al grounddigit resistance and soil resistivity …...1.1 international electrical symbols signifies...

DIGITAL GROUNDRESISTANCE AND SOILRESISTIVITY TESTERS

E N G L I S H User Manual

46204630

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 #: ______________________________

Model #: 4620 / 4630

Please fill in the appropriate date as indicated:

Date Received: _________________________________

Date Calibration Due: _______________________

Chauvin Arnoux®, Inc.d.b.a AEMC® Instrumentswww.aemc.com

Digital Ground Resistance Tester Model 4620 and 4630 1

Table of Contents

1. INTRODUCTION ................................................................................. 31.1 International Electrical Symbols ................................................41.2 DefinitionofMeasurementCategories .....................................41.3 ReceivingYourShipment ..........................................................41.4 OrderingInformation .................................................................5

1.4.1 Kits,AccessoriesandReplacementParts ....................6

2. PRODUCT FEATURES ......................................................................... 72.1 ControlandConnectorFeatures(Model4620) .......................72.2 ControlandConnectorFeatures(Model4630) ........................82.3 FaultIndicatorLEDs .................................................................9

2.3.1 X-ZFault .......................................................................92.3.2 Xv-YHighResistance ...................................................92.3.3 Xv-YHighNoise ............................................................9

2.4 Buzzer .....................................................................................102.5 Over-rangeIndication .............................................................102.6 FaultLEDIndication–TipsandSolutions ..............................10

3. SPECIFICATIONS ............................................................................. 113.1 Electrical .................................................................................113.2 Mechanical ..............................................................................123.3 Environmental .........................................................................133.4 Safety ......................................................................................133.5 Auto-ranging ...........................................................................13

4. GROUNDING THEORY ....................................................................... 144.1 GroundingElectrodeResistance ............................................14

4.1.1 EffectofElectrodeSize/DepthonResistance ............164.1.2 EffectsofSoilResistivityonElectrodeResistance .....174.1.3 FactorsAffectingSoilResistivity .................................174.1.4 EffectofGroundRodDepthonResistance ................20

4.2 GroundResistanceValues .....................................................214.3 GroundResistanceTestingPrinciple .....................................23

4.3.1 PositionofAuxiliaryElectrodesinMeasurements ......24

2 Digital Ground Resistance Tester Model 4620 and 4630

4.4 MeasuringResistanceofGroundElectrodes ........................264.4.1 AuxiliaryElectrodeSpacing ........................................28

4.5 MultipleElectrodeSystem ......................................................28

5. OPERATION ..................................................................................... 305.1 GroundResistanceMeasurementProcedure .......................305.2 2-PointMeasurement(SimplifiedMeasurement) ...................315.3 ContinuityMeasurement .........................................................325.4 SoilResistivityMeasurements ................................................32

5.4.1 PurposesofSoilResistivity ........................................325.4.2 TypesofResistivityMeasurements ............................33

5.5 SoilResistivityMeasurementProcedure(4-Point) .................34

5.6 How to Use 25ΩCalibrationChecker(accessory) ................36

6. MAINTENANCE ................................................................................ 376.1 Warning..................................................................................376.2 Disassembly ...........................................................................376.3 PowerSupply ..........................................................................38

6.3.1 TestingtheBattery ......................................................386.3.2 ReplacingtheBattery(Model4620) ...........................396.3.3 RechargingtheBattery(Model4630) .........................396.3.4 ReplacingtheSafetyFuse ..........................................40

6.4 Cleaning ..................................................................................406.5 Storage ...................................................................................40RepairandCalibration ....................................................................41TechnicalandSalesAssistance ......................................................41Limited Warranty .............................................................................42WarrantyRepairs ............................................................................42


CHAPTER 1

INTRODUCTION

WARNING “It should be impressed on all personnel that a lethal potential can exist between the station ground and a remote ground if a system fault involving the station ground occurs while tests are being made. Since one of the objects of tests on a station ground is the establishment of the location of an effectively remote point for both current and potential electrodes, the leads to the electrodes must be treated as though a possible potential could exist between these test leads and any point on the station ground grid.”

- excerpted from IEEE Std. 81-1962

Thesesafetywarningsareprovidedtoensurethesafetyofper-sonnelandproperoperationoftheinstrument.• The instrumentmust not be operated beyond its specified

operatingrange.• Safetyistheresponsibilityoftheoperator.• Allmetalobjectsorwiresconnectedtotheelectricalsystem

shouldbeassumedtobelethaluntiltested.Groundingsys-temsarenoexception.

• Useextremecautionwhenusingtheinstrumentaroundener-gizedelectricalequipment.

• Neverattempttousetheinstrumenttotwistorprythegroundelectrode or ground wire away from the equipment beinggrounded.

• AEMC®Instrumentsconsiderstheuseofrubberglovestobeanexcellentsafetypracticeeveniftheequipmentisproperlyoperatedandcorrectlygrounded.

• Alwaysinspecttheinstrumentandleadspriortouse.Replaceanydefectivepartsimmediately.


1.1 International Electrical Symbols

Signifies that the instrument is protected by double or reinforced insulation.

This symbol on the instrument indicates a WARNING and that the operator must refer to the user manual for instructions before operating the instrument. In this manual, the symbol preceding instructions indicates that if the instructions are not followed, bodily injury, installation/sample and/or product damage may result.Risk of electric shock. The voltage at the parts marked with this symbol may be dangerous.

In conformity with WEEE 2002/96/EC

1.2 Definition of Measurement Categories

1.3 Receiving Your ShipmentUponreceivingyourshipment,makesurethatthecontentsareconsistentwiththeorderinginformation.Notifyyourdistributorofanymissingitems.Iftheequipmentappearstobedamaged,fileaclaimimmediatelywiththecarrierandnotifyyourdistributoratonce,givingadetaileddescriptionofanydamage.Savethedamagedpackingcontainertosubstantiateyourclaim.Donotuseequipmentwhichisdamagedorappearstobedamaged.

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.


1.4 Ordering Information

Ground Resistance Tester Model 4620 ............................Cat. #2130.43Includes 8 C cell batteries and user manual.

Ground Resistance Tester Model 4620 Kit (150 ft) .........Cat. #2135.19Includes ground tester, two 150 ft color-coded leads on spools (red/blue), one 30 ft lead (green), two T-shaped auxiliary ground electrodes, set of two 5 ft color-coded (red/blue) leads, set of 5 spaded lugs, one 100 ft AEMC® tape measure, 8 C cell batteries, carrying bag and user manual.

Ground Resistance Tester Model 4620 Kit (300 ft) .........Cat. #2135.20Includes ground tester, two 300 ft color-coded leads on spools (red/blue), two 100 ft color-coded leads (hand-tied, green/black), four T-shaped auxiliary ground electrodes, set of two 5 ft color-coded (red/blue) leads, set of 5 spaded lugs, one 100 ft AEMC® tape measure, 8 C cell batteries, carrying bag and user manual.

