Extech Instruments GRT350 User manual

UserManual
EarthResistanceandResistivityTester

ModelGRT350
AdditionalUserManualTranslationsavailableatwww.extech.com
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GRT350‐en‐GB_v1.312/16
2
Introduction
ThankyouforselectingtheExtechInstrumentsModelGRT350EarthResistanceandResistivity
Tester.TheGRT350hasbeendesignedandtestedaccordingtotheIECPublication348,safety
requirementsforElectronicMeasuringApparatus,EN61010‐1,EN61326‐1,EN61557‐1,EN
61557‐5andothersafetystandards.Thisdeviceisshippedfullytestedandcalibratedand,with
properuse,willprovideyearsofreliableservice.Pleasevisitourwebsite(www.extech.com)to
checkforthelatestversionofthisUserGuide,ProductUpdates,ProductRegistration,and
CustomerSupport.

Features
Microprocessorcontrolledwithadvancedsafetyfeatures
TwolineLCDdisplay
Auto‐Ranging
Earthresistancetestingwiththreeranges:0‐20Ω/0‐200Ω/0‐2kΩ
Earthvoltagemeasuringrangeof0‐300Vac
AutomaticC(current)spikecheck.
AutomaticP(potential)spikecheck.
2‐wiretest
3‐wiretest
4‐wiretest
EarthResistivity(Wenner–4terminal)
Autopoweroff
Lowbatteryindicator
Datahold
200memorylocationstosavetestdata
Safetystandard:EN61010‐1CATIV300V,EN61326‐1

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GRT350‐en‐GB_v1.312/16
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SafetyInformation
 Readtheallsafetyinformationcarefullybeforeattemptingtooperatethemeter.
 Usethemeteronlyasspecifiedinthismanual.Otherwise,theprotectionprovidedbythe
metermaybeimpaired.
 Ratedenvironmentalconditions:
Indoor&outdooruse
InstallationCategoryIV300V
PollutionDegree2
Altitudeupto2000m
RelativeHumidity80%maximum
Ambienttemperature0‐40°C

ObservetheInternationalElectricalSymbolslistedbelow:
Doubleinsulation
Thissymbol,adjacenttoaterminal,indicatesthat,undernormaluse,hazardous
voltagesmaybepresent
Thissymbol,adjacenttoanothersymbolorterminal,indicatestheusermustrefer
tothemanualforfurtherinformation.
Earth(ground)terminal
 EquipmentcomplieswithcurrentEUdirectives
WARNING
Toavoidelectricalshock,donottouchtheterminalsduringtests
NeverapplyVoltagehigherthan300VacrossP1andP2terminals
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GRT350‐en‐GB_v1.312/16
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1
2
3
4
5
6
7
8
9
10
11 12 13
MeterDescription

1.C1terminal(Blacktestleadconnection)
2.P1terminal(Greentestleadconnection)
3.P2terminal(Yellowtestleadconnection)
4.C2terminal(Redtestleadconnection)
5Display
6.RcLED
7.RpLED
8.Savebutton
9.Cursorbuttons
10. Cursorbuttons
11.ESCbutton
12.Powerbutton
13.TEST/STOPbutton
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GRT350‐en‐GB_v1.312/16
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Operation
BatteryVoltagecheck
Pressthe"ON/OFF"button,if"BatteryLow"appearsonthedisplay,replacethebatteries.
EarthVoltagemeasurement

