Meter Test

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Thetester measuresdirectlythe resistanceof the earth andalsomeasurethegroundresistivity.Thesturdy,elegantand compact body makes the instrument portable,easy-to-useHand-heldinstrument.

,Digital Earth Resistance Tester

FourTerminals markedasE1,P1,E2& P2. The instrumentis poweredby rechargeableNicd Cells.

Model: DEL - 2000

Low battery(LOBATor .0. sign) indicationappearson LCD INTRODUCTION: DigitalEarthresistance testeris directreplacement of the conventionIlandgeneratortypetester.It is designedfor measurement of theresistance of earthusedin powercircuits, Telecommunication,Railway electrification, domestic & industrialelectricalinstallation,lightingprotectioninstallation andvariousotherelectricalsystems.Theinstrumentperform equallywellinTerrainwheretheconductivity ofthesoilislowe.g. in mountaineous areasandin placeswherepowerfulstrayearth currentexist.

indicatesthatthebatterygoesdown,whichcanbe rechargedby connectingmainsA.C.supplythroughchargingchordprovided withtheinstrument. OPERATINGPRINCIPLE

Theprincipleusedin measuring theearthresistance is basedonsimpleohm'slaw.FourElectrodesA,B,C,Dareburiedin theearth,theresistanceofwhichisto betestedatadistanceof20 metersfrom eachotherasshowninFig.1 1

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E2

P1

The instrumentis speciallydesignedfor making straightforwardandapproximate soil investigation of thekind neededin agricultural,geologicalresearchandin planningof largecivilengineering projectssuchastunnels,Dams,Drainage, Sewerage schemes, Tube-Railways etc. \.

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A.C.

signalis appliedto electrodesA and0 andvoltage

developedacrosselectrodesBand C dueto flow of current throughthe earthis measuredby ammeterM. If currentis constant,thevoltagemeasured will bedirectlyprop,ortional to theearthresistance.

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PRINCIPLEOFMEASUREMENT: To find out Resistance of earthconnection,three terminalmethodisto beused.

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If the instrumentis to be usedfor aboveapplication, Terminals E1&P1istobeshorted(asshowninFig.4 below) e1

P-1 ~\I8W.S ~ ,..., MIl

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RUIo!EN , S

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1

P2

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A currentis passedthroughthe EARTHPLATEto an auxiliary electrodeA in the earth at a distanceawayfrom the earthplate. A secondauxiliaryelectrodeBIsInsertedbetweenEARTHPLATE AND "A", and the potential differenceV between'E and B Is measuredfor a givencurrent I so that the resistanceof earth connection is VII. The placing of the auxiliary electrodeIs howeverimportant.FollowingIsthe curvewhich givena plot of

distanceofBfromEversusmeasured resistance.

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TerminalP2 hasto be connectedto Potentialspikeand terminal E2to the auxiliaryEarthas shownin Fig.Underthis conditionmeterwil givetheresistanceoftheearthingconnection and the earth.Toavoiderror due to the wire resistances,first shortthewiresandnotedownthe meterreading.Thenconnect the wires to the differentelectrodesas explainedabove,This readingminus the readingwith wire shortedwill give actual valuedof resistance.Thedistanced1andd2 mayrangefrom 20 to 30metersdependinguponthesoil.

SPECIFICATION:

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Regularmodelhavingrange.

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OF B FROM E

Whenearthingresistanceis low,the spacingbetween the earthplateand auxiliaryelectrodemay be 20 to 30 meters. Theexactvaluecanbedecidedbyactualexperiment. --

0-20ohms(Readingscanbetakenupto19.99ohms) 0-200ohms(Readingscanbetakenupto199.9ohms) Otherrangesinstrumentcanbesuppliedagainstspecific requirements.

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HOWTOOPERATE THEINSTRUMENT:

TECHNICAL DATA: Display Dimension

3.5digit LCDdisplay.