Ground Resistance Tester Model 4620 Kit (500 ft) .........Cat. #2135.21Includes ground tester, two 500 ft color-coded leads on spools (red/blue), two 100 ft color-coded leads (hand-tied, green/black), one 30 ft lead (green), four T-shaped auxiliary ground electrodes, set of two 5 ft color-coded (red/blue) leads, set of 5 spaded lugs, one 100 ft AEMC® tape measure, 8 C cell batteries, carrying bag and user manual.

Ground Resistance Tester Model 4630 ............................Cat. #2130.44Includes rechargeable battery, AC power cord and user manual.

Ground Resistance Tester Model 4630 Kit (150 ft) .........Cat. #2135.22Includes ground tester, two 150 ft color-coded leads on spools (red/blue), one 30 ft lead (green), two T-shaped auxiliary ground electrodes, set of two 5 ft color-coded (red/blue) leads, set of 5 spaded lugs, one 100 ft AEMC® tape measure, rechargeable battery, carrying bag and user manual.

Ground Resistance Tester Model 4630 Kit (300 ft) .........Cat. #2135.23Includes ground tester, two 300 ft color-coded leads on spools (red/blue), two 100 ft color-coded leads (hand-tied, green/black), four T-shaped auxiliary ground electrodes, set of two 5 ft color-coded (red/blue) leads, set of 5 spaded lugs, one 100 ft AEMC® tape measure, rechargeable battery, carrying bag and user manual.

Ground Resistance Tester Model 4630 Kit (500 ft) .........Cat. #2135.24Includes ground tester, two 500 ft color-coded leads on spools (red/blue), two 100 ft color-coded leads (hand-tied, green/black), one 30 ft lead (green), four T-shaped auxiliary ground electrodes, set of two 5 ft color-coded (red/blue) leads, set of 5 spaded lugs, one 100 ft AEMC® tape measure, rechargeable battery, carrying bag and user manual.


1.4.1 Kits, Accessories and Replacement Parts

Test Kit for 3-Point Testing (150 ft) ..................................Cat. #2135.35Includes two 150 ft color-coded leads on spools (red/blue), one 30 ft lead (green), two T-shaped auxiliary ground electrodes, set of two 5 ft color-coded (red/blue) leads, set of 5 spaded lugs, one 100 ft AEMC® tape measure and carrying bag.

Test Kit for 4-Point Testing (300 ft) ..................................Cat. #2135.36Includes two 300 ft color-coded leads on spools (red/blue), two 100 ft color-coded leads (hand-tied, green/black), four T-shaped auxiliary ground electrodes, set of two 5 ft color-coded (red/blue) leads, set of 5 spaded lugs, one 100 ft AEMC® tape measure and carrying bag.

Test Kit for 4-Point Testing (500 ft) ..................................Cat. #2135.37Includes two 500 ft color-coded leads on spools (red/blue), two 100 ft color-coded leads (hand-tied, green/black), one 30 ft lead (green), four T-shaped auxiliary ground electrodes, set of two 5 ft color-coded (red/blue) leads, set of 5 spaded lugs, one 100 ft AEMC® tape measure and carrying bag.

Test Kit for 3-Point Testing (Supplemental for 4-Point Testing) ...Cat. #2135.38Includes two 100 ft color-coded leads (hand-tied, green/black), one 30 ft lead (green), two T-shaped auxiliary ground electrodes, set of 5 spaded lugs, one 100 ft AEMC® tape measure and carrying bag.

25Ω Calibration Checker .....................................................Cat. #2130.59Tape Measure – AEMC 100 ft..............................................Cat. #2130.60Set of 2, T-Shaped Auxiliary Ground Electrodes .................Cat. #2135.39Inverter – 12VDC to 120VAC 200 Watt for vehicle use ........Cat. #2135.43

Fuse – Set of 5, 0.1A, >250V, 0.25 x 1.25" .........................Cat. #2970.12Replacement 9.6V Rechargeable Battery Pack (4630) .......Cat. #2960.21

115V Power Cord ................................................................Cat. #5000.14

Download the Ground Tester Workbook at www.aemc.com

Order Accessories and Replacement Parts Directly OnlineCheck our Storefront at www.aemc.com/store for availability

Lead – Replacement set of 2, 5 ft color-coded (red/blue) for use with Ground Tester reels incorporating banana jack input ........Cat. #5000.34

Ground Rod – Set of 2, 17" Stainless Steel T-shaped Auxiliary Ground Electrodes .............................................Cat. #2135.44


CHAPTER 2

PRODUCT FEATURES

2.1 Control and Connector Features (Model 4620)

Ω

1. Low battery indicator2. Input terminal Z (H)3. Input terminal Y (S)4. Input terminal Xv (ES)5. Input terminal X (E)6. X-Z Fault indicator

Figure 1

7. Xv-Y High Resistance indicator8. Xv-Y High Noise indicator9. Display (with backlight - lights up when

the TEST button is pressed)10. Fuse holder11. TEST button

(when released, turns the unit OFF)

2

1

3

4

5

11

10

9

86 7


2.2 Control and Connector Features (Model 4630)

Ω

1. Low battery indicator2. AC power input3. Input terminal Z (H)4. Input terminal Y (S)5. Input terminal Xv (ES)6. Input terminal X (E)

Figure 2

7. X-Z Fault indicator8. Xv-Y High Resistance indicator9. Xv-Y High Noise indicator

10. Display (with backlight)11. Fuse holder12. Test button

3

2

1

4

5

6

12

11

10

97 8


2.3 Fault Indicator LEDsThethreeindicatorsconfirmthatthecorrectmeasurementisbeingtaken,ifnoneofthemarelit.

2.3.1 X-Z Fault

ThisLEDsignalsthatthevoltagebetweenterminalsXandZexceeds30Vpeak.Therearefourpossiblecauses:

• theresistanceofthecurrentcircuitbetweenXandZistoohigh• interferencevoltageinthecurrentcircuitistoohigh• thefuseisblown• thecircuitisopen(leadnotconnected)

2.3.2 Xv-Y High ResistanceThisLEDsignalsthattheresistanceinthevoltagecircuit(betweenXvandYorXandY)istoohigh(approx50kΩ)orthatthecircuitmaybeopen.

• Flashingwill continue throughout themeasurement,even if theresistance drops below the threshold (e.g. after reconnectingor lowering auxiliary rod resistance). In this case, you mustreleasethepush-buttonandpressagainafterthefaulthasbeencorrected.

• Occasionally, a stray voltage above 4.5Vmay also set off thislight.

• Checktheleadsforapossiblesolution.

2.3.3 Xv-Y High NoiseThisLEDsignals thepresenceof excessiveelectrical noise (13Vpeakapprox)inthevoltagecircuit(betweenXvandYorXandY).

• Oneremedyistouseshieldedleadsfromtheinstrumenttotheauxiliaryelectrodes.

• Connectalltheshieldstotherodundertest.


2.4 BuzzerTheModels4620and4630featureabuzzer,whichwillsoundwhentheterminals of the tester are connected to a voltage source. The soundvolume is proportional to the voltage up to 30V approximately, thenbecomes stable.

