Guangzhou Liwei FR2000+ User manual

CONTENT
I. SafetyPrecautionsand Procedures............................................ 2
II. BriefIntroduction........................................................................ 4
III.Rangeand Acuracy................................................................... 5
.TechnicalSecifications............................................................. 5
Ⅴ .StructureofMeter .................................................................... 7
Ⅵ . LCDDisplay.............................................................................. 8
Ⅶ . Measuring Principle................................................................ 10
Ⅷ. OperationMethod ................................................................. 11
1.BootUp.............................................................................. 11
2. BatteryVoltage Check....................................................... 10
3. Resistance Test................................................................. 11
4.ClockSettings .................................................................... 13
5.AlarmSettings................................................................. 11
6. DateLock........................................................................ 14
7. DataStorage / Review / Delete....................................... 13
Ⅸ．BatteryInstructions............................................................... 14
Ⅹ．FieldApplication .................................................................... 14
Ⅺ． Accessories....................................................................... 21

.SafetyRules and Pecautions
Thankyou forpurchasing ourcompany's clampgrounding
resistance tester.Beforeusing the instrumentforthe firsttime,
inordertoavoidpossibleelectricshockorpersonalinjury,please
be sureto: readandstrictlyobservethesafetyrules and
precautionslistedinthismanual.
Inany case,use thisinstrumentshouldpayspecialattention to
safety
²The instrument isdesigned, producedand inspected
accordingtoIEC61010safetyspecifications.
²Inanycase, the use ofthisinstrument shouldpayspecial
attention tosafety.
²Whenmeasuring, high-frequencysignalgeneratorssuch as
mobilephones shouldnot be usednext tothe meter toavoid
errors.
²Payattention tothe textand symbolson the bodyofthe
instrument.
²Beforeuse, makesurethat the instrument and accessories
areingood conditionbeforeuse.
²Beforestarting the machine, press the trigger once or twice to
ensurethat the jawsareclosed properly.
²Donotmeasureinaflammableplace. Sparks maycause an
explosion.

²Donotwithholdthetriggerand do notclamp any
wires whenturning onthemeter
²After the power isturned on normally, the "OLΩ"symbolis
displayed, andthe measured object can beclamped.
²Donot place and storetheinstrument for along period oftime
under conditions ofhightemperature, humidity, condensation,
and direct sunlight.
²Whenreplacing the batterywiththe meter, make surethe
meteristurned off.
²The instrument displaysthebatteryvoltage low symbol
“”,shouldreplace thebatteryintime, otherwiseit will
leadtoground error.
²The jaw contact surfaces must be kept cleanand cannot be
wiped withcorrosives andrough objects.
²Whenopeningthe trigger,avoidthe impact ofthe clamp,
especiallythe jaw joint.
²Whenthe clampmetermeasuresthe resistance, the clamp
head willmakeaslight noise, which isnormal. Notethe
“deep-beep-beep--” soundthat distinguishesthe alarm.
²Payattention tothe measuringrangeand useenvironment
specifiedbythisinstrument.
²Donotmeasurethe leadcurrent abovethe upper limit ofthe
clampmeter.
²The use, disassembly, calibration and maintenanceofthis
instrument must be performedbyauthorized personnel.

²Because ofthe reason ofthisinstrument, if it isdangerous to
continue using it, itshouldbe immediatelystopped and sealed
immediately, and it shouldbe handledbyaqualified
organization.
²The ""safetywarning sign inthe instrument and manual
must be operated strictlyinaccordancewiththe contentsof
thismanual.
Ⅱ.BriefIntroduction
Clampgroundresistance tester,also knownas loop
resistancetester,isused totestgrounding resistance.The
instrumentuses anewblackluxuryscreen design,resistance and
currentdisplayinthe samescreen,and alsohas areal-timeclock,
datastorage,dataaccess,alarm,automaticshutdownand other
functions.The machine isbeautifuland upscale,hasawide range,
highresolution,convenientoperation,easytocarry,accurate,
reliable,stableperformance,strong anti-interferenceability.
Moreover,ithas ashockproof,dustproof,moisture-proofstructure
and isacommonlyused and indispensableinstrumentfor
telecommunications,electricity,meteorology,computerrooms,oil
fields,electromechanicalinstallation and maintenance,and
industrialenterprises thatuse electricityas industrialpoweror
energy.It issuitableformeasuringvariousgroundingresistances
such as telecommunications,electricity,meteorology,computer

