefullscale length, theauto-range is triggered, the redauto-range (x10)LEDlightsup.Thepointergoesbacktothebeginningofthescaleandresumesitstravel.Thereadingsshouldbemultipliedby10whenthex10LEDison.
4.1.3 Safety Check - Voltage Test Beforemeasuring insulation resistance, confirm that thesample is fullydischarged (particularly indielectricandcapacitancesamples)and thatthesampleisnotconnectedtoanenergizedcircuit.
Toperformthevoltagetest,settherangeselectiontoV(MΩ),connectandreadontheredvoltagescale(600VACmax).DO NOT CRANK.Ifmeasur-ingonaDCcircuit,thepointerwilldeflectbutthemeasurementmaybeinaccurate.
4.1.4 Insulation Resistance Testing (MΩ Range)Aftercheckingforalivecircuit(seeSafetyCheckabove),selecttheMΩ rangeandconnectthemegohmmeter.Severalconnectionexamplesareillustrated further. Crank the handle until the amber LED on the upperright-handsidelights,ensuringappropriatetestvoltageattheoutput.
MegohmmeterModels1210N/1250N 15
SPOT TESTINGAsageneralruleinspottesting,testvoltageshouldbeapplieduntilnovariationinreadingisnotedfor15secondsorappliedforafixed60sec-onds.Oncapacitancecircuits,crankingforuptoaminuteormoremaybenecessarytofullychargethesample.Whatminimumvalueshouldbemeasured?TheIEEEstandardN°43-2000statesthatitisimpossibletospecifythevalueofinsulationresistanceatwhichawindingwillfailelectri-cally,butonmotors,minimumreadingsgenerallystatedare:
Rated Voltage R minimum250 or less 2 MΩ
460 2 MΩ
Thereisnofixedfigurefordeterminingwhatisgoodandbadinresistancereadings,butagoodguidewouldbe1megohmforeveryonehundredappliedoperatingvolts,asaminimumfigure.Thisappliestomotorsandtransformers.When the insulation resistancegets this low,anelectricalbreak-down can be expected at any time and rewinding or replacingshouldbeconsidered.
It isnotunusual forawinding tobe10 to100 times therecommendedminimum value (IEEE standard 43-2000: Recommended Practice for Testing Insulation Resistance of Rotating Machinery),butthisvarieswithtemperatureandhumidity.
RATIO TESTINGIntimeresistancereading(DielectricAbsorptionRatio),readingsaretakenat30secondsand60secondstoobtainthedielectricabsorptionratio.
Insulationresistance@60s
Insulationresistance@30s
Thistestisusefultoincreasetheaccuracyofspottesting.Ingeneral,aratioof1.25:2orbettershouldberequired.Aratiobelowthisindicatesthatrepairisprobablyneeded.
RememberthataDCinsulationtestmaybeusedforacceptancetesting,butismorecommonlyusedtocheckthegradualdeteriorationofequip-mentoveritslife.Consultyourequipmentmanufacturerforspecifictestortestvoltageifnotknown.
Insulationresistancedecreaseswithmoisture,temperatureandageandshouldberecordedovertimeatagiventemperatureandcorrected.
=DielectricAbsorptionratio(DAR)
16 MegohmmeterModels1210N/1250N
4.1.5 Successful Insulation Resistance Testing• Checkwith the equipmentmanufacturer for factory insulation resis-
tancereadings.
• Donotrelyoninsulationresistancetestingaloneasproofofwindingconditions.
• Donotexpectthesamevalueforallpartsofallmachines.
• Observe consistent test time duration, recognizing that total currentthroughinsulationundertestwillvarywithtime.
• Correctallreadingsproperlytoastandardreferencetemperature(seeIEEEstd#43-2000,Temperature Correction Curve).
• Knowwhatyouaretesting.Isolatethepieceofequipmentfromothercircuitry.
• Watchtrendsratherthanrelyingonsingle“spot”readings.
4.1.6 Insulation Measurement — ConnectionsFigure3showstheconnectionstomeasuretheinsulationofoneconduc-tor to the other conductors.The cable should be disconnected at bothendstoavoidleakagethroughswitchboardsandpanels.