2.5 Over-range IndicationOver-rangeisindicatedwhenthedisplayreads1,orwhenthedisplayisblinkingandtheindicatorislit.

2.6 Fault LED Indication – Tips and SolutionsTheLEDindicatorsshowexcessiveelectroderesistanceandexcessivetransientnoiseand/orstraycurrent.

Intheeventofanincorrectmeasurementindication:

• ImprovethequalityoftheconnectiontoearthofauxiliarygroundelectrodesYandZ.Zisthemostlikelysourceofproblemscausedbyexcessiveelectroderesistance.

• Checkconnectionsforcontinuitybetweenleadsandelectrodes.• Be sure that electrodes are properly inserted; they should be

buriedasmuchaspossible.• Ifhighelectroderesistancestillexistsafterproperlyinsertingaux-

iliaryelectrodesintotheearth,trypouringwateronandaroundtheauxiliaryelectrodes.Thiswillimprovetheirelectricalconnec-tiontoearth.

• Ifstraycurrentsaresuspected,onesolutiontoreducetheirinflu-enceistomovebothYandZelectrodesinanarcrelativetotheXelectrode(try,e.g.a90°shift),andtestagain.

• Displayof0.00:XvandYareshort-circuited.• Displayof<0:XandZorXvandYrodsarereversed.

NOTE: Accuracy may be affected by auxiliary ground rod (Ry, Rz) resistance levels and by stray signal levels (earth currents).


CHAPTER 3

SPECIFICATIONS

3.1 ElectricalMeasurement Range:Auto-ranging0to2000Ω

Range 20Ω 200Ω 2000ΩMeasurement 0 to 19.99Ω 20 to 199.9Ω 200 to 1999ΩResolution 10mΩ 100mΩ 1ΩTest Current 10mA 1mA 0.1mAAccuracy 2% of Reading ± 1ct ± 5% of Reading ± 3ctsOpen Voltage <42V peak

Operating Frequency:128Hzsquarewave

Max. Auxiliary Rod Resistance:Range 20Ω 200Ω 2000ΩCurrent Circuit 3kΩ 30kΩ 50kΩVoltage Circuit 50kΩ

Response Time: 4to8secondsapproxforastabilizedmeasurement

Interference:TheModels4620&4630aredesignedtorejecthighlevelsofinterferencevoltage(DC,50/60Hz,harmonics)

• DCvoltageinserieswithX:20V• ACvoltageinserieswithY:13Vpeak(@16.67,50,60,400Hz)• ACvoltageinserieswithZ:32Vpeak(@16.67,50,60,400Hz)

Accuracies and specifications are given for an ambient temperature of 23°C ±3°K, RH of 45 to 55%, battery power at 9.5V, auxiliary resistance at the measurement terminals = 0, no stray voltage, an electrical field < 1V/m, and a magnetic field from 0 to 40A/m.

Voltage Detection Range:20to250VACbetweentheXandZterminalsorbetweentheXvandZterminals.

Frequency: DCat450Hz

Voltage Withstanding:Bothmodelsarefuseprotected.Intheeventofasystemfault,theunitscanwithstand250VACor100VDC.

Fuse Protection: Highbreakingcapacity-0.1A,>250V,0.25x1.25"


Model 4620

Power Source: Eight1.5VCcellbatteries

Battery Life: 4500measurementsof15secondseach

Low Battery Indicator: Ifthe indicatorlightsup,thebatteriesarelosingpower.

Model 4630

Power Source:NiMHrechargeablecell(4630)

Battery Life: 2000measurementsof15secondseach

Battery Charging:Externalrecharge-120-230V/50-60Hz,20VAChargetime-6hrstoattain80%ofthebatterycapacity

Low Battery Indicator: Ifthe“CHARGE”indicatorturnsonsolidRED,thebatteryneedstobecharged.

3.2 MechanicalConnection:Color-codedterminalsacceptspadelugswithminimumgapof6mmorstandard4mmbananajacks.

Display:2000-count7segmentLCD,approx1"high(3-1/2digit)LCDalsoindicatesoverrange,testleadshortsandleadreversals.Blueelectroluminescentbacklight.

Dimensions:10.8x9.7x5.0"(273x247x127mm)

Weight:Model4620:6.28lbs(2.85kg)Model4630:7.38lbs(3.35kg)

Colors:Case-safetyyellow;Frontpanel-gray

Mechanical Protection:TheModels4620and4630havesuccessfullyundergonealltherequiredmechanicaltestsandthereforemeetalltherequirementsofthestandardsEN61557andEN61010-1.


3.3 EnvironmentalOperating Temperature:14°to131°F(-10°to55°C),0to90%RH

Storage Temperature:-40°to158°F(-40°to70°C),0to90%RHwithbatteriesremoved

3.4 Safety

Ingress Protection:IP 53

Electrical:EN61010EN6155730Vrms,CATIII,PollutionDegree2

Electromagnetic Compatibility:EN61326

*Specifications are subject to change without notice

3.5 Auto-rangingTheselectionofthemeasurementcurrentisdependingontheresistancetomeasure.

When the instrument is turned ON, the measurement starts on thesmallestcurrentrange(100µA).Ifthemeasurementisbetween185and1950cts, the range stays the same (100µA). If the measurement isunder 185cts, thecurrent ismultipliedby10 (within10mAmax). If it isabove1950cts,thecurrentisdividedby10(withoutgoingunder100µA).

Thisisdonetoavoidswitchingbackandforthbetweenrangeswhenyouaremeasuring190Ω. It ispossible todisplay190.0or190Ωdependingontheautomaticrangeselection.


CHAPTER 4

GROUNDING THEORY

4.1 Grounding Electrode ResistanceFigure3illustratesagroundingrod.Theresistanceoftheelectrodehasthefollowingcomponents:

• theresistanceofthemetalandthatoftheconnectiontoit• thecontactresistanceofthesurroundingearthtotheelectrode• theresistanceinthesurroundingearth

Morespecifically:

A) Groundingelectrodesareusuallymadeofaveryconductivemetal(copper)withadequatecrosssectionssothatoverallresistanceisnegligible.

B) TheNationalInstituteofStandardandTechnology(N.I.S.T.)hasdemonstratedthattheresistancebetweentheelectrodeandthesurrounding earth is negligible if the electrode is free of paint,greaseorothercoating,andiftheearthisfirmlypacked.

Ground Rod

and Clamp

Contact

Resistance

Between Rod

and Soil

Concentric

Shells of

Earth

Figure 3


C) Theonlycomponentremainingistheresistanceofthesurround-ingearth.Theelectrodecanbethoughtofasbeingsurroundedby concentric shells of earth or soil, all of the same thickness.The closer the shell to the electrode, the smaller its surface;hence,thegreateritsresistance.Thefartherawaytheshellsarefromtheelectrode,thegreaterthesurfaceoftheshell;hence,thelowertheresistance.Eventually,addingshellsatadistancefromthegroundingelectrodewillnolongernoticeablyaffecttheoverallearthresistancesurroundingtheelectrode.Thedistanceatwhichthiseffectoccursisreferredtoastheeffectiveresistanceareaandisdirectlydependentonthedepthofthegroundingelectrode.

