4-Terminal Earth/Ground Resistance And Soil Resistivity .
DET4 SeriesEarth/Ground Resistance & Soil Resistivity TestersDET4 Series4-Terminal Earth/Ground Resistanceand Soil Resistivity TestersDESCRIPTIONMegger’s popular 4-terminal ground testing instrumentfamily includes four basic models with different kit variantsfor each that include select accessories for greater testingflexibility. The four basic units are:ModelDescriptionDET4TD2Dry-cell battery powered basic 4-terminaltesterDET4TR2Rechargeable battery powered basic4-terminal testerDET4TC2Dry-cell battery powered 4-terminal testerwith selectable test frequencies, greatermeasurement sensitivity and attached rodtechnique and stakeless measurementcapabilityDET4TCR2Rechargeable battery powered 4-terminaltester with selectable test frequencies,greater measurement sensitivity andattached rod technique and stakelessmeasurement capabilityThe top-end models (DET4TC2 and DET4TCR2) includea current measuring function for ART (Attached RodTechnique) testing capabilities. With this added function,on-site grounds can be tested separately without having toremove the utility connection (as explained further in thisdocument). They also provide stakeless testing capability.This method allows the operator to use the instrumentlike a clamp-on ground tester in applications where thatmethod is viable, while also being able to operate as a fallof potential tester if required.n2, 3 and 4 point testingnStakeless (clamp-on) testing capabilitynART (Attached Rod Technique) capabilitynMultiple, user selectable test frequenciesnResistance measurement range to200,000 ΩnIP54 ratednWarning indicators prevent test failurenSimple one button operationnIncluded leads, stakes, calibrationcertificate and rugged carry caseThe basic kit includes the test leads, stakes, batteries andcalibration certificate, delivered in a tough polypropylenecarry case – everything you need to start testing in onepackage.All models are rated to IP54, making them truly outdoorinstruments. They are designed to meet stringent safetystandards and are rated CAT IV 100 V. The ground testershave been designed to be easy to use – a large selectorswitch makes selection of 2, 3 or 4 pole tests easy withgloved hands – and the design makes the fitting of shortinglinks to perform 2-pole tests a thing of the past. A large,clear, easy to read LCD and thumb sized test buttonalso make the instruments particularly well suited to theoutdoor conditions of ground testing. In addition to thisease of use feature, the instruments automatically checkthe connection and conditions of the P spike, C spike,and also the level of ground noise, indicating the statuson the display. They also include a voltmeter to enablemeasurement of ground voltage.The DET4TD2 and DET4TR2 can measure resistance from0.01 ohms to 20 kΩ, while the DET4TC2 and DET4TCR2can measure resistance from 0.01 ohms to 200 kΩ, a keycapability for soil resistivity testing. Also, to allow accuratetesting in noisy environments, the instruments are capableof rejecting noise up to 40 V peak to peak.The DET4TD2 and DET4TC2 are powered by eight AAbatteries which are widely available and also give excellenttesting time – the status of these batteries is given by a bargraph on the LCD display, allowing the operator to decidewhen to change the batteries before they expire. TheDET4TR2 and DET4TCR2 are powered from rechargeable