Cable Insulation
Conductor Under Test
Fus
Figure 3
MegohmmeterModels1210N/1250N 17
Figures4and5showtheconnectionsfortestinginsulationfromasupplyconductortoground(motorframe).
Cable Insulation
Conductor Under Test
Fus
Figure 4
Fus
Cable Insulation
Conductor Under Test
Figure 5
Figure6showstheconnectionstoatransformer(lightingordistribution).Make sure that the switches and/or circuit breakers on both sides areopen.Checkthehighvoltagewindingtoground,lowvoltagetoground,andtheresistancebetweenthemwithnowindingground.
18 MegohmmeterModels1210N/1250N
Tested Winding
TransformerGrounding Lug
Fus
Figure 6
Figure7showstheconnectionsformeasuringtheinsulationofathree-phase line to groundby connecting the jumpersbetweenphases.Thisgivesareadingofallconductorsatonce.Ifaloadsuchasamotor,heater,etc.,isattachedtotheotherendoftheline,itwillreadtheloadresistancetogroundat thesametime.Byremoving the jumpers, readingscanbemadebetweentheindividualconductorsandground.
~~
~ ~~~
Jumpers
Fus
Figure 7
MegohmmeterModels1210N/1250N 19
4.1.7 Insulation Resistance Measurements on MotorsFigure8showsreadingtheresistancetogroundofathree-phasemotorwinding.Sincethethree-phasemotorsareinternallyconnected,itisonlynecessarytoconnectoneleadtothemotorleadandtheotherleadtothemotorframeasshown.
Fus
Figure 8
Figure9shows thewindingsofa three-phasemotorseparated.Some-times thiscanbedoneat the lead terminals,whileother times theendbellsmustberemovedtogetattheleadwiresofthecoils.Byconnectingthemegohmmeterasshown, thephase insulationresistancevaluecannowbedetermined.Readbetweenphases“A”and“B”,then“B”and“C”,then“C”and“A”.
A
B
C
Fus
Figure 9
20 MegohmmeterModels1210N/1250N
Figure10showsconnectionsfortestinginsulationfromasupplyconduc-torinaswitchboxtoground(motorframe).Anidenticaltestmaybecarriedoutfromthemotorstarter.
Motor Side of Switch:Connection to One Leg
GroundedMotor Frame
Starter In
Fus
Figure 10
MegohmmeterModels1210N/1250N 21
4.2 UsingtheModel1250N
4.2.1 Instrument Ground TerminalTheMegohmmeterModel1250Nisequippedwithaninstrumentgroundterminalforenhancedusersafety.Groundyourinstrumentwheninuse.
4.2.2 Auto-rangingHow it works:When the pointer reaches approximately 90%of the fullscale length, the auto-range is triggered, the red auto-range (x10) LEDlightsup.Thepointergoesbacktothebeginningofthescaleandresumesitstravel.Thereadingsshouldbemultipliedby10whenthex10LEDison.
4.2.3 Safety Check - Voltage Test Beforemeasuring insulation resistance, confirm that thesample is fullydischarged (particularly indielectricandcapacitancesamples)and thatthesampleisnotconnectedtoanenergizedcircuit.
Toperformthevoltagetest,settherangeselectionto500V,connectandreadontheredvoltagescale(600VACmax).DO NOT CRANK.Ifmeasur-ingonaDCcircuit,thepointerwilldeflectbutthemeasurementmaybeinaccurate.
4.2.4 Utilization of the Guard Terminal
G
A
E
BC
E = Exposed surface
A = Insulation
B = Shield
C = Conductor
Figure 13
22 MegohmmeterModels1210N/1250N
Guardterminalsareusefulwhenmeasuringhighresistancevaluesandforstabilizingreadings.
When testing the insulation at the end of a cable, it is necessary toeliminatetheerrorfromsurfaceleakagewhichoccurs,particularlyathighresistancevalues.Thepurposeoftheguardterminalistoprovideathirdterminalwithinthepathofthesurfaceleakage“E”.ConnecttheinstrumentasshowninFigure13.