In theory, the ground resistancemay be derived from the general for-mula:

R = ρ Resistance=ResistivityxLA

LengthArea

Thisformulaclearlyillustrateswhytheshellsofconcentricearthdecreaseinresistancethefarthertheyarefromthegroundrod:

R=ResistivityofSoilx ThicknessofShellArea

Inthecaseofgroundresistance,uniformearth(orsoil)resistivitythrough-out thevolume isassumed,although this isseldomthecase innature.The equations for systems of electrodes are very complex and oftenexpressedonlyasapproximations.Themostcommonlyusedformulaforsinglegroundelectrodesystems,developedbyProfessorH.R.DwightoftheMassachusettsInstituteofTechnology,follows:

4Lr

R =ρ

2πLIn -1

R=resistanceinohmsofthegroundrodtotheearth(orsoil)

L=groundingelectrodelength

r=groundingelectroderadius

ρ=averageresistivityinohms-cm


4.1.1 Effect of Ground Electrode Size and Depth on Resistance

Size: Increasing thediameter of the roddoesnotmaterially reduce itsresistance.Doublingthediameterreducesresistancebylessthan10%.

0

25

50

75

100

1/2 5/8 3/4 1 1 1/4 1 1/2 1 3/4

Rod Diameter (inches)

Resis

tance in %

Figure 4

Depth: As a ground rod is driven deeper into the earth, its resistanceissubstantiallyreduced.Ingeneral,doublingtherodlengthreducestheresistancebyanadditional40%.

5 15 25 35 40 50 60 70

1

2

3

45

6

8

10

20

30

40

60

80

100

200

Driven Depth in Feet

Ground Resistance Versus Ground Rod Depth

Re

sis

tan

ce

in

Oh

ms

1/2" dia.1" dia.

Figure 5


NEC®2014250.52(A)(5)requiresaminimumof8ft(2.4m)oftheelec-trodetobe incontactwith thesoil.Themostcommonofelectrode isa10ft(3m)cylindricalrodwhichmeetstheNEC®code,whichrequiresaminimumdiameterof5/8”(1.59cm).

4.1.2 Effects of Soil Resistivity on Ground Electrode ResistanceDwight’s formula,citedpreviously,showsthat theresistance toearthofgroundingelectrodesdependsnotonlyonthedepthandsurfaceareaofgroundingelectrodesbutonsoilresistivityaswell.Soilresistivity isthekeyfactorthatdetermineswhattheresistanceofagroundingelectrodewillbe,andtowhatdepthitmustbedriventoobtainlowgroundresistance.Theresistivityofthesoilvarieswidelythroughouttheworldandchangesseasonally.Soilresistivityisdeterminedlargelybyitscontentofelectro-lytes,consistingofmoisture,mineralsanddissolvedsalts.Adrysoilhashighresistivityifitcontainsnosolublesalts.

Soil

Ashes, cinders, brine, waste

Clay, shale, gumbo, loam

Same, with varying proportions

of sand and gravel

Gravel, sand, stones with

little clay or loam

590

340

1020

59,000

2370

4060

15,800

94,000

7000

16,300

135,000

458,000

Resistivity, Ω-cm

Minimum Average Maximum

Table 1

4.1.3 Factors Affecting Soil Resistivity

Twosamplesofsoil,whenthoroughlydried,maybecomeinfactverygoodinsulators,havingaresistivityinexcessof109ohm-centimeters.Theresis-tivityofthesoilsampleisseentochangequiterapidlyuntilapproximatelytwentypercentorgreatermoisturecontentisreached.


0

2.5

5

10

15

20

30

> 109

250,000

165,000

53,000

19,000

12,000

6400

> 109

150,000

43,000

18,500

10,500

6300

4200

Resistivity, Ω-cmMoisture content,

% by weight Top Soil Sandy Loam

Table 2

Theresistivityofthesoilisalsoinfluencedbytemperature.Table3showsthevariationoftheresistivityofsandyloam,containing15.2%moisture,withtemperaturechangesfrom20°to-15°C.Inthistemperaturerangetheresistivityisseentovaryfrom7200to330,000ohm-centimeters.

20

10

0

0

-5

-15

68

50

32 (water)

32 (ice)

23

14

7200

9900

13,800

30,000

79,000

330,000

Resistivity

Ω-cm

Temperature

°C °F

Table 3

Becausesoil resistivitydirectly relates tomoisturecontentand temper-ature, it is reasonable to assume that the resistance of any groundingsystemwillvarythroughoutthedifferentseasonsoftheyear.Suchvaria-tionsareshowninFigure6below.


Since both temperature and moisture content become more stable atgreaterdistancesbelowthesurfaceoftheearth,itfollowsthatagroundingsystem(tobemosteffectiveatalltimes)shouldbeconstructedwiththegroundroddrivendownaconsiderabledistancebelowthesurfaceoftheearth.Bestresultsareobtainedifthegroundrodreachesthewatertable.

0

20

40

60

80

Jan.

Mar.

May

July

Sept.

Nov.

Jan.

Mar.

May

July

Curve 1

Curve 2

Figure 6

Seasonal variation of earth resistance with an electrode of 3/4" pipe in rather stony clay soil. Depth of electrode in earth is 3 ft for Curve 1, and 10 ft for Curve 2.

Insomelocations,theresistivityoftheearthissohighthatlow-resistancegroundingcanbeobtainedonlyatconsiderableexpenseandwithanelab-orategroundingsystem.Insuchsituations, itmaybeeconomical touseagroundrodsystemoflimitedsizeandtoreducethegroundresistivitybyperiodicallyincreasingthesolublechemicalcontentofthesoil.Table4showsthesubstantialreductioninresistivityofsandyloambroughtaboutbyanincreaseinchemicalsaltcontent.

0

0.1

1.0

5

10

20

10,700

1800

460

190

130

100

The Effect of Salt* Content on the Resistivity of Soil(sandy loam, moisture content, 15% by weight, temperature 17°C)

Added Salt

% by weight of moisture

Resistivity

(Ohm-centimeters)

Table 4


Chemicallytreatedsoilisalsosubjecttoconsiderablevariationofresistivitywithchangesintemperature,asshowninTable5.If salt treatment is employed, it is necessary to use auxiliary groundelectrodes,whichwillresistchemicalcorrosion.

20100-5

-13

110142190312

1440

The Effect of Temperature on the Resistivity of Soil Contining Salt*(sandy loam, 20% moisture; salt 5% of weight of moisture)

Temperature ˚C Resistivity (Ohm-centimeters)

Table 5

*Such as copper sulfate, sodium carbonate and others. Salts must be EPA or local ordinance approved prior to use.