rooms,oilfields,powerdistribution lines,transmission lines of iron
towers,gas stations,factorygroundingnetworks,and lightning
rods.
The clampgroundresistance tester iscontrolled bythe
microprocessorand canaccuratelydetectthe ground resistance.It
uses afastfilteringtechnique tominimizeinterference.Atthe same
timedatastorage anddataupload functions
Ⅲ.RangeandAcuracy
1.Ranges and AccuracyofMeasurement
Mode Range Resolution Accuracy
Resistance
0.010Ω-0.099Ω 0.001Ω ±（1%＋0.01Ω）
0.10Ω-0.99Ω 0.01Ω ±（1%＋0.01Ω）
1.0Ω-49.9Ω 0.1Ω ±（1%＋0.1Ω）
50.0Ω-99.5Ω 0.5Ω ±（1.5%＋0.5Ω）
100Ω-199Ω 1Ω ±（2%＋1Ω）
200Ω-395Ω 5Ω ±（5%＋5Ω）
400-590Ω 10Ω ±（10%＋10Ω）
Ⅳ. Rangeand Acuracy
Functions Groundresistancetest,Loopresistancetest
AmbientTemperature
and Humidity
23℃±5℃，below75%rh
PowerSupply DC 6V （4AAalkalinedrybatteries）

Range GroundResistance：0.01-500Ω
MeasureMethod Mutualinduction
ResistanceResolution
0.001Ω
Jaw Size 55mm×32mm
Clock Function Have
DisplayMode 4-digitLCD display,black screendesign
LCD Size 46mm×29mm
MeterSize L/W/H：285mm×85mm×58mm
MeasureTime 2times/second
DataStorage 500 groups，"MEM" storageindication,display"FULL"
symbolindicatesthat storageisfull
DataReview "MR" symbolindicateswhen looking up data
Overflowdisplay "OL" symbolindicatesover-rangeoverflow
InterferenceTest Automaticallyidentifyinterferencesignals,the"NOISE"
symbolindicateswhen theinterferencecurrentis large
AlarmFunction Alarm when themeasuredvalueexceeds thealarmsetting
value
BatteryVoltage Real-timedisplayofbattery power, remindingtimely
chargingwhen batteryvoltageislow
Automaticshut-down Turn offafter5minutes
PowerConsumption 50mAMax
Weight Meter：1180g(includingbattery)
Working Temperature
and Humidity -10℃～40℃；below80%rh

StorageTemperature
and Humidity -20℃～60℃；below70%rh
Insulation Resistance Above20MΩ(500Vbetween circuitandcase)
Pressureresistance AC3700V/rms(between circuitandcase)
External Magnetic
Field
＜40A/m
ExternalElectricField ＜1V/m
SuitableforSafety
Regulations
IEC61010-1(CAT Ⅲ300V、CATIV150V、Pollution
degree2)；IEC61010-031；IEC61557-1(earthresistance)；
Ⅴ.Structure of Meter
IV.StructureofMeter

1. ClampJaw2. Trigger3. LCD
4. POWERKey5. MODE Key6.ALAlarm FunctionKey
7.MEMKey8. SET Key9. HOLDKey
10.CALIBRATIONLOOP:1
11. CALIBRATIONLOOP:10
Ⅵ.LiquidCrystalDisplay
(1). Jaw Open Symbol
(2).AlarmSymbol
(3). SymbolofGreaterThan
(4). DC ACSymbol
(5). Symbolofdataaccess
(6). Symbolofdatamemory
(7). Noisesignal