Ifthereisnoshieldat“B”,useacopperwirewoundseveraltimesaroundtheexposedsurface“B”.(Note:Ifashieldisnotavailableandyoudonotmakeupashieldaround“B”andconnect to theguard terminal (-), themeasurementwillbeerroneousand lead toconfusionas to thecable’sstate.)
Iftheguardterminalisnotconnectedat“B”,theinstrumentmeasuresthecurrent “I” flowing through the insulationanda surface leakagecurrent“i1”.SeeFigure14.
To EARTH
terminal
I
To LINE
terminal
NO CONNECTION
to Guard terminal
A
B
C
Ry
Rx
Rz
Rx: resistance through insulation
Ry: surface resistance
Rz: surface resistance
i 1
Figure 14
MegohmmeterModels1210N/1250N 23
Whentheguardterminalisconnectedat“B”,theinstrumentmeasuresthecurrent“I”andnotthesurfaceleakagecurrent“i1”,whichisnotincludedinthemeasurement.SeeFigure15.Thistypeofmeasurementwillgivethetruevalueoftheresistance“Rx”,providingthe“Ry”and“Rz”arenottoolow.
To EARTH
terminal
I
To LINE
terminal
To Guard terminal
A
B
C
Ry
Rx
Rz
Rx: resistance through insulation
Ry: surface resistance
Rz: surface resistance
i 1
Figure 15
4.2.5 Insulation Resistance Testing (MΩ Range)After checking for a live circuit (see safety check), select the test volt-age and connect themegohmmeter. Several connection examples areillustrated further. Crank the handle until the green LED on the upperright-hand side lights, ensuring that the selected test voltagehasbeenreached.
TEST VOLTAGENopublishedstandardtellswhichvoltagetochooseforanygivenwinding.However,publishedrecommendationscouldbesummarizedasfollows:
Rated Voltage of Motor Test VoltageBelow115 250V
115 250or500V230 500V460 500or1000V
24 MegohmmeterModels1210N/1250N
SPOT TESTINGAsageneralruleinspottesting,testvoltageshouldbeapplieduntilnovariationinreadingisnotedfor15secondsorappliedforafixed60sec-onds.Oncapacitancecircuits,crankingforuptoaminuteormoremaybenecessarytofullychargethesample.Whatminimumvalueshouldbemeasured?TheIEEEstandardN°43-2000statesthatitisimpossibletospecifythevalueofinsulationresistanceatwhichawindingwillfailelectri-cally,butonmotors,minimumreadingsgenerallystatedare:
Rated Voltage R minimum250 or less 2 MΩ
460 2 MΩ
Thereisnofixedfigurefordeterminingwhatisgoodandbadinresistancereadings,butagoodguidewouldbe1megohmforeveryonehundredappliedoperatingvolts,asaminimumfigure.Thisappliestomotorsandtransformers.When the insulation resistancegets this low,anelectricalbreak-down can be expected at any time and rewinding or replacingshouldbeconsidered.
It isnotunusual forawinding tobe10 to100 times therecommendedminimum value (IEEE standard 43-2000: Recommended Practice for Testing Insulation Resistance of Rotating Machinery),butthisvarieswithtemperatureandhumidity.
RATIO TESTINGIntimeresistancereading(DielectricAbsorptionRatio),readingsaretakenat30secondsand60secondstoobtainthedielectricabsorptionratio.
Insulationresistance@60s
Insulationresistance@30s
Thistestisusefultoincreasetheaccuracyofspottesting.Ingeneral,aratioof1.25:2orbettershouldberequired.Aratiobelowthisindicatesthatrepairisprobablyneeded.
RememberthataDCinsulationtestmaybeusedforacceptancetesting,butismorecommonlyusedtocheckthegradualdeteriorationofequip-mentoveritslife.Consultyourequipmentmanufacturerforspecifictestortestvoltageifnotknown.
Insulationresistancedecreaseswithmoisture,temperatureandageandshouldberecordedovertimeatagiventemperatureandcorrected.