4.1.4 Effect of Ground Rod Depth on ResistanceToassisttheengineerindeterminingtheapproximategroundroddepthrequired to obtain a desired resistance, a device called theGroundingNomographmaybeused.TheNomograph,showninFigure7,indicatesthattoobtainagroundingresistanceof20ohmsinasoilwitharesistivityof10,000ohm-centimeters,a5/8"ODrodmustbedriven20ft.NotethatthevaluesindicatedontheNomographarebasedontheassumptionthatthesoilishomogeneousand,therefore,hasuniformresistivity.TheNomo-graphvalueisanapproximation.


Grounding Nomograph

Ground RodResistance-Ohms

Soil Resistivity(Ohm-centimeters)

Rod DepthFeet

Rod DiameterInches

R

P

D

DIA

20

30

40

90

50

60

70

80

100

15

10

1

5

2

4

3

5/8

1/4

1/2

3/4

1

1.5

8

7

6

5

4

3

2

10000

15000

100000

50000

40000

30000

20000

3000

500

1000

2000

4000

5000

20

30

10090

80

7060

50

40

15

1

2

3

4

5

6

7

8

9

10

K

Figure 7

1. SelectrequiredresistanceonRscale.2. SelectapparentresistivityonPscale.3. Lay straightedge on R and P scale, and allow to intersect with K

scale.4. MarkKscalepoint.5. LaystraightedgeonKscalepointandDIAscale,andallowtointersect

withDscale.6. PointonDscalewillberoddepthrequiredforresistanceonRscale.

4.2 Ground Resistance ValuesNEC®2008article250.56regardingtheresistanceofrod,pipeandplateelectrodesstatesthatiftherod,pipe,orplatedoesnothavearesistanceof25Ωorlesstogroundshallbeaugmentedbyoneadditionalelectrodeofanyofthetypesspecifiedby250.52(A)(4)through(A)(8).Wheremultiplerod,pipeorplateelectrodesareinstalledtomeettherequirementsofthesection,theyshallnotbelessthan6feetapart.


FPN:Theparallelingefficiencyofrodslongerthan8feetisimprovedbyspacinggreaterthan6feetapart.

TheNationalElectricalCode®(NEC®)statesthattheresistancetogroundshallnotexceed25Ω.This isanupper limitandguideline,sincemuchlowerresistanceisrequiredinmanyinstances.

“How low in resistance should a ground be?”Anarbitraryanswertothisinohmsisdifficult.Thelowerthegroundresis-tance,thesafer,andforpositiveprotectionofpersonnelandequipment,itisworththeefforttoaimforlessthanoneohm.Itisgenerallyimpracticaltoreachsuchalowresistancealongadistributionsystemoratransmis-sionlineorinsmallsubstations.Insomeregions,resistancesof5Ω or less maybeobtainedwithoutmuchtrouble.Inothers,itmaybedifficulttobringresistanceofdrivengroundsbelow100Ω.

Accepted industry standards stipulate that transmission substationsshouldbedesignednottoexceedoneohmresistance.Indistributionsub-stations,themaximumrecommendedresistanceis5Ω.Inmostcases,theburiedgridsystemofanysubstationwillprovidethedesiredresistance.

Inlightindustrialorintelecommunicationscentraloffices,5Ωisoftentheacceptedvalue.Forlightningprotection,thearrestersshouldbecoupledwithamaximumgroundresistanceof1Ω.

Theseparameterscanusuallybemetwiththeproperapplicationofbasicgroundingtheory.Therewillalwaysexistcircumstanceswhichwillmakeit difficult to obtain the ground resistance required by theNEC®.Whenthesesituationsdevelop,severalmethodsof loweringthegroundresis-tancecanbeemployed.Theseincludeparallelrodsystems,deepdrivenrod systemsutilizing sectional rods and chemical treatment of the soil.Additionalmethods,discussedinotherpublisheddata,areburiedplates,buried conductors (counterpoise), electrically connected building steel,andelectricallyconnectedconcretereinforcedsteel.

Electricallyconnectingtoexistingwaterandgasdistributionsystemswasoftenconsideredtoyieldlowgroundresistance;however,recentdesignchangesutilizingnon-metallicpipesandinsulatingjointshavemadethismethodofobtaininga lowresistancegroundquestionableand inmanyinstancesunreliable.

Auxiliarygroundelectrodeswillberequiredinhighvoltagetransmissionlines,wheremaximum resistance of 15 ohms is recommended, and indistributionlines,wheremaximumresistanceof25ohmsispreferred.AllelectricalsystemsconstructedinaccordancewiththeNationalElectricalCode®,shouldnotexceed25ohms.


Themeasurementofgroundresistancesmayonlybeaccomplishedwithspeciallydesignedtestequipment.MostinstrumentsusetheFallofPoten-tial principleofalternatingcurrent (AC)circulatingbetweenanauxiliaryelectrodeandthegroundelectrodeundertest;thereadingwillbegiveninohmsandrepresentstheresistanceofthegroundelectrodetothesur-roundingearth.AEMC®Instrumentshasalsorecentlyintroducedaclamp-ongroundresistancetester.

The National Electrical Code® and NEC® are registered trademarks of the National Fire Pro-tection Association.

4.3 Ground Resistance Testing Principle (Fall-of-Potential — 3-Point Measurement)

3-Pointmeasurementisusedtomeasureresistancetogroundofauxiliarygroundelectrodesandgrids.ThepotentialdifferencebetweenrodsXandYismeasuredbyavoltmeter,andthecurrentflowbetweenrodsXandZismeasuredbyanammeter.

ByOhm’sLawE=RIorR=E/I,wemayobtain thegroundelectroderesistance R.IfE=20VandI=1A,then:

R===20ohmsEI

201

Itisnotnecessarytocarryoutallthemeasurementswhenusingagroundtester.Thegroundtesterwillmeasuredirectlybygeneratingitsowncur-rentanddisplayingtheresistanceofthegroundelectrode.


Z (H)Y (S)X (E)

VOLTMETER (E)

AUXILIARY

POTENTIAL

ELECTRODE

GROUND

ELECTRODE

UNDER TEST

AUXILIARY

CURRENT

ELECTRODE

AMMETER (I)

CURRENT

SUPPLY

R

EARTH

Figure 8

NOTE: Terminals X and Xv are shorted together in 3-Point measurement.

4.3.1 Position of the Auxiliary Electrodes in MeasurementsThegoalinpreciselymeasuringtheresistancetogroundistoplacetheauxiliarycurrentelectrodeZfarenoughfromthegroundelectrodeundertestsothattheauxiliarypotentialelectrodeYwillbeoutsideoftheeffec-tiveresistanceareasofboththegroundelectrodeandtheauxiliarycurrentelectrode.ThebestwaytofindoutiftheauxiliarypotentialrodYisoutsidetheeffectiveresistanceareasistomoveitbetweenXandZandtotakeareadingateachlocation.IftheauxiliarypotentialrodYisinaneffectiveresistancearea(orinbothiftheyoverlap),bydisplacingit,thereadingstakenwillvarynoticeablyinvalue.Undertheseconditions,noexactvaluefortheresistancetogroundmaybedetermined.