(8). Datalocksymbol
(9). Symbolofbattery
(10). Resistance unit
(11). 4-digitalLCDfigures display
(12). Current unit
(13). 2-DigitalNo. OfDataStorage Unit
(14). 4-digitalLCDcurrentand clockdisplay
Description ofSpecial Symbols
. Symbolofan open jaw: Asajawisinthe openstate,
the symbolshows.Atthispoint, triggermaybe artificially
pressed,orthe jawshave been seriouslypolluted,and can
no longer continue tomeasure.
⑵. “Er”Boot-strap errorsymbol,Maybe pressing triggerorjaw
has been openedwhen thepower isturnon.
⑶.Symboloflowbatteryvoltage:whenthe batteryvoltage
islowerthan5.2V,the symbolshows,itcannotguarantee
accuracyofthe measurements.Batteries shouldbereplaced.
⑷. "OL "symbolindicates thatthe measured resistance has
exceeded theupper limit ofthe Meter.
⑸."L0.01 "symbol indicates thatthe measured resistance has
exceeded thelower limit ofthe Meter.
⑹. "OLA"symbolindicates thatthe measured currenthas
exceeded theupper limit ofthe Meter.
⑺.Alarmsymbol:when the measuredvalue isgreaterthan

the criticalvalue ofalarmsetting, the symbolflashes, and the
meterissued byintermittent "beep--beep –beep--" sound.
⑻. MEM Symbolofdatastorage,flashing when saving data
⑼. MR Reviewdatasymbol,displaywhen viewingdata,and
displaythe number ofstored dataat the sametime.
⑽. NOISE symbol:Thissymbolflashes when thereisalarge
interference currentinthegroundloop beingtested.Atthe
sametime,the instrumentsoundsa “beep-beep-beep-”
prompt. Atthispoint, the accuracyofthe testcannotbe
guaranteed.
. Measuring Principle
The basicprincipleofthe groundresistance measurement ofthe
clamp-type grounding resistance meteristomeasurethe
loopresistance.See below.The jawsectionofthe clamp
meterconsistsofavoltage coil andacurrentcoil.The
voltage coil provides theexcitation signalandinducesa
potentialVon the circuitundertest. Underthe action ofthe
potentialV,acurrentIwillbe generatedinthe circuitunder
test. The clampmetermeasures Vand Iand uses the
followingformulatoobtainthe measuredresistanceR.
R=V/I

Ⅷ.Operation Method
1.Bootup
Boot,DONOTpressthetrigger,don’topenjaws,nor
clampanywire
Bootcomplete,show “OL ”,thenpress thetrigger,
openjaws, clampthemeasuredwire
Beforebootingup, thetriggershouldbepressed for
acoupleof times toensurethejawsarewell closed.
Boot, mustmaintainclampmeternaturalresting
state,don’tflipClamp,don’tbeimposedoutside
force on thejaw,otherwise cannotguarantee the
accuracyof measurement
Press the power button toswitch on and off. The instrument is
automaticallycalibrated when itisturned on.Whenthe poweris
turned on, OLΩ” isdisplayedandthe resistancemeasurement
mode isautomaticallyentered.Ifthereisno normalself-calibration,
the instrumentwill displaythe Er”symboltoindicatethatthe