=DielectricAbsorptionratio(DAR)
MegohmmeterModels1210N/1250N 25
4.2.6 Successful Insulation Resistance Testing• Checkwith the equipmentmanufacturer for factory insulation resis-
tancereadings.
• Donotrelyoninsulationresistancetestingaloneasproofofwindingconditions.
• Donotexpectthesamevalueforallpartsofallmachines.
• Observe consistent test time duration, recognizing that total currentthroughinsulationundertestwillvarywithtime.
• Correctallreadingsproperlytoastandardreferencetemperature(seeIEEEstd#43-2000,Temperature Correction Curve).
• Knowwhatyouaretesting.Isolatethepieceofequipmentfromothercircuitry.
• Watchtrendsratherthanrelyingonsingle“spot”readings.
4.2.7 Insulation Measurement - ConnectionsFigures16and17showtheconnectionstomeasuretheinsulationofoneconductortotheotherconductors.Theconnectiontotheguardterminalisusedtoeliminatetheeffectsofsurfaceleakageacrossexposedinsulationatoneendofthecable.RefertothesectiononUtilizationoftheGuardTerminal.Thecableshouldbedisconnectedatbothendstoavoidleakagethroughswitchboardsandpanels.
G
Cable Insulation
Conductor Under Test
Figure 16
26 MegohmmeterModels1210N/1250N
G
Cable Insulation
Conductor Under Test
Figure 17
Figure18showstheconnectionstoatransformer(lightingordistribution).Make sure that the switches and/or circuit breakers on both sides areopen.Checkthehighvoltagewindingtoground,lowvoltagetoground,andtheresistancebetweenthemwithnowindingground.
Tested Winding
TransformerGrounding Lug
G
Figure 18
MegohmmeterModels1210N/1250N 27
Figure19showstheconnectionsformeasuringtheinsulationofathree-phase line to groundby connecting the jumpersbetweenphases.Thisgivesareadingofallconductorsatonce.Ifaloadsuchasamotor,heater,etc.,isattachedtotheotherendoftheline,itwillreadtheloadresistancetogroundat thesametime.Byremoving the jumpers, readingscanbemadebetweentheindividualconductorsandground.
~~
~ ~~~
Jumpers
G
Figure 19
28 MegohmmeterModels1210N/1250N
4.2.8 Insulation Resistance Measurements on MotorsFigure20showsreadingtheresistancetogroundofathree-phasemotorwinding.Sincethethree-phasemotorsareinternallyconnected,itisonlynecessarytoconnectoneleadtothemotorleadandtheotherleadtothemotorframeasshown.
G
Figure 20
Figure21showsthewindingsofathree-phasemotorseparated.Some-timesthiscanbedoneattheleadterminalswhileothertimestheendbellsmustberemovedtogetattheleadwiresofthecoils.Byconnectingthemegohmmeterasshown,thephaseinsulationresistancevaluecannowbedetermined.Readbetweenphases“A”and“B”,then“B”and“C”,then“C”and“A”.
A
B
C
G
Figure 21
MegohmmeterModels1210N/1250N 29
Figure22showsconnectionsfortestinginsulationfromasupplyconduc-torinaswitchboxtoground(motorframe).Anidenticaltestmaybecarriedoutfromthemotorstarter.
Motor Side of Switch:Connection to One Leg
GroundedMotor Frame
Starter In
G
Figure 22
30 MegohmmeterModels1210N/1250N
CHAPTER 5
MAINTENANCE
5.1 Warning • Formaintenanceuseonlyoriginalfactoryreplacementparts.
• To avoid electrical shock, do not attempt to perform any servicingunlessyouarequalifiedtodoso.
• Do not perform any servicewhile theMegohmmeterModel 1210N/1250Nisonanycircuit.
• Toavoidelectricalshockand/ordamagetotheinstrument,donotletwaterorotherforeignagentsintotheelectronicmodule.
Warning: IfthecrankspeedLEDisnotONduringtesting,thereadingisnotvalid.
5.2 CleaningThemegohmmetermay be gently cleanedwith a soft cloth, soap andwater. Dry immediately after cleaning.Avoidwater penetration into theelectronicmodule.