X-Y Distance

Re

sis

tan

ce

Reading Variation

Effective Resistance

Areas (Overlapping)

X Y' Y Y'' Z

Figure 9

On the other hand, if the auxiliary potential rodY is located outside oftheeffectiveresistanceareas,asYismovedbackandforththereadingvariationisminimal.Thereadingstakenshouldberelativelyclosetoeachother,andarethebestvaluesfortheresistancetogroundofthegroundX.Thereadingsshouldbeplottedtoensurethattheylieina“plateau”regionasshowninFigure10.

X-Y Distance

Resis

tance

Reading Variation

Effective Resistance

Areas (No Overlap)

X Y Y Y'' Z

Figure 10


4.4 Measuring Resistance of Ground Electrodes (62% Method)

The 62%method has been adopted after graphical consideration andafteractualtest.Itisthemostaccuratemethodbutislimitedbythefactthatthegroundtestedisasingleunit.

Thismethodappliesonlywhenallthreeelectrodesareinastraightlineandthegroundisasingleelectrode,pipe,orplate,etc.,asinFigure11.

Alligator Clips

Y ZX52% 62% 72%0% 100% of distance

between X and Z

Ground Rod Y Electrode Z Electrode

Ground Rod

Y Electrode Z Electrode

GroundStrip

-10% 3rdMeasurement

+10% 2ndMeasurement

Ω

Figure 11

ConsiderFigure12,whichshowstheeffectiveresistanceareas(concentricshells)ofthegroundelectrodeXandoftheauxiliarycurrentelectrodeZ.Theresistanceareasoverlap.

If readings were taken by moving the auxiliary potential electrode YtowardseitherXorZ, the readingdifferentialswouldbegreatandonecould not obtain a readingwithin a reasonable band of tolerance.ThesensitiveareasoverlapandactconstantlytoincreaseresistanceasYismovedawayfromX.


Distance from Y to Ground Electrode

Re

sis

tan

ce

Overlapping Effective

Resistance Areas

X Y Z

Ground

Electrode

Under Test

Auxiliary

Potential

Electrode

Auxiliary

Current

Electrode

Figure 12

NowconsiderFigure 13,where theXandZelectrodesare sufficientlyspacedsothattheareasofeffectiveresistancedonotoverlap.Ifweplottheresistance,measuredwefindthatthemeasurementsleveloffwhenYisplacedat62%ofthedistancefromXtoZ,andthatthereadingsoneithersideoftheinitialYsettingaremostlikelytobewithintheestablishedtoleranceband.Thistolerancebandisdefinedbytheuserandexpressedasapercentoftheinitialreading:±2%,±5%,±10%,etc.

Resis

tance

Distance from Y to Ground Electrode

Effective

Resistance

Areas Do

Not Overlap

X Y Z

Ground

Electrode

Under Test

Auxiliary

Potential

Electrode

Auxiliary

Current

Electrode

D

62% of D 38% of D

Resistance ofAuxiliary CurrentElectrode

Resistance of Earth Electrode

Figure 13


4.4.1 Auxiliary Electrode SpacingNodefinitedistancebetweenXandZcanbegiven,sincethisdistanceisrelativetothediameteroftheelectrodetested,itslength,thehomogeneityof the soil tested, andparticularly, the effective resistanceareas.How-ever,anapproximatedistancemaybedeterminedfromthefollowingchartwhichisgivenforahomogeneoussoilandanelectrodeof1"indiameter.(Foradiameterof1/2",reducethedistanceby10%;foradiameterof2"increasethedistanceby10%.)

Depth Driven Distance to Y Distance to Z

6 ft 45 ft 72 ft

8 ft 50 ft 80 ft

10 ft 55 ft 88 ft

12 ft 60 ft 96 ft

18 ft 71 ft 115 ft

20 ft 74 ft 120 ft

30 ft 86 ft 140 ft

Approximate Distance to Auxiliary Electrodes

Using the 62% Method

Table 6

4.5 Multiple Electrode SystemAsingledrivengroundelectrodeisaneconomicalandsimplemeansofmakingagoodgroundsystem,butsometimesasinglerodwillnotprovidesufficientlowresistance,andseveralgroundelectrodeswillbedrivenandconnectedinparallelbyacable.

Veryoftenwhentwo,threeorfourgroundelectrodesareused,theyaredriveninastraightline.Whenfourormoreareused,ahollowsquarecon-figurationisusedandthegroundelectrodesarestillconnectedinparallelandequallyspaced(Figure14).

Inmultipleelectrodesystems,the62%methodelectrodespacingmaynolongerbeapplieddirectly.Thedistanceoftheauxiliaryelectrodesisnowbasedonthemaximumgriddistance(e.g.inasquare,thediagonal;inaline,thetotallength).Asquarehavingasideof20 ftwillhaveadiagonalofapproximately28ft.


DIAGONAL

DIA

GO

NA

L

a

a a

a

Figure 14

6 ft

8 ft

10 ft

12 ft

14 ft

16 ft

18 ft

20 ft

30 ft

40 ft

50 ft

60 ft

80 ft

100 ft

120 ft

140 ft

160 ft

180 ft

200 ft

78 ft

87 ft

100 ft

105 ft

118 ft

124 ft

130 ft

136 ft

161 ft

186 ft

211 ft

230 ft

273 ft

310 ft

341 ft

372 ft

390 ft

434 ft

453 ft

125 ft

140 ft

160 ft

170 ft

190 ft

200 ft

210 ft

220 ft

260 ft

300 ft

340 ft

370 ft

440 ft

500 ft

550 ft

600 ft

630 ft

700 ft

730 ft

Multiple Electrode System

Max Grid Distance Distance to Y Distance to Z

Table 7


CHAPTER 5

OPERATION

5.1 Ground Resistance Measurement Procedure (3-Point)

Alligator ClipsGround Rod

XY Electrode Z Electrode

GroundStrip

Ω

Figure 15

WARNING: Use extreme caution when disconnecting the ground connection from the rest of the circuit. Current may be flowing and a dangerous potential could exist between the disconnected wires.

• XandXv(E,ES)areshorted• DisconnectshortinglinkbetweenYandZ(S,H)• ConnectXtothegroundrodtobetested• ConnectY(S)tothecenterelectrode• ConnectZ(H)totheouterelectrode• Depressthe“Test”buttontomeasuregroundresistance


5.2 2-Point Measurement (Simplified Measurement)

Thisisanalternativemethodto3-Pointmeasurementwhen an excellent ground is already available.