DET4 SeriesEarth/Ground Resistance & Soil Resistivity TestersAA cells. The battery charger is built in and the instrumentis supplied with an AC/DC adapter. For all instruments, thebattery status is displayed using a bar-graph.The DET4TC2 and DET4TCR2 include additionalcapabilities. By using the optional ICLAMP the user canaugment the traditional fall-of-potential measurementmethod with ART (Attached Rod Technique), which allowselectrode testing without disconnection and also leakagecurrent measurements down to 0.5 mA. A second optionalclamp, the VCLAMP, enables true stakeless (clamp-on)measurements to be made in situations where drivingstakes is not practical.The DET4TC2 and DET4TCR2 also feature a backlitdisplay, which extends the operational environment ofthe instrument to cable cellars and other dark locations.Finally, all units have selectable 25 V or 50 V output forcompliance with IEC 61557-5. The 25 V output is requiredfor testing in agricultural environments.The maintenance of an adequate low resistance groundconnection is essential to both the protection andperformance of any electrical system. Ground testingshould be performed both upon installation, to meetdesign specification, and periodically thereafter in orderto maintain service. All Megger models can also performbonding tests (using an ac signal), to determine thatadequate connection has been made from equipment tothe grounding system, and can perform soil resistivitytests. This additional function can be used in prospecting,locating, and designing new grounding electrodes andsystems. Furthermore, the addition of built-in currentclamp capability enables fall of potential testing of attachedgrounds (ART) without lifting the utility connection andthe addition of voltage clamp technology enables stakelesstesting from the same instrument.Grounding electrodes from simple to complex systems canbe tested, including:n Primary and secondary electrical grounding systemsn Utility pole groundsn Lightning protection systemsn Residential groundsn Machinery safety groundsn Computer and communication system groundsn EMI/RFI system groundsn Antenna and pedestal groundsn CATV system groundsFEATURES AND BENEFITSStakeless testing capability, which allows the operatorto use the instrument like a clamp-on tester in applications where the method is viablen Attached Rod Technique capability, which allows fallof potential testing without the need to disconnect theground rodn Multiple, user selectable test frequencies allows theoperator to find the most effective frequency for makingthe measurementn 200,000 Ω measurement range provides the ability tomeasure the resistivity of any type of soiln User selectable test voltage ensures that the units can beused in agricultural environmentsn Microprocessor control for improved error detectionn Clear, unambiguous warnings and error indications ensure the reliability of the reading and reduce test timen Rugged, weatherproof case to IP54 makes the units trulyoutdoor instrumentsn Backlit LCD allows for testing in dark environmentsn Noise rejection to 40 V pk to pk allows accurate testingin noisy environmentsn Testing kits and certificates supplied — everythingneeded to start testing immediatelyn Accuracy of 2% of reading enhances reliability of measurementsn Voltmeter function included allows you to measure theground voltage and enhances operator safetyn CAT IV 100V provides increased operator safetynModel DET4TCR2 shown performing the stakeless ground testing methodusing only clamps.APPLICATIONSProper grounding provides many varied benefits to bothpeople and facilities. It lessens the chance of injury dueto faulty installation, reduces the likelihood of damagefrom lightning strikes and induced voltages, improvesthe performance of computer, communication and othersensitive equipment and protects against static electricityfrom friction. Over time, ground systems can degrade orbecome ineffective. Corrosion and weather influencesexert mechanical strain on ground rods and cause metalliccorrosion. Catastrophic events like lightning strikes or largefault currents can cause instant degradation. In addition,soil resistivity can change over time due to environmentalconditions and facility expansion can create differentground system needs.The risks from ground system deterioration includepotentially deadly electrical shock situations, plant-wideequipment damage, disruption in the performance ofsensitive equipment and heat build-up on a single piece ofelectrical equipment.
