Megger DET3 Series, Sales Manual

Page 1: ... Sales guide M Me eg gg ge er r D DE ET T4 4T TC C a an nd d D DE ET T4 4T TC CR R 2 2 3 3 a an nd d 4 4 P Po ol le e E Ea ar rt th h T Te es st te er rs s The latest additions to the DET Earth testing range Providing a solution to every earth testing challenge ...

Page 2: ...T4TC R Verses Fluke 1623 12 DET4TC R Verses Fluke 1625 13 DET4TC R verses Metrel M2124C 14 Appendix A 15 Application Guide 15 The ART of earth electrode testing 15 Just a little aside 16 Megger gets down to earth with ART 16 Don t underestimate the power of ART 18 The problem with Spheres of Influence 19 We all like ART but sometimes it s misunderstood 21 Some resistance to ART 22 The Best Applica...

Page 3: ... ICLAMP and VCLAMP DET4TCR Kit 2 3 4 pole rechargeable earth testers with ART and Stakeless testing complete with ICLAMP and VCLAMP The new DET4 range replaces the complete DET5 4 range which has an intended obsolescence date of 30th June 2007 The complete contractor series of Earth testers can now be summarised by the following chart DET4TC R Selection Chart Where does the name come from D E T 4T...

Page 4: ...novative high quality and comes supplied in a tough hard carry case similar to the instrument carry case The kit consist of the following Four twist in auger style test spikes Four test leads 2 x 50m 2 x 30m o Supplied on four reels with test lead wind in while mounted on test spike feature o Reels have innovative test lead brushing feature to clean while winding in Tape measure Kit part number 63...

Page 5: ...nsive damage to equipment fire or serious injury Lightning strike protection Improve equipment performance by reducing noise levels Static electricity dissipation Prevent dangerously high step or contact voltages present during fault or high load conditions another safety issue o Earth systems require testing both immediately after installation and at regular intervals thereafter as part of a main...

Page 6: ...be repeatable ideal for monitoring the earth electrode condition over time Stakeless measurements made in 4 pole mode allow all test lead resistances to be ignored In summary with the addition of ART and Stakeless testing DET4TC R is an excellent replacement for the DET5 4 The DET4TC R provides real additional benefits to the customer in terms of ease of use and the ability to take measurements in...

Page 7: ...Megger Limited PWS Nov 06 DET4TC R Launch 7 TECHNICAL OVERVIEW ...

Page 8: ...sing ART The classic three terminal test method has a disadvantage namely that the electrode under test must be disconnected from the system it is supposed to protect in the event of a power system fault The reason for this is that the injected test current will take all possible routes to ground and not all of it will necessarily flow through the electrode under test In this case the instrument w...

Page 9: ...sconnect an individual electrode for testing Also there might be insufficient space to perform a classic three terminal resistance measurement The stakeless test method using both VCLAMP and ICLAMP can be used to obtain a measurement for the electrode under test A defined test voltage is injected into the system using the VCLAMP inducing a current I to flow and be measured by the ICLAMP The model ...

Page 10: ...ability ART A With the addition of an ICLAMP the instrument is able to take 3 or 4 pole measurements of earth electrodes without disconnecting them B Saves both time and aggravation having to undo rusted connections No need to shut down supply to ensure safety F Stakeless testing capability A No need to drive test spikes in ground to perform measurement B Allows testing in areas when driving test ...

Page 11: ...P Current measuring clamp and connecting lead VCLAMP Voltage inducing clamp calibration check pcb lead 6220 824 Calibration check box Calibration check pcb 6220 803 Right angled terminal adaptor set 12V vehicle charge lead 6320 245 Professional ground test kit 2x50m 2x30m 4 auger stakes carry case List prices are provided on a separate price list sheet COMPETITOR ANALYSIS Separate full competitor ...

Page 12: ...8 25 or 50V user selectable output voltage a Required in agricultural locations to protect livestock b 1623 is only 48V 9 Ground voltage measurement range 10 Ground current measurement using ICLAMP 11 Easy to use with quick start guide on lid colour coded terminals and clear display 12 Selective ART accuracy a Megger 5 3 dig b Fluke 7 3 dig 13 Superior operating and storage temperature range 14 DE...

Page 13: ...lear display 8 Carry case to keep leads and spikes together with the instrument a Fluke only supply carry case with kit version or as option b Blow moulded carry case make ideal tray for instrument when used on the ground 9 Supplied with free calibration certificate 10 3 Year Warranty Fluke 1625 advantages 1 ART maximum noise current immunity is 3A a DET4TC has 2A immunity 2 Stakeless maximum nois...