Incongestedareaswherefindingroomtodrivethetwoauxiliarygroundelectrodesmaybeaproblem,the2-Pointmeasurementmethodmaybeapplied.The readingobtainedwillbe thatof the twogrounds inseries.Therefore,thewaterpipeorothergroundmustbeverylowinresistancesothatitwillbenegligibleinthefinalmeasurement.Theleadresistanceswillalsobemeasuredandshouldbededucted from thefinalmeasure-ment.Thismethodisnotasaccurateas3-Pointmethod(62%method),asitisparticularlyaffectedbythedistancebetweenthetestedelectrodeandthedeadgroundorwaterpipe.Thismethodshouldnotbeusedasastandardprocedure,butratherasabackupintightareas.

Procedure:• ShortXandXv(E,ES)• ShortYandZ(S,H)• ConnectXtogroundrodtobemeasured• ConnectZtoanelectrode• Measureasinthe3-Pointmethod

Grounding conductor

Ground

level

Ground

rodButt plate

Utility

pole

Terminals shorted

Metallic Water Pipe

(Y-Z shorted)

Ω

Figure 16


5.3 Continuity MeasurementConnecttheshortinglink,suppliedwiththeinstrument,betweenXandXv(EandEs).ConnectashortwireorjumpercablebetweenYandZ(HandS)asshowninFigure17.Continuitymeasurement ismadewith two leads,one fromX-Xvand theotherfromY-Z.Pushthe“Test”buttontomeasurecontinuity.Thisisagoodtesttoverifybondingbetweengroundingelectrodeandthegroundwire.

Ω

Figure 17

5.4 Soil Resistivity Measurements

5.4.1 Purposes of Soil Resistivity

Soilresistivitymeasurementshavethreepurposes:

1. Suchdata isused tomakesub-surfacegeophysical surveysasanaidinidentifyingorelocations,depthtobedrockandothergeologicalphenomena.

2. Resistivityhasadirect impacton thedegreeofcorrosion inunder-groundpipelines.A decrease in resistivity relates to an increase incorrosiveactivityandthereforedictatestheprotectivetreatmenttobeused.


3. Soilresistivitydirectlyaffectsthedesignofagroundingsystem,andit is to that task that thisdiscussion isdirected.Whendesigninganextensivegroundingsystem,itisadvisabletolocatetheareaoflowestsoil resistivity in order to achieve the most economical groundinginstallation.

5.4.2 Types of Resistivity Measurements

Therearetwotypesofresistivitymeasurements:• 2-Pointmethod

The2-Pointmethodissimplytheresistancemeasuredbetweentwopoints.

• 4-PointmethodFormostapplications, themostaccuratemethod is the4-Pointmethod,which is used by theAEMC® InstrumentsModel 4620and 4630 Ground Testers. The 4-Point method, as the nameimplies,requirestheinsertionoffourequallyspaced,in-lineelec-trodesintothetestarea.Aknowncurrentfromaconstantcurrentgeneratorispassedbetweentheoutermostelectrodes(XandZ).Thepotentialdrop(afunctionoftheresistance)isthenmeasuredacrossthetwoinnermostelectrodes(XvandY).TheModels4620and4630arecalibratedtoreaddirectlyinohms.

b<A

20 A A A

Z electrodeY electrodeXv electrodeX electrode

Ω

Figure 18


5.5 Soil Resistivity Measurement Procedure (4-Point)

Givenasizeabletractoflandinwhichtodeterminetheoptimumsoilresis-tivity,someintuitionisinorder.Assumingthattheobjectiveislowresis-tivity, preference should be given to an area containingmoist loam asopposed toadry sandyarea.Considerationmustalsobegiven to thedepthatwhichresistivityisrequired.

• DisconnecttheshortinglinkfromtheXandXvterminals.• Arrangetheelectrodes inastraight line.Besurethatdistances

between electrodes are identical.Example:10ftbetweeneachelectrodeforauxiliarygroundelec-trodesthatwillbedriven10ftdeep(SeeFigure18).

• Thedistancebetweenpolesisproportionaltotheaveragedepthofthesoilsampleyouwishtomake.

• Theelectrodesshouldbeplacedatadepthofapproximately6"(0.15m),sothatthedepthisapproximately1/20thofthedistancebetween electrodes.

• UseleadstoconnecttheX,Xv,Y,andZelectrodestotherespec-tiveterminalsontheDigitalGroundResistanceTester.

• Pressthe“Test”button.• Readtheresistancelevel(R)indicatedonthedisplay.• In the event of difficulties in performing measurements,

consult the previous instructions concerning ground resistancemeasurements.

• Applythefollowingformulainordertodetermineresistivity(ρ):

ρ = 2πxRxA

A = distance between electrodes in cm

ρ = resistivity in Ωcm

R=ohmsreadingobtainedonModel4620/4630

Example 1: For measurement performed in soil with a high limestone content, the reading is R = 225Ω, with A = 300cm (3m).

ρ = 2πx225Ωx300cm

ρ=423,900Ωcm


Example 2: After inspection, the area to be investigated has been narrowed down to a plot of ground approximately 75 square feet (22.5m2). Assume that you need to determine the resistivity at a depth of 15 ft (457cm). The distance “A” between the electrodes must then be equivalent to the depth at which average resistivity is to be determined (15ft or 450cm). Using the more simplified Wenner formula (ρ = 2πAR), the electrode depth must then be 1/20th of the electrode spacing or 8-7/8" (22.5cm). If the electrode spacing is greater than 1/20th of the electrode spacing, the following formula must be used:

ρ =4πaR

1 + 2aa2 + 4b2

aa2 + b2

Lay out the electrodes in a grid pattern (Figure 20) and connect to the Model 4630 as shown in Figure 19. Proceed as follows:

• RemovetheshortinglinkbetweenXandXv

• Connectallfourauxiliarygroundelectrodes

Example 3: If the reading is R = 15:

ρ(resistivity)=2πxRxA

A(distancebetweenelectrodes)=450cm

ρ=6.28x15x450=42,390Ωcm

R

B

X Xv Y Z

AA A

Ω

Figure 19


AAA

A

A

A

Figure 20

5.6 How to Use 25Ω Calibration Checker (optional accessory)

The calibration checker is good for both the 4620 and 4630. It has aresistance of 25Ω. The procedure to use the calibration checker is asfollows:

• LoosentheX,Xv,YandZterminals.• InsertthecalibrationcheckerasshowninFigure21.• TightendowntheterminalsX,Xv,YandZ.• Pushdownthe“Test”button.• Compare thereadingon thedisplay to themeasurement range

providedbelow.

NOTE: For alignment purposes of the calibration checker, it is recommended that the shorting links remain connected.

If a check performed on the Model 4630 or 4620 displays a readingbetween 24.1Ω and 25.9Ω (as inFigure21), the instrument is in goodworkingcondition.Thereadingsareforanambienttemperaturebetween68°and79°F(25°C±3°C).

25

Ω C

AL

IBR

AT

ION

CH

EC

KE

R

®

INSTRUMENTS

Ω

Figure 21


CHAPTER 6

MAINTENANCE

6.1 Warning

Please make sure that you have already read and fully understand the WARN-ING section on page 3.

• Toavoidelectricalshock,donotattempttoperformanyservicingunlessyouarequalifiedtodoso.