DET4 SeriesEarth/Ground Resistance & Soil Resistivity TestersSPECIFICATIONSResistance range: 0.01 to 200 kΩ autoranging(0.01 to 20kΩ for models DET4TD2 and DET4TR2)Resistance accuracy:2P measurements2% 3 digits3P measurements2% 3 digits4P measurements2% 3 digitsART measurements5% 3 digitsStakeless measurements 7% 3 digitsMaximum probe resistance:DET4TD2 and DET4TR2Rp limit: 100kΩ (50V output voltage)Rc limit: 100kΩ (50V output voltage)Limits reduced to 50kΩ for 25V output voltageLimits reduced to 5kΩ for 0.01 Ω resolutionDET4TC2 and DET4TCR2Rp limit: 200kΩ (50V output voltage)Rc limit: 200kΩ (50V output voltage)Limits reduced to 100kΩ for 25V output voltageLimits reduced to 5kΩ for 0.01 Ω resolutionEarth voltage range: 0 – 100 VEarth voltage accuracy: 2% 2 V2-wire test: Yes, all models3-wire test: Yes, all models4-wire test: Yes, all modelsART (Attached Rod Technique): DET4TC2, DET4TCR2Stakeless test: DET4TC2 and DET4TCR2Ground current range (with current measuring clamp):0.5 mA to 19.9 AGround current accuracy: 5% 3 digitsDisplay:DET4TD2 and DET4TR2: 3-1/2 digit high contrast LCDDET4TC2 and DET4TCR2: 3-1/2 digit high contrast LCD, backlitSTAKELESS (CLAMP-ON) TESTINGThe DET4TC2 and DET4TCR2 include stakeless, orclamp-on testing capability. In effect, these models canbe operated in the same way as a clamp-on groundtester, eliminating the need to disconnect the groundunder test and drive test probes in certain ground systemtesting applications. This method is also useful whenTest frequency: 94, 105, 111 and 128 Hz(128 Hz for DET4TD2 and DET4TR2)Test voltage: 25 V or 50 V, user selectable (factory setting 50 V)Test current: 450 micro-amps at 25 V or 50 V (selectable),4.5 mA at 25 VNoise rejection: 40V pk to pkNoise check: AutomaticC spike check: AutomaticP spike check: AutomaticBattery type: 8 1.5 V AA cells (8 1.5 V AA NiMH rechargeablecells – DET4TR2 and DET4TCR2)Battery life: 3 hours, 700 consecutive testsSafety: EN61010-1 CAT IV 100 VTerminals: 4 mm plug type (test leads)Ingress protection: IP54EMC: Meets the requirements of EN61326-1:1998 for use in heavyindustrial areas, including amendment 1Dimensions: 8 x 5.7 x 3.2 in. (203 x 148 x 78 mm)Weight: 2.2 lb (1 kg)Operating temperature range: 5º to 131º F (-15º to 55º C)Storage temperature range: -40º to 158º F (-40º to 70º C)Humidity: 95% RH non-condensing at 104º F (40º C)Standards ComplianceComplies with the requirements of KEMA K85B.Complies with the following parts of EN61557, “Electrical safetyin low voltage distribution systems up to 1000 V a.c. and 1500 Vd.c. - Equipment for testing, measuring or monitoring of protectivemeasures”.Part 1 - General requirementsPart 5 - Resistance to earththere is insufficient space to perform a classic fall-ofpotential measurement. In addition the units can be usedto measure ground leakage or phase current.The user simply clamps the optional ICLAMP (currentclamp) and VCLAMP (voltage clamp) around the groundunder test in the manner prescribed in the operator’smanual and takes the reading. A defined test voltage isinjected into the system using the VCLAMP, inducing acurrent, I, to flow and be measured by the ICLAMP. Theinstrument then calculates the approximate resistance ofthe ground under test.The stakeless method is subject to the same limitationsfaced by the traditional clamp-on ground tester. It iseffective only in situations with multiple grounds inparallel and cannot be proofed like a fall-of-potentialtest. In situations where the stakeless method reading isquestionable, a full fall-of-potential test is recommended.The advantage of the DET4TC2 and DET4TCR2 is that theunits include both test methods in a single instrument,making them the most versatile units available.