Page 14: ...a Required in agricultural locations to protect livestock b M2124C is 40V output only 5 Backlight on display 6 Battery life not specified 7 Battery status indicator a Indication of remaining battery life 8 Temperature specifications a M2124C not specified 9 Ground noise voltage rejection 40V pk to pk a M2124C not specified 10 Ground voltage measurement range Metrel M2124C advantages 1 2 pole DC bo...

Page 15: ... a building s earth wiring This can also involve downtime or reduce the degree of protection to the installation Now Megger has a solution to this problem in the form of A R T the Attached Rod Technique When the earth tester injects a test current into an electrode which is still connected to the system current not only flows down the electrode under test but back into the building s system and do...

Page 16: ... like other earth testers When in the normal 3P mode the DET4TC injects a test current at 128Hz X to C terminals so as not to clash with the generation frequency and its harmonics The voltage measurement is then taken X to P terminals at this frequency therefore enabling the instrument to ignore other currents flowing in the earth system The rest is simply down to ohms law to calculate the resista...

Page 17: ... the instrument In other words the electrode measured can have a resistance up to 20 times that of the total system and still be measured Values higher than 20 times cannot be measured using ART and so you will need to carry out a traditional 3 pole measurement See over leaf Potential Probe P Current Probe C Ground Electrodes Building earth connection s I Total I Ie Ie Ie Ie Ie Test I Total 20 X ...

Page 18: ...ctrode you were trying to test is at least 20 times that Usually enough information to make a decision In addition you can also measure the standing leakage current in each individual electrode The DET4TC with ICLAMP is a flexible addition to your testing toolkit Let s imagine we were trying to measure the resistance of an earth path A above Then using ICLAMP the low current symbol shown above app...

Page 19: ...pheres of Influence However there is another factor to take into account and that is the sphere of influence around the earth electrode s and the buildings earth paths whether it s through water gas pipes or metal framework Consider the following diagram Here the spheres of influence are outside each other resulting in the equivalent circuit shown underneath ART should subject to the 20 1 rule wor...

Page 20: ...ectively we now have earth coupling occurring hence the difference in equivalent circuit The overlap in the spheres of influence introduces additional impedances that make resolving the resistance of the electrode difficult using ART The result will cause either be the clamp low symbol appearing or an unexpectedly high reading If this happens proceed with the traditional 3 pole method with the ele...

Page 21: ...e the earth resistance of the guy line with the clamp around it But the guy lines on this tower are all shorted together The current being measured by ICLAMP is flowing not just to ground at the anchor point but back up the other guy lines and to ground via the tower This means the calculated resistance will be incorrect for the anchor point Always consider where the test current is going to flow ...

Page 22: ...s to the electrode system under test Now the potential measurement is taken at the electrode connection rather than the instrument X terminal The result is the lead resistance is totally ignored The Best Application of ART There are many applications where ART work extremely well These include Field of earth Earth Farms Pole mounted transformers Domestic TT earth electrode systems Single guy lines...

Page 23: ...minals Then clamp both of them around the electrode under test or the cable connected to the electrode and press the test button simple However there are a few simple things to remember The first is that there must be at least 100mm gap between the clamps This is to ensure the field around the clamps do not interfere with each other The result would be incorrect readings Lets take a look at the te...

Page 24: ...allel paths the more parallel paths there are the more accurate the reading becomes With many parallel earth paths the reading will become almost identical to the actual value of the earth electrode being measured Since the measurement is a complete loop another useful feature of this measurement is that the resistance of the cables and all connections are measured So any poor connections will be ...

Page 25: ...quirement to remove these links just clamp the ICLAMP and VCLAMP around the tape or link Incorrect use of Stakeless testing The stakeless method is not unfortunately to coin a phrase miss stakeless As with the ART method test current must go through the earth mass to be able to measure the earth resistance Used incorrectly the method may give misleading results Removable links Jug handles Link rem...

Page 26: ...ication of Stakeless testing There are many applications where Stakeless testing will work extremely well These include Field of earth Earth Farms Pole mounted transformer electrodes Pole mounted transformer guy line when connected to earth system Earthing in Sub station cable cellars o It is often impossible to drive in test stakes so this is an ideal application for Stakeless measurements Single...