• Toavoidelectricalshockand/ordamagetotheinstrument,donotgetwaterorotherforeignagentsintothecase.

• TurntheinstrumentOFFanddisconnecttheunitfromallcircuitsbeforeopeningthecase.

• Usespecifiedsparepartsonly.

6.2 DisassemblyNecessary equipment:

• ATorxACX.10screwdriverorsimilar• APhillipsscrewdriver

WiththePhillipsscrewdriver,removethe4screws(1)atthebackofthecaseandfreetheinternalunit(2)fromtheyellowcase(3).


To open the internal unit:• Settheunitupside-downonthetableandopenthebatterycompart-

ment(4)byremovingthe2Phillipsscrewsholdingthelatch.Then,freethebattery(5)orthebatteries(dependingonthetypeofinstrument).

• Removethe2Torxscrews(6) in thebottomof thebatterycompart-ment.

• Togetaccesstothetwoconnectors(9)linkingthepowersupplyanddisplayboardstogether,liftupthecoveroftheinternalunit.Oncetheseconnectorsarefree,itispossibletocompletelypullawaythebottompartfromthecover.

• Thedisplayboard(7)isconnectedtothefrontplate.• Thepowersupplyboard(8)isconnectedtothebottomofthebody.

To free the display board from the cover:• Removethe3Phillipsscrewsandunsolderallthewiresconnect-

ingtotheterminalsandtothefuse.

To free the power supply board from the bottom of the body:• Removethe6Phillipsscrewsatthebackofthebodyanddiscon-

necttheconnectorcomingfromthebattery.

6.3 Power Supply

6.3.1 Testing the Battery• Short-circuittheXandZterminals.• Pressthe“TEST”button.• Ifthelowbatteryorchargeindicatorlightsuponthedisplayyou

willneedtoreplaceorrechargethebatteries.


6.3.2 Replacing the Battery (Model 4620)• Detachthefourscrewsonthebottomoftheyellowcase.• Removetheshellandfrontpanelassembly.• Unscrew the two fasteningscrewson thebatterycompartment,

thenremovethecover.• Removethe8batteriesandreplacethem.

To replace thebatterieswith rechargeablecells (1.2V -2Ahorabove,NiCdorNiMHofthesamesize):

• Removetheplugunderthebatteries.• Settheswitchtotheposition:NiCd/NiMH• Replacetheplug.• Insertthe8rechargeablecells.

NOTE: The Model 4620 does not have a built-in battery charger. The rechargeable cells will need to be charged outside the instrument.

6.3.3 Recharging the Battery (Model 4630)• Connectthebatterychargeconnectortothemains.• TheCHARGEindicatorlightwillturnred.• Whenthebatteryischarged,theCHARGEindicatorwillbecome

green.• The charge time is approximately 6 hrs for 80% of the battery

capacity.

To achieve maximum charge capacity:• Disconnectthepowercord(thegreenLEDwillgooutinapproxi-

mately20sec).• Reconnectthepowercord.Thechargewillresumewherethefirst

chargeleftoff,andcontinueuntilmaximumcapacityisachieved.

NOTE: If the unit has been stored for a long period of time, recharge the bat-tery before use.

NOTE: 1/2 hr charge provides enough power for one day of measurements (approx 135 measurements lasting 15 sec).


6.3.4 Replacing the Safety Fuse

Tocheckthefusecontinuity,shortcircuittheXandZterminalsandmakeameasurement.IftheFAULTindicatorlightflashes,itmeansthatthefuseis blown.

Toreplacethefuse:

NOTE: Do not replace the fuse when the instrument is connected.

• Thefuseislocatedonthefrontofthefaceplate.• Usingascrewdriver,turnthescrewaquarterofaturn.• Takeoutthesupportcontainingthefuse.• Replacethefuse(0.1A,>250V,0.25x1.25").• Replacethesupportandscrewitbackin.

6.4 Cleaning

NOTE: Disconnect the instrument from any source of electricity.

• Useasoftclothlightlydampenedwithsoapywater.• Rinsewithadampclothandthendrywithadrycloth.• Donotusealcohol,solventsorhydrocarbons.

6.5 StorageIf theModel4620 isnotused fora longperiodof time (twomonthsormore),removethebatteriesandstorethemseparately.

If theModel4630 isnotused fora longperiodof time (twomonthsormore),itisrecommendedtochargethebatteryforafewhours.


Repair and Calibration

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®Instruments15 Faraday DriveDover,NH03820USAPhone:(800)945-2362(Ext.360)

(603)749-6434(Ext.360)Fax: (603)742-2346or(603)749-6309E-mail:[email protected]

(Orcontactyourauthorizeddistributor)Costsforrepair,standardcalibration,andcalibrationtraceabletoN.I.S.T.areavailable.NOTE: You must obtain a CSA# before returning any instrument.

Technical and Sales Assistance

Ifyouareexperiencinganytechnicalproblems,orrequireanyassistancewiththeproperoperationorapplicationofyourinstrument,pleasecall,mail,faxore-mailourtechnicalsupportteam:

ChauvinArnoux®,Inc.d.b.a.AEMC®Instruments200FoxboroughBoulevardFoxborough,MA02035USAPhone:(800)343-1391

(508)698-2115Fax: (508)698-2118E-mail:[email protected]

NOTE: Do not ship Instruments to our Foxborough, MA address.


Limited Warranty

TheModels4620and4630arewarranted to theowner foraperiodof two yearsfromthedateoforiginalpurchaseagainstdefectsinmanufacture.Thislimitedwarranty isgivenbyAEMC® Instruments,notby thedistributor fromwhomitwaspurchased.Thiswarrantyisvoidiftheunithasbeentamperedwith,abusedor if thedefect is related toservicenotperformedbyAEMC®

Instruments.

Full warranty coverage and product registration is available on our website at www.aemc.com/warranty.html.

Please print the online Warranty Coverage Information for your records.

What AEMC® Instruments will do:Ifamalfunctionoccurswithinthewarrantyperiod,youmayreturntheinstrumenttousforrepair,providedwehaveyourwarrantyregistrationinformationonfileoraproofofpurchase.AEMC®Instrumentswill,atitsoption,repairorreplacethefaultymaterial.

REGISTER ONLINE AT:www.aemc.com

Warranty Repairs

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®Instruments15FaradayDrive•Dover,NH03820USAPhone:(800)945-2362(Ext.360)

(603)749-6434(Ext.360)Fax: (603)742-2346or(603)749-6309E-mail:[email protected]

Caution:Toprotectyourselfagainstin-transitloss,werecommendyouinsureyourreturnedmaterial.

NOTE: You must obtain a CSA# before returning any instrument.


Notes:

01/20

99-MAN100259v22

Chauvin Arnoux®, Inc. d.b.a. AEMC® Instruments15FaradayDrive•Dover,NH03820USA•Phone:(603)749-6434•Fax:(603)742-2346

www.aemc.com

al grounddigit resistance and soil resistivity …...1.1 international electrical symbols signifies...

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