1. Connectthetestleadsasshownbelow.
MAX.
AC 300V
P2C2
C1P1
H
S
EES
12

(1) Earthelectrode(rod)undertest(2)Testspike
2. Pressthe"ON/OFF"buttonandwaitfor“SelectFunction”toappearonthedisplay.
3. Pressthe"►"button3timesandwaitfor"ACV"toappearonthedisplay.
4. Pressthe"TEST/STOP"button.
5. Theearthvoltagewillappearonthedisplayifitispresent.
6. PressSAVEtosavethemeasurementinLogmemory.
7. PressESCtoreturntothe“SelectFunction”display.
MeasurementConsiderations
Two‐terminaltestingofearthresistanceisappropriateformostgeneralpurposetestingin
normallyconductivesoil.However,two‐terminalmeasurementsincludetestleadandcontact
resistanceinthemeasurementandtheresultwillbeareadingslightlyhigherthanthetrueearth
resistance.
Whenmeasuredresultsarehigherthandesiredorifmeasurementdirectivesrequiremulti‐
terminaltechniques,switchtothe3or4terminaltechniquesasneeded.
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GRT350‐en‐GB_v1.312/16
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EarthResistancemeasurement
Note:Themeasuredresultsmaybeinfluencedbyinductiveorcapacitivecouplingifthetest
leadsaretwistedoradjacenttoeachother.
WhenconnectingtheProbes,keeptheleadsseparated.
Setup
InsertthePotentialelectrodes(P)andtheCurrentelectrodes(C)asdeepaspossibleintothe
soil.Thedistancebetweenelectrodesmustbe5to10m(16to32’).

Four‐terminalearthresistancemeasurements
12
MAX.
AC 300V
H
S
EES
P
2
C
2
C
1
P
1
3
(1)Earthelectrode(rod)undertest(2)Potentialspike(3)Currentspike


Three‐terminalearthresistancemeasurements
12
MAX.
AC 300V
HSEES
P
2
C
2
C
1
P
1
3
(1)Earthelectrode(rod)undertest(2)Potentialspike(3)Currentspike


Two‐terminalearthresistancemeasurements
12
MAX.
AC 300V
P2C2
C1P1
H
S
EES
(1)Earthelectrode(rod)undertest(2)Potentialspike
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GRT350‐en‐GB_v1.312/16
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Testing
1. Connectthetestleadsfor2,3or4terminalEarthResistancetesting.
P1=Greenlead,C1=Blacklead,P2=Yellowlead,C2=Redlead
2. PresstheON/OFFbuttonandwaitforthe“SelectFunction”screentoappear.
8. Pressthe"►"buttontoselect"2P","3P"or"4P"dependingonthetest.
3. Press"TEST/STOP"buttontobeginthetest.
4. Themeterwillbeepwhilethetestisinprogress(forapproximately10seconds)andthen
thereadingwillappearonthelowerlineofthedisplay.
5. PressSAVEtosavetheresultsinLogmemory.
6. PressESCtoreturntothe“SelectFunction”display.

Notesfor"Rc"&"Rp"LEDindications:
Rc:Notestcurrentoutput.Checktheconnectionsandsettings.
Rp:IfRpisonandthedisplayindicates“>2kΩ”,theearthresistanceisgreaterthan2000Ω.
EarthResistivityTesting(ρ)(Wenner4‐pointmethod)
Insertthefourelectrodesatequaldistances(andinastraightline)atanintervalof1to30m(3.3
to32.3’)apart.Thedepthshouldbe5%(orless)thedistancebetweentheelectrodes.

Forexample:ifthedistancebetweentheelectrodesis5m(16’),theelectrodesshouldbe
insertedtoadepthof25cm(10”).(500cmx5%=25cm)
NOTE:Thelengthcanbesetbetween1and50m(3.3’and164’).


1. Connectthetestleadsfor4terminaltesting.
7. PresstheON/OFFbuttonandwaitforthe“SelectFunction”screentoappear.
2. Pressthe"►"buttonandselect"Resistivity".
3. Press"TEST/STOP"button.Thesettinglengthwilldisplayonthescreen.
4. Pressthe"►"or"◄"arrowbuttonstosetthecountupordown.
5. Press"TEST/STOP"buttontobeginthetest.
6. PressSAVEtosavetheresultsinLogmemory.
7. PressESCtoreturntothe“SelectFunction”display.





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GRT350‐en‐GB_v1.312/16
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SaveFunction
Themeterpermitssavingmeasurementsinupto200memorylocations.
Whenatesthascompleted,presstheSAVEbuttontostorethemeasureddata.