power-on erroroccurs.The common cause ofthepower-on error
isthatthe jawsarenotclosed properly、plunge the wires etc.
when startingup.
5minutes afterpoweron automaticallyshutdown,beforethe
automaticshutdowndevice will flash for30 seconds,then press
the power button will delay the switch time5minutes..
2.BatteryVoltageCheck
Afterthe poweristurned on, if the LCD showsthe batteryvoltage
lowsymbol “”,it indicatesthatthe batteryisrunning low. Please
replace thebattery.Sufficientbatterypowertoensuretheaccuracyofthe
measurement.
3.ResistanceTest
Whentheuserthinks thatthegroundedvalue
doesnotconform tothenormal, you canuse a
randomcalibration ringtocheckwhetherthe
clampmeterisnormal. Thecheck ring has two
resistancesof 1Ωand10Ω.
Afterthe power-on self testiscompleted, the large middledigit
shows “OLΩ” andresistance measurementcan be performed. Atthis
point,withholdthetrigger,open thejaws,clampthe circuit undertest,
and read theresistance value.
The largemiddledigit shows"OLΩ",indicating thatthe measured
resistance exceedstheupperlimit ofthe clamp meter.
The middlelarge numbershows"L0.01 Ω",indicating thatthe
measured resistance exceedsthe lowerlimit ofthe clamp meter.

Resistance + clockmode:
The measuredresistance loopresistance
is0.51Ω.
The number ofsavegroupsis1and the
loopgroundvoltagetobe measured is0.0V.
Resistance + clockmode:
The circuitofthe measuredresistance exceedsthe lowerlimit,
The number ofsavegroupsis8and the current timeis12:08
4．ClockSettings
Afterpoweron,long press the "SET"button (morethan 3
seconds)toenterthe clocksetting mode.When the timedata
flashes,itisinthe modified state.Press the "AL"button orthe
"MEM" button toincreaseordecreasethe correspondingdata.
Short pressthe "MODE"button toswitch.Tomodifythe data,press
the "SET"button againtosaveand exit.

5.Alarm Settings
Afterpoweron, short press "AL"keytoturnon oroffthe alarm function,
long press "AL" keytosetthe resistance alarmvalue, press the "SET"
keyand "MEM"keytochange the currentsize, short press "MODE"key
toswitch Alarmmode, longpress "AL"keytosaveandexit.When the
measured resistance isgreaterthan the alarmcriticalsetting and the
alarmisturned on, the meterflashesthe “”symboland issuesa
“beep-beep-beep--”alarmsound. The maximumvalue ofthe ground
resistance alarmsetting is200Ω.Asshownbelow:
6.DateLock
Afterthe measurementisstableafterpoweron, short press
“HOLD”keytolock thecurrentdisplaydata, savethedata,andpress
“HOLD”keyagain to exit lock mode. Asshownbelow:
7．DataStorage/ Review/ Delete
Whenthemeasurementiscompleted afterpoweron,short
press "HOLD"keytostoredata,"MEM" symbolflashesand
automaticallynumbers,ifthe memoryisfull,the instrumentflashes
todisplay"MEM" symbol,press "MEM" keytoenterthe data
review,storedatareadinginterface"MR"symboldisplay.Press

AL”or SET”keytoselectthecorresponding dataofthe array
numberwithastepvalue of1,and press MEM”againtoexit.
See the figurebelow.The left figureflashesthe MEM”symbol
when the dataisstored.The currentstorage groupnumberis1;
the middlefigureisthedatareference mode,andthe current
number ofreference groupsis1.
Inthe datareviewstate,longpressthe "SET"button,then
press the "POWER"buttontodeletethe storeddata
Ⅸ.BatteryInstructions
When the voltage dropsto5.2V,the batterysymbol""is
displayed. Pleasereplace the battery.Lowbatteryvoltage affects
measurementaccuracy.
Ⅹ.FieldApplication
1.Multi-PointGrounding System
Asforthe multi-pointgroundingsystem(suchas electricity
transmission towergroundingsystem,grounding cable
communications systems,certainbuildings,etc.), Theyusually