Makesurethemegohmmeterandallleadsaredrybeforefurtheruse.
MegohmmeterModels1210N/1250N 31
RepairandCalibration
Toensurethatyourinstrumentmeetsfactoryspecifications,werecommendthatitbescheduledbacktoourfactoryServiceCenteratone-yearintervalsforrecalibration,orasrequiredbyotherstandardsorinternalprocedures.
For instrument repair and calibration:Youmust contactourServiceCenter foraCustomerServiceAuthorizationNumber(CSA#).Thiswillensurethatwhenyourinstrumentarrives,itwillbetrackedandprocessedpromptly.PleasewritetheCSA#ontheoutsideoftheshipping container. If the instrument is returned for calibration,weneed toknowifyouwantastandardcalibration,oracalibrationtraceabletoN.I.S.T.(Includescalibrationcertificateplusrecordedcalibrationdata).
Ship To: ChauvinArnoux®,Inc.d.b.a.AEMC®Instruments 15 Faraday Drive Dover,NH03820USA Phone:(800)945-2362(Ext.360) (603)749-6434(Ext.360) Fax: (603)742-2346or(603)749-6309 E-mail:[email protected]
(Orcontactyourauthorizeddistributor)Costsforrepair,standardcalibration,andcalibrationtraceabletoN.I.S.T.areavailable.NOTE: You must obtain a CSA# before returning any instrument.
TechnicalandSalesAssistance
Ifyouareexperiencinganytechnicalproblems,orrequireanyassistancewiththeproperoperationorapplicationofyourinstrument,pleasecall,mail,faxore-mailourtechnicalsupportteam:
ChauvinArnoux®,Inc.d.b.a.AEMC®Instruments 200FoxboroughBoulevard Foxborough,MA02035USA Phone:(800)343-1391 (508)698-2115 Fax: (508)698-2118 E-mail: [email protected] www.aemc.com
NOTE: Do not ship Instruments to our Foxborough, MA address.
32 MegohmmeterModels1210N/1250N
Limited Warranty
TheModels1210Nand1250Narewarrantedtotheownerforaperiodofoneyearfromthedateoforiginalpurchaseagainstdefectsinmanufacture.Thislimitedwarranty isgivenbyAEMC® Instruments,notby thedistributor fromwhomitwaspurchased.Thiswarrantyisvoidiftheunithasbeentamperedwith,abusedor if thedefect is related toservicenotperformedbyAEMC® Instruments.
For full and detailed warranty coverage, please read the Warranty Coverage Information, which is attached to the Warranty Registration Card (if enclosed) or is available at www.aemc.com. Please keep the Warranty Coverage Information with your records.
What AEMC® Instruments will do:If a malfunction occurs within the one-year period, you may return theinstrument to us for repair, provided we have your warranty registrationinformation on file or a proof of purchase. AEMC® Instruments will, at itsoption,repairorreplacethefaultymaterial.
REGISTER ONLINE AT:www.aemc.com
WarrantyRepairs
What you must do to return an Instrument for Warranty Repair: First, request aCustomerServiceAuthorizationNumber (CSA#) by phoneorbyfaxfromourServiceDepartment(seeaddressbelow),thenreturntheinstrumentalongwith thesignedCSAForm.Pleasewrite theCSA#on theoutsideoftheshippingcontainer.Returntheinstrument,postageorshipmentpre-paidto:
Ship To: ChauvinArnoux®,Inc.d.b.a.AEMC®Instruments 15FaradayDrive•Dover,NH03820USA Phone:(800)945-2362(Ext.360) (603)749-6434(Ext.360) Fax: (603)742-2346or(603)749-6309 E-mail:[email protected]
Caution:Toprotectyourselfagainstin-transitloss,werecommendyouinsureyourreturnedmaterial.
NOTE: You must obtain a CSA# before returning any instrument.
Chauvin Arnoux®, Inc. d.b.a. AEMC® Instruments15FaradayDrive•Dover,NH03820USA•Phone:(603)749-6434•Fax:(603)742-2346
www.aemc.com
09/08
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