DET4 SeriesEarth/Ground Resistance & Soil Resistivity TestersART (ATTACHED ROD TECHNIQUE)TESTING CAPABILITYThe DET4TC2 and DET4TCR2 include the additionaltesting capability that we have termed ART, for AttachedRod Technique. A nagging problem with traditionalground testing has been the requirement to “lift” (i.e.,disconnect) the utility connection. Once the groundingconductor (the main conductor that connects the facilityto the ground rod or grid) has been attached to thegrounding electrode, the utility ground becomes a parallelresistance. The utility neutral is typically bonded to theground bus at the service entrance and this connection,during a ground test, causes test current to flow backthrough the utility ground as well as through the testelectrode. Test current divides according to Law of ParallelResistance, but the tester makes its measurement based ontotal current flow. The reading is the combined parallelresistance of the on-site ground and the utility protection.This is a valid measurement, but not of the test electrodeexclusively.This poses a considerable problem in many commontesting situations. If a commissioning test were required todetermine if design specifications had been met for a newfacility, such a reading would be insufficient. Lightningprotection requiring a short, straight path into the earth,could also not be properly validated. But lifting the utilityconnection poses several problems, not the least of whichis the breaking of what is often a welded bond, in additionto the temporary loss of protection.Clamp-on ground testers, which measure groundresistance by clamping around the rod and inducing atest current onto it, are only a limited solution. They canaccurately measure resistance of a single rod in a parallelsystem by inducing the test current onto the clampedrod and utilizing all the parallel grounds as the return.Collectively, these returns, typically the multiple groundsof the utility, contribute little to the loop measurement.This is essentially the reverse of the operation of atraditional tester, which uses the current probe asthe return while current “goes to ground” through allparallels collectively. This technique solves the problemof separately measuring an attached rod, but leaves theproblem that it cannot be proven.A clamp-on measurement has to be accepted on faithand its reliability is based squarely on the knowledgeand experience of the operator, leaving a large marginfor “human error.” In complex, multiply connected gridsand other grounding schemes, return paths may existthat are entirely metallic, not including earth at all. Theclamp-on test current will circulate through such pathsand give a reading, essentially a continuity reading of thegrid structure having nothing to do with soil resistance.Such readings will be low, and appear to the uninformedas acceptable grounds. The responsibility for makingthese determinations falls squarely on the operator.But even when properly addressed, there is no way ofdemonstrating the competence of the readings to a thirdparty, such as a client. They must simply be accepted.The ART testing capability combines the advantages ofboth of these technologies to produce a method thatcan reliably measure an attached ground, and proveit! A built-in clamp input, used in conjunction with theoptional ICLAMP accessory, connected below the point ofseparation of the parallel test currents, measures only thecurrent flowing through the test ground, not that goingback through the utility. This current value is then used bythe microprocessor to calculate ground resistance, strictlyin accordance with Fall of Potential or its derivativeprocedures, supported by IEEE Standard 81 for properground testing, and subject to the appropriate proofs.The ART method employs leads and probes just as doesany traditional tester. Ground resistance can be profiledand graphed by moving the potential probe against theposition of the current probe, and a Fall of Potential graph,Slope Method mathematical proof, or any of the otherproven methods utilized to demonstrate the accuracy ofthe test. The only thing different from the operation of afamiliar, traditional ground tester is that the clamp permitsseparation of the test currents in an attached or otherwiseparallel-grounded system. This technique enables localgrounds to be tested without lifting the utility connection,yet with the ease, reliability and confidence of a separatecommissioning test.Current measuring clamp (inset)for ART testing capability
DET4 SeriesEarth/Ground Resistance & Soil Resistivity TestersSELECTION GUIDETestsOutputPower SupplyNoise RejectionSafety RatingIngress ProtectionIncluded AccessoriesWarrantyModel No.DET4TD2DET4TR2DET4TC2DET4TCR2Cat. No.1000-3471000-3241000-3451000-3462-Pole Measurementnnnn3-Pole Measurementnnnn4-Pole MeasurementnnnnSoil ResistivitynnnnART (Attached RodnnTechnique) CapabilityStakeless (Clamp-on)nnMeasurement CapabilityResistance Range 0.01 to 20,000 Ω 0.01 to 200,000 ΩGround Voltage Range0 to 100 VGround Current Range 0.5 mA to 19.9 A(with ICLAMP) CapabilitySelectable Voltage (25/50 V)nnnnTest Frequency 128 Hz 94, 105, 111, 128 HzAlkaline BatteriesnnRechargeable Batteriesnn40 V Peak-to-PeaknnnnCAT IV 100 VnnnnRated to IP54nnnnHard Carry CasennnnTest Leads (49 ft, 33 ft,nnnn33 ft, 10 ft) and SpikesCertificate of Calibrationnnnn3 YearnnnnCONFIGURATION OPTIONSDET4TC2 Clamps1000-365nnnnnDET4TC2 Kit1000-404nnnnnDET4TCR2 Clamps1000-366nnnnnnDET4TCR2 Kit1000-405nnnnnnRechargeablebatteriesCat. No.Alkaline batteriesModel No.PowerSupplyEarth/ground kit,C/N 6320-245ICLAMP andVCLAMPField CalibratorExternal ac/dcAdapterLeads (49 ft, 33 ft,33 ft, 10 ft) and Spikes4 Right-angleterminal adaptersHard carry caseIncluded Accessoriesnnnnnn*The Professional Ground Testing Kit (C/N 6320-245) includes two 164 ft (50 m) leads and two 98 ft(30 m) leads on retractable reels, four auger-style ground spikes, a tape measure and a separate hardcarry case.NOTE: Using the ICLAMP allows the operator to make ART measurements. Using the ICLAMP andVCLAMP allows the operator to make stakeless (clamp-on) measurements.