pass the overhead groundwire(cableshielding layer) connected
toformagrounding system.See below.AstheMeterisinthe
abovemeasurement, itsequivalentelectriccircuitisshowninthe
figurebelow:
Where: R1isthetarget groundingresistance.
R
0
isthe equivalentresistance ofthe otherentiretower
groundingresistances paralleled.
Althoughstrictlyon the theoreticalgrounding,because ofthe
existence ofso-called "mutualresistance”, R
0
isnotthe usual
parallelvalue inthe senseofelectricalengineering (slightlyhigher
than itsIECparalleloutputvalue). Butbecauseatower-grounding
hemispherewas muchsmallerthan the distancebetween the
towers,and withagreatnumberoflocations afterall,R0ismuch
smaller than R1. Therefore, it can be justifiedtoassumeR0=0from
an engineering perspective.Inthisway,the resistance we
measured shouldbe R1.
Times ofcomparing testsindifferentenvironmentsand different
occasions withthetraditionalmethod proved thatthe above
assumptionisentirelyreasonable.

2. LimitedPointGrounding System
Thisisalso quitecommon.Forexample,insometowers,five
towersarelinkedwitheach otherthrough overheadgroundwire;
Besides,the groundingofsomeofthe buildings isnotan
independentgroundinggrid,butseveralgrounding bodies
connected witheach other through the wire.
Undersuch circumstances,the aboveR0regarded as 0,will yield
moreerror on the resultsofthe measurement.
Due tothesamereasonsmentioned above,wemayignorethe
impactofthe mutualresistance;and the equivalentresistanceof
the grounding resistanceparallelediscalculatedbythe usual
sense.Thus,forthe groundingsystemofN(Nissmaller,butlarger
than 2) grounding bodies, it can offerNequations:
.
.
.
T R
RRR
R=
+++
+
−)1(21
1
......
11 1
R
1T
R
R
3
R
2
R
1
1
......
1
1
1
=
+
+
+
+
T
R
RRR
R2
31
21
......
11 1=
+++
+

Where:R1、R2、……RN aregroundingresistances ofNgrounding
bodies.
R
1T、R2T、……RNT arethe resistances measured withthe
Meter inthe different grounding branches.
It isnonlinearequations withNunknownnumbersand Nequations.
It indeedhasadefinitesolution,butitisverydifficulttosolvethe
issueartificially, even impossiblewhen Nislarger.
Therefore,you’reexpected tobuythe Limited-PointGrounding
SystemSolution softwareproduced byourcompany.Userscan
use the officecomputerornotebookcomputertocarryout
solutions.
Inprinciple,inadditiontoignoring the mutualresistance,this
method doesnothavethe measurementerrorcaused by
neglecting R0.
However,usersneed topayattention tothat: inresponse tothe
numberofthe grounding bodies mutuallylinked inyourgrounding
system, it isnecessarytomeasurethe samenumber ofthe testing
values forcalculatingofthe program,notmoreorless.Andthe
programwouldoutputthe samenumberofgroundingresistance
values.
3. Single-PointGrounding System
Fromthe measuring principle,EARTHTESTERseries Metercan
onlymeasurethe loop resistance,and the single-pointgroundingis
notmeasured.However,userswill beabletouseatesting line
veryneartothe earthelectrode ofthe grounding systemto
artificiallycreatealoopfortesting.The following presentedistwo

kindsofmethods forthe single-pointgrounding measurementby
use ofthe Meter.Thesetwomethodscan be appliedtothe
occasions beyond the reach ofthe traditionalvoltage-current
testing methods.
.Two-PointMethod
Asshowninthe figurebelow,inthe vicinityofthe measured
groundingbodyRA, find anindependentgroundingbodyofbetter
groundingstateRB (forexample,nearawaterpipeorabuilding).
RAand RBlinewillconnecttoeach otherusingasingletestingline.
Asthe resistancevalue measuredbythe Meteristhe value ofthe
seriesresistance fromthe testing line andtwogrounding
resistances.
RT=RA+ RB + RL
Where: RT isthe resistancevalue measured withthe Meter.
R
L
isthe resistancevalueofthe testing line.
Metercan measureouttheresistancevalue byconnectingthe
test lineswithbothends.
So,if the measurementvalueofthe Meterissmallerthan the
allowablevalue ofthegroundingresistance,then the two
groundingbodiesarequalified for grounding resistance.