Thedisplaywillshowthelocationnumberofthesaveddata.“SAVE###”

LOGDisplay
1. PresstheON/OFFbuttonandwaitforthe“SelectFunction”screentoappear.
2. Pressthe“►”buttonandselect“LOGDisplay”.
3. Pressthe“TEST/STOP”button.Thelognumberwilldisplayonthescreen.
4. Pressthe"►"or"◄"arrowbuttontoscrollthroughthesaveddata.
5. PressESCtogetbacktothe“SelectFunction”display.

LOGClear
1. PresstheON/OFFbuttonandwaitforthe“SelectFunction”screentoappear.
2. Pressthe“►”buttonandselect“LOGClear”
3. Pressthe“TEST/STOP”button.“Areyousure?”willdisplayonthescreen.
4. Pressthe“TEST/STOP”buttontoclearthelogdata.“Successful!”willdisplayonthe
screen.
5. Pressthe“TEST/STOP”buttontoverifythatthedatalogisclear.“NoLogdata”will
displayonthescreen.
6. PressESCtogetbacktothe“SelectFunction”display.
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GRT350‐en‐GB_v1.312/16
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Maintenance
1. Rearcover
2. Batterycompartment
3. Fuse

FuseReplacement
1. Disconnectthetestleadsfromtheinstrument.
2. Removetherearcoverbyremovingthetwoscrews.
3. Removeandreplacethefusewithanewoneofthesamevalueandsize
0.5A/500V,(5x20mm).
4. Replaceandsecuretherearcover.

Batteryreplacement
When“BatteryLow”appearsonthedisplay,replacethebatteries.
1. Disconnectthetestleadsfromtheinstrumentandremovetherearcoverandthe
batteries.
2. Replacewitheight1.5VAAbatteries,takingcaretoobservecorrectpolarity.
3. Reinstallbatteryholderandbatterycover.

Neverdisposeofusedbatteriesorrechargeablebatteriesinhouseholdwaste.
Asconsumers,usersarelegallyrequiredtotakeusedbatteriestoappropriatecollection
sites,theretailstorewherethebatterieswerepurchased,orwhereverbatteriesaresold.
Disposal:Donotdisposeofthisinstrumentinhouseholdwaste.Theuserisobligatedto
takeend‐of‐lifedevicestoadesignatedcollectionpointforthedisposalofelectricaland
electronicequipment.
Cleaning
WARNING:Toavoidelectricalshockordamagetothemeter,donotallowwaterinsidethe
case.
Periodicallywipethecasewithadampclothanddetergent,donotuseabrasivesorsolvents.
1
2
3
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GRT350‐en‐GB_v1.312/16
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Specifications
EarthResistanceRangesRanges:0‐20Ω,0‐200Ω,0‐2kΩ 
Accuracy:±(2%rdg+3dgt)
EarthResistanceResolution0‐20Ω:0.01Ω
0‐200Ω:0.1Ω
0‐2kΩ:1Ω
EarthVoltageRange:0‐300VAC(50/60Hz)
Accuracy:±(2%rdg+3dgt)
EarthResistivityRanges(ρ)
(ρ=2πLR)
L=distancebetweenprobes
R=resistance
0.06‐6.28kΩ.m
0.62‐62.8kΩ.m
6.28‐628kΩ.m
TestFrequency820Hz
TestCurrent2mA
DataMemory200manuallocations
TestleadlengthsGreenlead5m(16ft)
Blacklead10m(32ft)
Yellowlead10m(32ft)
Redlead15m(49ft)
Temperature&HumidityOperating:0to50°C(32to122°F);≦80%R.H.
Storage:‐10to60°C(14to140°F);≦80%R.H.
Altitude2000m(6500’)max
PowerSource1.5V(AA)x8batteries
Dimensions250(L)x190(W)x110(D)mm(9.84x7.5x4.33”)
WeightApprox.1430g(batteriesinstalled)
Fuse500mA/500V(5x20mm)fastblow,ceramictype
SafetyStandardsCATIV‐300V,EN61010‐1,EN61326‐1,EN61557‐1,EN61557‐5
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