DET4 SeriesEarth/Ground Resistance & Soil Resistivity TestersDET4TC2 OPERATIONTest lead connections(at rear)LCD DisplayResistancemeasurementsettings25V / 50V outputvoltage selectbuttonSelector switchTest buttonFrequencyselect buttonBacklightcontrol buttonVoltage and currentmeasurement settingsDET4TC2 DISPLAY Warning - referto user manualBattery chargeindicatorMeasuringrangeOver/underrange indicatorPotential probe resistanceindicator (OK or high)Current probe resistance(OK or high)Ground noise voltageindicator (OK or high)
DET4 SeriesEarth/Ground Resistance & Soil Resistivity TestersOPTIONAL ACCESSORY KITSProfessional KitCat. No. 6320-245Red and black cable reels,164 ft (50 m); yellow andgreen cable reels, 98 ft(30 m); earth electrodeleads, 13 ft (4 m) green;4 mm shrouded plug andlarge croc clip; 4 auger-stylespikes; molded polyethylenecarrying case; fiberglassmeasuring tape, 164 ft (50 m)Each instrument comes complete with three sets of leads, two testspikes, instruction manual CD, and a rugged carrying case, (currentmeasuring clamp, shown, is an optional accessory for performing theART testing capability using the DET4TC2 and DET4TCR2 only.)Soil Resistivity KitCat. No. 250586Set of four test leads, 50ft. (15 m); two pair of 20in. (51 cm) ground rods;padded case to holdinstrument, leads androdsDeluxe Kit,Cat. No. 250581Terminal Adapters are used toallow the DET4 Series units’terminals to accept alternativecable connections.Set of three color-codedtest leads, 25, 50, 100 ft.(8, 15, 30 m); two 20-in.(51 cm) ground rods;padded case to holdinstrument, leads and rodsStandard Kit,Cat. No. 250579Three color-coded testleads, 25, 50, 100 ft.(8, 15, 30 m); two 20-in.(51 cm) ground rods;canvas accessory case forleads and rods onlyStandard KitCat. No. 6310-755Hammer, 2.5 lb (1.13kg); four galvanized steelspikes, 0.5 in. (12 mm);two spike extractors; fourleads in carrying case
DET4 SeriesEarth/Ground Resistance & Soil Resistivity TestersORDERING INFORMATIONItem (Qty)Cat. No.Item (Qty)DET4TD21000-347Standard accessory kit (hammer, spikes, sional ground testing kit(2 x 50m, 2 x 30m,
DET4 Series 4-Terminal Earth/Ground Resistance and Soil Resistivity Testers n 2, 3 and 4 point testing n Stakeless (clamp-on) testing capability n ART (Attached Rod Technique) capability n Multiple, user selectable test frequencies n Resistance measurement range to 200,000 Ω n IP54 rated n Warning indicators prevent test failure n Simple one button operation n Included leads, stakes, calibration
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Ground Resistance Tester Models 3711 and 3731 - 6 - Description The Ground Resistance Tester, Models 3711 and 3731, measure ground rod and small grid resistance through any season, without the use of auxiliary ground rods. Clamp-on ground resistance testers are used in multi-grounded systems without disconnecting the ground under test.
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