Weight PowerSource'

575gms(Approx)

172x 98x 38x mm(Approx) Re-chargeable Nicdcells.

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ACCESSORIES: (a)CarryingCase (b)ChargingChord (c) InstructionManual

OPTIONAL ACCESSORIES:

After completingthetesting,the selectorknobshouldbe turned to "OFF"position and digits over the display will disappear.

TESTING KITWILLBESUPPLIED ONREQUIREMENT ATEXTRA .

COST.TESTINGKITCONTAINS :-

4NOS. 1NO. 4NOS. iNO. 1 NO.

SPIKES HAMMER LENGHT OF CABLE PLIER SCREWDRIVER ALLINONECANVAS BAG.

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To operatethe instrument,first turn the rangeselection switch to higher ohms rangeposition,the digital displaywill comein actionandwill readzero.Connectthetest leadsto the four terminalsasperprocedur,e for testinggivenhereafterPress theTestSwitchthe LCDdisplaywill indicatetheresistance.Ifthe reading is smaller than the lower range availablewith the instrument,the rangeselectorswitch may be turnedto lower rangeavailablewith the instrument,the rangeselectorswitch maybeturnedto lowerrangeposition.If"La BAT" indication appearson the left upperside on displayby pressingthe Test switch, it indicatesthat the batteriesgoes down and needs charging.Connectthe chargingadopterto the instrumentand chargeit for 12Hrs.beforetesting.

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[P~CiD§!!.E!-gFJ~!!-~ MEASUREMENT OFEARTHRESISTANCE ANDEARTH RESISTIVITY: ThedigitalEarthResistance testerhasfour terminals markedas E1,P1,P2& E2is suitablefor measuringEarth resistance aswellasEarthresistivity. ,b.

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MEASUREMENT OFEARTHRESISTANCE: To measureEarthresistance with digitalearthtester,it shouldbeusedasthreeterminaltype.ForthatTerming E1&P1is to be shorterandconnectedto the Earthconnectionwhose resistance hastobefound(AsshowninFig.5)

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EARTH

EARTH TESTER

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All thefour spikesto beburiedin onestraightlineand

50' to 70' I SO'to 70'

distancebetweenthemto bekeptsame. Thevalueof"L"maybekeptbetween50'to 70'

EARTH EARTHPLATE UNDERTEST

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Takethe readingby pressingtheTestswitch(TakingCare

ofRa~ge Factor)Observed valueisinohms, ConnectasperFig.5 andtakethereadingby pressingthe Testswitch. Notedownthe readingdisplayedon the LCDof the instrument.

Thevalueof EarthResistivity"p "may beobtainedfrom thefollowingformula. "

p = 2 1t LRohms-cms.

MEASUREMENT OFEARTHRESISTIVITY: TofindouttheearthResistivityfor preferredpositioning anddepthof proposedelectrode system,fourterminalsmethod istobeused.Connect theinstrument terminalsasperFig6.

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Where R = Valueof EarthResistance measuredinohms. L = Distancebetweenspikesincm. 1t

= 3.14

p = Earth'sResistivityinohms- ems.

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MEASUREMENTOFRESISTANCE

CAUTION:

(Noninductiveor Non-Capacitive) Connectthe unknownResistance'X' as per Fig.7 below andthe resistancecanbedirectlyreadoverthe LCDof themeter bypressingthetestswitch. EARTH TESTER

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SincetheinstrumentsupplyA.C.voltageto thetest object,theobjecthavingnoreactance canonlybetested.

,. PRECAUTIONS: (1) Testing should start from higher ranges to lower ranges. (2)

It is necessary to reduce the resistance of the auxiliary earthing by moisting the soil near the electrodes or by using several earth electrodes in parallel.

(3)

During tests, leads of predetermined resistances should be used and taken care of when taking reading particularly in the lower ranges Le. the lead resistance should be measured before measurement of Earth Resistance or any other resistance.

UNKNOWN RESISTANCE

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